check in the original version of dde linux26.

9 files changed, 11090 insertions, 0 deletions

diff --git a/libdde_linux26/lib/src/fs/.svn/all-wcprops b/libdde_linux26/lib/src/fs/.svn/all-wcprops
new file mode 100644
index 00000000..b87b0b35
--- /dev/null
+++ b/libdde_linux26/lib/src/fs/.svn/all-wcprops
@@ -0,0 +1,23 @@
+K 25
+svn:wc:ra_dav:version-url
+V 61
+/repos/tudos/!svn/ver/455/trunk/l4/pkg/dde/linux26/lib/src/fs
+END
+block_dev.c
+K 25
+svn:wc:ra_dav:version-url
+V 73
+/repos/tudos/!svn/ver/455/trunk/l4/pkg/dde/linux26/lib/src/fs/block_dev.c
+END
+buffer.c
+K 25
+svn:wc:ra_dav:version-url
+V 70
+/repos/tudos/!svn/ver/455/trunk/l4/pkg/dde/linux26/lib/src/fs/buffer.c
+END
+char_dev.c
+K 25
+svn:wc:ra_dav:version-url
+V 72
+/repos/tudos/!svn/ver/455/trunk/l4/pkg/dde/linux26/lib/src/fs/char_dev.c
+END
diff --git a/libdde_linux26/lib/src/fs/.svn/entries b/libdde_linux26/lib/src/fs/.svn/entries
new file mode 100644
index 00000000..fa781e75
--- /dev/null
+++ b/libdde_linux26/lib/src/fs/.svn/entries
@@ -0,0 +1,130 @@
+9
+
+dir
+465
+http://svn.tudos.org/repos/tudos/trunk/l4/pkg/dde/linux26/lib/src/fs
+http://svn.tudos.org/repos/tudos
+
+
+
+2009-05-20T14:32:55.606606Z
+455
+l4check
+
+
+svn:special svn:externals svn:needs-lock
+
+
+
+
+
+
+
+
+
+
+
+a704ac0b-3a55-4d43-a2a9-7be6f07c34fb
+
+block_dev.c
+file
+
+
+
+
+2009-11-15T17:17:10.000000Z
+eb568fcd29a19e618484d4b5543c680f
+2009-05-20T14:32:55.606606Z
+455
+l4check
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+33946
+
+buffer.c
+file
+
+
+
+
+2009-11-15T17:17:10.000000Z
+4d9f46822ca7a0a24129334ac2d50dd2
+2009-05-20T14:32:55.606606Z
+455
+l4check
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+92122
+
+char_dev.c
+file
+
+
+
+
+2009-11-15T17:17:10.000000Z
+7dd8da71bba451311d6d91135ae21bf2
+2009-05-20T14:32:55.606606Z
+455
+l4check
+
+
+
+
+
+
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+
+13672
+
diff --git a/libdde_linux26/lib/src/fs/.svn/format b/libdde_linux26/lib/src/fs/.svn/format
new file mode 100644
index 00000000..ec635144
--- /dev/null
+++ b/libdde_linux26/lib/src/fs/.svn/format
@@ -0,0 +1 @@
+9
diff --git a/libdde_linux26/lib/src/fs/.svn/text-base/block_dev.c.svn-base b/libdde_linux26/lib/src/fs/.svn/text-base/block_dev.c.svn-base
new file mode 100644
index 00000000..4c4c2f64
--- /dev/null
+++ b/libdde_linux26/lib/src/fs/.svn/text-base/block_dev.c.svn-base
@@ -0,0 +1,1422 @@
+/*
+ *  linux/fs/block_dev.c
+ *
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ *  Copyright (C) 2001  Andrea Arcangeli <andrea@suse.de> SuSE
+ */
+
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/fcntl.h>
+#include <linux/slab.h>
+#include <linux/kmod.h>
+#include <linux/major.h>
+#include <linux/smp_lock.h>
+#include <linux/device_cgroup.h>
+#include <linux/highmem.h>
+#include <linux/blkdev.h>
+#include <linux/module.h>
+#include <linux/blkpg.h>
+#include <linux/buffer_head.h>
+#include <linux/writeback.h>
+#include <linux/mpage.h>
+#include <linux/mount.h>
+#include <linux/uio.h>
+#include <linux/namei.h>
+#include <linux/log2.h>
+#include <asm/uaccess.h>
+#include "internal.h"
+
+#ifdef DDE_LINUX
+#include "local.h"
+#endif
+
+struct bdev_inode {
+	struct block_device bdev;
+	struct inode vfs_inode;
+};
+
+static const struct address_space_operations def_blk_aops;
+
+static inline struct bdev_inode *BDEV_I(struct inode *inode)
+{
+	return container_of(inode, struct bdev_inode, vfs_inode);
+}
+
+inline struct block_device *I_BDEV(struct inode *inode)
+{
+	return &BDEV_I(inode)->bdev;
+}
+
+EXPORT_SYMBOL(I_BDEV);
+
+static sector_t max_block(struct block_device *bdev)
+{
+	sector_t retval = ~((sector_t)0);
+	loff_t sz = i_size_read(bdev->bd_inode);
+
+	if (sz) {
+		unsigned int size = block_size(bdev);
+		unsigned int sizebits = blksize_bits(size);
+		retval = (sz >> sizebits);
+	}
+	return retval;
+}
+
+/* Kill _all_ buffers and pagecache , dirty or not.. */
+static void kill_bdev(struct block_device *bdev)
+{
+	if (bdev->bd_inode->i_mapping->nrpages == 0)
+		return;
+	invalidate_bh_lrus();
+	truncate_inode_pages(bdev->bd_inode->i_mapping, 0);
+}	
+
+int set_blocksize(struct block_device *bdev, int size)
+{
+	/* Size must be a power of two, and between 512 and PAGE_SIZE */
+	if (size > PAGE_SIZE || size < 512 || !is_power_of_2(size))
+		return -EINVAL;
+
+	/* Size cannot be smaller than the size supported by the device */
+	if (size < bdev_hardsect_size(bdev))
+		return -EINVAL;
+
+	/* Don't change the size if it is same as current */
+	if (bdev->bd_block_size != size) {
+		sync_blockdev(bdev);
+		bdev->bd_block_size = size;
+		bdev->bd_inode->i_blkbits = blksize_bits(size);
+		kill_bdev(bdev);
+	}
+	return 0;
+}
+
+EXPORT_SYMBOL(set_blocksize);
+
+int sb_set_blocksize(struct super_block *sb, int size)
+{
+	if (set_blocksize(sb->s_bdev, size))
+		return 0;
+	/* If we get here, we know size is power of two
+	 * and it's value is between 512 and PAGE_SIZE */
+	sb->s_blocksize = size;
+	sb->s_blocksize_bits = blksize_bits(size);
+	return sb->s_blocksize;
+}
+
+EXPORT_SYMBOL(sb_set_blocksize);
+
+int sb_min_blocksize(struct super_block *sb, int size)
+{
+	int minsize = bdev_hardsect_size(sb->s_bdev);
+	if (size < minsize)
+		size = minsize;
+	return sb_set_blocksize(sb, size);
+}
+
+EXPORT_SYMBOL(sb_min_blocksize);
+
+static int
+blkdev_get_block(struct inode *inode, sector_t iblock,
+		struct buffer_head *bh, int create)
+{
+	if (iblock >= max_block(I_BDEV(inode))) {
+		if (create)
+			return -EIO;
+
+		/*
+		 * for reads, we're just trying to fill a partial page.
+		 * return a hole, they will have to call get_block again
+		 * before they can fill it, and they will get -EIO at that
+		 * time
+		 */
+		return 0;
+	}
+	bh->b_bdev = I_BDEV(inode);
+	bh->b_blocknr = iblock;
+	set_buffer_mapped(bh);
+	return 0;
+}
+
+static int
+blkdev_get_blocks(struct inode *inode, sector_t iblock,
+		struct buffer_head *bh, int create)
+{
+	sector_t end_block = max_block(I_BDEV(inode));
+	unsigned long max_blocks = bh->b_size >> inode->i_blkbits;
+
+	if ((iblock + max_blocks) > end_block) {
+		max_blocks = end_block - iblock;
+		if ((long)max_blocks <= 0) {
+			if (create)
+				return -EIO;	/* write fully beyond EOF */
+			/*
+			 * It is a read which is fully beyond EOF.  We return
+			 * a !buffer_mapped buffer
+			 */
+			max_blocks = 0;
+		}
+	}
+
+	bh->b_bdev = I_BDEV(inode);
+	bh->b_blocknr = iblock;
+	bh->b_size = max_blocks << inode->i_blkbits;
+	if (max_blocks)
+		set_buffer_mapped(bh);
+	return 0;
+}
+
+static ssize_t
+blkdev_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
+			loff_t offset, unsigned long nr_segs)
+{
+	struct file *file = iocb->ki_filp;
+	struct inode *inode = file->f_mapping->host;
+
+#ifndef DDE_LINUX
+	return blockdev_direct_IO_no_locking(rw, iocb, inode, I_BDEV(inode),
+				iov, offset, nr_segs, blkdev_get_blocks, NULL);
+#else
+	WARN_UNIMPL;
+	return 0;
+#endif /* DDE_LINUX */
+}
+
+static int blkdev_writepage(struct page *page, struct writeback_control *wbc)
+{
+	return block_write_full_page(page, blkdev_get_block, wbc);
+}
+
+static int blkdev_readpage(struct file * file, struct page * page)
+{
+	return block_read_full_page(page, blkdev_get_block);
+}
+
+static int blkdev_write_begin(struct file *file, struct address_space *mapping,
+			loff_t pos, unsigned len, unsigned flags,
+			struct page **pagep, void **fsdata)
+{
+	*pagep = NULL;
+	return block_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
+				blkdev_get_block);
+}
+
+static int blkdev_write_end(struct file *file, struct address_space *mapping,
+			loff_t pos, unsigned len, unsigned copied,
+			struct page *page, void *fsdata)
+{
+	int ret;
+	ret = block_write_end(file, mapping, pos, len, copied, page, fsdata);
+
+	unlock_page(page);
+	page_cache_release(page);
+
+	return ret;
+}
+
+/*
+ * private llseek:
+ * for a block special file file->f_path.dentry->d_inode->i_size is zero
+ * so we compute the size by hand (just as in block_read/write above)
+ */
+static loff_t block_llseek(struct file *file, loff_t offset, int origin)
+{
+	struct inode *bd_inode = file->f_mapping->host;
+	loff_t size;
+	loff_t retval;
+
+	mutex_lock(&bd_inode->i_mutex);
+	size = i_size_read(bd_inode);
+
+	switch (origin) {
+		case 2:
+			offset += size;
+			break;
+		case 1:
+			offset += file->f_pos;
+	}
+	retval = -EINVAL;
+	if (offset >= 0 && offset <= size) {
+		if (offset != file->f_pos) {
+			file->f_pos = offset;
+		}
+		retval = offset;
+	}
+	mutex_unlock(&bd_inode->i_mutex);
+	return retval;
+}
+	
+/*
+ *	Filp is never NULL; the only case when ->fsync() is called with
+ *	NULL first argument is nfsd_sync_dir() and that's not a directory.
+ */
+ 
+static int block_fsync(struct file *filp, struct dentry *dentry, int datasync)
+{
+	return sync_blockdev(I_BDEV(filp->f_mapping->host));
+}
+
+/*
+ * pseudo-fs
+ */
+
+static  __cacheline_aligned_in_smp DEFINE_SPINLOCK(bdev_lock);
+static struct kmem_cache * bdev_cachep __read_mostly;
+
+static struct inode *bdev_alloc_inode(struct super_block *sb)
+{
+	struct bdev_inode *ei = kmem_cache_alloc(bdev_cachep, GFP_KERNEL);
+	if (!ei)
+		return NULL;
+	return &ei->vfs_inode;
+}
+
+static void bdev_destroy_inode(struct inode *inode)
+{
+	struct bdev_inode *bdi = BDEV_I(inode);
+
+	bdi->bdev.bd_inode_backing_dev_info = NULL;
+	kmem_cache_free(bdev_cachep, bdi);
+}
+
+static void init_once(void *foo)
+{
+	struct bdev_inode *ei = (struct bdev_inode *) foo;
+	struct block_device *bdev = &ei->bdev;
+
+	memset(bdev, 0, sizeof(*bdev));
+	mutex_init(&bdev->bd_mutex);
+	sema_init(&bdev->bd_mount_sem, 1);
+	INIT_LIST_HEAD(&bdev->bd_inodes);
+	INIT_LIST_HEAD(&bdev->bd_list);
+#ifdef CONFIG_SYSFS
+	INIT_LIST_HEAD(&bdev->bd_holder_list);
+#endif
+	inode_init_once(&ei->vfs_inode);
+	/* Initialize mutex for freeze. */
+	mutex_init(&bdev->bd_fsfreeze_mutex);
+}
+
+static inline void __bd_forget(struct inode *inode)
+{
+	list_del_init(&inode->i_devices);
+	inode->i_bdev = NULL;
+	inode->i_mapping = &inode->i_data;
+}
+
+static void bdev_clear_inode(struct inode *inode)
+{
+	struct block_device *bdev = &BDEV_I(inode)->bdev;
+	struct list_head *p;
+	spin_lock(&bdev_lock);
+	while ( (p = bdev->bd_inodes.next) != &bdev->bd_inodes ) {
+		__bd_forget(list_entry(p, struct inode, i_devices));
+	}
+	list_del_init(&bdev->bd_list);
+	spin_unlock(&bdev_lock);
+}
+
+static const struct super_operations bdev_sops = {
+	.statfs = simple_statfs,
+	.alloc_inode = bdev_alloc_inode,
+	.destroy_inode = bdev_destroy_inode,
+	.drop_inode = generic_delete_inode,
+	.clear_inode = bdev_clear_inode,
+};
+
+static int bd_get_sb(struct file_system_type *fs_type,
+	int flags, const char *dev_name, void *data, struct vfsmount *mnt)
+{
+	return get_sb_pseudo(fs_type, "bdev:", &bdev_sops, 0x62646576, mnt);
+}
+
+static struct file_system_type bd_type = {
+	.name		= "bdev",
+	.get_sb		= bd_get_sb,
+	.kill_sb	= kill_anon_super,
+};
+
+struct super_block *blockdev_superblock __read_mostly;
+
+void __init bdev_cache_init(void)
+{
+	int err;
+	struct vfsmount *bd_mnt;
+
+	bdev_cachep = kmem_cache_create("bdev_cache", sizeof(struct bdev_inode),
+			0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
+				SLAB_MEM_SPREAD|SLAB_PANIC),
+			init_once);
+	err = register_filesystem(&bd_type);
+	if (err)
+		panic("Cannot register bdev pseudo-fs");
+	bd_mnt = kern_mount(&bd_type);
+	if (IS_ERR(bd_mnt))
+		panic("Cannot create bdev pseudo-fs");
+	blockdev_superblock = bd_mnt->mnt_sb;	/* For writeback */
+}
+
+/*
+ * Most likely _very_ bad one - but then it's hardly critical for small
+ * /dev and can be fixed when somebody will need really large one.
+ * Keep in mind that it will be fed through icache hash function too.
+ */
+static inline unsigned long hash(dev_t dev)
+{
+	return MAJOR(dev)+MINOR(dev);
+}
+
+static int bdev_test(struct inode *inode, void *data)
+{
+	return BDEV_I(inode)->bdev.bd_dev == *(dev_t *)data;
+}
+
+static int bdev_set(struct inode *inode, void *data)
+{
+	BDEV_I(inode)->bdev.bd_dev = *(dev_t *)data;
+	return 0;
+}
+
+static LIST_HEAD(all_bdevs);
+
+struct block_device *bdget(dev_t dev)
+{
+	struct block_device *bdev;
+	struct inode *inode;
+
+	printk_all_partitions();
+
+	inode = iget5_locked(blockdev_superblock, hash(dev),
+			bdev_test, bdev_set, &dev);
+
+	if (!inode)
+		return NULL;
+
+	bdev = &BDEV_I(inode)->bdev;
+
+	if (inode->i_state & I_NEW) {
+		bdev->bd_contains = NULL;
+		bdev->bd_inode = inode;
+		bdev->bd_block_size = (1 << inode->i_blkbits);
+		bdev->bd_part_count = 0;
+		bdev->bd_invalidated = 0;
+		inode->i_mode = S_IFBLK;
+		inode->i_rdev = dev;
+		inode->i_bdev = bdev;
+		inode->i_data.a_ops = &def_blk_aops;
+		mapping_set_gfp_mask(&inode->i_data, GFP_USER);
+		inode->i_data.backing_dev_info = &default_backing_dev_info;
+		spin_lock(&bdev_lock);
+		list_add(&bdev->bd_list, &all_bdevs);
+		spin_unlock(&bdev_lock);
+		unlock_new_inode(inode);
+	}
+	return bdev;
+}
+
+EXPORT_SYMBOL(bdget);
+
+long nr_blockdev_pages(void)
+{
+	struct block_device *bdev;
+	long ret = 0;
+	spin_lock(&bdev_lock);
+	list_for_each_entry(bdev, &all_bdevs, bd_list) {
+		ret += bdev->bd_inode->i_mapping->nrpages;
+	}
+	spin_unlock(&bdev_lock);
+	return ret;
+}
+
+void bdput(struct block_device *bdev)
+{
+	iput(bdev->bd_inode);
+}
+
+EXPORT_SYMBOL(bdput);
+ 
+static struct block_device *bd_acquire(struct inode *inode)
+{
+	struct block_device *bdev;
+
+	spin_lock(&bdev_lock);
+	bdev = inode->i_bdev;
+	if (bdev) {
+		atomic_inc(&bdev->bd_inode->i_count);
+		spin_unlock(&bdev_lock);
+		return bdev;
+	}
+	spin_unlock(&bdev_lock);
+
+	bdev = bdget(inode->i_rdev);
+	if (bdev) {
+		spin_lock(&bdev_lock);
+		if (!inode->i_bdev) {
+			/*
+			 * We take an additional bd_inode->i_count for inode,
+			 * and it's released in clear_inode() of inode.
+			 * So, we can access it via ->i_mapping always
+			 * without igrab().
+			 */
+			atomic_inc(&bdev->bd_inode->i_count);
+			inode->i_bdev = bdev;
+			inode->i_mapping = bdev->bd_inode->i_mapping;
+			list_add(&inode->i_devices, &bdev->bd_inodes);
+		}
+		spin_unlock(&bdev_lock);
+	}
+	return bdev;
+}
+
+/* Call when you free inode */
+
+void bd_forget(struct inode *inode)
+{
+	struct block_device *bdev = NULL;
+
+	spin_lock(&bdev_lock);
+	if (inode->i_bdev) {
+		if (!sb_is_blkdev_sb(inode->i_sb))
+			bdev = inode->i_bdev;
+		__bd_forget(inode);
+	}
+	spin_unlock(&bdev_lock);
+
+	if (bdev)
+		iput(bdev->bd_inode);
+}
+
+int bd_claim(struct block_device *bdev, void *holder)
+{
+	int res;
+	spin_lock(&bdev_lock);
+
+	/* first decide result */
+	if (bdev->bd_holder == holder)
+		res = 0;	 /* already a holder */
+	else if (bdev->bd_holder != NULL)
+		res = -EBUSY; 	 /* held by someone else */
+	else if (bdev->bd_contains == bdev)
+		res = 0;  	 /* is a whole device which isn't held */
+
+	else if (bdev->bd_contains->bd_holder == bd_claim)
+		res = 0; 	 /* is a partition of a device that is being partitioned */
+	else if (bdev->bd_contains->bd_holder != NULL)
+		res = -EBUSY;	 /* is a partition of a held device */
+	else
+		res = 0;	 /* is a partition of an un-held device */
+
+	/* now impose change */
+	if (res==0) {
+		/* note that for a whole device bd_holders
+		 * will be incremented twice, and bd_holder will
+		 * be set to bd_claim before being set to holder
+		 */
+		bdev->bd_contains->bd_holders ++;
+		bdev->bd_contains->bd_holder = bd_claim;
+		bdev->bd_holders++;
+		bdev->bd_holder = holder;
+	}
+	spin_unlock(&bdev_lock);
+	return res;
+}
+
+EXPORT_SYMBOL(bd_claim);
+
+void bd_release(struct block_device *bdev)
+{
+	spin_lock(&bdev_lock);
+	if (!--bdev->bd_contains->bd_holders)
+		bdev->bd_contains->bd_holder = NULL;
+	if (!--bdev->bd_holders)
+		bdev->bd_holder = NULL;
+	spin_unlock(&bdev_lock);
+}
+
+EXPORT_SYMBOL(bd_release);
+
+#ifdef CONFIG_SYSFS
+/*
+ * Functions for bd_claim_by_kobject / bd_release_from_kobject
+ *
+ *     If a kobject is passed to bd_claim_by_kobject()
+ *     and the kobject has a parent directory,
+ *     following symlinks are created:
+ *        o from the kobject to the claimed bdev
+ *        o from "holders" directory of the bdev to the parent of the kobject
+ *     bd_release_from_kobject() removes these symlinks.
+ *
+ *     Example:
+ *        If /dev/dm-0 maps to /dev/sda, kobject corresponding to
+ *        /sys/block/dm-0/slaves is passed to bd_claim_by_kobject(), then:
+ *           /sys/block/dm-0/slaves/sda --> /sys/block/sda
+ *           /sys/block/sda/holders/dm-0 --> /sys/block/dm-0
+ */
+
+static int add_symlink(struct kobject *from, struct kobject *to)
+{
+	if (!from || !to)
+		return 0;
+	return sysfs_create_link(from, to, kobject_name(to));
+}
+
+static void del_symlink(struct kobject *from, struct kobject *to)
+{
+	if (!from || !to)
+		return;
+	sysfs_remove_link(from, kobject_name(to));
+}
+
+/*
+ * 'struct bd_holder' contains pointers to kobjects symlinked by
+ * bd_claim_by_kobject.
+ * It's connected to bd_holder_list which is protected by bdev->bd_sem.
+ */
+struct bd_holder {
+	struct list_head list;	/* chain of holders of the bdev */
+	int count;		/* references from the holder */
+	struct kobject *sdir;	/* holder object, e.g. "/block/dm-0/slaves" */
+	struct kobject *hdev;	/* e.g. "/block/dm-0" */
+	struct kobject *hdir;	/* e.g. "/block/sda/holders" */
+	struct kobject *sdev;	/* e.g. "/block/sda" */
+};
+
+/*
+ * Get references of related kobjects at once.
+ * Returns 1 on success. 0 on failure.
+ *
+ * Should call bd_holder_release_dirs() after successful use.
+ */
+static int bd_holder_grab_dirs(struct block_device *bdev,
+			struct bd_holder *bo)
+{
+	if (!bdev || !bo)
+		return 0;
+
+	bo->sdir = kobject_get(bo->sdir);
+	if (!bo->sdir)
+		return 0;
+
+	bo->hdev = kobject_get(bo->sdir->parent);
+	if (!bo->hdev)
+		goto fail_put_sdir;
+
+	bo->sdev = kobject_get(&part_to_dev(bdev->bd_part)->kobj);
+	if (!bo->sdev)
+		goto fail_put_hdev;
+
+	bo->hdir = kobject_get(bdev->bd_part->holder_dir);
+	if (!bo->hdir)
+		goto fail_put_sdev;
+
+	return 1;
+
+fail_put_sdev:
+	kobject_put(bo->sdev);
+fail_put_hdev:
+	kobject_put(bo->hdev);
+fail_put_sdir:
+	kobject_put(bo->sdir);
+
+	return 0;
+}
+
+/* Put references of related kobjects at once. */
+static void bd_holder_release_dirs(struct bd_holder *bo)
+{
+	kobject_put(bo->hdir);
+	kobject_put(bo->sdev);
+	kobject_put(bo->hdev);
+	kobject_put(bo->sdir);
+}
+
+static struct bd_holder *alloc_bd_holder(struct kobject *kobj)
+{
+	struct bd_holder *bo;
+
+	bo = kzalloc(sizeof(*bo), GFP_KERNEL);
+	if (!bo)
+		return NULL;
+
+	bo->count = 1;
+	bo->sdir = kobj;
+
+	return bo;
+}
+
+static void free_bd_holder(struct bd_holder *bo)
+{
+	kfree(bo);
+}
+
+/**
+ * find_bd_holder - find matching struct bd_holder from the block device
+ *
+ * @bdev:	struct block device to be searched
+ * @bo:		target struct bd_holder
+ *
+ * Returns matching entry with @bo in @bdev->bd_holder_list.
+ * If found, increment the reference count and return the pointer.
+ * If not found, returns NULL.
+ */
+static struct bd_holder *find_bd_holder(struct block_device *bdev,
+					struct bd_holder *bo)
+{
+	struct bd_holder *tmp;
+
+	list_for_each_entry(tmp, &bdev->bd_holder_list, list)
+		if (tmp->sdir == bo->sdir) {
+			tmp->count++;
+			return tmp;
+		}
+
+	return NULL;
+}
+
+/**
+ * add_bd_holder - create sysfs symlinks for bd_claim() relationship
+ *
+ * @bdev:	block device to be bd_claimed
+ * @bo:		preallocated and initialized by alloc_bd_holder()
+ *
+ * Add @bo to @bdev->bd_holder_list, create symlinks.
+ *
+ * Returns 0 if symlinks are created.
+ * Returns -ve if something fails.
+ */
+static int add_bd_holder(struct block_device *bdev, struct bd_holder *bo)
+{
+	int err;
+
+	if (!bo)
+		return -EINVAL;
+
+	if (!bd_holder_grab_dirs(bdev, bo))
+		return -EBUSY;
+
+	err = add_symlink(bo->sdir, bo->sdev);
+	if (err)
+		return err;
+
+	err = add_symlink(bo->hdir, bo->hdev);
+	if (err) {
+		del_symlink(bo->sdir, bo->sdev);
+		return err;
+	}
+
+	list_add_tail(&bo->list, &bdev->bd_holder_list);
+	return 0;
+}
+
+/**
+ * del_bd_holder - delete sysfs symlinks for bd_claim() relationship
+ *
+ * @bdev:	block device to be bd_claimed
+ * @kobj:	holder's kobject
+ *
+ * If there is matching entry with @kobj in @bdev->bd_holder_list
+ * and no other bd_claim() from the same kobject,
+ * remove the struct bd_holder from the list, delete symlinks for it.
+ *
+ * Returns a pointer to the struct bd_holder when it's removed from the list
+ * and ready to be freed.
+ * Returns NULL if matching claim isn't found or there is other bd_claim()
+ * by the same kobject.
+ */
+static struct bd_holder *del_bd_holder(struct block_device *bdev,
+					struct kobject *kobj)
+{
+	struct bd_holder *bo;
+
+	list_for_each_entry(bo, &bdev->bd_holder_list, list) {
+		if (bo->sdir == kobj) {
+			bo->count--;
+			BUG_ON(bo->count < 0);
+			if (!bo->count) {
+				list_del(&bo->list);
+				del_symlink(bo->sdir, bo->sdev);
+				del_symlink(bo->hdir, bo->hdev);
+				bd_holder_release_dirs(bo);
+				return bo;
+			}
+			break;
+		}
+	}
+
+	return NULL;
+}
+
+/**
+ * bd_claim_by_kobject - bd_claim() with additional kobject signature
+ *
+ * @bdev:	block device to be claimed
+ * @holder:	holder's signature
+ * @kobj:	holder's kobject
+ *
+ * Do bd_claim() and if it succeeds, create sysfs symlinks between
+ * the bdev and the holder's kobject.
+ * Use bd_release_from_kobject() when relesing the claimed bdev.
+ *
+ * Returns 0 on success. (same as bd_claim())
+ * Returns errno on failure.
+ */
+static int bd_claim_by_kobject(struct block_device *bdev, void *holder,
+				struct kobject *kobj)
+{
+	int err;
+	struct bd_holder *bo, *found;
+
+	if (!kobj)
+		return -EINVAL;
+
+	bo = alloc_bd_holder(kobj);
+	if (!bo)
+		return -ENOMEM;
+
+	mutex_lock(&bdev->bd_mutex);
+
+	err = bd_claim(bdev, holder);
+	if (err)
+		goto fail;
+
+	found = find_bd_holder(bdev, bo);
+	if (found)
+		goto fail;
+
+	err = add_bd_holder(bdev, bo);
+	if (err)
+		bd_release(bdev);
+	else
+		bo = NULL;
+fail:
+	mutex_unlock(&bdev->bd_mutex);
+	free_bd_holder(bo);
+	return err;
+}
+
+/**
+ * bd_release_from_kobject - bd_release() with additional kobject signature
+ *
+ * @bdev:	block device to be released
+ * @kobj:	holder's kobject
+ *
+ * Do bd_release() and remove sysfs symlinks created by bd_claim_by_kobject().
+ */
+static void bd_release_from_kobject(struct block_device *bdev,
+					struct kobject *kobj)
+{
+	if (!kobj)
+		return;
+
+	mutex_lock(&bdev->bd_mutex);
+	bd_release(bdev);
+	free_bd_holder(del_bd_holder(bdev, kobj));
+	mutex_unlock(&bdev->bd_mutex);
+}
+
+/**
+ * bd_claim_by_disk - wrapper function for bd_claim_by_kobject()
+ *
+ * @bdev:	block device to be claimed
+ * @holder:	holder's signature
+ * @disk:	holder's gendisk
+ *
+ * Call bd_claim_by_kobject() with getting @disk->slave_dir.
+ */
+int bd_claim_by_disk(struct block_device *bdev, void *holder,
+			struct gendisk *disk)
+{
+	return bd_claim_by_kobject(bdev, holder, kobject_get(disk->slave_dir));
+}
+EXPORT_SYMBOL_GPL(bd_claim_by_disk);
+
+/**
+ * bd_release_from_disk - wrapper function for bd_release_from_kobject()
+ *
+ * @bdev:	block device to be claimed
+ * @disk:	holder's gendisk
+ *
+ * Call bd_release_from_kobject() and put @disk->slave_dir.
+ */
+void bd_release_from_disk(struct block_device *bdev, struct gendisk *disk)
+{
+	bd_release_from_kobject(bdev, disk->slave_dir);
+	kobject_put(disk->slave_dir);
+}
+EXPORT_SYMBOL_GPL(bd_release_from_disk);
+#endif
+
+/*
+ * Tries to open block device by device number.  Use it ONLY if you
+ * really do not have anything better - i.e. when you are behind a
+ * truly sucky interface and all you are given is a device number.  _Never_
+ * to be used for internal purposes.  If you ever need it - reconsider
+ * your API.
+ */
+struct block_device *open_by_devnum(dev_t dev, fmode_t mode)
+{
+	struct block_device *bdev = bdget(dev);
+	int err = -ENOMEM;
+	if (bdev)
+		err = blkdev_get(bdev, mode);
+	return err ? ERR_PTR(err) : bdev;
+}
+
+EXPORT_SYMBOL(open_by_devnum);
+
+/**
+ * flush_disk - invalidates all buffer-cache entries on a disk
+ *
+ * @bdev:      struct block device to be flushed
+ *
+ * Invalidates all buffer-cache entries on a disk. It should be called
+ * when a disk has been changed -- either by a media change or online
+ * resize.
+ */
+static void flush_disk(struct block_device *bdev)
+{
+	if (__invalidate_device(bdev)) {
+		char name[BDEVNAME_SIZE] = "";
+
+		if (bdev->bd_disk)
+			disk_name(bdev->bd_disk, 0, name);
+		printk(KERN_WARNING "VFS: busy inodes on changed media or "
+		       "resized disk %s\n", name);
+	}
+
+	if (!bdev->bd_disk)
+		return;
+	if (disk_partitionable(bdev->bd_disk))
+		bdev->bd_invalidated = 1;
+}
+
+/**
+ * check_disk_size_change - checks for disk size change and adjusts bdev size.
+ * @disk: struct gendisk to check
+ * @bdev: struct bdev to adjust.
+ *
+ * This routine checks to see if the bdev size does not match the disk size
+ * and adjusts it if it differs.
+ */
+void check_disk_size_change(struct gendisk *disk, struct block_device *bdev)
+{
+	loff_t disk_size, bdev_size;
+
+	disk_size = (loff_t)get_capacity(disk) << 9;
+	bdev_size = i_size_read(bdev->bd_inode);
+	if (disk_size != bdev_size) {
+		char name[BDEVNAME_SIZE];
+
+		disk_name(disk, 0, name);
+		printk(KERN_INFO
+		       "%s: detected capacity change from %lld to %lld\n",
+		       name, bdev_size, disk_size);
+		i_size_write(bdev->bd_inode, disk_size);
+		flush_disk(bdev);
+	}
+}
+EXPORT_SYMBOL(check_disk_size_change);
+
+/**
+ * revalidate_disk - wrapper for lower-level driver's revalidate_disk call-back
+ * @disk: struct gendisk to be revalidated
+ *
+ * This routine is a wrapper for lower-level driver's revalidate_disk
+ * call-backs.  It is used to do common pre and post operations needed
+ * for all revalidate_disk operations.
+ */
+int revalidate_disk(struct gendisk *disk)
+{
+	struct block_device *bdev;
+	int ret = 0;
+
+	if (disk->fops->revalidate_disk)
+		ret = disk->fops->revalidate_disk(disk);
+
+	bdev = bdget_disk(disk, 0);
+	if (!bdev)
+		return ret;
+
+	mutex_lock(&bdev->bd_mutex);
+	check_disk_size_change(disk, bdev);
+	mutex_unlock(&bdev->bd_mutex);
+	bdput(bdev);
+	return ret;
+}
+EXPORT_SYMBOL(revalidate_disk);
+
+/*
+ * This routine checks whether a removable media has been changed,
+ * and invalidates all buffer-cache-entries in that case. This
+ * is a relatively slow routine, so we have to try to minimize using
+ * it. Thus it is called only upon a 'mount' or 'open'. This
+ * is the best way of combining speed and utility, I think.
+ * People changing diskettes in the middle of an operation deserve
+ * to lose :-)
+ */
+int check_disk_change(struct block_device *bdev)
+{
+	struct gendisk *disk = bdev->bd_disk;
+	struct block_device_operations * bdops = disk->fops;
+
+	if (!bdops->media_changed)
+		return 0;
+	if (!bdops->media_changed(bdev->bd_disk))
+		return 0;
+
+	flush_disk(bdev);
+	if (bdops->revalidate_disk)
+		bdops->revalidate_disk(bdev->bd_disk);
+	return 1;
+}
+
+EXPORT_SYMBOL(check_disk_change);
+
+void bd_set_size(struct block_device *bdev, loff_t size)
+{
+	unsigned bsize = bdev_hardsect_size(bdev);
+
+	bdev->bd_inode->i_size = size;
+	while (bsize < PAGE_CACHE_SIZE) {
+		if (size & bsize)
+			break;
+		bsize <<= 1;
+	}
+	bdev->bd_block_size = bsize;
+	bdev->bd_inode->i_blkbits = blksize_bits(bsize);
+}
+EXPORT_SYMBOL(bd_set_size);
+
+static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part);
+
+/*
+ * bd_mutex locking:
+ *
+ *  mutex_lock(part->bd_mutex)
+ *    mutex_lock_nested(whole->bd_mutex, 1)
+ */
+
+static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
+{
+	struct gendisk *disk;
+	int ret;
+	int partno;
+	int perm = 0;
+
+	if (mode & FMODE_READ)
+		perm |= MAY_READ;
+	if (mode & FMODE_WRITE)
+		perm |= MAY_WRITE;
+	/*
+	 * hooks: /n/, see "layering violations".
+	 */
+	ret = devcgroup_inode_permission(bdev->bd_inode, perm);
+	if (ret != 0) {
+		bdput(bdev);
+		return ret;
+	}
+
+	lock_kernel();
+ restart:
+
+	ret = -ENXIO;
+	disk = get_gendisk(bdev->bd_dev, &partno);
+	if (!disk)
+		goto out_unlock_kernel;
+
+	mutex_lock_nested(&bdev->bd_mutex, for_part);
+	if (!bdev->bd_openers) {
+		bdev->bd_disk = disk;
+		bdev->bd_contains = bdev;
+		if (!partno) {
+			struct backing_dev_info *bdi;
+
+			ret = -ENXIO;
+			bdev->bd_part = disk_get_part(disk, partno);
+			if (!bdev->bd_part)
+				goto out_clear;
+
+			if (disk->fops->open) {
+				ret = disk->fops->open(bdev, mode);
+				if (ret == -ERESTARTSYS) {
+					/* Lost a race with 'disk' being
+					 * deleted, try again.
+					 * See md.c
+					 */
+					disk_put_part(bdev->bd_part);
+					bdev->bd_part = NULL;
+					module_put(disk->fops->owner);
+					put_disk(disk);
+					bdev->bd_disk = NULL;
+					mutex_unlock(&bdev->bd_mutex);
+					goto restart;
+				}
+				if (ret)
+					goto out_clear;
+			}
+			if (!bdev->bd_openers) {
+				bd_set_size(bdev,(loff_t)get_capacity(disk)<<9);
+				bdi = blk_get_backing_dev_info(bdev);
+				if (bdi == NULL)
+					bdi = &default_backing_dev_info;
+				bdev->bd_inode->i_data.backing_dev_info = bdi;
+			}
+			if (bdev->bd_invalidated)
+				rescan_partitions(disk, bdev);
+		} else {
+			struct block_device *whole;
+			whole = bdget_disk(disk, 0);
+			ret = -ENOMEM;
+			if (!whole)
+				goto out_clear;
+			BUG_ON(for_part);
+			ret = __blkdev_get(whole, mode, 1);
+			if (ret)
+				goto out_clear;
+			bdev->bd_contains = whole;
+			bdev->bd_inode->i_data.backing_dev_info =
+			   whole->bd_inode->i_data.backing_dev_info;
+			bdev->bd_part = disk_get_part(disk, partno);
+			if (!(disk->flags & GENHD_FL_UP) ||
+			    !bdev->bd_part || !bdev->bd_part->nr_sects) {
+				ret = -ENXIO;
+				goto out_clear;
+			}
+			bd_set_size(bdev, (loff_t)bdev->bd_part->nr_sects << 9);
+		}
+	} else {
+		put_disk(disk);
+		module_put(disk->fops->owner);
+		disk = NULL;
+		if (bdev->bd_contains == bdev) {
+			if (bdev->bd_disk->fops->open) {
+				ret = bdev->bd_disk->fops->open(bdev, mode);
+				if (ret)
+					goto out_unlock_bdev;
+			}
+			if (bdev->bd_invalidated)
+				rescan_partitions(bdev->bd_disk, bdev);
+		}
+	}
+	bdev->bd_openers++;
+	if (for_part)
+		bdev->bd_part_count++;
+	mutex_unlock(&bdev->bd_mutex);
+	unlock_kernel();
+	return 0;
+
+ out_clear:
+	disk_put_part(bdev->bd_part);
+	bdev->bd_disk = NULL;
+	bdev->bd_part = NULL;
+	bdev->bd_inode->i_data.backing_dev_info = &default_backing_dev_info;
+	if (bdev != bdev->bd_contains)
+		__blkdev_put(bdev->bd_contains, mode, 1);
+	bdev->bd_contains = NULL;
+ out_unlock_bdev:
+	mutex_unlock(&bdev->bd_mutex);
+ out_unlock_kernel:
+	unlock_kernel();
+
+	if (disk)
+		module_put(disk->fops->owner);
+	put_disk(disk);
+	bdput(bdev);
+
+	return ret;
+}
+
+int blkdev_get(struct block_device *bdev, fmode_t mode)
+{
+	return __blkdev_get(bdev, mode, 0);
+}
+EXPORT_SYMBOL(blkdev_get);
+
+static int blkdev_open(struct inode * inode, struct file * filp)
+{
+	struct block_device *bdev;
+	int res;
+
+	/*
+	 * Preserve backwards compatibility and allow large file access
+	 * even if userspace doesn't ask for it explicitly. Some mkfs
+	 * binary needs it. We might want to drop this workaround
+	 * during an unstable branch.
+	 */
+	filp->f_flags |= O_LARGEFILE;
+
+	if (filp->f_flags & O_NDELAY)
+		filp->f_mode |= FMODE_NDELAY;
+	if (filp->f_flags & O_EXCL)
+		filp->f_mode |= FMODE_EXCL;
+	if ((filp->f_flags & O_ACCMODE) == 3)
+		filp->f_mode |= FMODE_WRITE_IOCTL;
+
+	bdev = bd_acquire(inode);
+	if (bdev == NULL)
+		return -ENOMEM;
+
+	filp->f_mapping = bdev->bd_inode->i_mapping;
+
+	res = blkdev_get(bdev, filp->f_mode);
+	if (res)
+		return res;
+
+	if (filp->f_mode & FMODE_EXCL) {
+		res = bd_claim(bdev, filp);
+		if (res)
+			goto out_blkdev_put;
+	}
+
+	return 0;
+
+ out_blkdev_put:
+	blkdev_put(bdev, filp->f_mode);
+	return res;
+}
+
+static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
+{
+	int ret = 0;
+	struct gendisk *disk = bdev->bd_disk;
+	struct block_device *victim = NULL;
+
+	mutex_lock_nested(&bdev->bd_mutex, for_part);
+	lock_kernel();
+	if (for_part)
+		bdev->bd_part_count--;
+
+	if (!--bdev->bd_openers) {
+		sync_blockdev(bdev);
+		kill_bdev(bdev);
+	}
+	if (bdev->bd_contains == bdev) {
+		if (disk->fops->release)
+			ret = disk->fops->release(disk, mode);
+	}
+	if (!bdev->bd_openers) {
+		struct module *owner = disk->fops->owner;
+
+		put_disk(disk);
+		module_put(owner);
+		disk_put_part(bdev->bd_part);
+		bdev->bd_part = NULL;
+		bdev->bd_disk = NULL;
+		bdev->bd_inode->i_data.backing_dev_info = &default_backing_dev_info;
+		if (bdev != bdev->bd_contains)
+			victim = bdev->bd_contains;
+		bdev->bd_contains = NULL;
+	}
+	unlock_kernel();
+	mutex_unlock(&bdev->bd_mutex);
+	bdput(bdev);
+	if (victim)
+		__blkdev_put(victim, mode, 1);
+	return ret;
+}
+
+int blkdev_put(struct block_device *bdev, fmode_t mode)
+{
+	return __blkdev_put(bdev, mode, 0);
+}
+EXPORT_SYMBOL(blkdev_put);
+
+static int blkdev_close(struct inode * inode, struct file * filp)
+{
+	struct block_device *bdev = I_BDEV(filp->f_mapping->host);
+	if (bdev->bd_holder == filp)
+		bd_release(bdev);
+	return blkdev_put(bdev, filp->f_mode);
+}
+
+static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
+{
+	struct block_device *bdev = I_BDEV(file->f_mapping->host);
+	fmode_t mode = file->f_mode;
+
+	/*
+	 * O_NDELAY can be altered using fcntl(.., F_SETFL, ..), so we have
+	 * to updated it before every ioctl.
+	 */
+	if (file->f_flags & O_NDELAY)
+		mode |= FMODE_NDELAY;
+	else
+		mode &= ~FMODE_NDELAY;
+
+	return blkdev_ioctl(bdev, mode, cmd, arg);
+}
+
+/*
+ * Try to release a page associated with block device when the system
+ * is under memory pressure.
+ */
+static int blkdev_releasepage(struct page *page, gfp_t wait)
+{
+	struct super_block *super = BDEV_I(page->mapping->host)->bdev.bd_super;
+
+	if (super && super->s_op->bdev_try_to_free_page)
+		return super->s_op->bdev_try_to_free_page(super, page, wait);
+
+	return try_to_free_buffers(page);
+}
+
+static const struct address_space_operations def_blk_aops = {
+	.readpage	= blkdev_readpage,
+	.writepage	= blkdev_writepage,
+	.sync_page	= block_sync_page,
+	.write_begin	= blkdev_write_begin,
+	.write_end	= blkdev_write_end,
+	.writepages	= generic_writepages,
+	.releasepage	= blkdev_releasepage,
+	.direct_IO	= blkdev_direct_IO,
+};
+
+const struct file_operations def_blk_fops = {
+	.open		= blkdev_open,
+	.release	= blkdev_close,
+#ifndef DDE_LINUX
+	.llseek		= block_llseek,
+	.read		= do_sync_read,
+	.write		= do_sync_write,
+  	.aio_read	= generic_file_aio_read,
+  	.aio_write	= generic_file_aio_write_nolock,
+	.mmap		= generic_file_mmap,
+	.fsync		= block_fsync,
+	.unlocked_ioctl	= block_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl	= compat_blkdev_ioctl,
+#endif
+	.splice_read	= generic_file_splice_read,
+	.splice_write	= generic_file_splice_write,
+#endif /* DDE_LINUX */
+};
+
+int ioctl_by_bdev(struct block_device *bdev, unsigned cmd, unsigned long arg)
+{
+	int res;
+	mm_segment_t old_fs = get_fs();
+	set_fs(KERNEL_DS);
+	res = blkdev_ioctl(bdev, 0, cmd, arg);
+	set_fs(old_fs);
+	return res;
+}
+
+EXPORT_SYMBOL(ioctl_by_bdev);
+
+/**
+ * lookup_bdev  - lookup a struct block_device by name
+ * @pathname:	special file representing the block device
+ *
+ * Get a reference to the blockdevice at @pathname in the current
+ * namespace if possible and return it.  Return ERR_PTR(error)
+ * otherwise.
+ */
+struct block_device *lookup_bdev(const char *pathname)
+{
+	struct block_device *bdev;
+	struct inode *inode;
+	struct path path;
+	int error;
+
+	if (!pathname || !*pathname)
+		return ERR_PTR(-EINVAL);
+
+	error = kern_path(pathname, LOOKUP_FOLLOW, &path);
+	if (error)
+		return ERR_PTR(error);
+
+	inode = path.dentry->d_inode;
+	error = -ENOTBLK;
+	if (!S_ISBLK(inode->i_mode))
+		goto fail;
+	error = -EACCES;
+	if (path.mnt->mnt_flags & MNT_NODEV)
+		goto fail;
+	error = -ENOMEM;
+	bdev = bd_acquire(inode);
+	if (!bdev)
+		goto fail;
+out:
+	path_put(&path);
+	return bdev;
+fail:
+	bdev = ERR_PTR(error);
+	goto out;
+}
+EXPORT_SYMBOL(lookup_bdev);
+
+/**
+ * open_bdev_exclusive  -  open a block device by name and set it up for use
+ *
+ * @path:	special file representing the block device
+ * @mode:	FMODE_... combination to pass be used
+ * @holder:	owner for exclusion
+ *
+ * Open the blockdevice described by the special file at @path, claim it
+ * for the @holder.
+ */
+struct block_device *open_bdev_exclusive(const char *path, fmode_t mode, void *holder)
+{
+	struct block_device *bdev;
+	int error = 0;
+
+	bdev = lookup_bdev(path);
+	if (IS_ERR(bdev))
+		return bdev;
+
+	error = blkdev_get(bdev, mode);
+	if (error)
+		return ERR_PTR(error);
+	error = -EACCES;
+	if ((mode & FMODE_WRITE) && bdev_read_only(bdev))
+		goto blkdev_put;
+	error = bd_claim(bdev, holder);
+	if (error)
+		goto blkdev_put;
+
+	return bdev;
+	
+blkdev_put:
+	blkdev_put(bdev, mode);
+	return ERR_PTR(error);
+}
+
+EXPORT_SYMBOL(open_bdev_exclusive);
+
+/**
+ * close_bdev_exclusive  -  close a blockdevice opened by open_bdev_exclusive()
+ *
+ * @bdev:	blockdevice to close
+ * @mode:	mode, must match that used to open.
+ *
+ * This is the counterpart to open_bdev_exclusive().
+ */
+void close_bdev_exclusive(struct block_device *bdev, fmode_t mode)
+{
+	bd_release(bdev);
+	blkdev_put(bdev, mode);
+}
+
+EXPORT_SYMBOL(close_bdev_exclusive);
+
+int __invalidate_device(struct block_device *bdev)
+{
+	struct super_block *sb = get_super(bdev);
+	int res = 0;
+
+	if (sb) {
+		/*
+		 * no need to lock the super, get_super holds the
+		 * read mutex so the filesystem cannot go away
+		 * under us (->put_super runs with the write lock
+		 * hold).
+		 */
+		shrink_dcache_sb(sb);
+		res = invalidate_inodes(sb);
+		drop_super(sb);
+	}
+	invalidate_bdev(bdev);
+	return res;
+}
+EXPORT_SYMBOL(__invalidate_device);
diff --git a/libdde_linux26/lib/src/fs/.svn/text-base/buffer.c.svn-base b/libdde_linux26/lib/src/fs/.svn/text-base/buffer.c.svn-base
new file mode 100644
index 00000000..d3b1c445
--- /dev/null
+++ b/libdde_linux26/lib/src/fs/.svn/text-base/buffer.c.svn-base
@@ -0,0 +1,3474 @@
+/*
+ *  linux/fs/buffer.c
+ *
+ *  Copyright (C) 1991, 1992, 2002  Linus Torvalds
+ */
+
+/*
+ * Start bdflush() with kernel_thread not syscall - Paul Gortmaker, 12/95
+ *
+ * Removed a lot of unnecessary code and simplified things now that
+ * the buffer cache isn't our primary cache - Andrew Tridgell 12/96
+ *
+ * Speed up hash, lru, and free list operations.  Use gfp() for allocating
+ * hash table, use SLAB cache for buffer heads. SMP threading.  -DaveM
+ *
+ * Added 32k buffer block sizes - these are required older ARM systems. - RMK
+ *
+ * async buffer flushing, 1999 Andrea Arcangeli <andrea@suse.de>
+ */
+
+#include <linux/kernel.h>
+#include <linux/syscalls.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/percpu.h>
+#include <linux/slab.h>
+#include <linux/capability.h>
+#include <linux/blkdev.h>
+#include <linux/file.h>
+#include <linux/quotaops.h>
+#include <linux/highmem.h>
+#include <linux/module.h>
+#include <linux/writeback.h>
+#include <linux/hash.h>
+#include <linux/suspend.h>
+#include <linux/buffer_head.h>
+#include <linux/task_io_accounting_ops.h>
+#include <linux/bio.h>
+#include <linux/notifier.h>
+#include <linux/cpu.h>
+#include <linux/bitops.h>
+#include <linux/mpage.h>
+#include <linux/bit_spinlock.h>
+
+static int fsync_buffers_list(spinlock_t *lock, struct list_head *list);
+
+#define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers)
+
+inline void
+init_buffer(struct buffer_head *bh, bh_end_io_t *handler, void *private)
+{
+	bh->b_end_io = handler;
+	bh->b_private = private;
+}
+
+static int sync_buffer(void *word)
+{
+	struct block_device *bd;
+	struct buffer_head *bh
+		= container_of(word, struct buffer_head, b_state);
+
+	smp_mb();
+	bd = bh->b_bdev;
+	if (bd)
+		blk_run_address_space(bd->bd_inode->i_mapping);
+	io_schedule();
+	return 0;
+}
+
+void __lock_buffer(struct buffer_head *bh)
+{
+	wait_on_bit_lock(&bh->b_state, BH_Lock, sync_buffer,
+							TASK_UNINTERRUPTIBLE);
+}
+EXPORT_SYMBOL(__lock_buffer);
+
+void unlock_buffer(struct buffer_head *bh)
+{
+	clear_bit_unlock(BH_Lock, &bh->b_state);
+	smp_mb__after_clear_bit();
+	wake_up_bit(&bh->b_state, BH_Lock);
+}
+
+/*
+ * Block until a buffer comes unlocked.  This doesn't stop it
+ * from becoming locked again - you have to lock it yourself
+ * if you want to preserve its state.
+ */
+void __wait_on_buffer(struct buffer_head * bh)
+{
+	wait_on_bit(&bh->b_state, BH_Lock, sync_buffer, TASK_UNINTERRUPTIBLE);
+}
+
+static void
+__clear_page_buffers(struct page *page)
+{
+	ClearPagePrivate(page);
+	set_page_private(page, 0);
+	page_cache_release(page);
+}
+
+
+static int quiet_error(struct buffer_head *bh)
+{
+	if (!test_bit(BH_Quiet, &bh->b_state) && printk_ratelimit())
+		return 0;
+	return 1;
+}
+
+
+static void buffer_io_error(struct buffer_head *bh)
+{
+	char b[BDEVNAME_SIZE];
+	printk(KERN_ERR "Buffer I/O error on device %s, logical block %Lu\n",
+			bdevname(bh->b_bdev, b),
+			(unsigned long long)bh->b_blocknr);
+}
+
+/*
+ * End-of-IO handler helper function which does not touch the bh after
+ * unlocking it.
+ * Note: unlock_buffer() sort-of does touch the bh after unlocking it, but
+ * a race there is benign: unlock_buffer() only use the bh's address for
+ * hashing after unlocking the buffer, so it doesn't actually touch the bh
+ * itself.
+ */
+static void __end_buffer_read_notouch(struct buffer_head *bh, int uptodate)
+{
+	if (uptodate) {
+		set_buffer_uptodate(bh);
+	} else {
+		/* This happens, due to failed READA attempts. */
+		clear_buffer_uptodate(bh);
+	}
+	unlock_buffer(bh);
+}
+
+/*
+ * Default synchronous end-of-IO handler..  Just mark it up-to-date and
+ * unlock the buffer. This is what ll_rw_block uses too.
+ */
+void end_buffer_read_sync(struct buffer_head *bh, int uptodate)
+{
+	__end_buffer_read_notouch(bh, uptodate);
+	put_bh(bh);
+}
+
+void end_buffer_write_sync(struct buffer_head *bh, int uptodate)
+{
+	char b[BDEVNAME_SIZE];
+
+	if (uptodate) {
+		set_buffer_uptodate(bh);
+	} else {
+		if (!buffer_eopnotsupp(bh) && !quiet_error(bh)) {
+			buffer_io_error(bh);
+			printk(KERN_WARNING "lost page write due to "
+					"I/O error on %s\n",
+				       bdevname(bh->b_bdev, b));
+		}
+		set_buffer_write_io_error(bh);
+		clear_buffer_uptodate(bh);
+	}
+	unlock_buffer(bh);
+	put_bh(bh);
+}
+
+/*
+ * Write out and wait upon all the dirty data associated with a block
+ * device via its mapping.  Does not take the superblock lock.
+ */
+int sync_blockdev(struct block_device *bdev)
+{
+#ifndef DDE_LINUX
+	int ret = 0;
+
+	if (bdev)
+		ret = filemap_write_and_wait(bdev->bd_inode->i_mapping);
+	return ret;
+#else
+	WARN_UNIMPL;
+	return 0;
+#endif /* DDE_LINUX */
+}
+EXPORT_SYMBOL(sync_blockdev);
+
+/*
+ * Write out and wait upon all dirty data associated with this
+ * device.   Filesystem data as well as the underlying block
+ * device.  Takes the superblock lock.
+ */
+int fsync_bdev(struct block_device *bdev)
+{
+#ifndef DDE_LINUX
+	struct super_block *sb = get_super(bdev);
+	if (sb) {
+		int res = fsync_super(sb);
+		drop_super(sb);
+		return res;
+	}
+	return sync_blockdev(bdev);
+#else
+	WARN_UNIMPL;
+	return -1;
+#endif
+}
+
+/**
+ * freeze_bdev  --  lock a filesystem and force it into a consistent state
+ * @bdev:	blockdevice to lock
+ *
+ * This takes the block device bd_mount_sem to make sure no new mounts
+ * happen on bdev until thaw_bdev() is called.
+ * If a superblock is found on this device, we take the s_umount semaphore
+ * on it to make sure nobody unmounts until the snapshot creation is done.
+ * The reference counter (bd_fsfreeze_count) guarantees that only the last
+ * unfreeze process can unfreeze the frozen filesystem actually when multiple
+ * freeze requests arrive simultaneously. It counts up in freeze_bdev() and
+ * count down in thaw_bdev(). When it becomes 0, thaw_bdev() will unfreeze
+ * actually.
+ */
+struct super_block *freeze_bdev(struct block_device *bdev)
+{
+	struct super_block *sb;
+	int error = 0;
+
+	mutex_lock(&bdev->bd_fsfreeze_mutex);
+	if (bdev->bd_fsfreeze_count > 0) {
+		bdev->bd_fsfreeze_count++;
+		sb = get_super(bdev);
+		mutex_unlock(&bdev->bd_fsfreeze_mutex);
+		return sb;
+	}
+	bdev->bd_fsfreeze_count++;
+
+	down(&bdev->bd_mount_sem);
+	sb = get_super(bdev);
+	if (sb && !(sb->s_flags & MS_RDONLY)) {
+		sb->s_frozen = SB_FREEZE_WRITE;
+		smp_wmb();
+
+		__fsync_super(sb);
+
+		sb->s_frozen = SB_FREEZE_TRANS;
+		smp_wmb();
+
+		sync_blockdev(sb->s_bdev);
+
+		if (sb->s_op->freeze_fs) {
+			error = sb->s_op->freeze_fs(sb);
+			if (error) {
+				printk(KERN_ERR
+					"VFS:Filesystem freeze failed\n");
+				sb->s_frozen = SB_UNFROZEN;
+				drop_super(sb);
+				up(&bdev->bd_mount_sem);
+				bdev->bd_fsfreeze_count--;
+				mutex_unlock(&bdev->bd_fsfreeze_mutex);
+				return ERR_PTR(error);
+			}
+		}
+	}
+
+	sync_blockdev(bdev);
+	mutex_unlock(&bdev->bd_fsfreeze_mutex);
+
+	return sb;	/* thaw_bdev releases s->s_umount and bd_mount_sem */
+}
+EXPORT_SYMBOL(freeze_bdev);
+
+/**
+ * thaw_bdev  -- unlock filesystem
+ * @bdev:	blockdevice to unlock
+ * @sb:		associated superblock
+ *
+ * Unlocks the filesystem and marks it writeable again after freeze_bdev().
+ */
+int thaw_bdev(struct block_device *bdev, struct super_block *sb)
+{
+	int error = 0;
+
+	mutex_lock(&bdev->bd_fsfreeze_mutex);
+	if (!bdev->bd_fsfreeze_count) {
+		mutex_unlock(&bdev->bd_fsfreeze_mutex);
+		return -EINVAL;
+	}
+
+	bdev->bd_fsfreeze_count--;
+	if (bdev->bd_fsfreeze_count > 0) {
+		if (sb)
+			drop_super(sb);
+		mutex_unlock(&bdev->bd_fsfreeze_mutex);
+		return 0;
+	}
+
+	if (sb) {
+		BUG_ON(sb->s_bdev != bdev);
+		if (!(sb->s_flags & MS_RDONLY)) {
+			if (sb->s_op->unfreeze_fs) {
+				error = sb->s_op->unfreeze_fs(sb);
+				if (error) {
+					printk(KERN_ERR
+						"VFS:Filesystem thaw failed\n");
+					sb->s_frozen = SB_FREEZE_TRANS;
+					bdev->bd_fsfreeze_count++;
+					mutex_unlock(&bdev->bd_fsfreeze_mutex);
+					return error;
+				}
+			}
+			sb->s_frozen = SB_UNFROZEN;
+			smp_wmb();
+			wake_up(&sb->s_wait_unfrozen);
+		}
+		drop_super(sb);
+	}
+
+	up(&bdev->bd_mount_sem);
+	mutex_unlock(&bdev->bd_fsfreeze_mutex);
+	return 0;
+}
+EXPORT_SYMBOL(thaw_bdev);
+
+/*
+ * Various filesystems appear to want __find_get_block to be non-blocking.
+ * But it's the page lock which protects the buffers.  To get around this,
+ * we get exclusion from try_to_free_buffers with the blockdev mapping's
+ * private_lock.
+ *
+ * Hack idea: for the blockdev mapping, i_bufferlist_lock contention
+ * may be quite high.  This code could TryLock the page, and if that
+ * succeeds, there is no need to take private_lock. (But if
+ * private_lock is contended then so is mapping->tree_lock).
+ */
+static struct buffer_head *
+__find_get_block_slow(struct block_device *bdev, sector_t block)
+{
+	struct inode *bd_inode = bdev->bd_inode;
+	struct address_space *bd_mapping = bd_inode->i_mapping;
+	struct buffer_head *ret = NULL;
+	pgoff_t index;
+	struct buffer_head *bh;
+	struct buffer_head *head;
+	struct page *page;
+	int all_mapped = 1;
+
+	index = block >> (PAGE_CACHE_SHIFT - bd_inode->i_blkbits);
+	page = find_get_page(bd_mapping, index);
+	if (!page)
+		goto out;
+
+	spin_lock(&bd_mapping->private_lock);
+	if (!page_has_buffers(page))
+		goto out_unlock;
+	head = page_buffers(page);
+	bh = head;
+	do {
+		if (bh->b_blocknr == block) {
+			ret = bh;
+			get_bh(bh);
+			goto out_unlock;
+		}
+		if (!buffer_mapped(bh))
+			all_mapped = 0;
+		bh = bh->b_this_page;
+	} while (bh != head);
+
+	/* we might be here because some of the buffers on this page are
+	 * not mapped.  This is due to various races between
+	 * file io on the block device and getblk.  It gets dealt with
+	 * elsewhere, don't buffer_error if we had some unmapped buffers
+	 */
+	if (all_mapped) {
+		printk("__find_get_block_slow() failed. "
+			"block=%llu, b_blocknr=%llu\n",
+			(unsigned long long)block,
+			(unsigned long long)bh->b_blocknr);
+		printk("b_state=0x%08lx, b_size=%zu\n",
+			bh->b_state, bh->b_size);
+		printk("device blocksize: %d\n", 1 << bd_inode->i_blkbits);
+	}
+out_unlock:
+	spin_unlock(&bd_mapping->private_lock);
+	page_cache_release(page);
+out:
+	return ret;
+}
+
+/* If invalidate_buffers() will trash dirty buffers, it means some kind
+   of fs corruption is going on. Trashing dirty data always imply losing
+   information that was supposed to be just stored on the physical layer
+   by the user.
+
+   Thus invalidate_buffers in general usage is not allwowed to trash
+   dirty buffers. For example ioctl(FLSBLKBUF) expects dirty data to
+   be preserved.  These buffers are simply skipped.
+  
+   We also skip buffers which are still in use.  For example this can
+   happen if a userspace program is reading the block device.
+
+   NOTE: In the case where the user removed a removable-media-disk even if
+   there's still dirty data not synced on disk (due a bug in the device driver
+   or due an error of the user), by not destroying the dirty buffers we could
+   generate corruption also on the next media inserted, thus a parameter is
+   necessary to handle this case in the most safe way possible (trying
+   to not corrupt also the new disk inserted with the data belonging to
+   the old now corrupted disk). Also for the ramdisk the natural thing
+   to do in order to release the ramdisk memory is to destroy dirty buffers.
+
+   These are two special cases. Normal usage imply the device driver
+   to issue a sync on the device (without waiting I/O completion) and
+   then an invalidate_buffers call that doesn't trash dirty buffers.
+
+   For handling cache coherency with the blkdev pagecache the 'update' case
+   is been introduced. It is needed to re-read from disk any pinned
+   buffer. NOTE: re-reading from disk is destructive so we can do it only
+   when we assume nobody is changing the buffercache under our I/O and when
+   we think the disk contains more recent information than the buffercache.
+   The update == 1 pass marks the buffers we need to update, the update == 2
+   pass does the actual I/O. */
+void invalidate_bdev(struct block_device *bdev)
+{
+	struct address_space *mapping = bdev->bd_inode->i_mapping;
+
+	if (mapping->nrpages == 0)
+		return;
+
+#ifndef DDE_LINUX
+	invalidate_bh_lrus();
+	invalidate_mapping_pages(mapping, 0, -1);
+#endif
+}
+
+/*
+ * Kick pdflush then try to free up some ZONE_NORMAL memory.
+ */
+static void free_more_memory(void)
+{
+	struct zone *zone;
+	int nid;
+
+#ifndef DDE_LINUX
+	wakeup_pdflush(1024);
+	yield();
+
+	for_each_online_node(nid) {
+		(void)first_zones_zonelist(node_zonelist(nid, GFP_NOFS),
+						gfp_zone(GFP_NOFS), NULL,
+						&zone);
+		if (zone)
+			try_to_free_pages(node_zonelist(nid, GFP_NOFS), 0,
+						GFP_NOFS);
+	}
+#else
+	WARN_UNIMPL;
+#endif
+}
+
+/*
+ * I/O completion handler for block_read_full_page() - pages
+ * which come unlocked at the end of I/O.
+ */
+static void end_buffer_async_read(struct buffer_head *bh, int uptodate)
+{
+	unsigned long flags;
+	struct buffer_head *first;
+	struct buffer_head *tmp;
+	struct page *page;
+	int page_uptodate = 1;
+
+	BUG_ON(!buffer_async_read(bh));
+
+	page = bh->b_page;
+	if (uptodate) {
+		set_buffer_uptodate(bh);
+	} else {
+		clear_buffer_uptodate(bh);
+		if (!quiet_error(bh))
+			buffer_io_error(bh);
+		SetPageError(page);
+	}
+
+	/*
+	 * Be _very_ careful from here on. Bad things can happen if
+	 * two buffer heads end IO at almost the same time and both
+	 * decide that the page is now completely done.
+	 */
+	first = page_buffers(page);
+	local_irq_save(flags);
+	bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
+	clear_buffer_async_read(bh);
+	unlock_buffer(bh);
+	tmp = bh;
+	do {
+		if (!buffer_uptodate(tmp))
+			page_uptodate = 0;
+		if (buffer_async_read(tmp)) {
+			BUG_ON(!buffer_locked(tmp));
+			goto still_busy;
+		}
+		tmp = tmp->b_this_page;
+	} while (tmp != bh);
+	bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
+	local_irq_restore(flags);
+
+	/*
+	 * If none of the buffers had errors and they are all
+	 * uptodate then we can set the page uptodate.
+	 */
+	if (page_uptodate && !PageError(page))
+		SetPageUptodate(page);
+	unlock_page(page);
+	return;
+
+still_busy:
+	bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
+	local_irq_restore(flags);
+	return;
+}
+
+/*
+ * Completion handler for block_write_full_page() - pages which are unlocked
+ * during I/O, and which have PageWriteback cleared upon I/O completion.
+ */
+static void end_buffer_async_write(struct buffer_head *bh, int uptodate)
+{
+	char b[BDEVNAME_SIZE];
+	unsigned long flags;
+	struct buffer_head *first;
+	struct buffer_head *tmp;
+	struct page *page;
+
+	BUG_ON(!buffer_async_write(bh));
+
+	page = bh->b_page;
+	if (uptodate) {
+		set_buffer_uptodate(bh);
+	} else {
+		if (!quiet_error(bh)) {
+			buffer_io_error(bh);
+			printk(KERN_WARNING "lost page write due to "
+					"I/O error on %s\n",
+			       bdevname(bh->b_bdev, b));
+		}
+		set_bit(AS_EIO, &page->mapping->flags);
+		set_buffer_write_io_error(bh);
+		clear_buffer_uptodate(bh);
+		SetPageError(page);
+	}
+
+	first = page_buffers(page);
+	local_irq_save(flags);
+	bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
+
+	clear_buffer_async_write(bh);
+	unlock_buffer(bh);
+	tmp = bh->b_this_page;
+	while (tmp != bh) {
+		if (buffer_async_write(tmp)) {
+			BUG_ON(!buffer_locked(tmp));
+			goto still_busy;
+		}
+		tmp = tmp->b_this_page;
+	}
+	bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
+	local_irq_restore(flags);
+	end_page_writeback(page);
+	return;
+
+still_busy:
+	bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
+	local_irq_restore(flags);
+	return;
+}
+
+/*
+ * If a page's buffers are under async readin (end_buffer_async_read
+ * completion) then there is a possibility that another thread of
+ * control could lock one of the buffers after it has completed
+ * but while some of the other buffers have not completed.  This
+ * locked buffer would confuse end_buffer_async_read() into not unlocking
+ * the page.  So the absence of BH_Async_Read tells end_buffer_async_read()
+ * that this buffer is not under async I/O.
+ *
+ * The page comes unlocked when it has no locked buffer_async buffers
+ * left.
+ *
+ * PageLocked prevents anyone starting new async I/O reads any of
+ * the buffers.
+ *
+ * PageWriteback is used to prevent simultaneous writeout of the same
+ * page.
+ *
+ * PageLocked prevents anyone from starting writeback of a page which is
+ * under read I/O (PageWriteback is only ever set against a locked page).
+ */
+static void mark_buffer_async_read(struct buffer_head *bh)
+{
+	bh->b_end_io = end_buffer_async_read;
+	set_buffer_async_read(bh);
+}
+
+void mark_buffer_async_write(struct buffer_head *bh)
+{
+	bh->b_end_io = end_buffer_async_write;
+	set_buffer_async_write(bh);
+}
+EXPORT_SYMBOL(mark_buffer_async_write);
+
+
+/*
+ * fs/buffer.c contains helper functions for buffer-backed address space's
+ * fsync functions.  A common requirement for buffer-based filesystems is
+ * that certain data from the backing blockdev needs to be written out for
+ * a successful fsync().  For example, ext2 indirect blocks need to be
+ * written back and waited upon before fsync() returns.
+ *
+ * The functions mark_buffer_inode_dirty(), fsync_inode_buffers(),
+ * inode_has_buffers() and invalidate_inode_buffers() are provided for the
+ * management of a list of dependent buffers at ->i_mapping->private_list.
+ *
+ * Locking is a little subtle: try_to_free_buffers() will remove buffers
+ * from their controlling inode's queue when they are being freed.  But
+ * try_to_free_buffers() will be operating against the *blockdev* mapping
+ * at the time, not against the S_ISREG file which depends on those buffers.
+ * So the locking for private_list is via the private_lock in the address_space
+ * which backs the buffers.  Which is different from the address_space 
+ * against which the buffers are listed.  So for a particular address_space,
+ * mapping->private_lock does *not* protect mapping->private_list!  In fact,
+ * mapping->private_list will always be protected by the backing blockdev's
+ * ->private_lock.
+ *
+ * Which introduces a requirement: all buffers on an address_space's
+ * ->private_list must be from the same address_space: the blockdev's.
+ *
+ * address_spaces which do not place buffers at ->private_list via these
+ * utility functions are free to use private_lock and private_list for
+ * whatever they want.  The only requirement is that list_empty(private_list)
+ * be true at clear_inode() time.
+ *
+ * FIXME: clear_inode should not call invalidate_inode_buffers().  The
+ * filesystems should do that.  invalidate_inode_buffers() should just go
+ * BUG_ON(!list_empty).
+ *
+ * FIXME: mark_buffer_dirty_inode() is a data-plane operation.  It should
+ * take an address_space, not an inode.  And it should be called
+ * mark_buffer_dirty_fsync() to clearly define why those buffers are being
+ * queued up.
+ *
+ * FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the
+ * list if it is already on a list.  Because if the buffer is on a list,
+ * it *must* already be on the right one.  If not, the filesystem is being
+ * silly.  This will save a ton of locking.  But first we have to ensure
+ * that buffers are taken *off* the old inode's list when they are freed
+ * (presumably in truncate).  That requires careful auditing of all
+ * filesystems (do it inside bforget()).  It could also be done by bringing
+ * b_inode back.
+ */
+
+/*
+ * The buffer's backing address_space's private_lock must be held
+ */
+static void __remove_assoc_queue(struct buffer_head *bh)
+{
+	list_del_init(&bh->b_assoc_buffers);
+	WARN_ON(!bh->b_assoc_map);
+	if (buffer_write_io_error(bh))
+		set_bit(AS_EIO, &bh->b_assoc_map->flags);
+	bh->b_assoc_map = NULL;
+}
+
+int inode_has_buffers(struct inode *inode)
+{
+	return !list_empty(&inode->i_data.private_list);
+}
+
+/*
+ * osync is designed to support O_SYNC io.  It waits synchronously for
+ * all already-submitted IO to complete, but does not queue any new
+ * writes to the disk.
+ *
+ * To do O_SYNC writes, just queue the buffer writes with ll_rw_block as
+ * you dirty the buffers, and then use osync_inode_buffers to wait for
+ * completion.  Any other dirty buffers which are not yet queued for
+ * write will not be flushed to disk by the osync.
+ */
+static int osync_buffers_list(spinlock_t *lock, struct list_head *list)
+{
+	struct buffer_head *bh;
+	struct list_head *p;
+	int err = 0;
+
+	spin_lock(lock);
+repeat:
+	list_for_each_prev(p, list) {
+		bh = BH_ENTRY(p);
+		if (buffer_locked(bh)) {
+			get_bh(bh);
+			spin_unlock(lock);
+			wait_on_buffer(bh);
+			if (!buffer_uptodate(bh))
+				err = -EIO;
+			brelse(bh);
+			spin_lock(lock);
+			goto repeat;
+		}
+	}
+	spin_unlock(lock);
+	return err;
+}
+
+/**
+ * sync_mapping_buffers - write out & wait upon a mapping's "associated" buffers
+ * @mapping: the mapping which wants those buffers written
+ *
+ * Starts I/O against the buffers at mapping->private_list, and waits upon
+ * that I/O.
+ *
+ * Basically, this is a convenience function for fsync().
+ * @mapping is a file or directory which needs those buffers to be written for
+ * a successful fsync().
+ */
+int sync_mapping_buffers(struct address_space *mapping)
+{
+	struct address_space *buffer_mapping = mapping->assoc_mapping;
+
+	if (buffer_mapping == NULL || list_empty(&mapping->private_list))
+		return 0;
+
+	return fsync_buffers_list(&buffer_mapping->private_lock,
+					&mapping->private_list);
+}
+EXPORT_SYMBOL(sync_mapping_buffers);
+
+/*
+ * Called when we've recently written block `bblock', and it is known that
+ * `bblock' was for a buffer_boundary() buffer.  This means that the block at
+ * `bblock + 1' is probably a dirty indirect block.  Hunt it down and, if it's
+ * dirty, schedule it for IO.  So that indirects merge nicely with their data.
+ */
+void write_boundary_block(struct block_device *bdev,
+			sector_t bblock, unsigned blocksize)
+{
+	struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize);
+	if (bh) {
+		if (buffer_dirty(bh))
+			ll_rw_block(WRITE, 1, &bh);
+		put_bh(bh);
+	}
+}
+
+void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode)
+{
+	struct address_space *mapping = inode->i_mapping;
+	struct address_space *buffer_mapping = bh->b_page->mapping;
+
+	mark_buffer_dirty(bh);
+	if (!mapping->assoc_mapping) {
+		mapping->assoc_mapping = buffer_mapping;
+	} else {
+		BUG_ON(mapping->assoc_mapping != buffer_mapping);
+	}
+	if (!bh->b_assoc_map) {
+		spin_lock(&buffer_mapping->private_lock);
+		list_move_tail(&bh->b_assoc_buffers,
+				&mapping->private_list);
+		bh->b_assoc_map = mapping;
+		spin_unlock(&buffer_mapping->private_lock);
+	}
+}
+EXPORT_SYMBOL(mark_buffer_dirty_inode);
+
+/*
+ * Mark the page dirty, and set it dirty in the radix tree, and mark the inode
+ * dirty.
+ *
+ * If warn is true, then emit a warning if the page is not uptodate and has
+ * not been truncated.
+ */
+static void __set_page_dirty(struct page *page,
+		struct address_space *mapping, int warn)
+{
+	spin_lock_irq(&mapping->tree_lock);
+	if (page->mapping) {	/* Race with truncate? */
+		WARN_ON_ONCE(warn && !PageUptodate(page));
+
+		if (mapping_cap_account_dirty(mapping)) {
+			__inc_zone_page_state(page, NR_FILE_DIRTY);
+			__inc_bdi_stat(mapping->backing_dev_info,
+					BDI_RECLAIMABLE);
+			task_dirty_inc(current);
+			task_io_account_write(PAGE_CACHE_SIZE);
+		}
+		radix_tree_tag_set(&mapping->page_tree,
+				page_index(page), PAGECACHE_TAG_DIRTY);
+	}
+	spin_unlock_irq(&mapping->tree_lock);
+	__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
+}
+
+/*
+ * Add a page to the dirty page list.
+ *
+ * It is a sad fact of life that this function is called from several places
+ * deeply under spinlocking.  It may not sleep.
+ *
+ * If the page has buffers, the uptodate buffers are set dirty, to preserve
+ * dirty-state coherency between the page and the buffers.  It the page does
+ * not have buffers then when they are later attached they will all be set
+ * dirty.
+ *
+ * The buffers are dirtied before the page is dirtied.  There's a small race
+ * window in which a writepage caller may see the page cleanness but not the
+ * buffer dirtiness.  That's fine.  If this code were to set the page dirty
+ * before the buffers, a concurrent writepage caller could clear the page dirty
+ * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean
+ * page on the dirty page list.
+ *
+ * We use private_lock to lock against try_to_free_buffers while using the
+ * page's buffer list.  Also use this to protect against clean buffers being
+ * added to the page after it was set dirty.
+ *
+ * FIXME: may need to call ->reservepage here as well.  That's rather up to the
+ * address_space though.
+ */
+int __set_page_dirty_buffers(struct page *page)
+{
+	int newly_dirty;
+	struct address_space *mapping = page_mapping(page);
+
+	if (unlikely(!mapping))
+		return !TestSetPageDirty(page);
+
+	spin_lock(&mapping->private_lock);
+	if (page_has_buffers(page)) {
+		struct buffer_head *head = page_buffers(page);
+		struct buffer_head *bh = head;
+
+		do {
+			set_buffer_dirty(bh);
+			bh = bh->b_this_page;
+		} while (bh != head);
+	}
+	newly_dirty = !TestSetPageDirty(page);
+	spin_unlock(&mapping->private_lock);
+
+	if (newly_dirty)
+		__set_page_dirty(page, mapping, 1);
+	return newly_dirty;
+}
+EXPORT_SYMBOL(__set_page_dirty_buffers);
+
+/*
+ * Write out and wait upon a list of buffers.
+ *
+ * We have conflicting pressures: we want to make sure that all
+ * initially dirty buffers get waited on, but that any subsequently
+ * dirtied buffers don't.  After all, we don't want fsync to last
+ * forever if somebody is actively writing to the file.
+ *
+ * Do this in two main stages: first we copy dirty buffers to a
+ * temporary inode list, queueing the writes as we go.  Then we clean
+ * up, waiting for those writes to complete.
+ * 
+ * During this second stage, any subsequent updates to the file may end
+ * up refiling the buffer on the original inode's dirty list again, so
+ * there is a chance we will end up with a buffer queued for write but
+ * not yet completed on that list.  So, as a final cleanup we go through
+ * the osync code to catch these locked, dirty buffers without requeuing
+ * any newly dirty buffers for write.
+ */
+static int fsync_buffers_list(spinlock_t *lock, struct list_head *list)
+{
+	struct buffer_head *bh;
+	struct list_head tmp;
+	struct address_space *mapping;
+	int err = 0, err2;
+
+	INIT_LIST_HEAD(&tmp);
+
+	spin_lock(lock);
+	while (!list_empty(list)) {
+		bh = BH_ENTRY(list->next);
+		mapping = bh->b_assoc_map;
+		__remove_assoc_queue(bh);
+		/* Avoid race with mark_buffer_dirty_inode() which does
+		 * a lockless check and we rely on seeing the dirty bit */
+		smp_mb();
+		if (buffer_dirty(bh) || buffer_locked(bh)) {
+			list_add(&bh->b_assoc_buffers, &tmp);
+			bh->b_assoc_map = mapping;
+			if (buffer_dirty(bh)) {
+				get_bh(bh);
+				spin_unlock(lock);
+				/*
+				 * Ensure any pending I/O completes so that
+				 * ll_rw_block() actually writes the current
+				 * contents - it is a noop if I/O is still in
+				 * flight on potentially older contents.
+				 */
+				ll_rw_block(SWRITE_SYNC, 1, &bh);
+				brelse(bh);
+				spin_lock(lock);
+			}
+		}
+	}
+
+	while (!list_empty(&tmp)) {
+		bh = BH_ENTRY(tmp.prev);
+		get_bh(bh);
+		mapping = bh->b_assoc_map;
+		__remove_assoc_queue(bh);
+		/* Avoid race with mark_buffer_dirty_inode() which does
+		 * a lockless check and we rely on seeing the dirty bit */
+		smp_mb();
+		if (buffer_dirty(bh)) {
+			list_add(&bh->b_assoc_buffers,
+				 &mapping->private_list);
+			bh->b_assoc_map = mapping;
+		}
+		spin_unlock(lock);
+		wait_on_buffer(bh);
+		if (!buffer_uptodate(bh))
+			err = -EIO;
+		brelse(bh);
+		spin_lock(lock);
+	}
+	
+	spin_unlock(lock);
+	err2 = osync_buffers_list(lock, list);
+	if (err)
+		return err;
+	else
+		return err2;
+}
+
+/*
+ * Invalidate any and all dirty buffers on a given inode.  We are
+ * probably unmounting the fs, but that doesn't mean we have already
+ * done a sync().  Just drop the buffers from the inode list.
+ *
+ * NOTE: we take the inode's blockdev's mapping's private_lock.  Which
+ * assumes that all the buffers are against the blockdev.  Not true
+ * for reiserfs.
+ */
+void invalidate_inode_buffers(struct inode *inode)
+{
+	if (inode_has_buffers(inode)) {
+		struct address_space *mapping = &inode->i_data;
+		struct list_head *list = &mapping->private_list;
+		struct address_space *buffer_mapping = mapping->assoc_mapping;
+
+		spin_lock(&buffer_mapping->private_lock);
+		while (!list_empty(list))
+			__remove_assoc_queue(BH_ENTRY(list->next));
+		spin_unlock(&buffer_mapping->private_lock);
+	}
+}
+EXPORT_SYMBOL(invalidate_inode_buffers);
+
+/*
+ * Remove any clean buffers from the inode's buffer list.  This is called
+ * when we're trying to free the inode itself.  Those buffers can pin it.
+ *
+ * Returns true if all buffers were removed.
+ */
+int remove_inode_buffers(struct inode *inode)
+{
+	int ret = 1;
+
+	if (inode_has_buffers(inode)) {
+		struct address_space *mapping = &inode->i_data;
+		struct list_head *list = &mapping->private_list;
+		struct address_space *buffer_mapping = mapping->assoc_mapping;
+
+		spin_lock(&buffer_mapping->private_lock);
+		while (!list_empty(list)) {
+			struct buffer_head *bh = BH_ENTRY(list->next);
+			if (buffer_dirty(bh)) {
+				ret = 0;
+				break;
+			}
+			__remove_assoc_queue(bh);
+		}
+		spin_unlock(&buffer_mapping->private_lock);
+	}
+	return ret;
+}
+
+/*
+ * Create the appropriate buffers when given a page for data area and
+ * the size of each buffer.. Use the bh->b_this_page linked list to
+ * follow the buffers created.  Return NULL if unable to create more
+ * buffers.
+ *
+ * The retry flag is used to differentiate async IO (paging, swapping)
+ * which may not fail from ordinary buffer allocations.
+ */
+struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
+		int retry)
+{
+	struct buffer_head *bh, *head;
+	long offset;
+
+try_again:
+	head = NULL;
+	offset = PAGE_SIZE;
+	while ((offset -= size) >= 0) {
+		bh = alloc_buffer_head(GFP_NOFS);
+		if (!bh)
+			goto no_grow;
+
+		bh->b_bdev = NULL;
+		bh->b_this_page = head;
+		bh->b_blocknr = -1;
+		head = bh;
+
+		bh->b_state = 0;
+		atomic_set(&bh->b_count, 0);
+		bh->b_private = NULL;
+		bh->b_size = size;
+
+		/* Link the buffer to its page */
+		set_bh_page(bh, page, offset);
+
+		init_buffer(bh, NULL, NULL);
+	}
+	return head;
+/*
+ * In case anything failed, we just free everything we got.
+ */
+no_grow:
+	if (head) {
+		do {
+			bh = head;
+			head = head->b_this_page;
+			free_buffer_head(bh);
+		} while (head);
+	}
+
+	/*
+	 * Return failure for non-async IO requests.  Async IO requests
+	 * are not allowed to fail, so we have to wait until buffer heads
+	 * become available.  But we don't want tasks sleeping with 
+	 * partially complete buffers, so all were released above.
+	 */
+	if (!retry)
+		return NULL;
+
+	/* We're _really_ low on memory. Now we just
+	 * wait for old buffer heads to become free due to
+	 * finishing IO.  Since this is an async request and
+	 * the reserve list is empty, we're sure there are 
+	 * async buffer heads in use.
+	 */
+	free_more_memory();
+	goto try_again;
+}
+EXPORT_SYMBOL_GPL(alloc_page_buffers);
+
+static inline void
+link_dev_buffers(struct page *page, struct buffer_head *head)
+{
+	struct buffer_head *bh, *tail;
+
+	bh = head;
+	do {
+		tail = bh;
+		bh = bh->b_this_page;
+	} while (bh);
+	tail->b_this_page = head;
+	attach_page_buffers(page, head);
+}
+
+/*
+ * Initialise the state of a blockdev page's buffers.
+ */ 
+static void
+init_page_buffers(struct page *page, struct block_device *bdev,
+			sector_t block, int size)
+{
+	struct buffer_head *head = page_buffers(page);
+	struct buffer_head *bh = head;
+	int uptodate = PageUptodate(page);
+
+	do {
+		if (!buffer_mapped(bh)) {
+			init_buffer(bh, NULL, NULL);
+			bh->b_bdev = bdev;
+			bh->b_blocknr = block;
+			if (uptodate)
+				set_buffer_uptodate(bh);
+			set_buffer_mapped(bh);
+		}
+		block++;
+		bh = bh->b_this_page;
+	} while (bh != head);
+}
+
+/*
+ * Create the page-cache page that contains the requested block.
+ *
+ * This is user purely for blockdev mappings.
+ */
+static struct page *
+grow_dev_page(struct block_device *bdev, sector_t block,
+		pgoff_t index, int size)
+{
+	struct inode *inode = bdev->bd_inode;
+	struct page *page;
+	struct buffer_head *bh;
+
+#ifdef DDE_LINUX
+	WARN_UNIMPL;
+	return NULL;
+#endif
+
+	page = find_or_create_page(inode->i_mapping, index,
+		(mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS)|__GFP_MOVABLE);
+	if (!page)
+		return NULL;
+
+	BUG_ON(!PageLocked(page));
+
+	if (page_has_buffers(page)) {
+		bh = page_buffers(page);
+		if (bh->b_size == size) {
+			init_page_buffers(page, bdev, block, size);
+			return page;
+		}
+		if (!try_to_free_buffers(page))
+			goto failed;
+	}
+
+	/*
+	 * Allocate some buffers for this page
+	 */
+	bh = alloc_page_buffers(page, size, 0);
+	if (!bh)
+		goto failed;
+
+	/*
+	 * Link the page to the buffers and initialise them.  Take the
+	 * lock to be atomic wrt __find_get_block(), which does not
+	 * run under the page lock.
+	 */
+	spin_lock(&inode->i_mapping->private_lock);
+	link_dev_buffers(page, bh);
+	init_page_buffers(page, bdev, block, size);
+	spin_unlock(&inode->i_mapping->private_lock);
+	return page;
+
+failed:
+	BUG();
+	unlock_page(page);
+	page_cache_release(page);
+	return NULL;
+}
+
+/*
+ * Create buffers for the specified block device block's page.  If
+ * that page was dirty, the buffers are set dirty also.
+ */
+static int
+grow_buffers(struct block_device *bdev, sector_t block, int size)
+{
+	struct page *page;
+	pgoff_t index;
+	int sizebits;
+
+	sizebits = -1;
+	do {
+		sizebits++;
+	} while ((size << sizebits) < PAGE_SIZE);
+
+	index = block >> sizebits;
+
+	/*
+	 * Check for a block which wants to lie outside our maximum possible
+	 * pagecache index.  (this comparison is done using sector_t types).
+	 */
+	if (unlikely(index != block >> sizebits)) {
+		char b[BDEVNAME_SIZE];
+
+		printk(KERN_ERR "%s: requested out-of-range block %llu for "
+			"device %s\n",
+			__func__, (unsigned long long)block,
+			bdevname(bdev, b));
+		return -EIO;
+	}
+	block = index << sizebits;
+	/* Create a page with the proper size buffers.. */
+	page = grow_dev_page(bdev, block, index, size);
+	if (!page)
+		return 0;
+	unlock_page(page);
+	page_cache_release(page);
+	return 1;
+}
+
+static struct buffer_head *
+__getblk_slow(struct block_device *bdev, sector_t block, int size)
+{
+	/* Size must be multiple of hard sectorsize */
+	if (unlikely(size & (bdev_hardsect_size(bdev)-1) ||
+			(size < 512 || size > PAGE_SIZE))) {
+		printk(KERN_ERR "getblk(): invalid block size %d requested\n",
+					size);
+		printk(KERN_ERR "hardsect size: %d\n",
+					bdev_hardsect_size(bdev));
+
+		dump_stack();
+		return NULL;
+	}
+
+	for (;;) {
+		struct buffer_head * bh;
+		int ret;
+
+		bh = __find_get_block(bdev, block, size);
+		if (bh)
+			return bh;
+
+		ret = grow_buffers(bdev, block, size);
+		if (ret < 0)
+			return NULL;
+		if (ret == 0)
+			free_more_memory();
+	}
+}
+
+/*
+ * The relationship between dirty buffers and dirty pages:
+ *
+ * Whenever a page has any dirty buffers, the page's dirty bit is set, and
+ * the page is tagged dirty in its radix tree.
+ *
+ * At all times, the dirtiness of the buffers represents the dirtiness of
+ * subsections of the page.  If the page has buffers, the page dirty bit is
+ * merely a hint about the true dirty state.
+ *
+ * When a page is set dirty in its entirety, all its buffers are marked dirty
+ * (if the page has buffers).
+ *
+ * When a buffer is marked dirty, its page is dirtied, but the page's other
+ * buffers are not.
+ *
+ * Also.  When blockdev buffers are explicitly read with bread(), they
+ * individually become uptodate.  But their backing page remains not
+ * uptodate - even if all of its buffers are uptodate.  A subsequent
+ * block_read_full_page() against that page will discover all the uptodate
+ * buffers, will set the page uptodate and will perform no I/O.
+ */
+
+/**
+ * mark_buffer_dirty - mark a buffer_head as needing writeout
+ * @bh: the buffer_head to mark dirty
+ *
+ * mark_buffer_dirty() will set the dirty bit against the buffer, then set its
+ * backing page dirty, then tag the page as dirty in its address_space's radix
+ * tree and then attach the address_space's inode to its superblock's dirty
+ * inode list.
+ *
+ * mark_buffer_dirty() is atomic.  It takes bh->b_page->mapping->private_lock,
+ * mapping->tree_lock and the global inode_lock.
+ */
+void mark_buffer_dirty(struct buffer_head *bh)
+{
+#ifndef DDE_LINUX
+	WARN_ON_ONCE(!buffer_uptodate(bh));
+
+	/*
+	 * Very *carefully* optimize the it-is-already-dirty case.
+	 *
+	 * Don't let the final "is it dirty" escape to before we
+	 * perhaps modified the buffer.
+	 */
+	if (buffer_dirty(bh)) {
+		smp_mb();
+		if (buffer_dirty(bh))
+			return;
+	}
+
+	if (!test_set_buffer_dirty(bh)) {
+		struct page *page = bh->b_page;
+		if (!TestSetPageDirty(page))
+			__set_page_dirty(page, page_mapping(page), 0);
+	}
+#else
+	WARN_UNIMPL;
+#endif
+}
+
+/*
+ * Decrement a buffer_head's reference count.  If all buffers against a page
+ * have zero reference count, are clean and unlocked, and if the page is clean
+ * and unlocked then try_to_free_buffers() may strip the buffers from the page
+ * in preparation for freeing it (sometimes, rarely, buffers are removed from
+ * a page but it ends up not being freed, and buffers may later be reattached).
+ */
+void __brelse(struct buffer_head * buf)
+{
+	if (atomic_read(&buf->b_count)) {
+		put_bh(buf);
+		return;
+	}
+	WARN(1, KERN_ERR "VFS: brelse: Trying to free free buffer\n");
+}
+
+/*
+ * bforget() is like brelse(), except it discards any
+ * potentially dirty data.
+ */
+void __bforget(struct buffer_head *bh)
+{
+	clear_buffer_dirty(bh);
+	if (bh->b_assoc_map) {
+		struct address_space *buffer_mapping = bh->b_page->mapping;
+
+		spin_lock(&buffer_mapping->private_lock);
+		list_del_init(&bh->b_assoc_buffers);
+		bh->b_assoc_map = NULL;
+		spin_unlock(&buffer_mapping->private_lock);
+	}
+	__brelse(bh);
+}
+
+static struct buffer_head *__bread_slow(struct buffer_head *bh)
+{
+	lock_buffer(bh);
+	if (buffer_uptodate(bh)) {
+		unlock_buffer(bh);
+		return bh;
+	} else {
+		get_bh(bh);
+		bh->b_end_io = end_buffer_read_sync;
+		submit_bh(READ, bh);
+		wait_on_buffer(bh);
+		if (buffer_uptodate(bh))
+			return bh;
+	}
+	brelse(bh);
+	return NULL;
+}
+
+/*
+ * Per-cpu buffer LRU implementation.  To reduce the cost of __find_get_block().
+ * The bhs[] array is sorted - newest buffer is at bhs[0].  Buffers have their
+ * refcount elevated by one when they're in an LRU.  A buffer can only appear
+ * once in a particular CPU's LRU.  A single buffer can be present in multiple
+ * CPU's LRUs at the same time.
+ *
+ * This is a transparent caching front-end to sb_bread(), sb_getblk() and
+ * sb_find_get_block().
+ *
+ * The LRUs themselves only need locking against invalidate_bh_lrus.  We use
+ * a local interrupt disable for that.
+ */
+
+#define BH_LRU_SIZE	8
+
+struct bh_lru {
+	struct buffer_head *bhs[BH_LRU_SIZE];
+};
+
+static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }};
+
+#ifdef CONFIG_SMP
+#define bh_lru_lock()	local_irq_disable()
+#define bh_lru_unlock()	local_irq_enable()
+#else
+#define bh_lru_lock()	preempt_disable()
+#define bh_lru_unlock()	preempt_enable()
+#endif
+
+static inline void check_irqs_on(void)
+{
+#ifdef irqs_disabled
+	BUG_ON(irqs_disabled());
+#endif
+}
+
+/*
+ * The LRU management algorithm is dopey-but-simple.  Sorry.
+ */
+static void bh_lru_install(struct buffer_head *bh)
+{
+	struct buffer_head *evictee = NULL;
+	struct bh_lru *lru;
+
+	check_irqs_on();
+	bh_lru_lock();
+	lru = &__get_cpu_var(bh_lrus);
+	if (lru->bhs[0] != bh) {
+		struct buffer_head *bhs[BH_LRU_SIZE];
+		int in;
+		int out = 0;
+
+		get_bh(bh);
+		bhs[out++] = bh;
+		for (in = 0; in < BH_LRU_SIZE; in++) {
+			struct buffer_head *bh2 = lru->bhs[in];
+
+			if (bh2 == bh) {
+				__brelse(bh2);
+			} else {
+				if (out >= BH_LRU_SIZE) {
+					BUG_ON(evictee != NULL);
+					evictee = bh2;
+				} else {
+					bhs[out++] = bh2;
+				}
+			}
+		}
+		while (out < BH_LRU_SIZE)
+			bhs[out++] = NULL;
+		memcpy(lru->bhs, bhs, sizeof(bhs));
+	}
+	bh_lru_unlock();
+
+	if (evictee)
+		__brelse(evictee);
+}
+
+/*
+ * Look up the bh in this cpu's LRU.  If it's there, move it to the head.
+ */
+static struct buffer_head *
+lookup_bh_lru(struct block_device *bdev, sector_t block, unsigned size)
+{
+	struct buffer_head *ret = NULL;
+	struct bh_lru *lru;
+	unsigned int i;
+
+	check_irqs_on();
+	bh_lru_lock();
+	lru = &__get_cpu_var(bh_lrus);
+	for (i = 0; i < BH_LRU_SIZE; i++) {
+		struct buffer_head *bh = lru->bhs[i];
+
+		if (bh && bh->b_bdev == bdev &&
+				bh->b_blocknr == block && bh->b_size == size) {
+			if (i) {
+				while (i) {
+					lru->bhs[i] = lru->bhs[i - 1];
+					i--;
+				}
+				lru->bhs[0] = bh;
+			}
+			get_bh(bh);
+			ret = bh;
+			break;
+		}
+	}
+	bh_lru_unlock();
+	return ret;
+}
+
+/*
+ * Perform a pagecache lookup for the matching buffer.  If it's there, refresh
+ * it in the LRU and mark it as accessed.  If it is not present then return
+ * NULL
+ */
+struct buffer_head *
+__find_get_block(struct block_device *bdev, sector_t block, unsigned size)
+{
+	struct buffer_head *bh = lookup_bh_lru(bdev, block, size);
+
+	if (bh == NULL) {
+		bh = __find_get_block_slow(bdev, block);
+		if (bh)
+			bh_lru_install(bh);
+	}
+	if (bh)
+		touch_buffer(bh);
+	return bh;
+}
+EXPORT_SYMBOL(__find_get_block);
+
+/*
+ * __getblk will locate (and, if necessary, create) the buffer_head
+ * which corresponds to the passed block_device, block and size. The
+ * returned buffer has its reference count incremented.
+ *
+ * __getblk() cannot fail - it just keeps trying.  If you pass it an
+ * illegal block number, __getblk() will happily return a buffer_head
+ * which represents the non-existent block.  Very weird.
+ *
+ * __getblk() will lock up the machine if grow_dev_page's try_to_free_buffers()
+ * attempt is failing.  FIXME, perhaps?
+ */
+struct buffer_head *
+__getblk(struct block_device *bdev, sector_t block, unsigned size)
+{
+	struct buffer_head *bh = __find_get_block(bdev, block, size);
+
+	might_sleep();
+	if (bh == NULL)
+		bh = __getblk_slow(bdev, block, size);
+	return bh;
+}
+EXPORT_SYMBOL(__getblk);
+
+/*
+ * Do async read-ahead on a buffer..
+ */
+void __breadahead(struct block_device *bdev, sector_t block, unsigned size)
+{
+	struct buffer_head *bh = __getblk(bdev, block, size);
+	if (likely(bh)) {
+		ll_rw_block(READA, 1, &bh);
+		brelse(bh);
+	}
+}
+EXPORT_SYMBOL(__breadahead);
+
+/**
+ *  __bread() - reads a specified block and returns the bh
+ *  @bdev: the block_device to read from
+ *  @block: number of block
+ *  @size: size (in bytes) to read
+ * 
+ *  Reads a specified block, and returns buffer head that contains it.
+ *  It returns NULL if the block was unreadable.
+ */
+struct buffer_head *
+__bread(struct block_device *bdev, sector_t block, unsigned size)
+{
+	struct buffer_head *bh = __getblk(bdev, block, size);
+
+	if (likely(bh) && !buffer_uptodate(bh))
+		bh = __bread_slow(bh);
+	return bh;
+}
+EXPORT_SYMBOL(__bread);
+
+/*
+ * invalidate_bh_lrus() is called rarely - but not only at unmount.
+ * This doesn't race because it runs in each cpu either in irq
+ * or with preempt disabled.
+ */
+static void invalidate_bh_lru(void *arg)
+{
+	struct bh_lru *b = &get_cpu_var(bh_lrus);
+	int i;
+
+	for (i = 0; i < BH_LRU_SIZE; i++) {
+		brelse(b->bhs[i]);
+		b->bhs[i] = NULL;
+	}
+	put_cpu_var(bh_lrus);
+}
+	
+void invalidate_bh_lrus(void)
+{
+#ifndef DDE_LINUX
+	on_each_cpu(invalidate_bh_lru, NULL, 1);
+#endif
+}
+EXPORT_SYMBOL_GPL(invalidate_bh_lrus);
+
+void set_bh_page(struct buffer_head *bh,
+		struct page *page, unsigned long offset)
+{
+	bh->b_page = page;
+	BUG_ON(offset >= PAGE_SIZE);
+	if (PageHighMem(page))
+		/*
+		 * This catches illegal uses and preserves the offset:
+		 */
+		bh->b_data = (char *)(0 + offset);
+	else
+		bh->b_data = page_address(page) + offset;
+}
+EXPORT_SYMBOL(set_bh_page);
+
+/*
+ * Called when truncating a buffer on a page completely.
+ */
+static void discard_buffer(struct buffer_head * bh)
+{
+	lock_buffer(bh);
+	clear_buffer_dirty(bh);
+	bh->b_bdev = NULL;
+	clear_buffer_mapped(bh);
+	clear_buffer_req(bh);
+	clear_buffer_new(bh);
+	clear_buffer_delay(bh);
+	clear_buffer_unwritten(bh);
+	unlock_buffer(bh);
+}
+
+/**
+ * block_invalidatepage - invalidate part of all of a buffer-backed page
+ *
+ * @page: the page which is affected
+ * @offset: the index of the truncation point
+ *
+ * block_invalidatepage() is called when all or part of the page has become
+ * invalidatedby a truncate operation.
+ *
+ * block_invalidatepage() does not have to release all buffers, but it must
+ * ensure that no dirty buffer is left outside @offset and that no I/O
+ * is underway against any of the blocks which are outside the truncation
+ * point.  Because the caller is about to free (and possibly reuse) those
+ * blocks on-disk.
+ */
+void block_invalidatepage(struct page *page, unsigned long offset)
+{
+	struct buffer_head *head, *bh, *next;
+	unsigned int curr_off = 0;
+
+	BUG_ON(!PageLocked(page));
+	if (!page_has_buffers(page))
+		goto out;
+
+	head = page_buffers(page);
+	bh = head;
+	do {
+		unsigned int next_off = curr_off + bh->b_size;
+		next = bh->b_this_page;
+
+		/*
+		 * is this block fully invalidated?
+		 */
+		if (offset <= curr_off)
+			discard_buffer(bh);
+		curr_off = next_off;
+		bh = next;
+	} while (bh != head);
+
+	/*
+	 * We release buffers only if the entire page is being invalidated.
+	 * The get_block cached value has been unconditionally invalidated,
+	 * so real IO is not possible anymore.
+	 */
+	if (offset == 0)
+		try_to_release_page(page, 0);
+out:
+	return;
+}
+EXPORT_SYMBOL(block_invalidatepage);
+
+/*
+ * We attach and possibly dirty the buffers atomically wrt
+ * __set_page_dirty_buffers() via private_lock.  try_to_free_buffers
+ * is already excluded via the page lock.
+ */
+void create_empty_buffers(struct page *page,
+			unsigned long blocksize, unsigned long b_state)
+{
+	struct buffer_head *bh, *head, *tail;
+
+	head = alloc_page_buffers(page, blocksize, 1);
+	bh = head;
+	do {
+		bh->b_state |= b_state;
+		tail = bh;
+		bh = bh->b_this_page;
+	} while (bh);
+	tail->b_this_page = head;
+
+	spin_lock(&page->mapping->private_lock);
+	if (PageUptodate(page) || PageDirty(page)) {
+		bh = head;
+		do {
+			if (PageDirty(page))
+				set_buffer_dirty(bh);
+			if (PageUptodate(page))
+				set_buffer_uptodate(bh);
+			bh = bh->b_this_page;
+		} while (bh != head);
+	}
+	attach_page_buffers(page, head);
+	spin_unlock(&page->mapping->private_lock);
+}
+EXPORT_SYMBOL(create_empty_buffers);
+
+/*
+ * We are taking a block for data and we don't want any output from any
+ * buffer-cache aliases starting from return from that function and
+ * until the moment when something will explicitly mark the buffer
+ * dirty (hopefully that will not happen until we will free that block ;-)
+ * We don't even need to mark it not-uptodate - nobody can expect
+ * anything from a newly allocated buffer anyway. We used to used
+ * unmap_buffer() for such invalidation, but that was wrong. We definitely
+ * don't want to mark the alias unmapped, for example - it would confuse
+ * anyone who might pick it with bread() afterwards...
+ *
+ * Also..  Note that bforget() doesn't lock the buffer.  So there can
+ * be writeout I/O going on against recently-freed buffers.  We don't
+ * wait on that I/O in bforget() - it's more efficient to wait on the I/O
+ * only if we really need to.  That happens here.
+ */
+void unmap_underlying_metadata(struct block_device *bdev, sector_t block)
+{
+	struct buffer_head *old_bh;
+
+	might_sleep();
+
+	old_bh = __find_get_block_slow(bdev, block);
+	if (old_bh) {
+		clear_buffer_dirty(old_bh);
+		wait_on_buffer(old_bh);
+		clear_buffer_req(old_bh);
+		__brelse(old_bh);
+	}
+}
+EXPORT_SYMBOL(unmap_underlying_metadata);
+
+/*
+ * NOTE! All mapped/uptodate combinations are valid:
+ *
+ *	Mapped	Uptodate	Meaning
+ *
+ *	No	No		"unknown" - must do get_block()
+ *	No	Yes		"hole" - zero-filled
+ *	Yes	No		"allocated" - allocated on disk, not read in
+ *	Yes	Yes		"valid" - allocated and up-to-date in memory.
+ *
+ * "Dirty" is valid only with the last case (mapped+uptodate).
+ */
+
+/*
+ * While block_write_full_page is writing back the dirty buffers under
+ * the page lock, whoever dirtied the buffers may decide to clean them
+ * again at any time.  We handle that by only looking at the buffer
+ * state inside lock_buffer().
+ *
+ * If block_write_full_page() is called for regular writeback
+ * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a
+ * locked buffer.   This only can happen if someone has written the buffer
+ * directly, with submit_bh().  At the address_space level PageWriteback
+ * prevents this contention from occurring.
+ */
+static int __block_write_full_page(struct inode *inode, struct page *page,
+			get_block_t *get_block, struct writeback_control *wbc)
+{
+	int err;
+	sector_t block;
+	sector_t last_block;
+	struct buffer_head *bh, *head;
+	const unsigned blocksize = 1 << inode->i_blkbits;
+	int nr_underway = 0;
+
+	BUG_ON(!PageLocked(page));
+
+	last_block = (i_size_read(inode) - 1) >> inode->i_blkbits;
+
+	if (!page_has_buffers(page)) {
+		create_empty_buffers(page, blocksize,
+					(1 << BH_Dirty)|(1 << BH_Uptodate));
+	}
+
+	/*
+	 * Be very careful.  We have no exclusion from __set_page_dirty_buffers
+	 * here, and the (potentially unmapped) buffers may become dirty at
+	 * any time.  If a buffer becomes dirty here after we've inspected it
+	 * then we just miss that fact, and the page stays dirty.
+	 *
+	 * Buffers outside i_size may be dirtied by __set_page_dirty_buffers;
+	 * handle that here by just cleaning them.
+	 */
+
+	block = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
+	head = page_buffers(page);
+	bh = head;
+
+	/*
+	 * Get all the dirty buffers mapped to disk addresses and
+	 * handle any aliases from the underlying blockdev's mapping.
+	 */
+	do {
+		if (block > last_block) {
+			/*
+			 * mapped buffers outside i_size will occur, because
+			 * this page can be outside i_size when there is a
+			 * truncate in progress.
+			 */
+			/*
+			 * The buffer was zeroed by block_write_full_page()
+			 */
+			clear_buffer_dirty(bh);
+			set_buffer_uptodate(bh);
+		} else if ((!buffer_mapped(bh) || buffer_delay(bh)) &&
+			   buffer_dirty(bh)) {
+			WARN_ON(bh->b_size != blocksize);
+			err = get_block(inode, block, bh, 1);
+			if (err)
+				goto recover;
+			clear_buffer_delay(bh);
+			if (buffer_new(bh)) {
+				/* blockdev mappings never come here */
+				clear_buffer_new(bh);
+				unmap_underlying_metadata(bh->b_bdev,
+							bh->b_blocknr);
+			}
+		}
+		bh = bh->b_this_page;
+		block++;
+	} while (bh != head);
+
+	do {
+		if (!buffer_mapped(bh))
+			continue;
+		/*
+		 * If it's a fully non-blocking write attempt and we cannot
+		 * lock the buffer then redirty the page.  Note that this can
+		 * potentially cause a busy-wait loop from pdflush and kswapd
+		 * activity, but those code paths have their own higher-level
+		 * throttling.
+		 */
+		if (wbc->sync_mode != WB_SYNC_NONE || !wbc->nonblocking) {
+			lock_buffer(bh);
+		} else if (!trylock_buffer(bh)) {
+			redirty_page_for_writepage(wbc, page);
+			continue;
+		}
+		if (test_clear_buffer_dirty(bh)) {
+			mark_buffer_async_write(bh);
+		} else {
+			unlock_buffer(bh);
+		}
+	} while ((bh = bh->b_this_page) != head);
+
+	/*
+	 * The page and its buffers are protected by PageWriteback(), so we can
+	 * drop the bh refcounts early.
+	 */
+	BUG_ON(PageWriteback(page));
+	set_page_writeback(page);
+
+	do {
+		struct buffer_head *next = bh->b_this_page;
+		if (buffer_async_write(bh)) {
+			submit_bh(WRITE, bh);
+			nr_underway++;
+		}
+		bh = next;
+	} while (bh != head);
+	unlock_page(page);
+
+	err = 0;
+done:
+	if (nr_underway == 0) {
+		/*
+		 * The page was marked dirty, but the buffers were
+		 * clean.  Someone wrote them back by hand with
+		 * ll_rw_block/submit_bh.  A rare case.
+		 */
+		end_page_writeback(page);
+
+		/*
+		 * The page and buffer_heads can be released at any time from
+		 * here on.
+		 */
+	}
+	return err;
+
+recover:
+	/*
+	 * ENOSPC, or some other error.  We may already have added some
+	 * blocks to the file, so we need to write these out to avoid
+	 * exposing stale data.
+	 * The page is currently locked and not marked for writeback
+	 */
+	bh = head;
+	/* Recovery: lock and submit the mapped buffers */
+	do {
+		if (buffer_mapped(bh) && buffer_dirty(bh) &&
+		    !buffer_delay(bh)) {
+			lock_buffer(bh);
+			mark_buffer_async_write(bh);
+		} else {
+			/*
+			 * The buffer may have been set dirty during
+			 * attachment to a dirty page.
+			 */
+			clear_buffer_dirty(bh);
+		}
+	} while ((bh = bh->b_this_page) != head);
+	SetPageError(page);
+	BUG_ON(PageWriteback(page));
+	mapping_set_error(page->mapping, err);
+	set_page_writeback(page);
+	do {
+		struct buffer_head *next = bh->b_this_page;
+		if (buffer_async_write(bh)) {
+			clear_buffer_dirty(bh);
+			submit_bh(WRITE, bh);
+			nr_underway++;
+		}
+		bh = next;
+	} while (bh != head);
+	unlock_page(page);
+	goto done;
+}
+
+/*
+ * If a page has any new buffers, zero them out here, and mark them uptodate
+ * and dirty so they'll be written out (in order to prevent uninitialised
+ * block data from leaking). And clear the new bit.
+ */
+void page_zero_new_buffers(struct page *page, unsigned from, unsigned to)
+{
+	unsigned int block_start, block_end;
+	struct buffer_head *head, *bh;
+
+	BUG_ON(!PageLocked(page));
+	if (!page_has_buffers(page))
+		return;
+
+	bh = head = page_buffers(page);
+	block_start = 0;
+	do {
+		block_end = block_start + bh->b_size;
+
+		if (buffer_new(bh)) {
+			if (block_end > from && block_start < to) {
+				if (!PageUptodate(page)) {
+					unsigned start, size;
+
+					start = max(from, block_start);
+					size = min(to, block_end) - start;
+
+					zero_user(page, start, size);
+					set_buffer_uptodate(bh);
+				}
+
+				clear_buffer_new(bh);
+				mark_buffer_dirty(bh);
+			}
+		}
+
+		block_start = block_end;
+		bh = bh->b_this_page;
+	} while (bh != head);
+}
+EXPORT_SYMBOL(page_zero_new_buffers);
+
+static int __block_prepare_write(struct inode *inode, struct page *page,
+		unsigned from, unsigned to, get_block_t *get_block)
+{
+	unsigned block_start, block_end;
+	sector_t block;
+	int err = 0;
+	unsigned blocksize, bbits;
+	struct buffer_head *bh, *head, *wait[2], **wait_bh=wait;
+
+	BUG_ON(!PageLocked(page));
+	BUG_ON(from > PAGE_CACHE_SIZE);
+	BUG_ON(to > PAGE_CACHE_SIZE);
+	BUG_ON(from > to);
+
+	blocksize = 1 << inode->i_blkbits;
+	if (!page_has_buffers(page))
+		create_empty_buffers(page, blocksize, 0);
+	head = page_buffers(page);
+
+	bbits = inode->i_blkbits;
+	block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits);
+
+	for(bh = head, block_start = 0; bh != head || !block_start;
+	    block++, block_start=block_end, bh = bh->b_this_page) {
+		block_end = block_start + blocksize;
+		if (block_end <= from || block_start >= to) {
+			if (PageUptodate(page)) {
+				if (!buffer_uptodate(bh))
+					set_buffer_uptodate(bh);
+			}
+			continue;
+		}
+		if (buffer_new(bh))
+			clear_buffer_new(bh);
+		if (!buffer_mapped(bh)) {
+			WARN_ON(bh->b_size != blocksize);
+			err = get_block(inode, block, bh, 1);
+			if (err)
+				break;
+			if (buffer_new(bh)) {
+				unmap_underlying_metadata(bh->b_bdev,
+							bh->b_blocknr);
+				if (PageUptodate(page)) {
+					clear_buffer_new(bh);
+					set_buffer_uptodate(bh);
+					mark_buffer_dirty(bh);
+					continue;
+				}
+				if (block_end > to || block_start < from)
+					zero_user_segments(page,
+						to, block_end,
+						block_start, from);
+				continue;
+			}
+		}
+		if (PageUptodate(page)) {
+			if (!buffer_uptodate(bh))
+				set_buffer_uptodate(bh);
+			continue; 
+		}
+		if (!buffer_uptodate(bh) && !buffer_delay(bh) &&
+		    !buffer_unwritten(bh) &&
+		     (block_start < from || block_end > to)) {
+			ll_rw_block(READ, 1, &bh);
+			*wait_bh++=bh;
+		}
+	}
+	/*
+	 * If we issued read requests - let them complete.
+	 */
+	while(wait_bh > wait) {
+		wait_on_buffer(*--wait_bh);
+		if (!buffer_uptodate(*wait_bh))
+			err = -EIO;
+	}
+	if (unlikely(err))
+		page_zero_new_buffers(page, from, to);
+	return err;
+}
+
+static int __block_commit_write(struct inode *inode, struct page *page,
+		unsigned from, unsigned to)
+{
+	unsigned block_start, block_end;
+	int partial = 0;
+	unsigned blocksize;
+	struct buffer_head *bh, *head;
+
+	blocksize = 1 << inode->i_blkbits;
+
+	for(bh = head = page_buffers(page), block_start = 0;
+	    bh != head || !block_start;
+	    block_start=block_end, bh = bh->b_this_page) {
+		block_end = block_start + blocksize;
+		if (block_end <= from || block_start >= to) {
+			if (!buffer_uptodate(bh))
+				partial = 1;
+		} else {
+			set_buffer_uptodate(bh);
+			mark_buffer_dirty(bh);
+		}
+		clear_buffer_new(bh);
+	}
+
+	/*
+	 * If this is a partial write which happened to make all buffers
+	 * uptodate then we can optimize away a bogus readpage() for
+	 * the next read(). Here we 'discover' whether the page went
+	 * uptodate as a result of this (potentially partial) write.
+	 */
+	if (!partial)
+		SetPageUptodate(page);
+	return 0;
+}
+
+/*
+ * block_write_begin takes care of the basic task of block allocation and
+ * bringing partial write blocks uptodate first.
+ *
+ * If *pagep is not NULL, then block_write_begin uses the locked page
+ * at *pagep rather than allocating its own. In this case, the page will
+ * not be unlocked or deallocated on failure.
+ */
+int block_write_begin(struct file *file, struct address_space *mapping,
+			loff_t pos, unsigned len, unsigned flags,
+			struct page **pagep, void **fsdata,
+			get_block_t *get_block)
+{
+#ifndef DDE_LINUX
+	struct inode *inode = mapping->host;
+	int status = 0;
+	struct page *page;
+	pgoff_t index;
+	unsigned start, end;
+	int ownpage = 0;
+
+	index = pos >> PAGE_CACHE_SHIFT;
+	start = pos & (PAGE_CACHE_SIZE - 1);
+	end = start + len;
+
+	page = *pagep;
+	if (page == NULL) {
+		ownpage = 1;
+		page = grab_cache_page_write_begin(mapping, index, flags);
+		if (!page) {
+			status = -ENOMEM;
+			goto out;
+		}
+		*pagep = page;
+	} else
+		BUG_ON(!PageLocked(page));
+
+	status = __block_prepare_write(inode, page, start, end, get_block);
+	if (unlikely(status)) {
+		ClearPageUptodate(page);
+
+		if (ownpage) {
+			unlock_page(page);
+			page_cache_release(page);
+			*pagep = NULL;
+
+#ifndef DDE_LINUX
+			/*
+			 * prepare_write() may have instantiated a few blocks
+			 * outside i_size.  Trim these off again. Don't need
+			 * i_size_read because we hold i_mutex.
+			 */
+			if (pos + len > inode->i_size)
+				vmtruncate(inode, inode->i_size);
+#endif
+		}
+	}
+
+out:
+	return status;
+#else
+	WARN_UNIMPL;
+	return -1;
+#endif
+}
+EXPORT_SYMBOL(block_write_begin);
+
+int block_write_end(struct file *file, struct address_space *mapping,
+			loff_t pos, unsigned len, unsigned copied,
+			struct page *page, void *fsdata)
+{
+	struct inode *inode = mapping->host;
+	unsigned start;
+
+	start = pos & (PAGE_CACHE_SIZE - 1);
+
+	if (unlikely(copied < len)) {
+		/*
+		 * The buffers that were written will now be uptodate, so we
+		 * don't have to worry about a readpage reading them and
+		 * overwriting a partial write. However if we have encountered
+		 * a short write and only partially written into a buffer, it
+		 * will not be marked uptodate, so a readpage might come in and
+		 * destroy our partial write.
+		 *
+		 * Do the simplest thing, and just treat any short write to a
+		 * non uptodate page as a zero-length write, and force the
+		 * caller to redo the whole thing.
+		 */
+		if (!PageUptodate(page))
+			copied = 0;
+
+		page_zero_new_buffers(page, start+copied, start+len);
+	}
+	flush_dcache_page(page);
+
+	/* This could be a short (even 0-length) commit */
+	__block_commit_write(inode, page, start, start+copied);
+
+	return copied;
+}
+EXPORT_SYMBOL(block_write_end);
+
+int generic_write_end(struct file *file, struct address_space *mapping,
+			loff_t pos, unsigned len, unsigned copied,
+			struct page *page, void *fsdata)
+{
+	struct inode *inode = mapping->host;
+	int i_size_changed = 0;
+
+	copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
+
+	/*
+	 * No need to use i_size_read() here, the i_size
+	 * cannot change under us because we hold i_mutex.
+	 *
+	 * But it's important to update i_size while still holding page lock:
+	 * page writeout could otherwise come in and zero beyond i_size.
+	 */
+	if (pos+copied > inode->i_size) {
+		i_size_write(inode, pos+copied);
+		i_size_changed = 1;
+	}
+
+	unlock_page(page);
+	page_cache_release(page);
+
+	/*
+	 * Don't mark the inode dirty under page lock. First, it unnecessarily
+	 * makes the holding time of page lock longer. Second, it forces lock
+	 * ordering of page lock and transaction start for journaling
+	 * filesystems.
+	 */
+	if (i_size_changed)
+		mark_inode_dirty(inode);
+
+	return copied;
+}
+EXPORT_SYMBOL(generic_write_end);
+
+/*
+ * block_is_partially_uptodate checks whether buffers within a page are
+ * uptodate or not.
+ *
+ * Returns true if all buffers which correspond to a file portion
+ * we want to read are uptodate.
+ */
+int block_is_partially_uptodate(struct page *page, read_descriptor_t *desc,
+					unsigned long from)
+{
+	struct inode *inode = page->mapping->host;
+	unsigned block_start, block_end, blocksize;
+	unsigned to;
+	struct buffer_head *bh, *head;
+	int ret = 1;
+
+	if (!page_has_buffers(page))
+		return 0;
+
+	blocksize = 1 << inode->i_blkbits;
+	to = min_t(unsigned, PAGE_CACHE_SIZE - from, desc->count);
+	to = from + to;
+	if (from < blocksize && to > PAGE_CACHE_SIZE - blocksize)
+		return 0;
+
+	head = page_buffers(page);
+	bh = head;
+	block_start = 0;
+	do {
+		block_end = block_start + blocksize;
+		if (block_end > from && block_start < to) {
+			if (!buffer_uptodate(bh)) {
+				ret = 0;
+				break;
+			}
+			if (block_end >= to)
+				break;
+		}
+		block_start = block_end;
+		bh = bh->b_this_page;
+	} while (bh != head);
+
+	return ret;
+}
+EXPORT_SYMBOL(block_is_partially_uptodate);
+
+/*
+ * Generic "read page" function for block devices that have the normal
+ * get_block functionality. This is most of the block device filesystems.
+ * Reads the page asynchronously --- the unlock_buffer() and
+ * set/clear_buffer_uptodate() functions propagate buffer state into the
+ * page struct once IO has completed.
+ */
+int block_read_full_page(struct page *page, get_block_t *get_block)
+{
+	struct inode *inode = page->mapping->host;
+	sector_t iblock, lblock;
+	struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE];
+	unsigned int blocksize;
+	int nr, i;
+	int fully_mapped = 1;
+
+	BUG_ON(!PageLocked(page));
+	blocksize = 1 << inode->i_blkbits;
+	if (!page_has_buffers(page))
+		create_empty_buffers(page, blocksize, 0);
+	head = page_buffers(page);
+
+	iblock = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
+	lblock = (i_size_read(inode)+blocksize-1) >> inode->i_blkbits;
+	bh = head;
+	nr = 0;
+	i = 0;
+
+	do {
+		if (buffer_uptodate(bh))
+			continue;
+
+		if (!buffer_mapped(bh)) {
+			int err = 0;
+
+			fully_mapped = 0;
+			if (iblock < lblock) {
+				WARN_ON(bh->b_size != blocksize);
+				err = get_block(inode, iblock, bh, 0);
+				if (err)
+					SetPageError(page);
+			}
+			if (!buffer_mapped(bh)) {
+				zero_user(page, i * blocksize, blocksize);
+				if (!err)
+					set_buffer_uptodate(bh);
+				continue;
+			}
+			/*
+			 * get_block() might have updated the buffer
+			 * synchronously
+			 */
+			if (buffer_uptodate(bh))
+				continue;
+		}
+		arr[nr++] = bh;
+	} while (i++, iblock++, (bh = bh->b_this_page) != head);
+
+	if (fully_mapped)
+		SetPageMappedToDisk(page);
+
+	if (!nr) {
+		/*
+		 * All buffers are uptodate - we can set the page uptodate
+		 * as well. But not if get_block() returned an error.
+		 */
+		if (!PageError(page))
+			SetPageUptodate(page);
+		unlock_page(page);
+		return 0;
+	}
+
+	/* Stage two: lock the buffers */
+	for (i = 0; i < nr; i++) {
+		bh = arr[i];
+		lock_buffer(bh);
+		mark_buffer_async_read(bh);
+	}
+
+	/*
+	 * Stage 3: start the IO.  Check for uptodateness
+	 * inside the buffer lock in case another process reading
+	 * the underlying blockdev brought it uptodate (the sct fix).
+	 */
+	for (i = 0; i < nr; i++) {
+		bh = arr[i];
+		if (buffer_uptodate(bh))
+			end_buffer_async_read(bh, 1);
+		else
+			submit_bh(READ, bh);
+	}
+	return 0;
+}
+
+/* utility function for filesystems that need to do work on expanding
+ * truncates.  Uses filesystem pagecache writes to allow the filesystem to
+ * deal with the hole.  
+ */
+int generic_cont_expand_simple(struct inode *inode, loff_t size)
+{
+	struct address_space *mapping = inode->i_mapping;
+	struct page *page;
+	void *fsdata;
+	unsigned long limit;
+	int err;
+
+	err = -EFBIG;
+        limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
+	if (limit != RLIM_INFINITY && size > (loff_t)limit) {
+		send_sig(SIGXFSZ, current, 0);
+		goto out;
+	}
+	if (size > inode->i_sb->s_maxbytes)
+		goto out;
+
+	err = pagecache_write_begin(NULL, mapping, size, 0,
+				AOP_FLAG_UNINTERRUPTIBLE|AOP_FLAG_CONT_EXPAND,
+				&page, &fsdata);
+	if (err)
+		goto out;
+
+	err = pagecache_write_end(NULL, mapping, size, 0, 0, page, fsdata);
+	BUG_ON(err > 0);
+
+out:
+	return err;
+}
+
+static int cont_expand_zero(struct file *file, struct address_space *mapping,
+			    loff_t pos, loff_t *bytes)
+{
+	struct inode *inode = mapping->host;
+	unsigned blocksize = 1 << inode->i_blkbits;
+	struct page *page;
+	void *fsdata;
+	pgoff_t index, curidx;
+	loff_t curpos;
+	unsigned zerofrom, offset, len;
+	int err = 0;
+
+	index = pos >> PAGE_CACHE_SHIFT;
+	offset = pos & ~PAGE_CACHE_MASK;
+
+	while (index > (curidx = (curpos = *bytes)>>PAGE_CACHE_SHIFT)) {
+		zerofrom = curpos & ~PAGE_CACHE_MASK;
+		if (zerofrom & (blocksize-1)) {
+			*bytes |= (blocksize-1);
+			(*bytes)++;
+		}
+		len = PAGE_CACHE_SIZE - zerofrom;
+
+		err = pagecache_write_begin(file, mapping, curpos, len,
+						AOP_FLAG_UNINTERRUPTIBLE,
+						&page, &fsdata);
+		if (err)
+			goto out;
+		zero_user(page, zerofrom, len);
+		err = pagecache_write_end(file, mapping, curpos, len, len,
+						page, fsdata);
+		if (err < 0)
+			goto out;
+		BUG_ON(err != len);
+		err = 0;
+
+		balance_dirty_pages_ratelimited(mapping);
+	}
+
+	/* page covers the boundary, find the boundary offset */
+	if (index == curidx) {
+		zerofrom = curpos & ~PAGE_CACHE_MASK;
+		/* if we will expand the thing last block will be filled */
+		if (offset <= zerofrom) {
+			goto out;
+		}
+		if (zerofrom & (blocksize-1)) {
+			*bytes |= (blocksize-1);
+			(*bytes)++;
+		}
+		len = offset - zerofrom;
+
+		err = pagecache_write_begin(file, mapping, curpos, len,
+						AOP_FLAG_UNINTERRUPTIBLE,
+						&page, &fsdata);
+		if (err)
+			goto out;
+		zero_user(page, zerofrom, len);
+		err = pagecache_write_end(file, mapping, curpos, len, len,
+						page, fsdata);
+		if (err < 0)
+			goto out;
+		BUG_ON(err != len);
+		err = 0;
+	}
+out:
+	return err;
+}
+
+/*
+ * For moronic filesystems that do not allow holes in file.
+ * We may have to extend the file.
+ */
+int cont_write_begin(struct file *file, struct address_space *mapping,
+			loff_t pos, unsigned len, unsigned flags,
+			struct page **pagep, void **fsdata,
+			get_block_t *get_block, loff_t *bytes)
+{
+	struct inode *inode = mapping->host;
+	unsigned blocksize = 1 << inode->i_blkbits;
+	unsigned zerofrom;
+	int err;
+
+	err = cont_expand_zero(file, mapping, pos, bytes);
+	if (err)
+		goto out;
+
+	zerofrom = *bytes & ~PAGE_CACHE_MASK;
+	if (pos+len > *bytes && zerofrom & (blocksize-1)) {
+		*bytes |= (blocksize-1);
+		(*bytes)++;
+	}
+
+	*pagep = NULL;
+	err = block_write_begin(file, mapping, pos, len,
+				flags, pagep, fsdata, get_block);
+out:
+	return err;
+}
+
+int block_prepare_write(struct page *page, unsigned from, unsigned to,
+			get_block_t *get_block)
+{
+	struct inode *inode = page->mapping->host;
+	int err = __block_prepare_write(inode, page, from, to, get_block);
+	if (err)
+		ClearPageUptodate(page);
+	return err;
+}
+
+int block_commit_write(struct page *page, unsigned from, unsigned to)
+{
+	struct inode *inode = page->mapping->host;
+	__block_commit_write(inode,page,from,to);
+	return 0;
+}
+
+/*
+ * block_page_mkwrite() is not allowed to change the file size as it gets
+ * called from a page fault handler when a page is first dirtied. Hence we must
+ * be careful to check for EOF conditions here. We set the page up correctly
+ * for a written page which means we get ENOSPC checking when writing into
+ * holes and correct delalloc and unwritten extent mapping on filesystems that
+ * support these features.
+ *
+ * We are not allowed to take the i_mutex here so we have to play games to
+ * protect against truncate races as the page could now be beyond EOF.  Because
+ * vmtruncate() writes the inode size before removing pages, once we have the
+ * page lock we can determine safely if the page is beyond EOF. If it is not
+ * beyond EOF, then the page is guaranteed safe against truncation until we
+ * unlock the page.
+ */
+int
+block_page_mkwrite(struct vm_area_struct *vma, struct page *page,
+		   get_block_t get_block)
+{
+	struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
+	unsigned long end;
+	loff_t size;
+	int ret = -EINVAL;
+
+	lock_page(page);
+	size = i_size_read(inode);
+	if ((page->mapping != inode->i_mapping) ||
+	    (page_offset(page) > size)) {
+		/* page got truncated out from underneath us */
+		goto out_unlock;
+	}
+
+	/* page is wholly or partially inside EOF */
+	if (((page->index + 1) << PAGE_CACHE_SHIFT) > size)
+		end = size & ~PAGE_CACHE_MASK;
+	else
+		end = PAGE_CACHE_SIZE;
+
+	ret = block_prepare_write(page, 0, end, get_block);
+	if (!ret)
+		ret = block_commit_write(page, 0, end);
+
+out_unlock:
+	unlock_page(page);
+	return ret;
+}
+
+/*
+ * nobh_write_begin()'s prereads are special: the buffer_heads are freed
+ * immediately, while under the page lock.  So it needs a special end_io
+ * handler which does not touch the bh after unlocking it.
+ */
+static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate)
+{
+	__end_buffer_read_notouch(bh, uptodate);
+}
+
+/*
+ * Attach the singly-linked list of buffers created by nobh_write_begin, to
+ * the page (converting it to circular linked list and taking care of page
+ * dirty races).
+ */
+static void attach_nobh_buffers(struct page *page, struct buffer_head *head)
+{
+	struct buffer_head *bh;
+
+	BUG_ON(!PageLocked(page));
+
+	spin_lock(&page->mapping->private_lock);
+	bh = head;
+	do {
+		if (PageDirty(page))
+			set_buffer_dirty(bh);
+		if (!bh->b_this_page)
+			bh->b_this_page = head;
+		bh = bh->b_this_page;
+	} while (bh != head);
+	attach_page_buffers(page, head);
+	spin_unlock(&page->mapping->private_lock);
+}
+
+/*
+ * On entry, the page is fully not uptodate.
+ * On exit the page is fully uptodate in the areas outside (from,to)
+ */
+int nobh_write_begin(struct file *file, struct address_space *mapping,
+			loff_t pos, unsigned len, unsigned flags,
+			struct page **pagep, void **fsdata,
+			get_block_t *get_block)
+{
+	struct inode *inode = mapping->host;
+	const unsigned blkbits = inode->i_blkbits;
+	const unsigned blocksize = 1 << blkbits;
+	struct buffer_head *head, *bh;
+	struct page *page;
+	pgoff_t index;
+	unsigned from, to;
+	unsigned block_in_page;
+	unsigned block_start, block_end;
+	sector_t block_in_file;
+	int nr_reads = 0;
+	int ret = 0;
+	int is_mapped_to_disk = 1;
+
+	index = pos >> PAGE_CACHE_SHIFT;
+	from = pos & (PAGE_CACHE_SIZE - 1);
+	to = from + len;
+
+	page = grab_cache_page_write_begin(mapping, index, flags);
+	if (!page)
+		return -ENOMEM;
+	*pagep = page;
+	*fsdata = NULL;
+
+	if (page_has_buffers(page)) {
+		unlock_page(page);
+		page_cache_release(page);
+		*pagep = NULL;
+		return block_write_begin(file, mapping, pos, len, flags, pagep,
+					fsdata, get_block);
+	}
+
+	if (PageMappedToDisk(page))
+		return 0;
+
+	/*
+	 * Allocate buffers so that we can keep track of state, and potentially
+	 * attach them to the page if an error occurs. In the common case of
+	 * no error, they will just be freed again without ever being attached
+	 * to the page (which is all OK, because we're under the page lock).
+	 *
+	 * Be careful: the buffer linked list is a NULL terminated one, rather
+	 * than the circular one we're used to.
+	 */
+	head = alloc_page_buffers(page, blocksize, 0);
+	if (!head) {
+		ret = -ENOMEM;
+		goto out_release;
+	}
+
+	block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits);
+
+	/*
+	 * We loop across all blocks in the page, whether or not they are
+	 * part of the affected region.  This is so we can discover if the
+	 * page is fully mapped-to-disk.
+	 */
+	for (block_start = 0, block_in_page = 0, bh = head;
+		  block_start < PAGE_CACHE_SIZE;
+		  block_in_page++, block_start += blocksize, bh = bh->b_this_page) {
+		int create;
+
+		block_end = block_start + blocksize;
+		bh->b_state = 0;
+		create = 1;
+		if (block_start >= to)
+			create = 0;
+		ret = get_block(inode, block_in_file + block_in_page,
+					bh, create);
+		if (ret)
+			goto failed;
+		if (!buffer_mapped(bh))
+			is_mapped_to_disk = 0;
+		if (buffer_new(bh))
+			unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
+		if (PageUptodate(page)) {
+			set_buffer_uptodate(bh);
+			continue;
+		}
+		if (buffer_new(bh) || !buffer_mapped(bh)) {
+			zero_user_segments(page, block_start, from,
+							to, block_end);
+			continue;
+		}
+		if (buffer_uptodate(bh))
+			continue;	/* reiserfs does this */
+		if (block_start < from || block_end > to) {
+			lock_buffer(bh);
+			bh->b_end_io = end_buffer_read_nobh;
+			submit_bh(READ, bh);
+			nr_reads++;
+		}
+	}
+
+	if (nr_reads) {
+		/*
+		 * The page is locked, so these buffers are protected from
+		 * any VM or truncate activity.  Hence we don't need to care
+		 * for the buffer_head refcounts.
+		 */
+		for (bh = head; bh; bh = bh->b_this_page) {
+			wait_on_buffer(bh);
+			if (!buffer_uptodate(bh))
+				ret = -EIO;
+		}
+		if (ret)
+			goto failed;
+	}
+
+	if (is_mapped_to_disk)
+		SetPageMappedToDisk(page);
+
+	*fsdata = head; /* to be released by nobh_write_end */
+
+	return 0;
+
+failed:
+	BUG_ON(!ret);
+	/*
+	 * Error recovery is a bit difficult. We need to zero out blocks that
+	 * were newly allocated, and dirty them to ensure they get written out.
+	 * Buffers need to be attached to the page at this point, otherwise
+	 * the handling of potential IO errors during writeout would be hard
+	 * (could try doing synchronous writeout, but what if that fails too?)
+	 */
+	attach_nobh_buffers(page, head);
+	page_zero_new_buffers(page, from, to);
+
+out_release:
+	unlock_page(page);
+	page_cache_release(page);
+	*pagep = NULL;
+
+	if (pos + len > inode->i_size)
+		vmtruncate(inode, inode->i_size);
+
+	return ret;
+}
+EXPORT_SYMBOL(nobh_write_begin);
+
+int nobh_write_end(struct file *file, struct address_space *mapping,
+			loff_t pos, unsigned len, unsigned copied,
+			struct page *page, void *fsdata)
+{
+	struct inode *inode = page->mapping->host;
+	struct buffer_head *head = fsdata;
+	struct buffer_head *bh;
+	BUG_ON(fsdata != NULL && page_has_buffers(page));
+
+	if (unlikely(copied < len) && head)
+		attach_nobh_buffers(page, head);
+	if (page_has_buffers(page))
+		return generic_write_end(file, mapping, pos, len,
+					copied, page, fsdata);
+
+	SetPageUptodate(page);
+	set_page_dirty(page);
+	if (pos+copied > inode->i_size) {
+		i_size_write(inode, pos+copied);
+		mark_inode_dirty(inode);
+	}
+
+	unlock_page(page);
+	page_cache_release(page);
+
+	while (head) {
+		bh = head;
+		head = head->b_this_page;
+		free_buffer_head(bh);
+	}
+
+	return copied;
+}
+EXPORT_SYMBOL(nobh_write_end);
+
+/*
+ * nobh_writepage() - based on block_full_write_page() except
+ * that it tries to operate without attaching bufferheads to
+ * the page.
+ */
+int nobh_writepage(struct page *page, get_block_t *get_block,
+			struct writeback_control *wbc)
+{
+	struct inode * const inode = page->mapping->host;
+	loff_t i_size = i_size_read(inode);
+	const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
+	unsigned offset;
+	int ret;
+
+	/* Is the page fully inside i_size? */
+	if (page->index < end_index)
+		goto out;
+
+	/* Is the page fully outside i_size? (truncate in progress) */
+	offset = i_size & (PAGE_CACHE_SIZE-1);
+	if (page->index >= end_index+1 || !offset) {
+		/*
+		 * The page may have dirty, unmapped buffers.  For example,
+		 * they may have been added in ext3_writepage().  Make them
+		 * freeable here, so the page does not leak.
+		 */
+#if 0
+		/* Not really sure about this  - do we need this ? */
+		if (page->mapping->a_ops->invalidatepage)
+			page->mapping->a_ops->invalidatepage(page, offset);
+#endif
+		unlock_page(page);
+		return 0; /* don't care */
+	}
+
+	/*
+	 * The page straddles i_size.  It must be zeroed out on each and every
+	 * writepage invocation because it may be mmapped.  "A file is mapped
+	 * in multiples of the page size.  For a file that is not a multiple of
+	 * the  page size, the remaining memory is zeroed when mapped, and
+	 * writes to that region are not written out to the file."
+	 */
+	zero_user_segment(page, offset, PAGE_CACHE_SIZE);
+out:
+	ret = mpage_writepage(page, get_block, wbc);
+	if (ret == -EAGAIN)
+		ret = __block_write_full_page(inode, page, get_block, wbc);
+	return ret;
+}
+EXPORT_SYMBOL(nobh_writepage);
+
+int nobh_truncate_page(struct address_space *mapping,
+			loff_t from, get_block_t *get_block)
+{
+	pgoff_t index = from >> PAGE_CACHE_SHIFT;
+	unsigned offset = from & (PAGE_CACHE_SIZE-1);
+	unsigned blocksize;
+	sector_t iblock;
+	unsigned length, pos;
+	struct inode *inode = mapping->host;
+	struct page *page;
+	struct buffer_head map_bh;
+	int err;
+
+	blocksize = 1 << inode->i_blkbits;
+	length = offset & (blocksize - 1);
+
+	/* Block boundary? Nothing to do */
+	if (!length)
+		return 0;
+
+	length = blocksize - length;
+	iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
+
+	page = grab_cache_page(mapping, index);
+	err = -ENOMEM;
+	if (!page)
+		goto out;
+
+	if (page_has_buffers(page)) {
+has_buffers:
+		unlock_page(page);
+		page_cache_release(page);
+		return block_truncate_page(mapping, from, get_block);
+	}
+
+	/* Find the buffer that contains "offset" */
+	pos = blocksize;
+	while (offset >= pos) {
+		iblock++;
+		pos += blocksize;
+	}
+
+	err = get_block(inode, iblock, &map_bh, 0);
+	if (err)
+		goto unlock;
+	/* unmapped? It's a hole - nothing to do */
+	if (!buffer_mapped(&map_bh))
+		goto unlock;
+
+	/* Ok, it's mapped. Make sure it's up-to-date */
+	if (!PageUptodate(page)) {
+		err = mapping->a_ops->readpage(NULL, page);
+		if (err) {
+			page_cache_release(page);
+			goto out;
+		}
+		lock_page(page);
+		if (!PageUptodate(page)) {
+			err = -EIO;
+			goto unlock;
+		}
+		if (page_has_buffers(page))
+			goto has_buffers;
+	}
+	zero_user(page, offset, length);
+	set_page_dirty(page);
+	err = 0;
+
+unlock:
+	unlock_page(page);
+	page_cache_release(page);
+out:
+	return err;
+}
+EXPORT_SYMBOL(nobh_truncate_page);
+
+int block_truncate_page(struct address_space *mapping,
+			loff_t from, get_block_t *get_block)
+{
+	pgoff_t index = from >> PAGE_CACHE_SHIFT;
+	unsigned offset = from & (PAGE_CACHE_SIZE-1);
+	unsigned blocksize;
+	sector_t iblock;
+	unsigned length, pos;
+	struct inode *inode = mapping->host;
+	struct page *page;
+	struct buffer_head *bh;
+	int err;
+
+	blocksize = 1 << inode->i_blkbits;
+	length = offset & (blocksize - 1);
+
+	/* Block boundary? Nothing to do */
+	if (!length)
+		return 0;
+
+	length = blocksize - length;
+	iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
+	
+	page = grab_cache_page(mapping, index);
+	err = -ENOMEM;
+	if (!page)
+		goto out;
+
+	if (!page_has_buffers(page))
+		create_empty_buffers(page, blocksize, 0);
+
+	/* Find the buffer that contains "offset" */
+	bh = page_buffers(page);
+	pos = blocksize;
+	while (offset >= pos) {
+		bh = bh->b_this_page;
+		iblock++;
+		pos += blocksize;
+	}
+
+	err = 0;
+	if (!buffer_mapped(bh)) {
+		WARN_ON(bh->b_size != blocksize);
+		err = get_block(inode, iblock, bh, 0);
+		if (err)
+			goto unlock;
+		/* unmapped? It's a hole - nothing to do */
+		if (!buffer_mapped(bh))
+			goto unlock;
+	}
+
+	/* Ok, it's mapped. Make sure it's up-to-date */
+	if (PageUptodate(page))
+		set_buffer_uptodate(bh);
+
+	if (!buffer_uptodate(bh) && !buffer_delay(bh) && !buffer_unwritten(bh)) {
+		err = -EIO;
+		ll_rw_block(READ, 1, &bh);
+		wait_on_buffer(bh);
+		/* Uhhuh. Read error. Complain and punt. */
+		if (!buffer_uptodate(bh))
+			goto unlock;
+	}
+
+	zero_user(page, offset, length);
+	mark_buffer_dirty(bh);
+	err = 0;
+
+unlock:
+	unlock_page(page);
+	page_cache_release(page);
+out:
+	return err;
+}
+
+/*
+ * The generic ->writepage function for buffer-backed address_spaces
+ */
+int block_write_full_page(struct page *page, get_block_t *get_block,
+			struct writeback_control *wbc)
+{
+	struct inode * const inode = page->mapping->host;
+	loff_t i_size = i_size_read(inode);
+	const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
+	unsigned offset;
+
+	/* Is the page fully inside i_size? */
+	if (page->index < end_index)
+		return __block_write_full_page(inode, page, get_block, wbc);
+
+	/* Is the page fully outside i_size? (truncate in progress) */
+	offset = i_size & (PAGE_CACHE_SIZE-1);
+	if (page->index >= end_index+1 || !offset) {
+		/*
+		 * The page may have dirty, unmapped buffers.  For example,
+		 * they may have been added in ext3_writepage().  Make them
+		 * freeable here, so the page does not leak.
+		 */
+		do_invalidatepage(page, 0);
+		unlock_page(page);
+		return 0; /* don't care */
+	}
+
+	/*
+	 * The page straddles i_size.  It must be zeroed out on each and every
+	 * writepage invokation because it may be mmapped.  "A file is mapped
+	 * in multiples of the page size.  For a file that is not a multiple of
+	 * the  page size, the remaining memory is zeroed when mapped, and
+	 * writes to that region are not written out to the file."
+	 */
+	zero_user_segment(page, offset, PAGE_CACHE_SIZE);
+	return __block_write_full_page(inode, page, get_block, wbc);
+}
+
+sector_t generic_block_bmap(struct address_space *mapping, sector_t block,
+			    get_block_t *get_block)
+{
+	struct buffer_head tmp;
+	struct inode *inode = mapping->host;
+	tmp.b_state = 0;
+	tmp.b_blocknr = 0;
+	tmp.b_size = 1 << inode->i_blkbits;
+	get_block(inode, block, &tmp, 0);
+	return tmp.b_blocknr;
+}
+
+static void end_bio_bh_io_sync(struct bio *bio, int err)
+{
+	struct buffer_head *bh = bio->bi_private;
+
+	if (err == -EOPNOTSUPP) {
+		set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
+		set_bit(BH_Eopnotsupp, &bh->b_state);
+	}
+
+	if (unlikely (test_bit(BIO_QUIET,&bio->bi_flags)))
+		set_bit(BH_Quiet, &bh->b_state);
+
+	bh->b_end_io(bh, test_bit(BIO_UPTODATE, &bio->bi_flags));
+	bio_put(bio);
+}
+
+int submit_bh(int rw, struct buffer_head * bh)
+{
+	struct bio *bio;
+	int ret = 0;
+
+	BUG_ON(!buffer_locked(bh));
+	BUG_ON(!buffer_mapped(bh));
+	BUG_ON(!bh->b_end_io);
+
+	/*
+	 * Mask in barrier bit for a write (could be either a WRITE or a
+	 * WRITE_SYNC
+	 */
+	if (buffer_ordered(bh) && (rw & WRITE))
+		rw |= WRITE_BARRIER;
+
+	/*
+	 * Only clear out a write error when rewriting
+	 */
+	if (test_set_buffer_req(bh) && (rw & WRITE))
+		clear_buffer_write_io_error(bh);
+
+	/*
+	 * from here on down, it's all bio -- do the initial mapping,
+	 * submit_bio -> generic_make_request may further map this bio around
+	 */
+	bio = bio_alloc(GFP_NOIO, 1);
+
+	bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9);
+	bio->bi_bdev = bh->b_bdev;
+	bio->bi_io_vec[0].bv_page = bh->b_page;
+	bio->bi_io_vec[0].bv_len = bh->b_size;
+	bio->bi_io_vec[0].bv_offset = bh_offset(bh);
+
+	bio->bi_vcnt = 1;
+	bio->bi_idx = 0;
+	bio->bi_size = bh->b_size;
+
+	bio->bi_end_io = end_bio_bh_io_sync;
+	bio->bi_private = bh;
+
+	bio_get(bio);
+	submit_bio(rw, bio);
+
+	if (bio_flagged(bio, BIO_EOPNOTSUPP))
+		ret = -EOPNOTSUPP;
+
+	bio_put(bio);
+	return ret;
+}
+
+/**
+ * ll_rw_block: low-level access to block devices (DEPRECATED)
+ * @rw: whether to %READ or %WRITE or %SWRITE or maybe %READA (readahead)
+ * @nr: number of &struct buffer_heads in the array
+ * @bhs: array of pointers to &struct buffer_head
+ *
+ * ll_rw_block() takes an array of pointers to &struct buffer_heads, and
+ * requests an I/O operation on them, either a %READ or a %WRITE.  The third
+ * %SWRITE is like %WRITE only we make sure that the *current* data in buffers
+ * are sent to disk. The fourth %READA option is described in the documentation
+ * for generic_make_request() which ll_rw_block() calls.
+ *
+ * This function drops any buffer that it cannot get a lock on (with the
+ * BH_Lock state bit) unless SWRITE is required, any buffer that appears to be
+ * clean when doing a write request, and any buffer that appears to be
+ * up-to-date when doing read request.  Further it marks as clean buffers that
+ * are processed for writing (the buffer cache won't assume that they are
+ * actually clean until the buffer gets unlocked).
+ *
+ * ll_rw_block sets b_end_io to simple completion handler that marks
+ * the buffer up-to-date (if approriate), unlocks the buffer and wakes
+ * any waiters. 
+ *
+ * All of the buffers must be for the same device, and must also be a
+ * multiple of the current approved size for the device.
+ */
+void ll_rw_block(int rw, int nr, struct buffer_head *bhs[])
+{
+	int i;
+
+	for (i = 0; i < nr; i++) {
+		struct buffer_head *bh = bhs[i];
+
+		if (rw == SWRITE || rw == SWRITE_SYNC)
+			lock_buffer(bh);
+		else if (!trylock_buffer(bh))
+			continue;
+
+		if (rw == WRITE || rw == SWRITE || rw == SWRITE_SYNC) {
+			if (test_clear_buffer_dirty(bh)) {
+				bh->b_end_io = end_buffer_write_sync;
+				get_bh(bh);
+				if (rw == SWRITE_SYNC)
+					submit_bh(WRITE_SYNC, bh);
+				else
+					submit_bh(WRITE, bh);
+				continue;
+			}
+		} else {
+			if (!buffer_uptodate(bh)) {
+				bh->b_end_io = end_buffer_read_sync;
+				get_bh(bh);
+				submit_bh(rw, bh);
+				continue;
+			}
+		}
+		unlock_buffer(bh);
+	}
+}
+
+/*
+ * For a data-integrity writeout, we need to wait upon any in-progress I/O
+ * and then start new I/O and then wait upon it.  The caller must have a ref on
+ * the buffer_head.
+ */
+int sync_dirty_buffer(struct buffer_head *bh)
+{
+	int ret = 0;
+
+	WARN_ON(atomic_read(&bh->b_count) < 1);
+	lock_buffer(bh);
+	if (test_clear_buffer_dirty(bh)) {
+		get_bh(bh);
+		bh->b_end_io = end_buffer_write_sync;
+		ret = submit_bh(WRITE, bh);
+		wait_on_buffer(bh);
+		if (buffer_eopnotsupp(bh)) {
+			clear_buffer_eopnotsupp(bh);
+			ret = -EOPNOTSUPP;
+		}
+		if (!ret && !buffer_uptodate(bh))
+			ret = -EIO;
+	} else {
+		unlock_buffer(bh);
+	}
+	return ret;
+}
+
+/*
+ * try_to_free_buffers() checks if all the buffers on this particular page
+ * are unused, and releases them if so.
+ *
+ * Exclusion against try_to_free_buffers may be obtained by either
+ * locking the page or by holding its mapping's private_lock.
+ *
+ * If the page is dirty but all the buffers are clean then we need to
+ * be sure to mark the page clean as well.  This is because the page
+ * may be against a block device, and a later reattachment of buffers
+ * to a dirty page will set *all* buffers dirty.  Which would corrupt
+ * filesystem data on the same device.
+ *
+ * The same applies to regular filesystem pages: if all the buffers are
+ * clean then we set the page clean and proceed.  To do that, we require
+ * total exclusion from __set_page_dirty_buffers().  That is obtained with
+ * private_lock.
+ *
+ * try_to_free_buffers() is non-blocking.
+ */
+static inline int buffer_busy(struct buffer_head *bh)
+{
+	return atomic_read(&bh->b_count) |
+		(bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock)));
+}
+
+static int
+drop_buffers(struct page *page, struct buffer_head **buffers_to_free)
+{
+	struct buffer_head *head = page_buffers(page);
+	struct buffer_head *bh;
+
+	bh = head;
+	do {
+		if (buffer_write_io_error(bh) && page->mapping)
+			set_bit(AS_EIO, &page->mapping->flags);
+		if (buffer_busy(bh))
+			goto failed;
+		bh = bh->b_this_page;
+	} while (bh != head);
+
+	do {
+		struct buffer_head *next = bh->b_this_page;
+
+		if (bh->b_assoc_map)
+			__remove_assoc_queue(bh);
+		bh = next;
+	} while (bh != head);
+	*buffers_to_free = head;
+	__clear_page_buffers(page);
+	return 1;
+failed:
+	return 0;
+}
+
+int try_to_free_buffers(struct page *page)
+{
+	struct address_space * const mapping = page->mapping;
+	struct buffer_head *buffers_to_free = NULL;
+	int ret = 0;
+
+	BUG_ON(!PageLocked(page));
+	if (PageWriteback(page))
+		return 0;
+
+	if (mapping == NULL) {		/* can this still happen? */
+		ret = drop_buffers(page, &buffers_to_free);
+		goto out;
+	}
+
+	spin_lock(&mapping->private_lock);
+	ret = drop_buffers(page, &buffers_to_free);
+
+	/*
+	 * If the filesystem writes its buffers by hand (eg ext3)
+	 * then we can have clean buffers against a dirty page.  We
+	 * clean the page here; otherwise the VM will never notice
+	 * that the filesystem did any IO at all.
+	 *
+	 * Also, during truncate, discard_buffer will have marked all
+	 * the page's buffers clean.  We discover that here and clean
+	 * the page also.
+	 *
+	 * private_lock must be held over this entire operation in order
+	 * to synchronise against __set_page_dirty_buffers and prevent the
+	 * dirty bit from being lost.
+	 */
+#ifndef DDE_LINUX
+	if (ret)
+		cancel_dirty_page(page, PAGE_CACHE_SIZE);
+#endif
+	spin_unlock(&mapping->private_lock);
+out:
+	if (buffers_to_free) {
+		struct buffer_head *bh = buffers_to_free;
+
+		do {
+			struct buffer_head *next = bh->b_this_page;
+			free_buffer_head(bh);
+			bh = next;
+		} while (bh != buffers_to_free);
+	}
+	return ret;
+}
+EXPORT_SYMBOL(try_to_free_buffers);
+
+void block_sync_page(struct page *page)
+{
+	struct address_space *mapping;
+
+	smp_mb();
+	mapping = page_mapping(page);
+	if (mapping)
+		blk_run_backing_dev(mapping->backing_dev_info, page);
+}
+
+/*
+ * There are no bdflush tunables left.  But distributions are
+ * still running obsolete flush daemons, so we terminate them here.
+ *
+ * Use of bdflush() is deprecated and will be removed in a future kernel.
+ * The `pdflush' kernel threads fully replace bdflush daemons and this call.
+ */
+SYSCALL_DEFINE2(bdflush, int, func, long, data)
+{
+	static int msg_count;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	if (msg_count < 5) {
+		msg_count++;
+		printk(KERN_INFO
+			"warning: process `%s' used the obsolete bdflush"
+			" system call\n", current->comm);
+		printk(KERN_INFO "Fix your initscripts?\n");
+	}
+
+	if (func == 1)
+		do_exit(0);
+	return 0;
+}
+
+/*
+ * Buffer-head allocation
+ */
+static struct kmem_cache *bh_cachep;
+
+/*
+ * Once the number of bh's in the machine exceeds this level, we start
+ * stripping them in writeback.
+ */
+static int max_buffer_heads;
+
+int buffer_heads_over_limit;
+
+struct bh_accounting {
+	int nr;			/* Number of live bh's */
+	int ratelimit;		/* Limit cacheline bouncing */
+};
+
+static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0};
+
+static void recalc_bh_state(void)
+{
+	int i;
+	int tot = 0;
+
+	if (__get_cpu_var(bh_accounting).ratelimit++ < 4096)
+		return;
+	__get_cpu_var(bh_accounting).ratelimit = 0;
+	for_each_online_cpu(i)
+		tot += per_cpu(bh_accounting, i).nr;
+	buffer_heads_over_limit = (tot > max_buffer_heads);
+}
+	
+struct buffer_head *alloc_buffer_head(gfp_t gfp_flags)
+{
+	struct buffer_head *ret = kmem_cache_alloc(bh_cachep, gfp_flags);
+	if (ret) {
+		INIT_LIST_HEAD(&ret->b_assoc_buffers);
+		get_cpu_var(bh_accounting).nr++;
+		recalc_bh_state();
+		put_cpu_var(bh_accounting);
+	}
+	return ret;
+}
+EXPORT_SYMBOL(alloc_buffer_head);
+
+void free_buffer_head(struct buffer_head *bh)
+{
+	BUG_ON(!list_empty(&bh->b_assoc_buffers));
+	kmem_cache_free(bh_cachep, bh);
+	get_cpu_var(bh_accounting).nr--;
+	recalc_bh_state();
+	put_cpu_var(bh_accounting);
+}
+EXPORT_SYMBOL(free_buffer_head);
+
+static void buffer_exit_cpu(int cpu)
+{
+	int i;
+	struct bh_lru *b = &per_cpu(bh_lrus, cpu);
+
+	for (i = 0; i < BH_LRU_SIZE; i++) {
+		brelse(b->bhs[i]);
+		b->bhs[i] = NULL;
+	}
+	get_cpu_var(bh_accounting).nr += per_cpu(bh_accounting, cpu).nr;
+	per_cpu(bh_accounting, cpu).nr = 0;
+	put_cpu_var(bh_accounting);
+}
+
+static int buffer_cpu_notify(struct notifier_block *self,
+			      unsigned long action, void *hcpu)
+{
+	if (action == CPU_DEAD || action == CPU_DEAD_FROZEN)
+		buffer_exit_cpu((unsigned long)hcpu);
+	return NOTIFY_OK;
+}
+
+/**
+ * bh_uptodate_or_lock - Test whether the buffer is uptodate
+ * @bh: struct buffer_head
+ *
+ * Return true if the buffer is up-to-date and false,
+ * with the buffer locked, if not.
+ */
+int bh_uptodate_or_lock(struct buffer_head *bh)
+{
+	if (!buffer_uptodate(bh)) {
+		lock_buffer(bh);
+		if (!buffer_uptodate(bh))
+			return 0;
+		unlock_buffer(bh);
+	}
+	return 1;
+}
+EXPORT_SYMBOL(bh_uptodate_or_lock);
+
+/**
+ * bh_submit_read - Submit a locked buffer for reading
+ * @bh: struct buffer_head
+ *
+ * Returns zero on success and -EIO on error.
+ */
+int bh_submit_read(struct buffer_head *bh)
+{
+	BUG_ON(!buffer_locked(bh));
+
+	if (buffer_uptodate(bh)) {
+		unlock_buffer(bh);
+		return 0;
+	}
+
+	get_bh(bh);
+	bh->b_end_io = end_buffer_read_sync;
+	submit_bh(READ, bh);
+	wait_on_buffer(bh);
+	if (buffer_uptodate(bh))
+		return 0;
+	return -EIO;
+}
+EXPORT_SYMBOL(bh_submit_read);
+
+static void
+init_buffer_head(void *data)
+{
+	struct buffer_head *bh = data;
+
+	memset(bh, 0, sizeof(*bh));
+	INIT_LIST_HEAD(&bh->b_assoc_buffers);
+}
+
+void __init buffer_init(void)
+{
+	int nrpages;
+
+	bh_cachep = kmem_cache_create("buffer_head",
+			sizeof(struct buffer_head), 0,
+				(SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
+				SLAB_MEM_SPREAD),
+				init_buffer_head);
+
+	/*
+	 * Limit the bh occupancy to 10% of ZONE_NORMAL
+	 */
+	nrpages = (nr_free_buffer_pages() * 10) / 100;
+	max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head));
+	hotcpu_notifier(buffer_cpu_notify, 0);
+}
+
+EXPORT_SYMBOL(__bforget);
+EXPORT_SYMBOL(__brelse);
+EXPORT_SYMBOL(__wait_on_buffer);
+EXPORT_SYMBOL(block_commit_write);
+EXPORT_SYMBOL(block_prepare_write);
+EXPORT_SYMBOL(block_page_mkwrite);
+EXPORT_SYMBOL(block_read_full_page);
+EXPORT_SYMBOL(block_sync_page);
+EXPORT_SYMBOL(block_truncate_page);
+EXPORT_SYMBOL(block_write_full_page);
+EXPORT_SYMBOL(cont_write_begin);
+EXPORT_SYMBOL(end_buffer_read_sync);
+EXPORT_SYMBOL(end_buffer_write_sync);
+EXPORT_SYMBOL(file_fsync);
+EXPORT_SYMBOL(fsync_bdev);
+EXPORT_SYMBOL(generic_block_bmap);
+EXPORT_SYMBOL(generic_cont_expand_simple);
+EXPORT_SYMBOL(init_buffer);
+EXPORT_SYMBOL(invalidate_bdev);
+EXPORT_SYMBOL(ll_rw_block);
+EXPORT_SYMBOL(mark_buffer_dirty);
+EXPORT_SYMBOL(submit_bh);
+EXPORT_SYMBOL(sync_dirty_buffer);
+EXPORT_SYMBOL(unlock_buffer);
diff --git a/libdde_linux26/lib/src/fs/.svn/text-base/char_dev.c.svn-base b/libdde_linux26/lib/src/fs/.svn/text-base/char_dev.c.svn-base
new file mode 100644
index 00000000..3b8e8b3d
--- /dev/null
+++ b/libdde_linux26/lib/src/fs/.svn/text-base/char_dev.c.svn-base
@@ -0,0 +1,572 @@
+/*
+ *  linux/fs/char_dev.c
+ *
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ */
+
+#include <linux/init.h>
+#include <linux/fs.h>
+#include <linux/kdev_t.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+
+#include <linux/major.h>
+#include <linux/errno.h>
+#include <linux/module.h>
+#include <linux/smp_lock.h>
+#include <linux/seq_file.h>
+
+#include <linux/kobject.h>
+#include <linux/kobj_map.h>
+#include <linux/cdev.h>
+#include <linux/mutex.h>
+#include <linux/backing-dev.h>
+
+#ifdef CONFIG_KMOD
+#include <linux/kmod.h>
+#endif
+#include "internal.h"
+
+#ifdef DDE_LINUX
+#include "local.h"
+#endif
+
+/*
+ * capabilities for /dev/mem, /dev/kmem and similar directly mappable character
+ * devices
+ * - permits shared-mmap for read, write and/or exec
+ * - does not permit private mmap in NOMMU mode (can't do COW)
+ * - no readahead or I/O queue unplugging required
+ */
+struct backing_dev_info directly_mappable_cdev_bdi = {
+	.capabilities	= (
+#ifdef CONFIG_MMU
+		/* permit private copies of the data to be taken */
+		BDI_CAP_MAP_COPY |
+#endif
+		/* permit direct mmap, for read, write or exec */
+		BDI_CAP_MAP_DIRECT |
+		BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP),
+};
+
+static struct kobj_map *cdev_map;
+
+static DEFINE_MUTEX(chrdevs_lock);
+
+static struct char_device_struct {
+	struct char_device_struct *next;
+	unsigned int major;
+	unsigned int baseminor;
+	int minorct;
+	char name[64];
+	struct cdev *cdev;		/* will die */
+} *chrdevs[CHRDEV_MAJOR_HASH_SIZE];
+
+/* index in the above */
+static inline int major_to_index(int major)
+{
+	return major % CHRDEV_MAJOR_HASH_SIZE;
+}
+
+#ifdef CONFIG_PROC_FS
+
+void chrdev_show(struct seq_file *f, off_t offset)
+{
+	struct char_device_struct *cd;
+
+	if (offset < CHRDEV_MAJOR_HASH_SIZE) {
+		mutex_lock(&chrdevs_lock);
+		for (cd = chrdevs[offset]; cd; cd = cd->next)
+			seq_printf(f, "%3d %s\n", cd->major, cd->name);
+		mutex_unlock(&chrdevs_lock);
+	}
+}
+
+#endif /* CONFIG_PROC_FS */
+
+/*
+ * Register a single major with a specified minor range.
+ *
+ * If major == 0 this functions will dynamically allocate a major and return
+ * its number.
+ *
+ * If major > 0 this function will attempt to reserve the passed range of
+ * minors and will return zero on success.
+ *
+ * Returns a -ve errno on failure.
+ */
+static struct char_device_struct *
+__register_chrdev_region(unsigned int major, unsigned int baseminor,
+			   int minorct, const char *name)
+{
+	struct char_device_struct *cd, **cp;
+	int ret = 0;
+	int i;
+
+	cd = kzalloc(sizeof(struct char_device_struct), GFP_KERNEL);
+	if (cd == NULL)
+		return ERR_PTR(-ENOMEM);
+
+	mutex_lock(&chrdevs_lock);
+
+	/* temporary */
+	if (major == 0) {
+		for (i = ARRAY_SIZE(chrdevs)-1; i > 0; i--) {
+			if (chrdevs[i] == NULL)
+				break;
+		}
+
+		if (i == 0) {
+			ret = -EBUSY;
+			goto out;
+		}
+		major = i;
+		ret = major;
+	}
+
+	cd->major = major;
+	cd->baseminor = baseminor;
+	cd->minorct = minorct;
+	strlcpy(cd->name, name, sizeof(cd->name));
+
+	i = major_to_index(major);
+
+	for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next)
+		if ((*cp)->major > major ||
+		    ((*cp)->major == major &&
+		     (((*cp)->baseminor >= baseminor) ||
+		      ((*cp)->baseminor + (*cp)->minorct > baseminor))))
+			break;
+
+	/* Check for overlapping minor ranges.  */
+	if (*cp && (*cp)->major == major) {
+		int old_min = (*cp)->baseminor;
+		int old_max = (*cp)->baseminor + (*cp)->minorct - 1;
+		int new_min = baseminor;
+		int new_max = baseminor + minorct - 1;
+
+		/* New driver overlaps from the left.  */
+		if (new_max >= old_min && new_max <= old_max) {
+			ret = -EBUSY;
+			goto out;
+		}
+
+		/* New driver overlaps from the right.  */
+		if (new_min <= old_max && new_min >= old_min) {
+			ret = -EBUSY;
+			goto out;
+		}
+	}
+
+	cd->next = *cp;
+	*cp = cd;
+	mutex_unlock(&chrdevs_lock);
+	return cd;
+out:
+	mutex_unlock(&chrdevs_lock);
+	kfree(cd);
+	return ERR_PTR(ret);
+}
+
+static struct char_device_struct *
+__unregister_chrdev_region(unsigned major, unsigned baseminor, int minorct)
+{
+	struct char_device_struct *cd = NULL, **cp;
+	int i = major_to_index(major);
+
+	mutex_lock(&chrdevs_lock);
+	for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next)
+		if ((*cp)->major == major &&
+		    (*cp)->baseminor == baseminor &&
+		    (*cp)->minorct == minorct)
+			break;
+	if (*cp) {
+		cd = *cp;
+		*cp = cd->next;
+	}
+	mutex_unlock(&chrdevs_lock);
+	return cd;
+}
+
+/**
+ * register_chrdev_region() - register a range of device numbers
+ * @from: the first in the desired range of device numbers; must include
+ *        the major number.
+ * @count: the number of consecutive device numbers required
+ * @name: the name of the device or driver.
+ *
+ * Return value is zero on success, a negative error code on failure.
+ */
+int register_chrdev_region(dev_t from, unsigned count, const char *name)
+{
+	struct char_device_struct *cd;
+	dev_t to = from + count;
+	dev_t n, next;
+
+	for (n = from; n < to; n = next) {
+		next = MKDEV(MAJOR(n)+1, 0);
+		if (next > to)
+			next = to;
+		cd = __register_chrdev_region(MAJOR(n), MINOR(n),
+			       next - n, name);
+		if (IS_ERR(cd))
+			goto fail;
+	}
+	return 0;
+fail:
+	to = n;
+	for (n = from; n < to; n = next) {
+		next = MKDEV(MAJOR(n)+1, 0);
+		kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n));
+	}
+	return PTR_ERR(cd);
+}
+
+/**
+ * alloc_chrdev_region() - register a range of char device numbers
+ * @dev: output parameter for first assigned number
+ * @baseminor: first of the requested range of minor numbers
+ * @count: the number of minor numbers required
+ * @name: the name of the associated device or driver
+ *
+ * Allocates a range of char device numbers.  The major number will be
+ * chosen dynamically, and returned (along with the first minor number)
+ * in @dev.  Returns zero or a negative error code.
+ */
+int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count,
+			const char *name)
+{
+	struct char_device_struct *cd;
+	cd = __register_chrdev_region(0, baseminor, count, name);
+	if (IS_ERR(cd))
+		return PTR_ERR(cd);
+	*dev = MKDEV(cd->major, cd->baseminor);
+	return 0;
+}
+
+/**
+ * register_chrdev() - Register a major number for character devices.
+ * @major: major device number or 0 for dynamic allocation
+ * @name: name of this range of devices
+ * @fops: file operations associated with this devices
+ *
+ * If @major == 0 this functions will dynamically allocate a major and return
+ * its number.
+ *
+ * If @major > 0 this function will attempt to reserve a device with the given
+ * major number and will return zero on success.
+ *
+ * Returns a -ve errno on failure.
+ *
+ * The name of this device has nothing to do with the name of the device in
+ * /dev. It only helps to keep track of the different owners of devices. If
+ * your module name has only one type of devices it's ok to use e.g. the name
+ * of the module here.
+ *
+ * This function registers a range of 256 minor numbers. The first minor number
+ * is 0.
+ */
+int register_chrdev(unsigned int major, const char *name,
+		    const struct file_operations *fops)
+{
+	struct char_device_struct *cd;
+	struct cdev *cdev;
+	char *s;
+	int err = -ENOMEM;
+
+	cd = __register_chrdev_region(major, 0, 256, name);
+	if (IS_ERR(cd))
+		return PTR_ERR(cd);
+	
+	cdev = cdev_alloc();
+	if (!cdev)
+		goto out2;
+
+	cdev->owner = fops->owner;
+	cdev->ops = fops;
+	kobject_set_name(&cdev->kobj, "%s", name);
+	for (s = strchr(kobject_name(&cdev->kobj),'/'); s; s = strchr(s, '/'))
+		*s = '!';
+		
+	err = cdev_add(cdev, MKDEV(cd->major, 0), 256);
+	if (err)
+		goto out;
+
+	cd->cdev = cdev;
+
+	return major ? 0 : cd->major;
+out:
+	kobject_put(&cdev->kobj);
+out2:
+	kfree(__unregister_chrdev_region(cd->major, 0, 256));
+	return err;
+}
+
+/**
+ * unregister_chrdev_region() - return a range of device numbers
+ * @from: the first in the range of numbers to unregister
+ * @count: the number of device numbers to unregister
+ *
+ * This function will unregister a range of @count device numbers,
+ * starting with @from.  The caller should normally be the one who
+ * allocated those numbers in the first place...
+ */
+void unregister_chrdev_region(dev_t from, unsigned count)
+{
+	dev_t to = from + count;
+	dev_t n, next;
+
+	for (n = from; n < to; n = next) {
+		next = MKDEV(MAJOR(n)+1, 0);
+		if (next > to)
+			next = to;
+		kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n));
+	}
+}
+
+void unregister_chrdev(unsigned int major, const char *name)
+{
+	struct char_device_struct *cd;
+	cd = __unregister_chrdev_region(major, 0, 256);
+	if (cd && cd->cdev)
+		cdev_del(cd->cdev);
+	kfree(cd);
+}
+
+static DEFINE_SPINLOCK(cdev_lock);
+
+static struct kobject *cdev_get(struct cdev *p)
+{
+	struct module *owner = p->owner;
+	struct kobject *kobj;
+
+	if (owner && !try_module_get(owner))
+		return NULL;
+	kobj = kobject_get(&p->kobj);
+	if (!kobj)
+		module_put(owner);
+	return kobj;
+}
+
+void cdev_put(struct cdev *p)
+{
+	if (p) {
+		struct module *owner = p->owner;
+		kobject_put(&p->kobj);
+		module_put(owner);
+	}
+}
+
+/*
+ * Called every time a character special file is opened
+ */
+static int chrdev_open(struct inode *inode, struct file *filp)
+{
+	struct cdev *p;
+	struct cdev *new = NULL;
+	int ret = 0;
+
+	spin_lock(&cdev_lock);
+	p = inode->i_cdev;
+	if (!p) {
+		struct kobject *kobj;
+		int idx;
+		spin_unlock(&cdev_lock);
+		kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx);
+		if (!kobj)
+			return -ENXIO;
+		new = container_of(kobj, struct cdev, kobj);
+		spin_lock(&cdev_lock);
+		/* Check i_cdev again in case somebody beat us to it while
+		   we dropped the lock. */
+		p = inode->i_cdev;
+		if (!p) {
+			inode->i_cdev = p = new;
+			inode->i_cindex = idx;
+			list_add(&inode->i_devices, &p->list);
+			new = NULL;
+		} else if (!cdev_get(p))
+			ret = -ENXIO;
+	} else if (!cdev_get(p))
+		ret = -ENXIO;
+	spin_unlock(&cdev_lock);
+	cdev_put(new);
+	if (ret)
+		return ret;
+
+	ret = -ENXIO;
+	filp->f_op = fops_get(p->ops);
+	if (!filp->f_op)
+		goto out_cdev_put;
+
+	if (filp->f_op->open) {
+		ret = filp->f_op->open(inode,filp);
+		if (ret)
+			goto out_cdev_put;
+	}
+
+	return 0;
+
+ out_cdev_put:
+	cdev_put(p);
+	return ret;
+}
+
+void cd_forget(struct inode *inode)
+{
+	spin_lock(&cdev_lock);
+	list_del_init(&inode->i_devices);
+	inode->i_cdev = NULL;
+	spin_unlock(&cdev_lock);
+}
+
+static void cdev_purge(struct cdev *cdev)
+{
+	spin_lock(&cdev_lock);
+	while (!list_empty(&cdev->list)) {
+		struct inode *inode;
+		inode = container_of(cdev->list.next, struct inode, i_devices);
+		list_del_init(&inode->i_devices);
+		inode->i_cdev = NULL;
+	}
+	spin_unlock(&cdev_lock);
+}
+
+/*
+ * Dummy default file-operations: the only thing this does
+ * is contain the open that then fills in the correct operations
+ * depending on the special file...
+ */
+const struct file_operations def_chr_fops = {
+	.open = chrdev_open,
+};
+
+static struct kobject *exact_match(dev_t dev, int *part, void *data)
+{
+	struct cdev *p = data;
+	return &p->kobj;
+}
+
+static int exact_lock(dev_t dev, void *data)
+{
+	struct cdev *p = data;
+	return cdev_get(p) ? 0 : -1;
+}
+
+/**
+ * cdev_add() - add a char device to the system
+ * @p: the cdev structure for the device
+ * @dev: the first device number for which this device is responsible
+ * @count: the number of consecutive minor numbers corresponding to this
+ *         device
+ *
+ * cdev_add() adds the device represented by @p to the system, making it
+ * live immediately.  A negative error code is returned on failure.
+ */
+int cdev_add(struct cdev *p, dev_t dev, unsigned count)
+{
+	p->dev = dev;
+	p->count = count;
+	return kobj_map(cdev_map, dev, count, NULL, exact_match, exact_lock, p);
+}
+
+static void cdev_unmap(dev_t dev, unsigned count)
+{
+	kobj_unmap(cdev_map, dev, count);
+}
+
+/**
+ * cdev_del() - remove a cdev from the system
+ * @p: the cdev structure to be removed
+ *
+ * cdev_del() removes @p from the system, possibly freeing the structure
+ * itself.
+ */
+void cdev_del(struct cdev *p)
+{
+	cdev_unmap(p->dev, p->count);
+	kobject_put(&p->kobj);
+}
+
+
+static void cdev_default_release(struct kobject *kobj)
+{
+	struct cdev *p = container_of(kobj, struct cdev, kobj);
+	cdev_purge(p);
+}
+
+static void cdev_dynamic_release(struct kobject *kobj)
+{
+	struct cdev *p = container_of(kobj, struct cdev, kobj);
+	cdev_purge(p);
+	kfree(p);
+}
+
+static struct kobj_type ktype_cdev_default = {
+	.release	= cdev_default_release,
+};
+
+static struct kobj_type ktype_cdev_dynamic = {
+	.release	= cdev_dynamic_release,
+};
+
+/**
+ * cdev_alloc() - allocate a cdev structure
+ *
+ * Allocates and returns a cdev structure, or NULL on failure.
+ */
+struct cdev *cdev_alloc(void)
+{
+	struct cdev *p = kzalloc(sizeof(struct cdev), GFP_KERNEL);
+	if (p) {
+		INIT_LIST_HEAD(&p->list);
+		kobject_init(&p->kobj, &ktype_cdev_dynamic);
+	}
+	return p;
+}
+
+/**
+ * cdev_init() - initialize a cdev structure
+ * @cdev: the structure to initialize
+ * @fops: the file_operations for this device
+ *
+ * Initializes @cdev, remembering @fops, making it ready to add to the
+ * system with cdev_add().
+ */
+void cdev_init(struct cdev *cdev, const struct file_operations *fops)
+{
+	memset(cdev, 0, sizeof *cdev);
+	INIT_LIST_HEAD(&cdev->list);
+	kobject_init(&cdev->kobj, &ktype_cdev_default);
+	cdev->ops = fops;
+}
+
+static struct kobject *base_probe(dev_t dev, int *part, void *data)
+{
+	if (request_module("char-major-%d-%d", MAJOR(dev), MINOR(dev)) > 0)
+		/* Make old-style 2.4 aliases work */
+		request_module("char-major-%d", MAJOR(dev));
+	return NULL;
+}
+
+void __init chrdev_init(void)
+{
+	cdev_map = kobj_map_init(base_probe, &chrdevs_lock);
+	bdi_init(&directly_mappable_cdev_bdi);
+}
+
+#ifndef LIBINPUT
+core_initcall(chrdev_init);
+#endif
+
+/* Let modules do char dev stuff */
+EXPORT_SYMBOL(register_chrdev_region);
+EXPORT_SYMBOL(unregister_chrdev_region);
+EXPORT_SYMBOL(alloc_chrdev_region);
+EXPORT_SYMBOL(cdev_init);
+EXPORT_SYMBOL(cdev_alloc);
+EXPORT_SYMBOL(cdev_del);
+EXPORT_SYMBOL(cdev_add);
+EXPORT_SYMBOL(register_chrdev);
+EXPORT_SYMBOL(unregister_chrdev);
+EXPORT_SYMBOL(directly_mappable_cdev_bdi);
diff --git a/libdde_linux26/lib/src/fs/block_dev.c b/libdde_linux26/lib/src/fs/block_dev.c
new file mode 100644
index 00000000..4c4c2f64
--- /dev/null
+++ b/libdde_linux26/lib/src/fs/block_dev.c
@@ -0,0 +1,1422 @@
+/*
+ *  linux/fs/block_dev.c
+ *
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ *  Copyright (C) 2001  Andrea Arcangeli <andrea@suse.de> SuSE
+ */
+
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/fcntl.h>
+#include <linux/slab.h>
+#include <linux/kmod.h>
+#include <linux/major.h>
+#include <linux/smp_lock.h>
+#include <linux/device_cgroup.h>
+#include <linux/highmem.h>
+#include <linux/blkdev.h>
+#include <linux/module.h>
+#include <linux/blkpg.h>
+#include <linux/buffer_head.h>
+#include <linux/writeback.h>
+#include <linux/mpage.h>
+#include <linux/mount.h>
+#include <linux/uio.h>
+#include <linux/namei.h>
+#include <linux/log2.h>
+#include <asm/uaccess.h>
+#include "internal.h"
+
+#ifdef DDE_LINUX
+#include "local.h"
+#endif
+
+struct bdev_inode {
+	struct block_device bdev;
+	struct inode vfs_inode;
+};
+
+static const struct address_space_operations def_blk_aops;
+
+static inline struct bdev_inode *BDEV_I(struct inode *inode)
+{
+	return container_of(inode, struct bdev_inode, vfs_inode);
+}
+
+inline struct block_device *I_BDEV(struct inode *inode)
+{
+	return &BDEV_I(inode)->bdev;
+}
+
+EXPORT_SYMBOL(I_BDEV);
+
+static sector_t max_block(struct block_device *bdev)
+{
+	sector_t retval = ~((sector_t)0);
+	loff_t sz = i_size_read(bdev->bd_inode);
+
+	if (sz) {
+		unsigned int size = block_size(bdev);
+		unsigned int sizebits = blksize_bits(size);
+		retval = (sz >> sizebits);
+	}
+	return retval;
+}
+
+/* Kill _all_ buffers and pagecache , dirty or not.. */
+static void kill_bdev(struct block_device *bdev)
+{
+	if (bdev->bd_inode->i_mapping->nrpages == 0)
+		return;
+	invalidate_bh_lrus();
+	truncate_inode_pages(bdev->bd_inode->i_mapping, 0);
+}	
+
+int set_blocksize(struct block_device *bdev, int size)
+{
+	/* Size must be a power of two, and between 512 and PAGE_SIZE */
+	if (size > PAGE_SIZE || size < 512 || !is_power_of_2(size))
+		return -EINVAL;
+
+	/* Size cannot be smaller than the size supported by the device */
+	if (size < bdev_hardsect_size(bdev))
+		return -EINVAL;
+
+	/* Don't change the size if it is same as current */
+	if (bdev->bd_block_size != size) {
+		sync_blockdev(bdev);
+		bdev->bd_block_size = size;
+		bdev->bd_inode->i_blkbits = blksize_bits(size);
+		kill_bdev(bdev);
+	}
+	return 0;
+}
+
+EXPORT_SYMBOL(set_blocksize);
+
+int sb_set_blocksize(struct super_block *sb, int size)
+{
+	if (set_blocksize(sb->s_bdev, size))
+		return 0;
+	/* If we get here, we know size is power of two
+	 * and it's value is between 512 and PAGE_SIZE */
+	sb->s_blocksize = size;
+	sb->s_blocksize_bits = blksize_bits(size);
+	return sb->s_blocksize;
+}
+
+EXPORT_SYMBOL(sb_set_blocksize);
+
+int sb_min_blocksize(struct super_block *sb, int size)
+{
+	int minsize = bdev_hardsect_size(sb->s_bdev);
+	if (size < minsize)
+		size = minsize;
+	return sb_set_blocksize(sb, size);
+}
+
+EXPORT_SYMBOL(sb_min_blocksize);
+
+static int
+blkdev_get_block(struct inode *inode, sector_t iblock,
+		struct buffer_head *bh, int create)
+{
+	if (iblock >= max_block(I_BDEV(inode))) {
+		if (create)
+			return -EIO;
+
+		/*
+		 * for reads, we're just trying to fill a partial page.
+		 * return a hole, they will have to call get_block again
+		 * before they can fill it, and they will get -EIO at that
+		 * time
+		 */
+		return 0;
+	}
+	bh->b_bdev = I_BDEV(inode);
+	bh->b_blocknr = iblock;
+	set_buffer_mapped(bh);
+	return 0;
+}
+
+static int
+blkdev_get_blocks(struct inode *inode, sector_t iblock,
+		struct buffer_head *bh, int create)
+{
+	sector_t end_block = max_block(I_BDEV(inode));
+	unsigned long max_blocks = bh->b_size >> inode->i_blkbits;
+
+	if ((iblock + max_blocks) > end_block) {
+		max_blocks = end_block - iblock;
+		if ((long)max_blocks <= 0) {
+			if (create)
+				return -EIO;	/* write fully beyond EOF */
+			/*
+			 * It is a read which is fully beyond EOF.  We return
+			 * a !buffer_mapped buffer
+			 */
+			max_blocks = 0;
+		}
+	}
+
+	bh->b_bdev = I_BDEV(inode);
+	bh->b_blocknr = iblock;
+	bh->b_size = max_blocks << inode->i_blkbits;
+	if (max_blocks)
+		set_buffer_mapped(bh);
+	return 0;
+}
+
+static ssize_t
+blkdev_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
+			loff_t offset, unsigned long nr_segs)
+{
+	struct file *file = iocb->ki_filp;
+	struct inode *inode = file->f_mapping->host;
+
+#ifndef DDE_LINUX
+	return blockdev_direct_IO_no_locking(rw, iocb, inode, I_BDEV(inode),
+				iov, offset, nr_segs, blkdev_get_blocks, NULL);
+#else
+	WARN_UNIMPL;
+	return 0;
+#endif /* DDE_LINUX */
+}
+
+static int blkdev_writepage(struct page *page, struct writeback_control *wbc)
+{
+	return block_write_full_page(page, blkdev_get_block, wbc);
+}
+
+static int blkdev_readpage(struct file * file, struct page * page)
+{
+	return block_read_full_page(page, blkdev_get_block);
+}
+
+static int blkdev_write_begin(struct file *file, struct address_space *mapping,
+			loff_t pos, unsigned len, unsigned flags,
+			struct page **pagep, void **fsdata)
+{
+	*pagep = NULL;
+	return block_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
+				blkdev_get_block);
+}
+
+static int blkdev_write_end(struct file *file, struct address_space *mapping,
+			loff_t pos, unsigned len, unsigned copied,
+			struct page *page, void *fsdata)
+{
+	int ret;
+	ret = block_write_end(file, mapping, pos, len, copied, page, fsdata);
+
+	unlock_page(page);
+	page_cache_release(page);
+
+	return ret;
+}
+
+/*
+ * private llseek:
+ * for a block special file file->f_path.dentry->d_inode->i_size is zero
+ * so we compute the size by hand (just as in block_read/write above)
+ */
+static loff_t block_llseek(struct file *file, loff_t offset, int origin)
+{
+	struct inode *bd_inode = file->f_mapping->host;
+	loff_t size;
+	loff_t retval;
+
+	mutex_lock(&bd_inode->i_mutex);
+	size = i_size_read(bd_inode);
+
+	switch (origin) {
+		case 2:
+			offset += size;
+			break;
+		case 1:
+			offset += file->f_pos;
+	}
+	retval = -EINVAL;
+	if (offset >= 0 && offset <= size) {
+		if (offset != file->f_pos) {
+			file->f_pos = offset;
+		}
+		retval = offset;
+	}
+	mutex_unlock(&bd_inode->i_mutex);
+	return retval;
+}
+	
+/*
+ *	Filp is never NULL; the only case when ->fsync() is called with
+ *	NULL first argument is nfsd_sync_dir() and that's not a directory.
+ */
+ 
+static int block_fsync(struct file *filp, struct dentry *dentry, int datasync)
+{
+	return sync_blockdev(I_BDEV(filp->f_mapping->host));
+}
+
+/*
+ * pseudo-fs
+ */
+
+static  __cacheline_aligned_in_smp DEFINE_SPINLOCK(bdev_lock);
+static struct kmem_cache * bdev_cachep __read_mostly;
+
+static struct inode *bdev_alloc_inode(struct super_block *sb)
+{
+	struct bdev_inode *ei = kmem_cache_alloc(bdev_cachep, GFP_KERNEL);
+	if (!ei)
+		return NULL;
+	return &ei->vfs_inode;
+}
+
+static void bdev_destroy_inode(struct inode *inode)
+{
+	struct bdev_inode *bdi = BDEV_I(inode);
+
+	bdi->bdev.bd_inode_backing_dev_info = NULL;
+	kmem_cache_free(bdev_cachep, bdi);
+}
+
+static void init_once(void *foo)
+{
+	struct bdev_inode *ei = (struct bdev_inode *) foo;
+	struct block_device *bdev = &ei->bdev;
+
+	memset(bdev, 0, sizeof(*bdev));
+	mutex_init(&bdev->bd_mutex);
+	sema_init(&bdev->bd_mount_sem, 1);
+	INIT_LIST_HEAD(&bdev->bd_inodes);
+	INIT_LIST_HEAD(&bdev->bd_list);
+#ifdef CONFIG_SYSFS
+	INIT_LIST_HEAD(&bdev->bd_holder_list);
+#endif
+	inode_init_once(&ei->vfs_inode);
+	/* Initialize mutex for freeze. */
+	mutex_init(&bdev->bd_fsfreeze_mutex);
+}
+
+static inline void __bd_forget(struct inode *inode)
+{
+	list_del_init(&inode->i_devices);
+	inode->i_bdev = NULL;
+	inode->i_mapping = &inode->i_data;
+}
+
+static void bdev_clear_inode(struct inode *inode)
+{
+	struct block_device *bdev = &BDEV_I(inode)->bdev;
+	struct list_head *p;
+	spin_lock(&bdev_lock);
+	while ( (p = bdev->bd_inodes.next) != &bdev->bd_inodes ) {
+		__bd_forget(list_entry(p, struct inode, i_devices));
+	}
+	list_del_init(&bdev->bd_list);
+	spin_unlock(&bdev_lock);
+}
+
+static const struct super_operations bdev_sops = {
+	.statfs = simple_statfs,
+	.alloc_inode = bdev_alloc_inode,
+	.destroy_inode = bdev_destroy_inode,
+	.drop_inode = generic_delete_inode,
+	.clear_inode = bdev_clear_inode,
+};
+
+static int bd_get_sb(struct file_system_type *fs_type,
+	int flags, const char *dev_name, void *data, struct vfsmount *mnt)
+{
+	return get_sb_pseudo(fs_type, "bdev:", &bdev_sops, 0x62646576, mnt);
+}
+
+static struct file_system_type bd_type = {
+	.name		= "bdev",
+	.get_sb		= bd_get_sb,
+	.kill_sb	= kill_anon_super,
+};
+
+struct super_block *blockdev_superblock __read_mostly;
+
+void __init bdev_cache_init(void)
+{
+	int err;
+	struct vfsmount *bd_mnt;
+
+	bdev_cachep = kmem_cache_create("bdev_cache", sizeof(struct bdev_inode),
+			0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
+				SLAB_MEM_SPREAD|SLAB_PANIC),
+			init_once);
+	err = register_filesystem(&bd_type);
+	if (err)
+		panic("Cannot register bdev pseudo-fs");
+	bd_mnt = kern_mount(&bd_type);
+	if (IS_ERR(bd_mnt))
+		panic("Cannot create bdev pseudo-fs");
+	blockdev_superblock = bd_mnt->mnt_sb;	/* For writeback */
+}
+
+/*
+ * Most likely _very_ bad one - but then it's hardly critical for small
+ * /dev and can be fixed when somebody will need really large one.
+ * Keep in mind that it will be fed through icache hash function too.
+ */
+static inline unsigned long hash(dev_t dev)
+{
+	return MAJOR(dev)+MINOR(dev);
+}
+
+static int bdev_test(struct inode *inode, void *data)
+{
+	return BDEV_I(inode)->bdev.bd_dev == *(dev_t *)data;
+}
+
+static int bdev_set(struct inode *inode, void *data)
+{
+	BDEV_I(inode)->bdev.bd_dev = *(dev_t *)data;
+	return 0;
+}
+
+static LIST_HEAD(all_bdevs);
+
+struct block_device *bdget(dev_t dev)
+{
+	struct block_device *bdev;
+	struct inode *inode;
+
+	printk_all_partitions();
+
+	inode = iget5_locked(blockdev_superblock, hash(dev),
+			bdev_test, bdev_set, &dev);
+
+	if (!inode)
+		return NULL;
+
+	bdev = &BDEV_I(inode)->bdev;
+
+	if (inode->i_state & I_NEW) {
+		bdev->bd_contains = NULL;
+		bdev->bd_inode = inode;
+		bdev->bd_block_size = (1 << inode->i_blkbits);
+		bdev->bd_part_count = 0;
+		bdev->bd_invalidated = 0;
+		inode->i_mode = S_IFBLK;
+		inode->i_rdev = dev;
+		inode->i_bdev = bdev;
+		inode->i_data.a_ops = &def_blk_aops;
+		mapping_set_gfp_mask(&inode->i_data, GFP_USER);
+		inode->i_data.backing_dev_info = &default_backing_dev_info;
+		spin_lock(&bdev_lock);
+		list_add(&bdev->bd_list, &all_bdevs);
+		spin_unlock(&bdev_lock);
+		unlock_new_inode(inode);
+	}
+	return bdev;
+}
+
+EXPORT_SYMBOL(bdget);
+
+long nr_blockdev_pages(void)
+{
+	struct block_device *bdev;
+	long ret = 0;
+	spin_lock(&bdev_lock);
+	list_for_each_entry(bdev, &all_bdevs, bd_list) {
+		ret += bdev->bd_inode->i_mapping->nrpages;
+	}
+	spin_unlock(&bdev_lock);
+	return ret;
+}
+
+void bdput(struct block_device *bdev)
+{
+	iput(bdev->bd_inode);
+}
+
+EXPORT_SYMBOL(bdput);
+ 
+static struct block_device *bd_acquire(struct inode *inode)
+{
+	struct block_device *bdev;
+
+	spin_lock(&bdev_lock);
+	bdev = inode->i_bdev;
+	if (bdev) {
+		atomic_inc(&bdev->bd_inode->i_count);
+		spin_unlock(&bdev_lock);
+		return bdev;
+	}
+	spin_unlock(&bdev_lock);
+
+	bdev = bdget(inode->i_rdev);
+	if (bdev) {
+		spin_lock(&bdev_lock);
+		if (!inode->i_bdev) {
+			/*
+			 * We take an additional bd_inode->i_count for inode,
+			 * and it's released in clear_inode() of inode.
+			 * So, we can access it via ->i_mapping always
+			 * without igrab().
+			 */
+			atomic_inc(&bdev->bd_inode->i_count);
+			inode->i_bdev = bdev;
+			inode->i_mapping = bdev->bd_inode->i_mapping;
+			list_add(&inode->i_devices, &bdev->bd_inodes);
+		}
+		spin_unlock(&bdev_lock);
+	}
+	return bdev;
+}
+
+/* Call when you free inode */
+
+void bd_forget(struct inode *inode)
+{
+	struct block_device *bdev = NULL;
+
+	spin_lock(&bdev_lock);
+	if (inode->i_bdev) {
+		if (!sb_is_blkdev_sb(inode->i_sb))
+			bdev = inode->i_bdev;
+		__bd_forget(inode);
+	}
+	spin_unlock(&bdev_lock);
+
+	if (bdev)
+		iput(bdev->bd_inode);
+}
+
+int bd_claim(struct block_device *bdev, void *holder)
+{
+	int res;
+	spin_lock(&bdev_lock);
+
+	/* first decide result */
+	if (bdev->bd_holder == holder)
+		res = 0;	 /* already a holder */
+	else if (bdev->bd_holder != NULL)
+		res = -EBUSY; 	 /* held by someone else */
+	else if (bdev->bd_contains == bdev)
+		res = 0;  	 /* is a whole device which isn't held */
+
+	else if (bdev->bd_contains->bd_holder == bd_claim)
+		res = 0; 	 /* is a partition of a device that is being partitioned */
+	else if (bdev->bd_contains->bd_holder != NULL)
+		res = -EBUSY;	 /* is a partition of a held device */
+	else
+		res = 0;	 /* is a partition of an un-held device */
+
+	/* now impose change */
+	if (res==0) {
+		/* note that for a whole device bd_holders
+		 * will be incremented twice, and bd_holder will
+		 * be set to bd_claim before being set to holder
+		 */
+		bdev->bd_contains->bd_holders ++;
+		bdev->bd_contains->bd_holder = bd_claim;
+		bdev->bd_holders++;
+		bdev->bd_holder = holder;
+	}
+	spin_unlock(&bdev_lock);
+	return res;
+}
+
+EXPORT_SYMBOL(bd_claim);
+
+void bd_release(struct block_device *bdev)
+{
+	spin_lock(&bdev_lock);
+	if (!--bdev->bd_contains->bd_holders)
+		bdev->bd_contains->bd_holder = NULL;
+	if (!--bdev->bd_holders)
+		bdev->bd_holder = NULL;
+	spin_unlock(&bdev_lock);
+}
+
+EXPORT_SYMBOL(bd_release);
+
+#ifdef CONFIG_SYSFS
+/*
+ * Functions for bd_claim_by_kobject / bd_release_from_kobject
+ *
+ *     If a kobject is passed to bd_claim_by_kobject()
+ *     and the kobject has a parent directory,
+ *     following symlinks are created:
+ *        o from the kobject to the claimed bdev
+ *        o from "holders" directory of the bdev to the parent of the kobject
+ *     bd_release_from_kobject() removes these symlinks.
+ *
+ *     Example:
+ *        If /dev/dm-0 maps to /dev/sda, kobject corresponding to
+ *        /sys/block/dm-0/slaves is passed to bd_claim_by_kobject(), then:
+ *           /sys/block/dm-0/slaves/sda --> /sys/block/sda
+ *           /sys/block/sda/holders/dm-0 --> /sys/block/dm-0
+ */
+
+static int add_symlink(struct kobject *from, struct kobject *to)
+{
+	if (!from || !to)
+		return 0;
+	return sysfs_create_link(from, to, kobject_name(to));
+}
+
+static void del_symlink(struct kobject *from, struct kobject *to)
+{
+	if (!from || !to)
+		return;
+	sysfs_remove_link(from, kobject_name(to));
+}
+
+/*
+ * 'struct bd_holder' contains pointers to kobjects symlinked by
+ * bd_claim_by_kobject.
+ * It's connected to bd_holder_list which is protected by bdev->bd_sem.
+ */
+struct bd_holder {
+	struct list_head list;	/* chain of holders of the bdev */
+	int count;		/* references from the holder */
+	struct kobject *sdir;	/* holder object, e.g. "/block/dm-0/slaves" */
+	struct kobject *hdev;	/* e.g. "/block/dm-0" */
+	struct kobject *hdir;	/* e.g. "/block/sda/holders" */
+	struct kobject *sdev;	/* e.g. "/block/sda" */
+};
+
+/*
+ * Get references of related kobjects at once.
+ * Returns 1 on success. 0 on failure.
+ *
+ * Should call bd_holder_release_dirs() after successful use.
+ */
+static int bd_holder_grab_dirs(struct block_device *bdev,
+			struct bd_holder *bo)
+{
+	if (!bdev || !bo)
+		return 0;
+
+	bo->sdir = kobject_get(bo->sdir);
+	if (!bo->sdir)
+		return 0;
+
+	bo->hdev = kobject_get(bo->sdir->parent);
+	if (!bo->hdev)
+		goto fail_put_sdir;
+
+	bo->sdev = kobject_get(&part_to_dev(bdev->bd_part)->kobj);
+	if (!bo->sdev)
+		goto fail_put_hdev;
+
+	bo->hdir = kobject_get(bdev->bd_part->holder_dir);
+	if (!bo->hdir)
+		goto fail_put_sdev;
+
+	return 1;
+
+fail_put_sdev:
+	kobject_put(bo->sdev);
+fail_put_hdev:
+	kobject_put(bo->hdev);
+fail_put_sdir:
+	kobject_put(bo->sdir);
+
+	return 0;
+}
+
+/* Put references of related kobjects at once. */
+static void bd_holder_release_dirs(struct bd_holder *bo)
+{
+	kobject_put(bo->hdir);
+	kobject_put(bo->sdev);
+	kobject_put(bo->hdev);
+	kobject_put(bo->sdir);
+}
+
+static struct bd_holder *alloc_bd_holder(struct kobject *kobj)
+{
+	struct bd_holder *bo;
+
+	bo = kzalloc(sizeof(*bo), GFP_KERNEL);
+	if (!bo)
+		return NULL;
+
+	bo->count = 1;
+	bo->sdir = kobj;
+
+	return bo;
+}
+
+static void free_bd_holder(struct bd_holder *bo)
+{
+	kfree(bo);
+}
+
+/**
+ * find_bd_holder - find matching struct bd_holder from the block device
+ *
+ * @bdev:	struct block device to be searched
+ * @bo:		target struct bd_holder
+ *
+ * Returns matching entry with @bo in @bdev->bd_holder_list.
+ * If found, increment the reference count and return the pointer.
+ * If not found, returns NULL.
+ */
+static struct bd_holder *find_bd_holder(struct block_device *bdev,
+					struct bd_holder *bo)
+{
+	struct bd_holder *tmp;
+
+	list_for_each_entry(tmp, &bdev->bd_holder_list, list)
+		if (tmp->sdir == bo->sdir) {
+			tmp->count++;
+			return tmp;
+		}
+
+	return NULL;
+}
+
+/**
+ * add_bd_holder - create sysfs symlinks for bd_claim() relationship
+ *
+ * @bdev:	block device to be bd_claimed
+ * @bo:		preallocated and initialized by alloc_bd_holder()
+ *
+ * Add @bo to @bdev->bd_holder_list, create symlinks.
+ *
+ * Returns 0 if symlinks are created.
+ * Returns -ve if something fails.
+ */
+static int add_bd_holder(struct block_device *bdev, struct bd_holder *bo)
+{
+	int err;
+
+	if (!bo)
+		return -EINVAL;
+
+	if (!bd_holder_grab_dirs(bdev, bo))
+		return -EBUSY;
+
+	err = add_symlink(bo->sdir, bo->sdev);
+	if (err)
+		return err;
+
+	err = add_symlink(bo->hdir, bo->hdev);
+	if (err) {
+		del_symlink(bo->sdir, bo->sdev);
+		return err;
+	}
+
+	list_add_tail(&bo->list, &bdev->bd_holder_list);
+	return 0;
+}
+
+/**
+ * del_bd_holder - delete sysfs symlinks for bd_claim() relationship
+ *
+ * @bdev:	block device to be bd_claimed
+ * @kobj:	holder's kobject
+ *
+ * If there is matching entry with @kobj in @bdev->bd_holder_list
+ * and no other bd_claim() from the same kobject,
+ * remove the struct bd_holder from the list, delete symlinks for it.
+ *
+ * Returns a pointer to the struct bd_holder when it's removed from the list
+ * and ready to be freed.
+ * Returns NULL if matching claim isn't found or there is other bd_claim()
+ * by the same kobject.
+ */
+static struct bd_holder *del_bd_holder(struct block_device *bdev,
+					struct kobject *kobj)
+{
+	struct bd_holder *bo;
+
+	list_for_each_entry(bo, &bdev->bd_holder_list, list) {
+		if (bo->sdir == kobj) {
+			bo->count--;
+			BUG_ON(bo->count < 0);
+			if (!bo->count) {
+				list_del(&bo->list);
+				del_symlink(bo->sdir, bo->sdev);
+				del_symlink(bo->hdir, bo->hdev);
+				bd_holder_release_dirs(bo);
+				return bo;
+			}
+			break;
+		}
+	}
+
+	return NULL;
+}
+
+/**
+ * bd_claim_by_kobject - bd_claim() with additional kobject signature
+ *
+ * @bdev:	block device to be claimed
+ * @holder:	holder's signature
+ * @kobj:	holder's kobject
+ *
+ * Do bd_claim() and if it succeeds, create sysfs symlinks between
+ * the bdev and the holder's kobject.
+ * Use bd_release_from_kobject() when relesing the claimed bdev.
+ *
+ * Returns 0 on success. (same as bd_claim())
+ * Returns errno on failure.
+ */
+static int bd_claim_by_kobject(struct block_device *bdev, void *holder,
+				struct kobject *kobj)
+{
+	int err;
+	struct bd_holder *bo, *found;
+
+	if (!kobj)
+		return -EINVAL;
+
+	bo = alloc_bd_holder(kobj);
+	if (!bo)
+		return -ENOMEM;
+
+	mutex_lock(&bdev->bd_mutex);
+
+	err = bd_claim(bdev, holder);
+	if (err)
+		goto fail;
+
+	found = find_bd_holder(bdev, bo);
+	if (found)
+		goto fail;
+
+	err = add_bd_holder(bdev, bo);
+	if (err)
+		bd_release(bdev);
+	else
+		bo = NULL;
+fail:
+	mutex_unlock(&bdev->bd_mutex);
+	free_bd_holder(bo);
+	return err;
+}
+
+/**
+ * bd_release_from_kobject - bd_release() with additional kobject signature
+ *
+ * @bdev:	block device to be released
+ * @kobj:	holder's kobject
+ *
+ * Do bd_release() and remove sysfs symlinks created by bd_claim_by_kobject().
+ */
+static void bd_release_from_kobject(struct block_device *bdev,
+					struct kobject *kobj)
+{
+	if (!kobj)
+		return;
+
+	mutex_lock(&bdev->bd_mutex);
+	bd_release(bdev);
+	free_bd_holder(del_bd_holder(bdev, kobj));
+	mutex_unlock(&bdev->bd_mutex);
+}
+
+/**
+ * bd_claim_by_disk - wrapper function for bd_claim_by_kobject()
+ *
+ * @bdev:	block device to be claimed
+ * @holder:	holder's signature
+ * @disk:	holder's gendisk
+ *
+ * Call bd_claim_by_kobject() with getting @disk->slave_dir.
+ */
+int bd_claim_by_disk(struct block_device *bdev, void *holder,
+			struct gendisk *disk)
+{
+	return bd_claim_by_kobject(bdev, holder, kobject_get(disk->slave_dir));
+}
+EXPORT_SYMBOL_GPL(bd_claim_by_disk);
+
+/**
+ * bd_release_from_disk - wrapper function for bd_release_from_kobject()
+ *
+ * @bdev:	block device to be claimed
+ * @disk:	holder's gendisk
+ *
+ * Call bd_release_from_kobject() and put @disk->slave_dir.
+ */
+void bd_release_from_disk(struct block_device *bdev, struct gendisk *disk)
+{
+	bd_release_from_kobject(bdev, disk->slave_dir);
+	kobject_put(disk->slave_dir);
+}
+EXPORT_SYMBOL_GPL(bd_release_from_disk);
+#endif
+
+/*
+ * Tries to open block device by device number.  Use it ONLY if you
+ * really do not have anything better - i.e. when you are behind a
+ * truly sucky interface and all you are given is a device number.  _Never_
+ * to be used for internal purposes.  If you ever need it - reconsider
+ * your API.
+ */
+struct block_device *open_by_devnum(dev_t dev, fmode_t mode)
+{
+	struct block_device *bdev = bdget(dev);
+	int err = -ENOMEM;
+	if (bdev)
+		err = blkdev_get(bdev, mode);
+	return err ? ERR_PTR(err) : bdev;
+}
+
+EXPORT_SYMBOL(open_by_devnum);
+
+/**
+ * flush_disk - invalidates all buffer-cache entries on a disk
+ *
+ * @bdev:      struct block device to be flushed
+ *
+ * Invalidates all buffer-cache entries on a disk. It should be called
+ * when a disk has been changed -- either by a media change or online
+ * resize.
+ */
+static void flush_disk(struct block_device *bdev)
+{
+	if (__invalidate_device(bdev)) {
+		char name[BDEVNAME_SIZE] = "";
+
+		if (bdev->bd_disk)
+			disk_name(bdev->bd_disk, 0, name);
+		printk(KERN_WARNING "VFS: busy inodes on changed media or "
+		       "resized disk %s\n", name);
+	}
+
+	if (!bdev->bd_disk)
+		return;
+	if (disk_partitionable(bdev->bd_disk))
+		bdev->bd_invalidated = 1;
+}
+
+/**
+ * check_disk_size_change - checks for disk size change and adjusts bdev size.
+ * @disk: struct gendisk to check
+ * @bdev: struct bdev to adjust.
+ *
+ * This routine checks to see if the bdev size does not match the disk size
+ * and adjusts it if it differs.
+ */
+void check_disk_size_change(struct gendisk *disk, struct block_device *bdev)
+{
+	loff_t disk_size, bdev_size;
+
+	disk_size = (loff_t)get_capacity(disk) << 9;
+	bdev_size = i_size_read(bdev->bd_inode);
+	if (disk_size != bdev_size) {
+		char name[BDEVNAME_SIZE];
+
+		disk_name(disk, 0, name);
+		printk(KERN_INFO
+		       "%s: detected capacity change from %lld to %lld\n",
+		       name, bdev_size, disk_size);
+		i_size_write(bdev->bd_inode, disk_size);
+		flush_disk(bdev);
+	}
+}
+EXPORT_SYMBOL(check_disk_size_change);
+
+/**
+ * revalidate_disk - wrapper for lower-level driver's revalidate_disk call-back
+ * @disk: struct gendisk to be revalidated
+ *
+ * This routine is a wrapper for lower-level driver's revalidate_disk
+ * call-backs.  It is used to do common pre and post operations needed
+ * for all revalidate_disk operations.
+ */
+int revalidate_disk(struct gendisk *disk)
+{
+	struct block_device *bdev;
+	int ret = 0;
+
+	if (disk->fops->revalidate_disk)
+		ret = disk->fops->revalidate_disk(disk);
+
+	bdev = bdget_disk(disk, 0);
+	if (!bdev)
+		return ret;
+
+	mutex_lock(&bdev->bd_mutex);
+	check_disk_size_change(disk, bdev);
+	mutex_unlock(&bdev->bd_mutex);
+	bdput(bdev);
+	return ret;
+}
+EXPORT_SYMBOL(revalidate_disk);
+
+/*
+ * This routine checks whether a removable media has been changed,
+ * and invalidates all buffer-cache-entries in that case. This
+ * is a relatively slow routine, so we have to try to minimize using
+ * it. Thus it is called only upon a 'mount' or 'open'. This
+ * is the best way of combining speed and utility, I think.
+ * People changing diskettes in the middle of an operation deserve
+ * to lose :-)
+ */
+int check_disk_change(struct block_device *bdev)
+{
+	struct gendisk *disk = bdev->bd_disk;
+	struct block_device_operations * bdops = disk->fops;
+
+	if (!bdops->media_changed)
+		return 0;
+	if (!bdops->media_changed(bdev->bd_disk))
+		return 0;
+
+	flush_disk(bdev);
+	if (bdops->revalidate_disk)
+		bdops->revalidate_disk(bdev->bd_disk);
+	return 1;
+}
+
+EXPORT_SYMBOL(check_disk_change);
+
+void bd_set_size(struct block_device *bdev, loff_t size)
+{
+	unsigned bsize = bdev_hardsect_size(bdev);
+
+	bdev->bd_inode->i_size = size;
+	while (bsize < PAGE_CACHE_SIZE) {
+		if (size & bsize)
+			break;
+		bsize <<= 1;
+	}
+	bdev->bd_block_size = bsize;
+	bdev->bd_inode->i_blkbits = blksize_bits(bsize);
+}
+EXPORT_SYMBOL(bd_set_size);
+
+static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part);
+
+/*
+ * bd_mutex locking:
+ *
+ *  mutex_lock(part->bd_mutex)
+ *    mutex_lock_nested(whole->bd_mutex, 1)
+ */
+
+static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
+{
+	struct gendisk *disk;
+	int ret;
+	int partno;
+	int perm = 0;
+
+	if (mode & FMODE_READ)
+		perm |= MAY_READ;
+	if (mode & FMODE_WRITE)
+		perm |= MAY_WRITE;
+	/*
+	 * hooks: /n/, see "layering violations".
+	 */
+	ret = devcgroup_inode_permission(bdev->bd_inode, perm);
+	if (ret != 0) {
+		bdput(bdev);
+		return ret;
+	}
+
+	lock_kernel();
+ restart:
+
+	ret = -ENXIO;
+	disk = get_gendisk(bdev->bd_dev, &partno);
+	if (!disk)
+		goto out_unlock_kernel;
+
+	mutex_lock_nested(&bdev->bd_mutex, for_part);
+	if (!bdev->bd_openers) {
+		bdev->bd_disk = disk;
+		bdev->bd_contains = bdev;
+		if (!partno) {
+			struct backing_dev_info *bdi;
+
+			ret = -ENXIO;
+			bdev->bd_part = disk_get_part(disk, partno);
+			if (!bdev->bd_part)
+				goto out_clear;
+
+			if (disk->fops->open) {
+				ret = disk->fops->open(bdev, mode);
+				if (ret == -ERESTARTSYS) {
+					/* Lost a race with 'disk' being
+					 * deleted, try again.
+					 * See md.c
+					 */
+					disk_put_part(bdev->bd_part);
+					bdev->bd_part = NULL;
+					module_put(disk->fops->owner);
+					put_disk(disk);
+					bdev->bd_disk = NULL;
+					mutex_unlock(&bdev->bd_mutex);
+					goto restart;
+				}
+				if (ret)
+					goto out_clear;
+			}
+			if (!bdev->bd_openers) {
+				bd_set_size(bdev,(loff_t)get_capacity(disk)<<9);
+				bdi = blk_get_backing_dev_info(bdev);
+				if (bdi == NULL)
+					bdi = &default_backing_dev_info;
+				bdev->bd_inode->i_data.backing_dev_info = bdi;
+			}
+			if (bdev->bd_invalidated)
+				rescan_partitions(disk, bdev);
+		} else {
+			struct block_device *whole;
+			whole = bdget_disk(disk, 0);
+			ret = -ENOMEM;
+			if (!whole)
+				goto out_clear;
+			BUG_ON(for_part);
+			ret = __blkdev_get(whole, mode, 1);
+			if (ret)
+				goto out_clear;
+			bdev->bd_contains = whole;
+			bdev->bd_inode->i_data.backing_dev_info =
+			   whole->bd_inode->i_data.backing_dev_info;
+			bdev->bd_part = disk_get_part(disk, partno);
+			if (!(disk->flags & GENHD_FL_UP) ||
+			    !bdev->bd_part || !bdev->bd_part->nr_sects) {
+				ret = -ENXIO;
+				goto out_clear;
+			}
+			bd_set_size(bdev, (loff_t)bdev->bd_part->nr_sects << 9);
+		}
+	} else {
+		put_disk(disk);
+		module_put(disk->fops->owner);
+		disk = NULL;
+		if (bdev->bd_contains == bdev) {
+			if (bdev->bd_disk->fops->open) {
+				ret = bdev->bd_disk->fops->open(bdev, mode);
+				if (ret)
+					goto out_unlock_bdev;
+			}
+			if (bdev->bd_invalidated)
+				rescan_partitions(bdev->bd_disk, bdev);
+		}
+	}
+	bdev->bd_openers++;
+	if (for_part)
+		bdev->bd_part_count++;
+	mutex_unlock(&bdev->bd_mutex);
+	unlock_kernel();
+	return 0;
+
+ out_clear:
+	disk_put_part(bdev->bd_part);
+	bdev->bd_disk = NULL;
+	bdev->bd_part = NULL;
+	bdev->bd_inode->i_data.backing_dev_info = &default_backing_dev_info;
+	if (bdev != bdev->bd_contains)
+		__blkdev_put(bdev->bd_contains, mode, 1);
+	bdev->bd_contains = NULL;
+ out_unlock_bdev:
+	mutex_unlock(&bdev->bd_mutex);
+ out_unlock_kernel:
+	unlock_kernel();
+
+	if (disk)
+		module_put(disk->fops->owner);
+	put_disk(disk);
+	bdput(bdev);
+
+	return ret;
+}
+
+int blkdev_get(struct block_device *bdev, fmode_t mode)
+{
+	return __blkdev_get(bdev, mode, 0);
+}
+EXPORT_SYMBOL(blkdev_get);
+
+static int blkdev_open(struct inode * inode, struct file * filp)
+{
+	struct block_device *bdev;
+	int res;
+
+	/*
+	 * Preserve backwards compatibility and allow large file access
+	 * even if userspace doesn't ask for it explicitly. Some mkfs
+	 * binary needs it. We might want to drop this workaround
+	 * during an unstable branch.
+	 */
+	filp->f_flags |= O_LARGEFILE;
+
+	if (filp->f_flags & O_NDELAY)
+		filp->f_mode |= FMODE_NDELAY;
+	if (filp->f_flags & O_EXCL)
+		filp->f_mode |= FMODE_EXCL;
+	if ((filp->f_flags & O_ACCMODE) == 3)
+		filp->f_mode |= FMODE_WRITE_IOCTL;
+
+	bdev = bd_acquire(inode);
+	if (bdev == NULL)
+		return -ENOMEM;
+
+	filp->f_mapping = bdev->bd_inode->i_mapping;
+
+	res = blkdev_get(bdev, filp->f_mode);
+	if (res)
+		return res;
+
+	if (filp->f_mode & FMODE_EXCL) {
+		res = bd_claim(bdev, filp);
+		if (res)
+			goto out_blkdev_put;
+	}
+
+	return 0;
+
+ out_blkdev_put:
+	blkdev_put(bdev, filp->f_mode);
+	return res;
+}
+
+static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
+{
+	int ret = 0;
+	struct gendisk *disk = bdev->bd_disk;
+	struct block_device *victim = NULL;
+
+	mutex_lock_nested(&bdev->bd_mutex, for_part);
+	lock_kernel();
+	if (for_part)
+		bdev->bd_part_count--;
+
+	if (!--bdev->bd_openers) {
+		sync_blockdev(bdev);
+		kill_bdev(bdev);
+	}
+	if (bdev->bd_contains == bdev) {
+		if (disk->fops->release)
+			ret = disk->fops->release(disk, mode);
+	}
+	if (!bdev->bd_openers) {
+		struct module *owner = disk->fops->owner;
+
+		put_disk(disk);
+		module_put(owner);
+		disk_put_part(bdev->bd_part);
+		bdev->bd_part = NULL;
+		bdev->bd_disk = NULL;
+		bdev->bd_inode->i_data.backing_dev_info = &default_backing_dev_info;
+		if (bdev != bdev->bd_contains)
+			victim = bdev->bd_contains;
+		bdev->bd_contains = NULL;
+	}
+	unlock_kernel();
+	mutex_unlock(&bdev->bd_mutex);
+	bdput(bdev);
+	if (victim)
+		__blkdev_put(victim, mode, 1);
+	return ret;
+}
+
+int blkdev_put(struct block_device *bdev, fmode_t mode)
+{
+	return __blkdev_put(bdev, mode, 0);
+}
+EXPORT_SYMBOL(blkdev_put);
+
+static int blkdev_close(struct inode * inode, struct file * filp)
+{
+	struct block_device *bdev = I_BDEV(filp->f_mapping->host);
+	if (bdev->bd_holder == filp)
+		bd_release(bdev);
+	return blkdev_put(bdev, filp->f_mode);
+}
+
+static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
+{
+	struct block_device *bdev = I_BDEV(file->f_mapping->host);
+	fmode_t mode = file->f_mode;
+
+	/*
+	 * O_NDELAY can be altered using fcntl(.., F_SETFL, ..), so we have
+	 * to updated it before every ioctl.
+	 */
+	if (file->f_flags & O_NDELAY)
+		mode |= FMODE_NDELAY;
+	else
+		mode &= ~FMODE_NDELAY;
+
+	return blkdev_ioctl(bdev, mode, cmd, arg);
+}
+
+/*
+ * Try to release a page associated with block device when the system
+ * is under memory pressure.
+ */
+static int blkdev_releasepage(struct page *page, gfp_t wait)
+{
+	struct super_block *super = BDEV_I(page->mapping->host)->bdev.bd_super;
+
+	if (super && super->s_op->bdev_try_to_free_page)
+		return super->s_op->bdev_try_to_free_page(super, page, wait);
+
+	return try_to_free_buffers(page);
+}
+
+static const struct address_space_operations def_blk_aops = {
+	.readpage	= blkdev_readpage,
+	.writepage	= blkdev_writepage,
+	.sync_page	= block_sync_page,
+	.write_begin	= blkdev_write_begin,
+	.write_end	= blkdev_write_end,
+	.writepages	= generic_writepages,
+	.releasepage	= blkdev_releasepage,
+	.direct_IO	= blkdev_direct_IO,
+};
+
+const struct file_operations def_blk_fops = {
+	.open		= blkdev_open,
+	.release	= blkdev_close,
+#ifndef DDE_LINUX
+	.llseek		= block_llseek,
+	.read		= do_sync_read,
+	.write		= do_sync_write,
+  	.aio_read	= generic_file_aio_read,
+  	.aio_write	= generic_file_aio_write_nolock,
+	.mmap		= generic_file_mmap,
+	.fsync		= block_fsync,
+	.unlocked_ioctl	= block_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl	= compat_blkdev_ioctl,
+#endif
+	.splice_read	= generic_file_splice_read,
+	.splice_write	= generic_file_splice_write,
+#endif /* DDE_LINUX */
+};
+
+int ioctl_by_bdev(struct block_device *bdev, unsigned cmd, unsigned long arg)
+{
+	int res;
+	mm_segment_t old_fs = get_fs();
+	set_fs(KERNEL_DS);
+	res = blkdev_ioctl(bdev, 0, cmd, arg);
+	set_fs(old_fs);
+	return res;
+}
+
+EXPORT_SYMBOL(ioctl_by_bdev);
+
+/**
+ * lookup_bdev  - lookup a struct block_device by name
+ * @pathname:	special file representing the block device
+ *
+ * Get a reference to the blockdevice at @pathname in the current
+ * namespace if possible and return it.  Return ERR_PTR(error)
+ * otherwise.
+ */
+struct block_device *lookup_bdev(const char *pathname)
+{
+	struct block_device *bdev;
+	struct inode *inode;
+	struct path path;
+	int error;
+
+	if (!pathname || !*pathname)
+		return ERR_PTR(-EINVAL);
+
+	error = kern_path(pathname, LOOKUP_FOLLOW, &path);
+	if (error)
+		return ERR_PTR(error);
+
+	inode = path.dentry->d_inode;
+	error = -ENOTBLK;
+	if (!S_ISBLK(inode->i_mode))
+		goto fail;
+	error = -EACCES;
+	if (path.mnt->mnt_flags & MNT_NODEV)
+		goto fail;
+	error = -ENOMEM;
+	bdev = bd_acquire(inode);
+	if (!bdev)
+		goto fail;
+out:
+	path_put(&path);
+	return bdev;
+fail:
+	bdev = ERR_PTR(error);
+	goto out;
+}
+EXPORT_SYMBOL(lookup_bdev);
+
+/**
+ * open_bdev_exclusive  -  open a block device by name and set it up for use
+ *
+ * @path:	special file representing the block device
+ * @mode:	FMODE_... combination to pass be used
+ * @holder:	owner for exclusion
+ *
+ * Open the blockdevice described by the special file at @path, claim it
+ * for the @holder.
+ */
+struct block_device *open_bdev_exclusive(const char *path, fmode_t mode, void *holder)
+{
+	struct block_device *bdev;
+	int error = 0;
+
+	bdev = lookup_bdev(path);
+	if (IS_ERR(bdev))
+		return bdev;
+
+	error = blkdev_get(bdev, mode);
+	if (error)
+		return ERR_PTR(error);
+	error = -EACCES;
+	if ((mode & FMODE_WRITE) && bdev_read_only(bdev))
+		goto blkdev_put;
+	error = bd_claim(bdev, holder);
+	if (error)
+		goto blkdev_put;
+
+	return bdev;
+	
+blkdev_put:
+	blkdev_put(bdev, mode);
+	return ERR_PTR(error);
+}
+
+EXPORT_SYMBOL(open_bdev_exclusive);
+
+/**
+ * close_bdev_exclusive  -  close a blockdevice opened by open_bdev_exclusive()
+ *
+ * @bdev:	blockdevice to close
+ * @mode:	mode, must match that used to open.
+ *
+ * This is the counterpart to open_bdev_exclusive().
+ */
+void close_bdev_exclusive(struct block_device *bdev, fmode_t mode)
+{
+	bd_release(bdev);
+	blkdev_put(bdev, mode);
+}
+
+EXPORT_SYMBOL(close_bdev_exclusive);
+
+int __invalidate_device(struct block_device *bdev)
+{
+	struct super_block *sb = get_super(bdev);
+	int res = 0;
+
+	if (sb) {
+		/*
+		 * no need to lock the super, get_super holds the
+		 * read mutex so the filesystem cannot go away
+		 * under us (->put_super runs with the write lock
+		 * hold).
+		 */
+		shrink_dcache_sb(sb);
+		res = invalidate_inodes(sb);
+		drop_super(sb);
+	}
+	invalidate_bdev(bdev);
+	return res;
+}
+EXPORT_SYMBOL(__invalidate_device);
diff --git a/libdde_linux26/lib/src/fs/buffer.c b/libdde_linux26/lib/src/fs/buffer.c
new file mode 100644
index 00000000..d3b1c445
--- /dev/null
+++ b/libdde_linux26/lib/src/fs/buffer.c
@@ -0,0 +1,3474 @@
+/*
+ *  linux/fs/buffer.c
+ *
+ *  Copyright (C) 1991, 1992, 2002  Linus Torvalds
+ */
+
+/*
+ * Start bdflush() with kernel_thread not syscall - Paul Gortmaker, 12/95
+ *
+ * Removed a lot of unnecessary code and simplified things now that
+ * the buffer cache isn't our primary cache - Andrew Tridgell 12/96
+ *
+ * Speed up hash, lru, and free list operations.  Use gfp() for allocating
+ * hash table, use SLAB cache for buffer heads. SMP threading.  -DaveM
+ *
+ * Added 32k buffer block sizes - these are required older ARM systems. - RMK
+ *
+ * async buffer flushing, 1999 Andrea Arcangeli <andrea@suse.de>
+ */
+
+#include <linux/kernel.h>
+#include <linux/syscalls.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/percpu.h>
+#include <linux/slab.h>
+#include <linux/capability.h>
+#include <linux/blkdev.h>
+#include <linux/file.h>
+#include <linux/quotaops.h>
+#include <linux/highmem.h>
+#include <linux/module.h>
+#include <linux/writeback.h>
+#include <linux/hash.h>
+#include <linux/suspend.h>
+#include <linux/buffer_head.h>
+#include <linux/task_io_accounting_ops.h>
+#include <linux/bio.h>
+#include <linux/notifier.h>
+#include <linux/cpu.h>
+#include <linux/bitops.h>
+#include <linux/mpage.h>
+#include <linux/bit_spinlock.h>
+
+static int fsync_buffers_list(spinlock_t *lock, struct list_head *list);
+
+#define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers)
+
+inline void
+init_buffer(struct buffer_head *bh, bh_end_io_t *handler, void *private)
+{
+	bh->b_end_io = handler;
+	bh->b_private = private;
+}
+
+static int sync_buffer(void *word)
+{
+	struct block_device *bd;
+	struct buffer_head *bh
+		= container_of(word, struct buffer_head, b_state);
+
+	smp_mb();
+	bd = bh->b_bdev;
+	if (bd)
+		blk_run_address_space(bd->bd_inode->i_mapping);
+	io_schedule();
+	return 0;
+}
+
+void __lock_buffer(struct buffer_head *bh)
+{
+	wait_on_bit_lock(&bh->b_state, BH_Lock, sync_buffer,
+							TASK_UNINTERRUPTIBLE);
+}
+EXPORT_SYMBOL(__lock_buffer);
+
+void unlock_buffer(struct buffer_head *bh)
+{
+	clear_bit_unlock(BH_Lock, &bh->b_state);
+	smp_mb__after_clear_bit();
+	wake_up_bit(&bh->b_state, BH_Lock);
+}
+
+/*
+ * Block until a buffer comes unlocked.  This doesn't stop it
+ * from becoming locked again - you have to lock it yourself
+ * if you want to preserve its state.
+ */
+void __wait_on_buffer(struct buffer_head * bh)
+{
+	wait_on_bit(&bh->b_state, BH_Lock, sync_buffer, TASK_UNINTERRUPTIBLE);
+}
+
+static void
+__clear_page_buffers(struct page *page)
+{
+	ClearPagePrivate(page);
+	set_page_private(page, 0);
+	page_cache_release(page);
+}
+
+
+static int quiet_error(struct buffer_head *bh)
+{
+	if (!test_bit(BH_Quiet, &bh->b_state) && printk_ratelimit())
+		return 0;
+	return 1;
+}
+
+
+static void buffer_io_error(struct buffer_head *bh)
+{
+	char b[BDEVNAME_SIZE];
+	printk(KERN_ERR "Buffer I/O error on device %s, logical block %Lu\n",
+			bdevname(bh->b_bdev, b),
+			(unsigned long long)bh->b_blocknr);
+}
+
+/*
+ * End-of-IO handler helper function which does not touch the bh after
+ * unlocking it.
+ * Note: unlock_buffer() sort-of does touch the bh after unlocking it, but
+ * a race there is benign: unlock_buffer() only use the bh's address for
+ * hashing after unlocking the buffer, so it doesn't actually touch the bh
+ * itself.
+ */
+static void __end_buffer_read_notouch(struct buffer_head *bh, int uptodate)
+{
+	if (uptodate) {
+		set_buffer_uptodate(bh);
+	} else {
+		/* This happens, due to failed READA attempts. */
+		clear_buffer_uptodate(bh);
+	}
+	unlock_buffer(bh);
+}
+
+/*
+ * Default synchronous end-of-IO handler..  Just mark it up-to-date and
+ * unlock the buffer. This is what ll_rw_block uses too.
+ */
+void end_buffer_read_sync(struct buffer_head *bh, int uptodate)
+{
+	__end_buffer_read_notouch(bh, uptodate);
+	put_bh(bh);
+}
+
+void end_buffer_write_sync(struct buffer_head *bh, int uptodate)
+{
+	char b[BDEVNAME_SIZE];
+
+	if (uptodate) {
+		set_buffer_uptodate(bh);
+	} else {
+		if (!buffer_eopnotsupp(bh) && !quiet_error(bh)) {
+			buffer_io_error(bh);
+			printk(KERN_WARNING "lost page write due to "
+					"I/O error on %s\n",
+				       bdevname(bh->b_bdev, b));
+		}
+		set_buffer_write_io_error(bh);
+		clear_buffer_uptodate(bh);
+	}
+	unlock_buffer(bh);
+	put_bh(bh);
+}
+
+/*
+ * Write out and wait upon all the dirty data associated with a block
+ * device via its mapping.  Does not take the superblock lock.
+ */
+int sync_blockdev(struct block_device *bdev)
+{
+#ifndef DDE_LINUX
+	int ret = 0;
+
+	if (bdev)
+		ret = filemap_write_and_wait(bdev->bd_inode->i_mapping);
+	return ret;
+#else
+	WARN_UNIMPL;
+	return 0;
+#endif /* DDE_LINUX */
+}
+EXPORT_SYMBOL(sync_blockdev);
+
+/*
+ * Write out and wait upon all dirty data associated with this
+ * device.   Filesystem data as well as the underlying block
+ * device.  Takes the superblock lock.
+ */
+int fsync_bdev(struct block_device *bdev)
+{
+#ifndef DDE_LINUX
+	struct super_block *sb = get_super(bdev);
+	if (sb) {
+		int res = fsync_super(sb);
+		drop_super(sb);
+		return res;
+	}
+	return sync_blockdev(bdev);
+#else
+	WARN_UNIMPL;
+	return -1;
+#endif
+}
+
+/**
+ * freeze_bdev  --  lock a filesystem and force it into a consistent state
+ * @bdev:	blockdevice to lock
+ *
+ * This takes the block device bd_mount_sem to make sure no new mounts
+ * happen on bdev until thaw_bdev() is called.
+ * If a superblock is found on this device, we take the s_umount semaphore
+ * on it to make sure nobody unmounts until the snapshot creation is done.
+ * The reference counter (bd_fsfreeze_count) guarantees that only the last
+ * unfreeze process can unfreeze the frozen filesystem actually when multiple
+ * freeze requests arrive simultaneously. It counts up in freeze_bdev() and
+ * count down in thaw_bdev(). When it becomes 0, thaw_bdev() will unfreeze
+ * actually.
+ */
+struct super_block *freeze_bdev(struct block_device *bdev)
+{
+	struct super_block *sb;
+	int error = 0;
+
+	mutex_lock(&bdev->bd_fsfreeze_mutex);
+	if (bdev->bd_fsfreeze_count > 0) {
+		bdev->bd_fsfreeze_count++;
+		sb = get_super(bdev);
+		mutex_unlock(&bdev->bd_fsfreeze_mutex);
+		return sb;
+	}
+	bdev->bd_fsfreeze_count++;
+
+	down(&bdev->bd_mount_sem);
+	sb = get_super(bdev);
+	if (sb && !(sb->s_flags & MS_RDONLY)) {
+		sb->s_frozen = SB_FREEZE_WRITE;
+		smp_wmb();
+
+		__fsync_super(sb);
+
+		sb->s_frozen = SB_FREEZE_TRANS;
+		smp_wmb();
+
+		sync_blockdev(sb->s_bdev);
+
+		if (sb->s_op->freeze_fs) {
+			error = sb->s_op->freeze_fs(sb);
+			if (error) {
+				printk(KERN_ERR
+					"VFS:Filesystem freeze failed\n");
+				sb->s_frozen = SB_UNFROZEN;
+				drop_super(sb);
+				up(&bdev->bd_mount_sem);
+				bdev->bd_fsfreeze_count--;
+				mutex_unlock(&bdev->bd_fsfreeze_mutex);
+				return ERR_PTR(error);
+			}
+		}
+	}
+
+	sync_blockdev(bdev);
+	mutex_unlock(&bdev->bd_fsfreeze_mutex);
+
+	return sb;	/* thaw_bdev releases s->s_umount and bd_mount_sem */
+}
+EXPORT_SYMBOL(freeze_bdev);
+
+/**
+ * thaw_bdev  -- unlock filesystem
+ * @bdev:	blockdevice to unlock
+ * @sb:		associated superblock
+ *
+ * Unlocks the filesystem and marks it writeable again after freeze_bdev().
+ */
+int thaw_bdev(struct block_device *bdev, struct super_block *sb)
+{
+	int error = 0;
+
+	mutex_lock(&bdev->bd_fsfreeze_mutex);
+	if (!bdev->bd_fsfreeze_count) {
+		mutex_unlock(&bdev->bd_fsfreeze_mutex);
+		return -EINVAL;
+	}
+
+	bdev->bd_fsfreeze_count--;
+	if (bdev->bd_fsfreeze_count > 0) {
+		if (sb)
+			drop_super(sb);
+		mutex_unlock(&bdev->bd_fsfreeze_mutex);
+		return 0;
+	}
+
+	if (sb) {
+		BUG_ON(sb->s_bdev != bdev);
+		if (!(sb->s_flags & MS_RDONLY)) {
+			if (sb->s_op->unfreeze_fs) {
+				error = sb->s_op->unfreeze_fs(sb);
+				if (error) {
+					printk(KERN_ERR
+						"VFS:Filesystem thaw failed\n");
+					sb->s_frozen = SB_FREEZE_TRANS;
+					bdev->bd_fsfreeze_count++;
+					mutex_unlock(&bdev->bd_fsfreeze_mutex);
+					return error;
+				}
+			}
+			sb->s_frozen = SB_UNFROZEN;
+			smp_wmb();
+			wake_up(&sb->s_wait_unfrozen);
+		}
+		drop_super(sb);
+	}
+
+	up(&bdev->bd_mount_sem);
+	mutex_unlock(&bdev->bd_fsfreeze_mutex);
+	return 0;
+}
+EXPORT_SYMBOL(thaw_bdev);
+
+/*
+ * Various filesystems appear to want __find_get_block to be non-blocking.
+ * But it's the page lock which protects the buffers.  To get around this,
+ * we get exclusion from try_to_free_buffers with the blockdev mapping's
+ * private_lock.
+ *
+ * Hack idea: for the blockdev mapping, i_bufferlist_lock contention
+ * may be quite high.  This code could TryLock the page, and if that
+ * succeeds, there is no need to take private_lock. (But if
+ * private_lock is contended then so is mapping->tree_lock).
+ */
+static struct buffer_head *
+__find_get_block_slow(struct block_device *bdev, sector_t block)
+{
+	struct inode *bd_inode = bdev->bd_inode;
+	struct address_space *bd_mapping = bd_inode->i_mapping;
+	struct buffer_head *ret = NULL;
+	pgoff_t index;
+	struct buffer_head *bh;
+	struct buffer_head *head;
+	struct page *page;
+	int all_mapped = 1;
+
+	index = block >> (PAGE_CACHE_SHIFT - bd_inode->i_blkbits);
+	page = find_get_page(bd_mapping, index);
+	if (!page)
+		goto out;
+
+	spin_lock(&bd_mapping->private_lock);
+	if (!page_has_buffers(page))
+		goto out_unlock;
+	head = page_buffers(page);
+	bh = head;
+	do {
+		if (bh->b_blocknr == block) {
+			ret = bh;
+			get_bh(bh);
+			goto out_unlock;
+		}
+		if (!buffer_mapped(bh))
+			all_mapped = 0;
+		bh = bh->b_this_page;
+	} while (bh != head);
+
+	/* we might be here because some of the buffers on this page are
+	 * not mapped.  This is due to various races between
+	 * file io on the block device and getblk.  It gets dealt with
+	 * elsewhere, don't buffer_error if we had some unmapped buffers
+	 */
+	if (all_mapped) {
+		printk("__find_get_block_slow() failed. "
+			"block=%llu, b_blocknr=%llu\n",
+			(unsigned long long)block,
+			(unsigned long long)bh->b_blocknr);
+		printk("b_state=0x%08lx, b_size=%zu\n",
+			bh->b_state, bh->b_size);
+		printk("device blocksize: %d\n", 1 << bd_inode->i_blkbits);
+	}
+out_unlock:
+	spin_unlock(&bd_mapping->private_lock);
+	page_cache_release(page);
+out:
+	return ret;
+}
+
+/* If invalidate_buffers() will trash dirty buffers, it means some kind
+   of fs corruption is going on. Trashing dirty data always imply losing
+   information that was supposed to be just stored on the physical layer
+   by the user.
+
+   Thus invalidate_buffers in general usage is not allwowed to trash
+   dirty buffers. For example ioctl(FLSBLKBUF) expects dirty data to
+   be preserved.  These buffers are simply skipped.
+  
+   We also skip buffers which are still in use.  For example this can
+   happen if a userspace program is reading the block device.
+
+   NOTE: In the case where the user removed a removable-media-disk even if
+   there's still dirty data not synced on disk (due a bug in the device driver
+   or due an error of the user), by not destroying the dirty buffers we could
+   generate corruption also on the next media inserted, thus a parameter is
+   necessary to handle this case in the most safe way possible (trying
+   to not corrupt also the new disk inserted with the data belonging to
+   the old now corrupted disk). Also for the ramdisk the natural thing
+   to do in order to release the ramdisk memory is to destroy dirty buffers.
+
+   These are two special cases. Normal usage imply the device driver
+   to issue a sync on the device (without waiting I/O completion) and
+   then an invalidate_buffers call that doesn't trash dirty buffers.
+
+   For handling cache coherency with the blkdev pagecache the 'update' case
+   is been introduced. It is needed to re-read from disk any pinned
+   buffer. NOTE: re-reading from disk is destructive so we can do it only
+   when we assume nobody is changing the buffercache under our I/O and when
+   we think the disk contains more recent information than the buffercache.
+   The update == 1 pass marks the buffers we need to update, the update == 2
+   pass does the actual I/O. */
+void invalidate_bdev(struct block_device *bdev)
+{
+	struct address_space *mapping = bdev->bd_inode->i_mapping;
+
+	if (mapping->nrpages == 0)
+		return;
+
+#ifndef DDE_LINUX
+	invalidate_bh_lrus();
+	invalidate_mapping_pages(mapping, 0, -1);
+#endif
+}
+
+/*
+ * Kick pdflush then try to free up some ZONE_NORMAL memory.
+ */
+static void free_more_memory(void)
+{
+	struct zone *zone;
+	int nid;
+
+#ifndef DDE_LINUX
+	wakeup_pdflush(1024);
+	yield();
+
+	for_each_online_node(nid) {
+		(void)first_zones_zonelist(node_zonelist(nid, GFP_NOFS),
+						gfp_zone(GFP_NOFS), NULL,
+						&zone);
+		if (zone)
+			try_to_free_pages(node_zonelist(nid, GFP_NOFS), 0,
+						GFP_NOFS);
+	}
+#else
+	WARN_UNIMPL;
+#endif
+}
+
+/*
+ * I/O completion handler for block_read_full_page() - pages
+ * which come unlocked at the end of I/O.
+ */
+static void end_buffer_async_read(struct buffer_head *bh, int uptodate)
+{
+	unsigned long flags;
+	struct buffer_head *first;
+	struct buffer_head *tmp;
+	struct page *page;
+	int page_uptodate = 1;
+
+	BUG_ON(!buffer_async_read(bh));
+
+	page = bh->b_page;
+	if (uptodate) {
+		set_buffer_uptodate(bh);
+	} else {
+		clear_buffer_uptodate(bh);
+		if (!quiet_error(bh))
+			buffer_io_error(bh);
+		SetPageError(page);
+	}
+
+	/*
+	 * Be _very_ careful from here on. Bad things can happen if
+	 * two buffer heads end IO at almost the same time and both
+	 * decide that the page is now completely done.
+	 */
+	first = page_buffers(page);
+	local_irq_save(flags);
+	bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
+	clear_buffer_async_read(bh);
+	unlock_buffer(bh);
+	tmp = bh;
+	do {
+		if (!buffer_uptodate(tmp))
+			page_uptodate = 0;
+		if (buffer_async_read(tmp)) {
+			BUG_ON(!buffer_locked(tmp));
+			goto still_busy;
+		}
+		tmp = tmp->b_this_page;
+	} while (tmp != bh);
+	bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
+	local_irq_restore(flags);
+
+	/*
+	 * If none of the buffers had errors and they are all
+	 * uptodate then we can set the page uptodate.
+	 */
+	if (page_uptodate && !PageError(page))
+		SetPageUptodate(page);
+	unlock_page(page);
+	return;
+
+still_busy:
+	bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
+	local_irq_restore(flags);
+	return;
+}
+
+/*
+ * Completion handler for block_write_full_page() - pages which are unlocked
+ * during I/O, and which have PageWriteback cleared upon I/O completion.
+ */
+static void end_buffer_async_write(struct buffer_head *bh, int uptodate)
+{
+	char b[BDEVNAME_SIZE];
+	unsigned long flags;
+	struct buffer_head *first;
+	struct buffer_head *tmp;
+	struct page *page;
+
+	BUG_ON(!buffer_async_write(bh));
+
+	page = bh->b_page;
+	if (uptodate) {
+		set_buffer_uptodate(bh);
+	} else {
+		if (!quiet_error(bh)) {
+			buffer_io_error(bh);
+			printk(KERN_WARNING "lost page write due to "
+					"I/O error on %s\n",
+			       bdevname(bh->b_bdev, b));
+		}
+		set_bit(AS_EIO, &page->mapping->flags);
+		set_buffer_write_io_error(bh);
+		clear_buffer_uptodate(bh);
+		SetPageError(page);
+	}
+
+	first = page_buffers(page);
+	local_irq_save(flags);
+	bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
+
+	clear_buffer_async_write(bh);
+	unlock_buffer(bh);
+	tmp = bh->b_this_page;
+	while (tmp != bh) {
+		if (buffer_async_write(tmp)) {
+			BUG_ON(!buffer_locked(tmp));
+			goto still_busy;
+		}
+		tmp = tmp->b_this_page;
+	}
+	bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
+	local_irq_restore(flags);
+	end_page_writeback(page);
+	return;
+
+still_busy:
+	bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
+	local_irq_restore(flags);
+	return;
+}
+
+/*
+ * If a page's buffers are under async readin (end_buffer_async_read
+ * completion) then there is a possibility that another thread of
+ * control could lock one of the buffers after it has completed
+ * but while some of the other buffers have not completed.  This
+ * locked buffer would confuse end_buffer_async_read() into not unlocking
+ * the page.  So the absence of BH_Async_Read tells end_buffer_async_read()
+ * that this buffer is not under async I/O.
+ *
+ * The page comes unlocked when it has no locked buffer_async buffers
+ * left.
+ *
+ * PageLocked prevents anyone starting new async I/O reads any of
+ * the buffers.
+ *
+ * PageWriteback is used to prevent simultaneous writeout of the same
+ * page.
+ *
+ * PageLocked prevents anyone from starting writeback of a page which is
+ * under read I/O (PageWriteback is only ever set against a locked page).
+ */
+static void mark_buffer_async_read(struct buffer_head *bh)
+{
+	bh->b_end_io = end_buffer_async_read;
+	set_buffer_async_read(bh);
+}
+
+void mark_buffer_async_write(struct buffer_head *bh)
+{
+	bh->b_end_io = end_buffer_async_write;
+	set_buffer_async_write(bh);
+}
+EXPORT_SYMBOL(mark_buffer_async_write);
+
+
+/*
+ * fs/buffer.c contains helper functions for buffer-backed address space's
+ * fsync functions.  A common requirement for buffer-based filesystems is
+ * that certain data from the backing blockdev needs to be written out for
+ * a successful fsync().  For example, ext2 indirect blocks need to be
+ * written back and waited upon before fsync() returns.
+ *
+ * The functions mark_buffer_inode_dirty(), fsync_inode_buffers(),
+ * inode_has_buffers() and invalidate_inode_buffers() are provided for the
+ * management of a list of dependent buffers at ->i_mapping->private_list.
+ *
+ * Locking is a little subtle: try_to_free_buffers() will remove buffers
+ * from their controlling inode's queue when they are being freed.  But
+ * try_to_free_buffers() will be operating against the *blockdev* mapping
+ * at the time, not against the S_ISREG file which depends on those buffers.
+ * So the locking for private_list is via the private_lock in the address_space
+ * which backs the buffers.  Which is different from the address_space 
+ * against which the buffers are listed.  So for a particular address_space,
+ * mapping->private_lock does *not* protect mapping->private_list!  In fact,
+ * mapping->private_list will always be protected by the backing blockdev's
+ * ->private_lock.
+ *
+ * Which introduces a requirement: all buffers on an address_space's
+ * ->private_list must be from the same address_space: the blockdev's.
+ *
+ * address_spaces which do not place buffers at ->private_list via these
+ * utility functions are free to use private_lock and private_list for
+ * whatever they want.  The only requirement is that list_empty(private_list)
+ * be true at clear_inode() time.
+ *
+ * FIXME: clear_inode should not call invalidate_inode_buffers().  The
+ * filesystems should do that.  invalidate_inode_buffers() should just go
+ * BUG_ON(!list_empty).
+ *
+ * FIXME: mark_buffer_dirty_inode() is a data-plane operation.  It should
+ * take an address_space, not an inode.  And it should be called
+ * mark_buffer_dirty_fsync() to clearly define why those buffers are being
+ * queued up.
+ *
+ * FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the
+ * list if it is already on a list.  Because if the buffer is on a list,
+ * it *must* already be on the right one.  If not, the filesystem is being
+ * silly.  This will save a ton of locking.  But first we have to ensure
+ * that buffers are taken *off* the old inode's list when they are freed
+ * (presumably in truncate).  That requires careful auditing of all
+ * filesystems (do it inside bforget()).  It could also be done by bringing
+ * b_inode back.
+ */
+
+/*
+ * The buffer's backing address_space's private_lock must be held
+ */
+static void __remove_assoc_queue(struct buffer_head *bh)
+{
+	list_del_init(&bh->b_assoc_buffers);
+	WARN_ON(!bh->b_assoc_map);
+	if (buffer_write_io_error(bh))
+		set_bit(AS_EIO, &bh->b_assoc_map->flags);
+	bh->b_assoc_map = NULL;
+}
+
+int inode_has_buffers(struct inode *inode)
+{
+	return !list_empty(&inode->i_data.private_list);
+}
+
+/*
+ * osync is designed to support O_SYNC io.  It waits synchronously for
+ * all already-submitted IO to complete, but does not queue any new
+ * writes to the disk.
+ *
+ * To do O_SYNC writes, just queue the buffer writes with ll_rw_block as
+ * you dirty the buffers, and then use osync_inode_buffers to wait for
+ * completion.  Any other dirty buffers which are not yet queued for
+ * write will not be flushed to disk by the osync.
+ */
+static int osync_buffers_list(spinlock_t *lock, struct list_head *list)
+{
+	struct buffer_head *bh;
+	struct list_head *p;
+	int err = 0;
+
+	spin_lock(lock);
+repeat:
+	list_for_each_prev(p, list) {
+		bh = BH_ENTRY(p);
+		if (buffer_locked(bh)) {
+			get_bh(bh);
+			spin_unlock(lock);
+			wait_on_buffer(bh);
+			if (!buffer_uptodate(bh))
+				err = -EIO;
+			brelse(bh);
+			spin_lock(lock);
+			goto repeat;
+		}
+	}
+	spin_unlock(lock);
+	return err;
+}
+
+/**
+ * sync_mapping_buffers - write out & wait upon a mapping's "associated" buffers
+ * @mapping: the mapping which wants those buffers written
+ *
+ * Starts I/O against the buffers at mapping->private_list, and waits upon
+ * that I/O.
+ *
+ * Basically, this is a convenience function for fsync().
+ * @mapping is a file or directory which needs those buffers to be written for
+ * a successful fsync().
+ */
+int sync_mapping_buffers(struct address_space *mapping)
+{
+	struct address_space *buffer_mapping = mapping->assoc_mapping;
+
+	if (buffer_mapping == NULL || list_empty(&mapping->private_list))
+		return 0;
+
+	return fsync_buffers_list(&buffer_mapping->private_lock,
+					&mapping->private_list);
+}
+EXPORT_SYMBOL(sync_mapping_buffers);
+
+/*
+ * Called when we've recently written block `bblock', and it is known that
+ * `bblock' was for a buffer_boundary() buffer.  This means that the block at
+ * `bblock + 1' is probably a dirty indirect block.  Hunt it down and, if it's
+ * dirty, schedule it for IO.  So that indirects merge nicely with their data.
+ */
+void write_boundary_block(struct block_device *bdev,
+			sector_t bblock, unsigned blocksize)
+{
+	struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize);
+	if (bh) {
+		if (buffer_dirty(bh))
+			ll_rw_block(WRITE, 1, &bh);
+		put_bh(bh);
+	}
+}
+
+void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode)
+{
+	struct address_space *mapping = inode->i_mapping;
+	struct address_space *buffer_mapping = bh->b_page->mapping;
+
+	mark_buffer_dirty(bh);
+	if (!mapping->assoc_mapping) {
+		mapping->assoc_mapping = buffer_mapping;
+	} else {
+		BUG_ON(mapping->assoc_mapping != buffer_mapping);
+	}
+	if (!bh->b_assoc_map) {
+		spin_lock(&buffer_mapping->private_lock);
+		list_move_tail(&bh->b_assoc_buffers,
+				&mapping->private_list);
+		bh->b_assoc_map = mapping;
+		spin_unlock(&buffer_mapping->private_lock);
+	}
+}
+EXPORT_SYMBOL(mark_buffer_dirty_inode);
+
+/*
+ * Mark the page dirty, and set it dirty in the radix tree, and mark the inode
+ * dirty.
+ *
+ * If warn is true, then emit a warning if the page is not uptodate and has
+ * not been truncated.
+ */
+static void __set_page_dirty(struct page *page,
+		struct address_space *mapping, int warn)
+{
+	spin_lock_irq(&mapping->tree_lock);
+	if (page->mapping) {	/* Race with truncate? */
+		WARN_ON_ONCE(warn && !PageUptodate(page));
+
+		if (mapping_cap_account_dirty(mapping)) {
+			__inc_zone_page_state(page, NR_FILE_DIRTY);
+			__inc_bdi_stat(mapping->backing_dev_info,
+					BDI_RECLAIMABLE);
+			task_dirty_inc(current);
+			task_io_account_write(PAGE_CACHE_SIZE);
+		}
+		radix_tree_tag_set(&mapping->page_tree,
+				page_index(page), PAGECACHE_TAG_DIRTY);
+	}
+	spin_unlock_irq(&mapping->tree_lock);
+	__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
+}
+
+/*
+ * Add a page to the dirty page list.
+ *
+ * It is a sad fact of life that this function is called from several places
+ * deeply under spinlocking.  It may not sleep.
+ *
+ * If the page has buffers, the uptodate buffers are set dirty, to preserve
+ * dirty-state coherency between the page and the buffers.  It the page does
+ * not have buffers then when they are later attached they will all be set
+ * dirty.
+ *
+ * The buffers are dirtied before the page is dirtied.  There's a small race
+ * window in which a writepage caller may see the page cleanness but not the
+ * buffer dirtiness.  That's fine.  If this code were to set the page dirty
+ * before the buffers, a concurrent writepage caller could clear the page dirty
+ * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean
+ * page on the dirty page list.
+ *
+ * We use private_lock to lock against try_to_free_buffers while using the
+ * page's buffer list.  Also use this to protect against clean buffers being
+ * added to the page after it was set dirty.
+ *
+ * FIXME: may need to call ->reservepage here as well.  That's rather up to the
+ * address_space though.
+ */
+int __set_page_dirty_buffers(struct page *page)
+{
+	int newly_dirty;
+	struct address_space *mapping = page_mapping(page);
+
+	if (unlikely(!mapping))
+		return !TestSetPageDirty(page);
+
+	spin_lock(&mapping->private_lock);
+	if (page_has_buffers(page)) {
+		struct buffer_head *head = page_buffers(page);
+		struct buffer_head *bh = head;
+
+		do {
+			set_buffer_dirty(bh);
+			bh = bh->b_this_page;
+		} while (bh != head);
+	}
+	newly_dirty = !TestSetPageDirty(page);
+	spin_unlock(&mapping->private_lock);
+
+	if (newly_dirty)
+		__set_page_dirty(page, mapping, 1);
+	return newly_dirty;
+}
+EXPORT_SYMBOL(__set_page_dirty_buffers);
+
+/*
+ * Write out and wait upon a list of buffers.
+ *
+ * We have conflicting pressures: we want to make sure that all
+ * initially dirty buffers get waited on, but that any subsequently
+ * dirtied buffers don't.  After all, we don't want fsync to last
+ * forever if somebody is actively writing to the file.
+ *
+ * Do this in two main stages: first we copy dirty buffers to a
+ * temporary inode list, queueing the writes as we go.  Then we clean
+ * up, waiting for those writes to complete.
+ * 
+ * During this second stage, any subsequent updates to the file may end
+ * up refiling the buffer on the original inode's dirty list again, so
+ * there is a chance we will end up with a buffer queued for write but
+ * not yet completed on that list.  So, as a final cleanup we go through
+ * the osync code to catch these locked, dirty buffers without requeuing
+ * any newly dirty buffers for write.
+ */
+static int fsync_buffers_list(spinlock_t *lock, struct list_head *list)
+{
+	struct buffer_head *bh;
+	struct list_head tmp;
+	struct address_space *mapping;
+	int err = 0, err2;
+
+	INIT_LIST_HEAD(&tmp);
+
+	spin_lock(lock);
+	while (!list_empty(list)) {
+		bh = BH_ENTRY(list->next);
+		mapping = bh->b_assoc_map;
+		__remove_assoc_queue(bh);
+		/* Avoid race with mark_buffer_dirty_inode() which does
+		 * a lockless check and we rely on seeing the dirty bit */
+		smp_mb();
+		if (buffer_dirty(bh) || buffer_locked(bh)) {
+			list_add(&bh->b_assoc_buffers, &tmp);
+			bh->b_assoc_map = mapping;
+			if (buffer_dirty(bh)) {
+				get_bh(bh);
+				spin_unlock(lock);
+				/*
+				 * Ensure any pending I/O completes so that
+				 * ll_rw_block() actually writes the current
+				 * contents - it is a noop if I/O is still in
+				 * flight on potentially older contents.
+				 */
+				ll_rw_block(SWRITE_SYNC, 1, &bh);
+				brelse(bh);
+				spin_lock(lock);
+			}
+		}
+	}
+
+	while (!list_empty(&tmp)) {
+		bh = BH_ENTRY(tmp.prev);
+		get_bh(bh);
+		mapping = bh->b_assoc_map;
+		__remove_assoc_queue(bh);
+		/* Avoid race with mark_buffer_dirty_inode() which does
+		 * a lockless check and we rely on seeing the dirty bit */
+		smp_mb();
+		if (buffer_dirty(bh)) {
+			list_add(&bh->b_assoc_buffers,
+				 &mapping->private_list);
+			bh->b_assoc_map = mapping;
+		}
+		spin_unlock(lock);
+		wait_on_buffer(bh);
+		if (!buffer_uptodate(bh))
+			err = -EIO;
+		brelse(bh);
+		spin_lock(lock);
+	}
+	
+	spin_unlock(lock);
+	err2 = osync_buffers_list(lock, list);
+	if (err)
+		return err;
+	else
+		return err2;
+}
+
+/*
+ * Invalidate any and all dirty buffers on a given inode.  We are
+ * probably unmounting the fs, but that doesn't mean we have already
+ * done a sync().  Just drop the buffers from the inode list.
+ *
+ * NOTE: we take the inode's blockdev's mapping's private_lock.  Which
+ * assumes that all the buffers are against the blockdev.  Not true
+ * for reiserfs.
+ */
+void invalidate_inode_buffers(struct inode *inode)
+{
+	if (inode_has_buffers(inode)) {
+		struct address_space *mapping = &inode->i_data;
+		struct list_head *list = &mapping->private_list;
+		struct address_space *buffer_mapping = mapping->assoc_mapping;
+
+		spin_lock(&buffer_mapping->private_lock);
+		while (!list_empty(list))
+			__remove_assoc_queue(BH_ENTRY(list->next));
+		spin_unlock(&buffer_mapping->private_lock);
+	}
+}
+EXPORT_SYMBOL(invalidate_inode_buffers);
+
+/*
+ * Remove any clean buffers from the inode's buffer list.  This is called
+ * when we're trying to free the inode itself.  Those buffers can pin it.
+ *
+ * Returns true if all buffers were removed.
+ */
+int remove_inode_buffers(struct inode *inode)
+{
+	int ret = 1;
+
+	if (inode_has_buffers(inode)) {
+		struct address_space *mapping = &inode->i_data;
+		struct list_head *list = &mapping->private_list;
+		struct address_space *buffer_mapping = mapping->assoc_mapping;
+
+		spin_lock(&buffer_mapping->private_lock);
+		while (!list_empty(list)) {
+			struct buffer_head *bh = BH_ENTRY(list->next);
+			if (buffer_dirty(bh)) {
+				ret = 0;
+				break;
+			}
+			__remove_assoc_queue(bh);
+		}
+		spin_unlock(&buffer_mapping->private_lock);
+	}
+	return ret;
+}
+
+/*
+ * Create the appropriate buffers when given a page for data area and
+ * the size of each buffer.. Use the bh->b_this_page linked list to
+ * follow the buffers created.  Return NULL if unable to create more
+ * buffers.
+ *
+ * The retry flag is used to differentiate async IO (paging, swapping)
+ * which may not fail from ordinary buffer allocations.
+ */
+struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
+		int retry)
+{
+	struct buffer_head *bh, *head;
+	long offset;
+
+try_again:
+	head = NULL;
+	offset = PAGE_SIZE;
+	while ((offset -= size) >= 0) {
+		bh = alloc_buffer_head(GFP_NOFS);
+		if (!bh)
+			goto no_grow;
+
+		bh->b_bdev = NULL;
+		bh->b_this_page = head;
+		bh->b_blocknr = -1;
+		head = bh;
+
+		bh->b_state = 0;
+		atomic_set(&bh->b_count, 0);
+		bh->b_private = NULL;
+		bh->b_size = size;
+
+		/* Link the buffer to its page */
+		set_bh_page(bh, page, offset);
+
+		init_buffer(bh, NULL, NULL);
+	}
+	return head;
+/*
+ * In case anything failed, we just free everything we got.
+ */
+no_grow:
+	if (head) {
+		do {
+			bh = head;
+			head = head->b_this_page;
+			free_buffer_head(bh);
+		} while (head);
+	}
+
+	/*
+	 * Return failure for non-async IO requests.  Async IO requests
+	 * are not allowed to fail, so we have to wait until buffer heads
+	 * become available.  But we don't want tasks sleeping with 
+	 * partially complete buffers, so all were released above.
+	 */
+	if (!retry)
+		return NULL;
+
+	/* We're _really_ low on memory. Now we just
+	 * wait for old buffer heads to become free due to
+	 * finishing IO.  Since this is an async request and
+	 * the reserve list is empty, we're sure there are 
+	 * async buffer heads in use.
+	 */
+	free_more_memory();
+	goto try_again;
+}
+EXPORT_SYMBOL_GPL(alloc_page_buffers);
+
+static inline void
+link_dev_buffers(struct page *page, struct buffer_head *head)
+{
+	struct buffer_head *bh, *tail;
+
+	bh = head;
+	do {
+		tail = bh;
+		bh = bh->b_this_page;
+	} while (bh);
+	tail->b_this_page = head;
+	attach_page_buffers(page, head);
+}
+
+/*
+ * Initialise the state of a blockdev page's buffers.
+ */ 
+static void
+init_page_buffers(struct page *page, struct block_device *bdev,
+			sector_t block, int size)
+{
+	struct buffer_head *head = page_buffers(page);
+	struct buffer_head *bh = head;
+	int uptodate = PageUptodate(page);
+
+	do {
+		if (!buffer_mapped(bh)) {
+			init_buffer(bh, NULL, NULL);
+			bh->b_bdev = bdev;
+			bh->b_blocknr = block;
+			if (uptodate)
+				set_buffer_uptodate(bh);
+			set_buffer_mapped(bh);
+		}
+		block++;
+		bh = bh->b_this_page;
+	} while (bh != head);
+}
+
+/*
+ * Create the page-cache page that contains the requested block.
+ *
+ * This is user purely for blockdev mappings.
+ */
+static struct page *
+grow_dev_page(struct block_device *bdev, sector_t block,
+		pgoff_t index, int size)
+{
+	struct inode *inode = bdev->bd_inode;
+	struct page *page;
+	struct buffer_head *bh;
+
+#ifdef DDE_LINUX
+	WARN_UNIMPL;
+	return NULL;
+#endif
+
+	page = find_or_create_page(inode->i_mapping, index,
+		(mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS)|__GFP_MOVABLE);
+	if (!page)
+		return NULL;
+
+	BUG_ON(!PageLocked(page));
+
+	if (page_has_buffers(page)) {
+		bh = page_buffers(page);
+		if (bh->b_size == size) {
+			init_page_buffers(page, bdev, block, size);
+			return page;
+		}
+		if (!try_to_free_buffers(page))
+			goto failed;
+	}
+
+	/*
+	 * Allocate some buffers for this page
+	 */
+	bh = alloc_page_buffers(page, size, 0);
+	if (!bh)
+		goto failed;
+
+	/*
+	 * Link the page to the buffers and initialise them.  Take the
+	 * lock to be atomic wrt __find_get_block(), which does not
+	 * run under the page lock.
+	 */
+	spin_lock(&inode->i_mapping->private_lock);
+	link_dev_buffers(page, bh);
+	init_page_buffers(page, bdev, block, size);
+	spin_unlock(&inode->i_mapping->private_lock);
+	return page;
+
+failed:
+	BUG();
+	unlock_page(page);
+	page_cache_release(page);
+	return NULL;
+}
+
+/*
+ * Create buffers for the specified block device block's page.  If
+ * that page was dirty, the buffers are set dirty also.
+ */
+static int
+grow_buffers(struct block_device *bdev, sector_t block, int size)
+{
+	struct page *page;
+	pgoff_t index;
+	int sizebits;
+
+	sizebits = -1;
+	do {
+		sizebits++;
+	} while ((size << sizebits) < PAGE_SIZE);
+
+	index = block >> sizebits;
+
+	/*
+	 * Check for a block which wants to lie outside our maximum possible
+	 * pagecache index.  (this comparison is done using sector_t types).
+	 */
+	if (unlikely(index != block >> sizebits)) {
+		char b[BDEVNAME_SIZE];
+
+		printk(KERN_ERR "%s: requested out-of-range block %llu for "
+			"device %s\n",
+			__func__, (unsigned long long)block,
+			bdevname(bdev, b));
+		return -EIO;
+	}
+	block = index << sizebits;
+	/* Create a page with the proper size buffers.. */
+	page = grow_dev_page(bdev, block, index, size);
+	if (!page)
+		return 0;
+	unlock_page(page);
+	page_cache_release(page);
+	return 1;
+}
+
+static struct buffer_head *
+__getblk_slow(struct block_device *bdev, sector_t block, int size)
+{
+	/* Size must be multiple of hard sectorsize */
+	if (unlikely(size & (bdev_hardsect_size(bdev)-1) ||
+			(size < 512 || size > PAGE_SIZE))) {
+		printk(KERN_ERR "getblk(): invalid block size %d requested\n",
+					size);
+		printk(KERN_ERR "hardsect size: %d\n",
+					bdev_hardsect_size(bdev));
+
+		dump_stack();
+		return NULL;
+	}
+
+	for (;;) {
+		struct buffer_head * bh;
+		int ret;
+
+		bh = __find_get_block(bdev, block, size);
+		if (bh)
+			return bh;
+
+		ret = grow_buffers(bdev, block, size);
+		if (ret < 0)
+			return NULL;
+		if (ret == 0)
+			free_more_memory();
+	}
+}
+
+/*
+ * The relationship between dirty buffers and dirty pages:
+ *
+ * Whenever a page has any dirty buffers, the page's dirty bit is set, and
+ * the page is tagged dirty in its radix tree.
+ *
+ * At all times, the dirtiness of the buffers represents the dirtiness of
+ * subsections of the page.  If the page has buffers, the page dirty bit is
+ * merely a hint about the true dirty state.
+ *
+ * When a page is set dirty in its entirety, all its buffers are marked dirty
+ * (if the page has buffers).
+ *
+ * When a buffer is marked dirty, its page is dirtied, but the page's other
+ * buffers are not.
+ *
+ * Also.  When blockdev buffers are explicitly read with bread(), they
+ * individually become uptodate.  But their backing page remains not
+ * uptodate - even if all of its buffers are uptodate.  A subsequent
+ * block_read_full_page() against that page will discover all the uptodate
+ * buffers, will set the page uptodate and will perform no I/O.
+ */
+
+/**
+ * mark_buffer_dirty - mark a buffer_head as needing writeout
+ * @bh: the buffer_head to mark dirty
+ *
+ * mark_buffer_dirty() will set the dirty bit against the buffer, then set its
+ * backing page dirty, then tag the page as dirty in its address_space's radix
+ * tree and then attach the address_space's inode to its superblock's dirty
+ * inode list.
+ *
+ * mark_buffer_dirty() is atomic.  It takes bh->b_page->mapping->private_lock,
+ * mapping->tree_lock and the global inode_lock.
+ */
+void mark_buffer_dirty(struct buffer_head *bh)
+{
+#ifndef DDE_LINUX
+	WARN_ON_ONCE(!buffer_uptodate(bh));
+
+	/*
+	 * Very *carefully* optimize the it-is-already-dirty case.
+	 *
+	 * Don't let the final "is it dirty" escape to before we
+	 * perhaps modified the buffer.
+	 */
+	if (buffer_dirty(bh)) {
+		smp_mb();
+		if (buffer_dirty(bh))
+			return;
+	}
+
+	if (!test_set_buffer_dirty(bh)) {
+		struct page *page = bh->b_page;
+		if (!TestSetPageDirty(page))
+			__set_page_dirty(page, page_mapping(page), 0);
+	}
+#else
+	WARN_UNIMPL;
+#endif
+}
+
+/*
+ * Decrement a buffer_head's reference count.  If all buffers against a page
+ * have zero reference count, are clean and unlocked, and if the page is clean
+ * and unlocked then try_to_free_buffers() may strip the buffers from the page
+ * in preparation for freeing it (sometimes, rarely, buffers are removed from
+ * a page but it ends up not being freed, and buffers may later be reattached).
+ */
+void __brelse(struct buffer_head * buf)
+{
+	if (atomic_read(&buf->b_count)) {
+		put_bh(buf);
+		return;
+	}
+	WARN(1, KERN_ERR "VFS: brelse: Trying to free free buffer\n");
+}
+
+/*
+ * bforget() is like brelse(), except it discards any
+ * potentially dirty data.
+ */
+void __bforget(struct buffer_head *bh)
+{
+	clear_buffer_dirty(bh);
+	if (bh->b_assoc_map) {
+		struct address_space *buffer_mapping = bh->b_page->mapping;
+
+		spin_lock(&buffer_mapping->private_lock);
+		list_del_init(&bh->b_assoc_buffers);
+		bh->b_assoc_map = NULL;
+		spin_unlock(&buffer_mapping->private_lock);
+	}
+	__brelse(bh);
+}
+
+static struct buffer_head *__bread_slow(struct buffer_head *bh)
+{
+	lock_buffer(bh);
+	if (buffer_uptodate(bh)) {
+		unlock_buffer(bh);
+		return bh;
+	} else {
+		get_bh(bh);
+		bh->b_end_io = end_buffer_read_sync;
+		submit_bh(READ, bh);
+		wait_on_buffer(bh);
+		if (buffer_uptodate(bh))
+			return bh;
+	}
+	brelse(bh);
+	return NULL;
+}
+
+/*
+ * Per-cpu buffer LRU implementation.  To reduce the cost of __find_get_block().
+ * The bhs[] array is sorted - newest buffer is at bhs[0].  Buffers have their
+ * refcount elevated by one when they're in an LRU.  A buffer can only appear
+ * once in a particular CPU's LRU.  A single buffer can be present in multiple
+ * CPU's LRUs at the same time.
+ *
+ * This is a transparent caching front-end to sb_bread(), sb_getblk() and
+ * sb_find_get_block().
+ *
+ * The LRUs themselves only need locking against invalidate_bh_lrus.  We use
+ * a local interrupt disable for that.
+ */
+
+#define BH_LRU_SIZE	8
+
+struct bh_lru {
+	struct buffer_head *bhs[BH_LRU_SIZE];
+};
+
+static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }};
+
+#ifdef CONFIG_SMP
+#define bh_lru_lock()	local_irq_disable()
+#define bh_lru_unlock()	local_irq_enable()
+#else
+#define bh_lru_lock()	preempt_disable()
+#define bh_lru_unlock()	preempt_enable()
+#endif
+
+static inline void check_irqs_on(void)
+{
+#ifdef irqs_disabled
+	BUG_ON(irqs_disabled());
+#endif
+}
+
+/*
+ * The LRU management algorithm is dopey-but-simple.  Sorry.
+ */
+static void bh_lru_install(struct buffer_head *bh)
+{
+	struct buffer_head *evictee = NULL;
+	struct bh_lru *lru;
+
+	check_irqs_on();
+	bh_lru_lock();
+	lru = &__get_cpu_var(bh_lrus);
+	if (lru->bhs[0] != bh) {
+		struct buffer_head *bhs[BH_LRU_SIZE];
+		int in;
+		int out = 0;
+
+		get_bh(bh);
+		bhs[out++] = bh;
+		for (in = 0; in < BH_LRU_SIZE; in++) {
+			struct buffer_head *bh2 = lru->bhs[in];
+
+			if (bh2 == bh) {
+				__brelse(bh2);
+			} else {
+				if (out >= BH_LRU_SIZE) {
+					BUG_ON(evictee != NULL);
+					evictee = bh2;
+				} else {
+					bhs[out++] = bh2;
+				}
+			}
+		}
+		while (out < BH_LRU_SIZE)
+			bhs[out++] = NULL;
+		memcpy(lru->bhs, bhs, sizeof(bhs));
+	}
+	bh_lru_unlock();
+
+	if (evictee)
+		__brelse(evictee);
+}
+
+/*
+ * Look up the bh in this cpu's LRU.  If it's there, move it to the head.
+ */
+static struct buffer_head *
+lookup_bh_lru(struct block_device *bdev, sector_t block, unsigned size)
+{
+	struct buffer_head *ret = NULL;
+	struct bh_lru *lru;
+	unsigned int i;
+
+	check_irqs_on();
+	bh_lru_lock();
+	lru = &__get_cpu_var(bh_lrus);
+	for (i = 0; i < BH_LRU_SIZE; i++) {
+		struct buffer_head *bh = lru->bhs[i];
+
+		if (bh && bh->b_bdev == bdev &&
+				bh->b_blocknr == block && bh->b_size == size) {
+			if (i) {
+				while (i) {
+					lru->bhs[i] = lru->bhs[i - 1];
+					i--;
+				}
+				lru->bhs[0] = bh;
+			}
+			get_bh(bh);
+			ret = bh;
+			break;
+		}
+	}
+	bh_lru_unlock();
+	return ret;
+}
+
+/*
+ * Perform a pagecache lookup for the matching buffer.  If it's there, refresh
+ * it in the LRU and mark it as accessed.  If it is not present then return
+ * NULL
+ */
+struct buffer_head *
+__find_get_block(struct block_device *bdev, sector_t block, unsigned size)
+{
+	struct buffer_head *bh = lookup_bh_lru(bdev, block, size);
+
+	if (bh == NULL) {
+		bh = __find_get_block_slow(bdev, block);
+		if (bh)
+			bh_lru_install(bh);
+	}
+	if (bh)
+		touch_buffer(bh);
+	return bh;
+}
+EXPORT_SYMBOL(__find_get_block);
+
+/*
+ * __getblk will locate (and, if necessary, create) the buffer_head
+ * which corresponds to the passed block_device, block and size. The
+ * returned buffer has its reference count incremented.
+ *
+ * __getblk() cannot fail - it just keeps trying.  If you pass it an
+ * illegal block number, __getblk() will happily return a buffer_head
+ * which represents the non-existent block.  Very weird.
+ *
+ * __getblk() will lock up the machine if grow_dev_page's try_to_free_buffers()
+ * attempt is failing.  FIXME, perhaps?
+ */
+struct buffer_head *
+__getblk(struct block_device *bdev, sector_t block, unsigned size)
+{
+	struct buffer_head *bh = __find_get_block(bdev, block, size);
+
+	might_sleep();
+	if (bh == NULL)
+		bh = __getblk_slow(bdev, block, size);
+	return bh;
+}
+EXPORT_SYMBOL(__getblk);
+
+/*
+ * Do async read-ahead on a buffer..
+ */
+void __breadahead(struct block_device *bdev, sector_t block, unsigned size)
+{
+	struct buffer_head *bh = __getblk(bdev, block, size);
+	if (likely(bh)) {
+		ll_rw_block(READA, 1, &bh);
+		brelse(bh);
+	}
+}
+EXPORT_SYMBOL(__breadahead);
+
+/**
+ *  __bread() - reads a specified block and returns the bh
+ *  @bdev: the block_device to read from
+ *  @block: number of block
+ *  @size: size (in bytes) to read
+ * 
+ *  Reads a specified block, and returns buffer head that contains it.
+ *  It returns NULL if the block was unreadable.
+ */
+struct buffer_head *
+__bread(struct block_device *bdev, sector_t block, unsigned size)
+{
+	struct buffer_head *bh = __getblk(bdev, block, size);
+
+	if (likely(bh) && !buffer_uptodate(bh))
+		bh = __bread_slow(bh);
+	return bh;
+}
+EXPORT_SYMBOL(__bread);
+
+/*
+ * invalidate_bh_lrus() is called rarely - but not only at unmount.
+ * This doesn't race because it runs in each cpu either in irq
+ * or with preempt disabled.
+ */
+static void invalidate_bh_lru(void *arg)
+{
+	struct bh_lru *b = &get_cpu_var(bh_lrus);
+	int i;
+
+	for (i = 0; i < BH_LRU_SIZE; i++) {
+		brelse(b->bhs[i]);
+		b->bhs[i] = NULL;
+	}
+	put_cpu_var(bh_lrus);
+}
+	
+void invalidate_bh_lrus(void)
+{
+#ifndef DDE_LINUX
+	on_each_cpu(invalidate_bh_lru, NULL, 1);
+#endif
+}
+EXPORT_SYMBOL_GPL(invalidate_bh_lrus);
+
+void set_bh_page(struct buffer_head *bh,
+		struct page *page, unsigned long offset)
+{
+	bh->b_page = page;
+	BUG_ON(offset >= PAGE_SIZE);
+	if (PageHighMem(page))
+		/*
+		 * This catches illegal uses and preserves the offset:
+		 */
+		bh->b_data = (char *)(0 + offset);
+	else
+		bh->b_data = page_address(page) + offset;
+}
+EXPORT_SYMBOL(set_bh_page);
+
+/*
+ * Called when truncating a buffer on a page completely.
+ */
+static void discard_buffer(struct buffer_head * bh)
+{
+	lock_buffer(bh);
+	clear_buffer_dirty(bh);
+	bh->b_bdev = NULL;
+	clear_buffer_mapped(bh);
+	clear_buffer_req(bh);
+	clear_buffer_new(bh);
+	clear_buffer_delay(bh);
+	clear_buffer_unwritten(bh);
+	unlock_buffer(bh);
+}
+
+/**
+ * block_invalidatepage - invalidate part of all of a buffer-backed page
+ *
+ * @page: the page which is affected
+ * @offset: the index of the truncation point
+ *
+ * block_invalidatepage() is called when all or part of the page has become
+ * invalidatedby a truncate operation.
+ *
+ * block_invalidatepage() does not have to release all buffers, but it must
+ * ensure that no dirty buffer is left outside @offset and that no I/O
+ * is underway against any of the blocks which are outside the truncation
+ * point.  Because the caller is about to free (and possibly reuse) those
+ * blocks on-disk.
+ */
+void block_invalidatepage(struct page *page, unsigned long offset)
+{
+	struct buffer_head *head, *bh, *next;
+	unsigned int curr_off = 0;
+
+	BUG_ON(!PageLocked(page));
+	if (!page_has_buffers(page))
+		goto out;
+
+	head = page_buffers(page);
+	bh = head;
+	do {
+		unsigned int next_off = curr_off + bh->b_size;
+		next = bh->b_this_page;
+
+		/*
+		 * is this block fully invalidated?
+		 */
+		if (offset <= curr_off)
+			discard_buffer(bh);
+		curr_off = next_off;
+		bh = next;
+	} while (bh != head);
+
+	/*
+	 * We release buffers only if the entire page is being invalidated.
+	 * The get_block cached value has been unconditionally invalidated,
+	 * so real IO is not possible anymore.
+	 */
+	if (offset == 0)
+		try_to_release_page(page, 0);
+out:
+	return;
+}
+EXPORT_SYMBOL(block_invalidatepage);
+
+/*
+ * We attach and possibly dirty the buffers atomically wrt
+ * __set_page_dirty_buffers() via private_lock.  try_to_free_buffers
+ * is already excluded via the page lock.
+ */
+void create_empty_buffers(struct page *page,
+			unsigned long blocksize, unsigned long b_state)
+{
+	struct buffer_head *bh, *head, *tail;
+
+	head = alloc_page_buffers(page, blocksize, 1);
+	bh = head;
+	do {
+		bh->b_state |= b_state;
+		tail = bh;
+		bh = bh->b_this_page;
+	} while (bh);
+	tail->b_this_page = head;
+
+	spin_lock(&page->mapping->private_lock);
+	if (PageUptodate(page) || PageDirty(page)) {
+		bh = head;
+		do {
+			if (PageDirty(page))
+				set_buffer_dirty(bh);
+			if (PageUptodate(page))
+				set_buffer_uptodate(bh);
+			bh = bh->b_this_page;
+		} while (bh != head);
+	}
+	attach_page_buffers(page, head);
+	spin_unlock(&page->mapping->private_lock);
+}
+EXPORT_SYMBOL(create_empty_buffers);
+
+/*
+ * We are taking a block for data and we don't want any output from any
+ * buffer-cache aliases starting from return from that function and
+ * until the moment when something will explicitly mark the buffer
+ * dirty (hopefully that will not happen until we will free that block ;-)
+ * We don't even need to mark it not-uptodate - nobody can expect
+ * anything from a newly allocated buffer anyway. We used to used
+ * unmap_buffer() for such invalidation, but that was wrong. We definitely
+ * don't want to mark the alias unmapped, for example - it would confuse
+ * anyone who might pick it with bread() afterwards...
+ *
+ * Also..  Note that bforget() doesn't lock the buffer.  So there can
+ * be writeout I/O going on against recently-freed buffers.  We don't
+ * wait on that I/O in bforget() - it's more efficient to wait on the I/O
+ * only if we really need to.  That happens here.
+ */
+void unmap_underlying_metadata(struct block_device *bdev, sector_t block)
+{
+	struct buffer_head *old_bh;
+
+	might_sleep();
+
+	old_bh = __find_get_block_slow(bdev, block);
+	if (old_bh) {
+		clear_buffer_dirty(old_bh);
+		wait_on_buffer(old_bh);
+		clear_buffer_req(old_bh);
+		__brelse(old_bh);
+	}
+}
+EXPORT_SYMBOL(unmap_underlying_metadata);
+
+/*
+ * NOTE! All mapped/uptodate combinations are valid:
+ *
+ *	Mapped	Uptodate	Meaning
+ *
+ *	No	No		"unknown" - must do get_block()
+ *	No	Yes		"hole" - zero-filled
+ *	Yes	No		"allocated" - allocated on disk, not read in
+ *	Yes	Yes		"valid" - allocated and up-to-date in memory.
+ *
+ * "Dirty" is valid only with the last case (mapped+uptodate).
+ */
+
+/*
+ * While block_write_full_page is writing back the dirty buffers under
+ * the page lock, whoever dirtied the buffers may decide to clean them
+ * again at any time.  We handle that by only looking at the buffer
+ * state inside lock_buffer().
+ *
+ * If block_write_full_page() is called for regular writeback
+ * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a
+ * locked buffer.   This only can happen if someone has written the buffer
+ * directly, with submit_bh().  At the address_space level PageWriteback
+ * prevents this contention from occurring.
+ */
+static int __block_write_full_page(struct inode *inode, struct page *page,
+			get_block_t *get_block, struct writeback_control *wbc)
+{
+	int err;
+	sector_t block;
+	sector_t last_block;
+	struct buffer_head *bh, *head;
+	const unsigned blocksize = 1 << inode->i_blkbits;
+	int nr_underway = 0;
+
+	BUG_ON(!PageLocked(page));
+
+	last_block = (i_size_read(inode) - 1) >> inode->i_blkbits;
+
+	if (!page_has_buffers(page)) {
+		create_empty_buffers(page, blocksize,
+					(1 << BH_Dirty)|(1 << BH_Uptodate));
+	}
+
+	/*
+	 * Be very careful.  We have no exclusion from __set_page_dirty_buffers
+	 * here, and the (potentially unmapped) buffers may become dirty at
+	 * any time.  If a buffer becomes dirty here after we've inspected it
+	 * then we just miss that fact, and the page stays dirty.
+	 *
+	 * Buffers outside i_size may be dirtied by __set_page_dirty_buffers;
+	 * handle that here by just cleaning them.
+	 */
+
+	block = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
+	head = page_buffers(page);
+	bh = head;
+
+	/*
+	 * Get all the dirty buffers mapped to disk addresses and
+	 * handle any aliases from the underlying blockdev's mapping.
+	 */
+	do {
+		if (block > last_block) {
+			/*
+			 * mapped buffers outside i_size will occur, because
+			 * this page can be outside i_size when there is a
+			 * truncate in progress.
+			 */
+			/*
+			 * The buffer was zeroed by block_write_full_page()
+			 */
+			clear_buffer_dirty(bh);
+			set_buffer_uptodate(bh);
+		} else if ((!buffer_mapped(bh) || buffer_delay(bh)) &&
+			   buffer_dirty(bh)) {
+			WARN_ON(bh->b_size != blocksize);
+			err = get_block(inode, block, bh, 1);
+			if (err)
+				goto recover;
+			clear_buffer_delay(bh);
+			if (buffer_new(bh)) {
+				/* blockdev mappings never come here */
+				clear_buffer_new(bh);
+				unmap_underlying_metadata(bh->b_bdev,
+							bh->b_blocknr);
+			}
+		}
+		bh = bh->b_this_page;
+		block++;
+	} while (bh != head);
+
+	do {
+		if (!buffer_mapped(bh))
+			continue;
+		/*
+		 * If it's a fully non-blocking write attempt and we cannot
+		 * lock the buffer then redirty the page.  Note that this can
+		 * potentially cause a busy-wait loop from pdflush and kswapd
+		 * activity, but those code paths have their own higher-level
+		 * throttling.
+		 */
+		if (wbc->sync_mode != WB_SYNC_NONE || !wbc->nonblocking) {
+			lock_buffer(bh);
+		} else if (!trylock_buffer(bh)) {
+			redirty_page_for_writepage(wbc, page);
+			continue;
+		}
+		if (test_clear_buffer_dirty(bh)) {
+			mark_buffer_async_write(bh);
+		} else {
+			unlock_buffer(bh);
+		}
+	} while ((bh = bh->b_this_page) != head);
+
+	/*
+	 * The page and its buffers are protected by PageWriteback(), so we can
+	 * drop the bh refcounts early.
+	 */
+	BUG_ON(PageWriteback(page));
+	set_page_writeback(page);
+
+	do {
+		struct buffer_head *next = bh->b_this_page;
+		if (buffer_async_write(bh)) {
+			submit_bh(WRITE, bh);
+			nr_underway++;
+		}
+		bh = next;
+	} while (bh != head);
+	unlock_page(page);
+
+	err = 0;
+done:
+	if (nr_underway == 0) {
+		/*
+		 * The page was marked dirty, but the buffers were
+		 * clean.  Someone wrote them back by hand with
+		 * ll_rw_block/submit_bh.  A rare case.
+		 */
+		end_page_writeback(page);
+
+		/*
+		 * The page and buffer_heads can be released at any time from
+		 * here on.
+		 */
+	}
+	return err;
+
+recover:
+	/*
+	 * ENOSPC, or some other error.  We may already have added some
+	 * blocks to the file, so we need to write these out to avoid
+	 * exposing stale data.
+	 * The page is currently locked and not marked for writeback
+	 */
+	bh = head;
+	/* Recovery: lock and submit the mapped buffers */
+	do {
+		if (buffer_mapped(bh) && buffer_dirty(bh) &&
+		    !buffer_delay(bh)) {
+			lock_buffer(bh);
+			mark_buffer_async_write(bh);
+		} else {
+			/*
+			 * The buffer may have been set dirty during
+			 * attachment to a dirty page.
+			 */
+			clear_buffer_dirty(bh);
+		}
+	} while ((bh = bh->b_this_page) != head);
+	SetPageError(page);
+	BUG_ON(PageWriteback(page));
+	mapping_set_error(page->mapping, err);
+	set_page_writeback(page);
+	do {
+		struct buffer_head *next = bh->b_this_page;
+		if (buffer_async_write(bh)) {
+			clear_buffer_dirty(bh);
+			submit_bh(WRITE, bh);
+			nr_underway++;
+		}
+		bh = next;
+	} while (bh != head);
+	unlock_page(page);
+	goto done;
+}
+
+/*
+ * If a page has any new buffers, zero them out here, and mark them uptodate
+ * and dirty so they'll be written out (in order to prevent uninitialised
+ * block data from leaking). And clear the new bit.
+ */
+void page_zero_new_buffers(struct page *page, unsigned from, unsigned to)
+{
+	unsigned int block_start, block_end;
+	struct buffer_head *head, *bh;
+
+	BUG_ON(!PageLocked(page));
+	if (!page_has_buffers(page))
+		return;
+
+	bh = head = page_buffers(page);
+	block_start = 0;
+	do {
+		block_end = block_start + bh->b_size;
+
+		if (buffer_new(bh)) {
+			if (block_end > from && block_start < to) {
+				if (!PageUptodate(page)) {
+					unsigned start, size;
+
+					start = max(from, block_start);
+					size = min(to, block_end) - start;
+
+					zero_user(page, start, size);
+					set_buffer_uptodate(bh);
+				}
+
+				clear_buffer_new(bh);
+				mark_buffer_dirty(bh);
+			}
+		}
+
+		block_start = block_end;
+		bh = bh->b_this_page;
+	} while (bh != head);
+}
+EXPORT_SYMBOL(page_zero_new_buffers);
+
+static int __block_prepare_write(struct inode *inode, struct page *page,
+		unsigned from, unsigned to, get_block_t *get_block)
+{
+	unsigned block_start, block_end;
+	sector_t block;
+	int err = 0;
+	unsigned blocksize, bbits;
+	struct buffer_head *bh, *head, *wait[2], **wait_bh=wait;
+
+	BUG_ON(!PageLocked(page));
+	BUG_ON(from > PAGE_CACHE_SIZE);
+	BUG_ON(to > PAGE_CACHE_SIZE);
+	BUG_ON(from > to);
+
+	blocksize = 1 << inode->i_blkbits;
+	if (!page_has_buffers(page))
+		create_empty_buffers(page, blocksize, 0);
+	head = page_buffers(page);
+
+	bbits = inode->i_blkbits;
+	block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits);
+
+	for(bh = head, block_start = 0; bh != head || !block_start;
+	    block++, block_start=block_end, bh = bh->b_this_page) {
+		block_end = block_start + blocksize;
+		if (block_end <= from || block_start >= to) {
+			if (PageUptodate(page)) {
+				if (!buffer_uptodate(bh))
+					set_buffer_uptodate(bh);
+			}
+			continue;
+		}
+		if (buffer_new(bh))
+			clear_buffer_new(bh);
+		if (!buffer_mapped(bh)) {
+			WARN_ON(bh->b_size != blocksize);
+			err = get_block(inode, block, bh, 1);
+			if (err)
+				break;
+			if (buffer_new(bh)) {
+				unmap_underlying_metadata(bh->b_bdev,
+							bh->b_blocknr);
+				if (PageUptodate(page)) {
+					clear_buffer_new(bh);
+					set_buffer_uptodate(bh);
+					mark_buffer_dirty(bh);
+					continue;
+				}
+				if (block_end > to || block_start < from)
+					zero_user_segments(page,
+						to, block_end,
+						block_start, from);
+				continue;
+			}
+		}
+		if (PageUptodate(page)) {
+			if (!buffer_uptodate(bh))
+				set_buffer_uptodate(bh);
+			continue; 
+		}
+		if (!buffer_uptodate(bh) && !buffer_delay(bh) &&
+		    !buffer_unwritten(bh) &&
+		     (block_start < from || block_end > to)) {
+			ll_rw_block(READ, 1, &bh);
+			*wait_bh++=bh;
+		}
+	}
+	/*
+	 * If we issued read requests - let them complete.
+	 */
+	while(wait_bh > wait) {
+		wait_on_buffer(*--wait_bh);
+		if (!buffer_uptodate(*wait_bh))
+			err = -EIO;
+	}
+	if (unlikely(err))
+		page_zero_new_buffers(page, from, to);
+	return err;
+}
+
+static int __block_commit_write(struct inode *inode, struct page *page,
+		unsigned from, unsigned to)
+{
+	unsigned block_start, block_end;
+	int partial = 0;
+	unsigned blocksize;
+	struct buffer_head *bh, *head;
+
+	blocksize = 1 << inode->i_blkbits;
+
+	for(bh = head = page_buffers(page), block_start = 0;
+	    bh != head || !block_start;
+	    block_start=block_end, bh = bh->b_this_page) {
+		block_end = block_start + blocksize;
+		if (block_end <= from || block_start >= to) {
+			if (!buffer_uptodate(bh))
+				partial = 1;
+		} else {
+			set_buffer_uptodate(bh);
+			mark_buffer_dirty(bh);
+		}
+		clear_buffer_new(bh);
+	}
+
+	/*
+	 * If this is a partial write which happened to make all buffers
+	 * uptodate then we can optimize away a bogus readpage() for
+	 * the next read(). Here we 'discover' whether the page went
+	 * uptodate as a result of this (potentially partial) write.
+	 */
+	if (!partial)
+		SetPageUptodate(page);
+	return 0;
+}
+
+/*
+ * block_write_begin takes care of the basic task of block allocation and
+ * bringing partial write blocks uptodate first.
+ *
+ * If *pagep is not NULL, then block_write_begin uses the locked page
+ * at *pagep rather than allocating its own. In this case, the page will
+ * not be unlocked or deallocated on failure.
+ */
+int block_write_begin(struct file *file, struct address_space *mapping,
+			loff_t pos, unsigned len, unsigned flags,
+			struct page **pagep, void **fsdata,
+			get_block_t *get_block)
+{
+#ifndef DDE_LINUX
+	struct inode *inode = mapping->host;
+	int status = 0;
+	struct page *page;
+	pgoff_t index;
+	unsigned start, end;
+	int ownpage = 0;
+
+	index = pos >> PAGE_CACHE_SHIFT;
+	start = pos & (PAGE_CACHE_SIZE - 1);
+	end = start + len;
+
+	page = *pagep;
+	if (page == NULL) {
+		ownpage = 1;
+		page = grab_cache_page_write_begin(mapping, index, flags);
+		if (!page) {
+			status = -ENOMEM;
+			goto out;
+		}
+		*pagep = page;
+	} else
+		BUG_ON(!PageLocked(page));
+
+	status = __block_prepare_write(inode, page, start, end, get_block);
+	if (unlikely(status)) {
+		ClearPageUptodate(page);
+
+		if (ownpage) {
+			unlock_page(page);
+			page_cache_release(page);
+			*pagep = NULL;
+
+#ifndef DDE_LINUX
+			/*
+			 * prepare_write() may have instantiated a few blocks
+			 * outside i_size.  Trim these off again. Don't need
+			 * i_size_read because we hold i_mutex.
+			 */
+			if (pos + len > inode->i_size)
+				vmtruncate(inode, inode->i_size);
+#endif
+		}
+	}
+
+out:
+	return status;
+#else
+	WARN_UNIMPL;
+	return -1;
+#endif
+}
+EXPORT_SYMBOL(block_write_begin);
+
+int block_write_end(struct file *file, struct address_space *mapping,
+			loff_t pos, unsigned len, unsigned copied,
+			struct page *page, void *fsdata)
+{
+	struct inode *inode = mapping->host;
+	unsigned start;
+
+	start = pos & (PAGE_CACHE_SIZE - 1);
+
+	if (unlikely(copied < len)) {
+		/*
+		 * The buffers that were written will now be uptodate, so we
+		 * don't have to worry about a readpage reading them and
+		 * overwriting a partial write. However if we have encountered
+		 * a short write and only partially written into a buffer, it
+		 * will not be marked uptodate, so a readpage might come in and
+		 * destroy our partial write.
+		 *
+		 * Do the simplest thing, and just treat any short write to a
+		 * non uptodate page as a zero-length write, and force the
+		 * caller to redo the whole thing.
+		 */
+		if (!PageUptodate(page))
+			copied = 0;
+
+		page_zero_new_buffers(page, start+copied, start+len);
+	}
+	flush_dcache_page(page);
+
+	/* This could be a short (even 0-length) commit */
+	__block_commit_write(inode, page, start, start+copied);
+
+	return copied;
+}
+EXPORT_SYMBOL(block_write_end);
+
+int generic_write_end(struct file *file, struct address_space *mapping,
+			loff_t pos, unsigned len, unsigned copied,
+			struct page *page, void *fsdata)
+{
+	struct inode *inode = mapping->host;
+	int i_size_changed = 0;
+
+	copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
+
+	/*
+	 * No need to use i_size_read() here, the i_size
+	 * cannot change under us because we hold i_mutex.
+	 *
+	 * But it's important to update i_size while still holding page lock:
+	 * page writeout could otherwise come in and zero beyond i_size.
+	 */
+	if (pos+copied > inode->i_size) {
+		i_size_write(inode, pos+copied);
+		i_size_changed = 1;
+	}
+
+	unlock_page(page);
+	page_cache_release(page);
+
+	/*
+	 * Don't mark the inode dirty under page lock. First, it unnecessarily
+	 * makes the holding time of page lock longer. Second, it forces lock
+	 * ordering of page lock and transaction start for journaling
+	 * filesystems.
+	 */
+	if (i_size_changed)
+		mark_inode_dirty(inode);
+
+	return copied;
+}
+EXPORT_SYMBOL(generic_write_end);
+
+/*
+ * block_is_partially_uptodate checks whether buffers within a page are
+ * uptodate or not.
+ *
+ * Returns true if all buffers which correspond to a file portion
+ * we want to read are uptodate.
+ */
+int block_is_partially_uptodate(struct page *page, read_descriptor_t *desc,
+					unsigned long from)
+{
+	struct inode *inode = page->mapping->host;
+	unsigned block_start, block_end, blocksize;
+	unsigned to;
+	struct buffer_head *bh, *head;
+	int ret = 1;
+
+	if (!page_has_buffers(page))
+		return 0;
+
+	blocksize = 1 << inode->i_blkbits;
+	to = min_t(unsigned, PAGE_CACHE_SIZE - from, desc->count);
+	to = from + to;
+	if (from < blocksize && to > PAGE_CACHE_SIZE - blocksize)
+		return 0;
+
+	head = page_buffers(page);
+	bh = head;
+	block_start = 0;
+	do {
+		block_end = block_start + blocksize;
+		if (block_end > from && block_start < to) {
+			if (!buffer_uptodate(bh)) {
+				ret = 0;
+				break;
+			}
+			if (block_end >= to)
+				break;
+		}
+		block_start = block_end;
+		bh = bh->b_this_page;
+	} while (bh != head);
+
+	return ret;
+}
+EXPORT_SYMBOL(block_is_partially_uptodate);
+
+/*
+ * Generic "read page" function for block devices that have the normal
+ * get_block functionality. This is most of the block device filesystems.
+ * Reads the page asynchronously --- the unlock_buffer() and
+ * set/clear_buffer_uptodate() functions propagate buffer state into the
+ * page struct once IO has completed.
+ */
+int block_read_full_page(struct page *page, get_block_t *get_block)
+{
+	struct inode *inode = page->mapping->host;
+	sector_t iblock, lblock;
+	struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE];
+	unsigned int blocksize;
+	int nr, i;
+	int fully_mapped = 1;
+
+	BUG_ON(!PageLocked(page));
+	blocksize = 1 << inode->i_blkbits;
+	if (!page_has_buffers(page))
+		create_empty_buffers(page, blocksize, 0);
+	head = page_buffers(page);
+
+	iblock = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
+	lblock = (i_size_read(inode)+blocksize-1) >> inode->i_blkbits;
+	bh = head;
+	nr = 0;
+	i = 0;
+
+	do {
+		if (buffer_uptodate(bh))
+			continue;
+
+		if (!buffer_mapped(bh)) {
+			int err = 0;
+
+			fully_mapped = 0;
+			if (iblock < lblock) {
+				WARN_ON(bh->b_size != blocksize);
+				err = get_block(inode, iblock, bh, 0);
+				if (err)
+					SetPageError(page);
+			}
+			if (!buffer_mapped(bh)) {
+				zero_user(page, i * blocksize, blocksize);
+				if (!err)
+					set_buffer_uptodate(bh);
+				continue;
+			}
+			/*
+			 * get_block() might have updated the buffer
+			 * synchronously
+			 */
+			if (buffer_uptodate(bh))
+				continue;
+		}
+		arr[nr++] = bh;
+	} while (i++, iblock++, (bh = bh->b_this_page) != head);
+
+	if (fully_mapped)
+		SetPageMappedToDisk(page);
+
+	if (!nr) {
+		/*
+		 * All buffers are uptodate - we can set the page uptodate
+		 * as well. But not if get_block() returned an error.
+		 */
+		if (!PageError(page))
+			SetPageUptodate(page);
+		unlock_page(page);
+		return 0;
+	}
+
+	/* Stage two: lock the buffers */
+	for (i = 0; i < nr; i++) {
+		bh = arr[i];
+		lock_buffer(bh);
+		mark_buffer_async_read(bh);
+	}
+
+	/*
+	 * Stage 3: start the IO.  Check for uptodateness
+	 * inside the buffer lock in case another process reading
+	 * the underlying blockdev brought it uptodate (the sct fix).
+	 */
+	for (i = 0; i < nr; i++) {
+		bh = arr[i];
+		if (buffer_uptodate(bh))
+			end_buffer_async_read(bh, 1);
+		else
+			submit_bh(READ, bh);
+	}
+	return 0;
+}
+
+/* utility function for filesystems that need to do work on expanding
+ * truncates.  Uses filesystem pagecache writes to allow the filesystem to
+ * deal with the hole.  
+ */
+int generic_cont_expand_simple(struct inode *inode, loff_t size)
+{
+	struct address_space *mapping = inode->i_mapping;
+	struct page *page;
+	void *fsdata;
+	unsigned long limit;
+	int err;
+
+	err = -EFBIG;
+        limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
+	if (limit != RLIM_INFINITY && size > (loff_t)limit) {
+		send_sig(SIGXFSZ, current, 0);
+		goto out;
+	}
+	if (size > inode->i_sb->s_maxbytes)
+		goto out;
+
+	err = pagecache_write_begin(NULL, mapping, size, 0,
+				AOP_FLAG_UNINTERRUPTIBLE|AOP_FLAG_CONT_EXPAND,
+				&page, &fsdata);
+	if (err)
+		goto out;
+
+	err = pagecache_write_end(NULL, mapping, size, 0, 0, page, fsdata);
+	BUG_ON(err > 0);
+
+out:
+	return err;
+}
+
+static int cont_expand_zero(struct file *file, struct address_space *mapping,
+			    loff_t pos, loff_t *bytes)
+{
+	struct inode *inode = mapping->host;
+	unsigned blocksize = 1 << inode->i_blkbits;
+	struct page *page;
+	void *fsdata;
+	pgoff_t index, curidx;
+	loff_t curpos;
+	unsigned zerofrom, offset, len;
+	int err = 0;
+
+	index = pos >> PAGE_CACHE_SHIFT;
+	offset = pos & ~PAGE_CACHE_MASK;
+
+	while (index > (curidx = (curpos = *bytes)>>PAGE_CACHE_SHIFT)) {
+		zerofrom = curpos & ~PAGE_CACHE_MASK;
+		if (zerofrom & (blocksize-1)) {
+			*bytes |= (blocksize-1);
+			(*bytes)++;
+		}
+		len = PAGE_CACHE_SIZE - zerofrom;
+
+		err = pagecache_write_begin(file, mapping, curpos, len,
+						AOP_FLAG_UNINTERRUPTIBLE,
+						&page, &fsdata);
+		if (err)
+			goto out;
+		zero_user(page, zerofrom, len);
+		err = pagecache_write_end(file, mapping, curpos, len, len,
+						page, fsdata);
+		if (err < 0)
+			goto out;
+		BUG_ON(err != len);
+		err = 0;
+
+		balance_dirty_pages_ratelimited(mapping);
+	}
+
+	/* page covers the boundary, find the boundary offset */
+	if (index == curidx) {
+		zerofrom = curpos & ~PAGE_CACHE_MASK;
+		/* if we will expand the thing last block will be filled */
+		if (offset <= zerofrom) {
+			goto out;
+		}
+		if (zerofrom & (blocksize-1)) {
+			*bytes |= (blocksize-1);
+			(*bytes)++;
+		}
+		len = offset - zerofrom;
+
+		err = pagecache_write_begin(file, mapping, curpos, len,
+						AOP_FLAG_UNINTERRUPTIBLE,
+						&page, &fsdata);
+		if (err)
+			goto out;
+		zero_user(page, zerofrom, len);
+		err = pagecache_write_end(file, mapping, curpos, len, len,
+						page, fsdata);
+		if (err < 0)
+			goto out;
+		BUG_ON(err != len);
+		err = 0;
+	}
+out:
+	return err;
+}
+
+/*
+ * For moronic filesystems that do not allow holes in file.
+ * We may have to extend the file.
+ */
+int cont_write_begin(struct file *file, struct address_space *mapping,
+			loff_t pos, unsigned len, unsigned flags,
+			struct page **pagep, void **fsdata,
+			get_block_t *get_block, loff_t *bytes)
+{
+	struct inode *inode = mapping->host;
+	unsigned blocksize = 1 << inode->i_blkbits;
+	unsigned zerofrom;
+	int err;
+
+	err = cont_expand_zero(file, mapping, pos, bytes);
+	if (err)
+		goto out;
+
+	zerofrom = *bytes & ~PAGE_CACHE_MASK;
+	if (pos+len > *bytes && zerofrom & (blocksize-1)) {
+		*bytes |= (blocksize-1);
+		(*bytes)++;
+	}
+
+	*pagep = NULL;
+	err = block_write_begin(file, mapping, pos, len,
+				flags, pagep, fsdata, get_block);
+out:
+	return err;
+}
+
+int block_prepare_write(struct page *page, unsigned from, unsigned to,
+			get_block_t *get_block)
+{
+	struct inode *inode = page->mapping->host;
+	int err = __block_prepare_write(inode, page, from, to, get_block);
+	if (err)
+		ClearPageUptodate(page);
+	return err;
+}
+
+int block_commit_write(struct page *page, unsigned from, unsigned to)
+{
+	struct inode *inode = page->mapping->host;
+	__block_commit_write(inode,page,from,to);
+	return 0;
+}
+
+/*
+ * block_page_mkwrite() is not allowed to change the file size as it gets
+ * called from a page fault handler when a page is first dirtied. Hence we must
+ * be careful to check for EOF conditions here. We set the page up correctly
+ * for a written page which means we get ENOSPC checking when writing into
+ * holes and correct delalloc and unwritten extent mapping on filesystems that
+ * support these features.
+ *
+ * We are not allowed to take the i_mutex here so we have to play games to
+ * protect against truncate races as the page could now be beyond EOF.  Because
+ * vmtruncate() writes the inode size before removing pages, once we have the
+ * page lock we can determine safely if the page is beyond EOF. If it is not
+ * beyond EOF, then the page is guaranteed safe against truncation until we
+ * unlock the page.
+ */
+int
+block_page_mkwrite(struct vm_area_struct *vma, struct page *page,
+		   get_block_t get_block)
+{
+	struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
+	unsigned long end;
+	loff_t size;
+	int ret = -EINVAL;
+
+	lock_page(page);
+	size = i_size_read(inode);
+	if ((page->mapping != inode->i_mapping) ||
+	    (page_offset(page) > size)) {
+		/* page got truncated out from underneath us */
+		goto out_unlock;
+	}
+
+	/* page is wholly or partially inside EOF */
+	if (((page->index + 1) << PAGE_CACHE_SHIFT) > size)
+		end = size & ~PAGE_CACHE_MASK;
+	else
+		end = PAGE_CACHE_SIZE;
+
+	ret = block_prepare_write(page, 0, end, get_block);
+	if (!ret)
+		ret = block_commit_write(page, 0, end);
+
+out_unlock:
+	unlock_page(page);
+	return ret;
+}
+
+/*
+ * nobh_write_begin()'s prereads are special: the buffer_heads are freed
+ * immediately, while under the page lock.  So it needs a special end_io
+ * handler which does not touch the bh after unlocking it.
+ */
+static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate)
+{
+	__end_buffer_read_notouch(bh, uptodate);
+}
+
+/*
+ * Attach the singly-linked list of buffers created by nobh_write_begin, to
+ * the page (converting it to circular linked list and taking care of page
+ * dirty races).
+ */
+static void attach_nobh_buffers(struct page *page, struct buffer_head *head)
+{
+	struct buffer_head *bh;
+
+	BUG_ON(!PageLocked(page));
+
+	spin_lock(&page->mapping->private_lock);
+	bh = head;
+	do {
+		if (PageDirty(page))
+			set_buffer_dirty(bh);
+		if (!bh->b_this_page)
+			bh->b_this_page = head;
+		bh = bh->b_this_page;
+	} while (bh != head);
+	attach_page_buffers(page, head);
+	spin_unlock(&page->mapping->private_lock);
+}
+
+/*
+ * On entry, the page is fully not uptodate.
+ * On exit the page is fully uptodate in the areas outside (from,to)
+ */
+int nobh_write_begin(struct file *file, struct address_space *mapping,
+			loff_t pos, unsigned len, unsigned flags,
+			struct page **pagep, void **fsdata,
+			get_block_t *get_block)
+{
+	struct inode *inode = mapping->host;
+	const unsigned blkbits = inode->i_blkbits;
+	const unsigned blocksize = 1 << blkbits;
+	struct buffer_head *head, *bh;
+	struct page *page;
+	pgoff_t index;
+	unsigned from, to;
+	unsigned block_in_page;
+	unsigned block_start, block_end;
+	sector_t block_in_file;
+	int nr_reads = 0;
+	int ret = 0;
+	int is_mapped_to_disk = 1;
+
+	index = pos >> PAGE_CACHE_SHIFT;
+	from = pos & (PAGE_CACHE_SIZE - 1);
+	to = from + len;
+
+	page = grab_cache_page_write_begin(mapping, index, flags);
+	if (!page)
+		return -ENOMEM;
+	*pagep = page;
+	*fsdata = NULL;
+
+	if (page_has_buffers(page)) {
+		unlock_page(page);
+		page_cache_release(page);
+		*pagep = NULL;
+		return block_write_begin(file, mapping, pos, len, flags, pagep,
+					fsdata, get_block);
+	}
+
+	if (PageMappedToDisk(page))
+		return 0;
+
+	/*
+	 * Allocate buffers so that we can keep track of state, and potentially
+	 * attach them to the page if an error occurs. In the common case of
+	 * no error, they will just be freed again without ever being attached
+	 * to the page (which is all OK, because we're under the page lock).
+	 *
+	 * Be careful: the buffer linked list is a NULL terminated one, rather
+	 * than the circular one we're used to.
+	 */
+	head = alloc_page_buffers(page, blocksize, 0);
+	if (!head) {
+		ret = -ENOMEM;
+		goto out_release;
+	}
+
+	block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits);
+
+	/*
+	 * We loop across all blocks in the page, whether or not they are
+	 * part of the affected region.  This is so we can discover if the
+	 * page is fully mapped-to-disk.
+	 */
+	for (block_start = 0, block_in_page = 0, bh = head;
+		  block_start < PAGE_CACHE_SIZE;
+		  block_in_page++, block_start += blocksize, bh = bh->b_this_page) {
+		int create;
+
+		block_end = block_start + blocksize;
+		bh->b_state = 0;
+		create = 1;
+		if (block_start >= to)
+			create = 0;
+		ret = get_block(inode, block_in_file + block_in_page,
+					bh, create);
+		if (ret)
+			goto failed;
+		if (!buffer_mapped(bh))
+			is_mapped_to_disk = 0;
+		if (buffer_new(bh))
+			unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
+		if (PageUptodate(page)) {
+			set_buffer_uptodate(bh);
+			continue;
+		}
+		if (buffer_new(bh) || !buffer_mapped(bh)) {
+			zero_user_segments(page, block_start, from,
+							to, block_end);
+			continue;
+		}
+		if (buffer_uptodate(bh))
+			continue;	/* reiserfs does this */
+		if (block_start < from || block_end > to) {
+			lock_buffer(bh);
+			bh->b_end_io = end_buffer_read_nobh;
+			submit_bh(READ, bh);
+			nr_reads++;
+		}
+	}
+
+	if (nr_reads) {
+		/*
+		 * The page is locked, so these buffers are protected from
+		 * any VM or truncate activity.  Hence we don't need to care
+		 * for the buffer_head refcounts.
+		 */
+		for (bh = head; bh; bh = bh->b_this_page) {
+			wait_on_buffer(bh);
+			if (!buffer_uptodate(bh))
+				ret = -EIO;
+		}
+		if (ret)
+			goto failed;
+	}
+
+	if (is_mapped_to_disk)
+		SetPageMappedToDisk(page);
+
+	*fsdata = head; /* to be released by nobh_write_end */
+
+	return 0;
+
+failed:
+	BUG_ON(!ret);
+	/*
+	 * Error recovery is a bit difficult. We need to zero out blocks that
+	 * were newly allocated, and dirty them to ensure they get written out.
+	 * Buffers need to be attached to the page at this point, otherwise
+	 * the handling of potential IO errors during writeout would be hard
+	 * (could try doing synchronous writeout, but what if that fails too?)
+	 */
+	attach_nobh_buffers(page, head);
+	page_zero_new_buffers(page, from, to);
+
+out_release:
+	unlock_page(page);
+	page_cache_release(page);
+	*pagep = NULL;
+
+	if (pos + len > inode->i_size)
+		vmtruncate(inode, inode->i_size);
+
+	return ret;
+}
+EXPORT_SYMBOL(nobh_write_begin);
+
+int nobh_write_end(struct file *file, struct address_space *mapping,
+			loff_t pos, unsigned len, unsigned copied,
+			struct page *page, void *fsdata)
+{
+	struct inode *inode = page->mapping->host;
+	struct buffer_head *head = fsdata;
+	struct buffer_head *bh;
+	BUG_ON(fsdata != NULL && page_has_buffers(page));
+
+	if (unlikely(copied < len) && head)
+		attach_nobh_buffers(page, head);
+	if (page_has_buffers(page))
+		return generic_write_end(file, mapping, pos, len,
+					copied, page, fsdata);
+
+	SetPageUptodate(page);
+	set_page_dirty(page);
+	if (pos+copied > inode->i_size) {
+		i_size_write(inode, pos+copied);
+		mark_inode_dirty(inode);
+	}
+
+	unlock_page(page);
+	page_cache_release(page);
+
+	while (head) {
+		bh = head;
+		head = head->b_this_page;
+		free_buffer_head(bh);
+	}
+
+	return copied;
+}
+EXPORT_SYMBOL(nobh_write_end);
+
+/*
+ * nobh_writepage() - based on block_full_write_page() except
+ * that it tries to operate without attaching bufferheads to
+ * the page.
+ */
+int nobh_writepage(struct page *page, get_block_t *get_block,
+			struct writeback_control *wbc)
+{
+	struct inode * const inode = page->mapping->host;
+	loff_t i_size = i_size_read(inode);
+	const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
+	unsigned offset;
+	int ret;
+
+	/* Is the page fully inside i_size? */
+	if (page->index < end_index)
+		goto out;
+
+	/* Is the page fully outside i_size? (truncate in progress) */
+	offset = i_size & (PAGE_CACHE_SIZE-1);
+	if (page->index >= end_index+1 || !offset) {
+		/*
+		 * The page may have dirty, unmapped buffers.  For example,
+		 * they may have been added in ext3_writepage().  Make them
+		 * freeable here, so the page does not leak.
+		 */
+#if 0
+		/* Not really sure about this  - do we need this ? */
+		if (page->mapping->a_ops->invalidatepage)
+			page->mapping->a_ops->invalidatepage(page, offset);
+#endif
+		unlock_page(page);
+		return 0; /* don't care */
+	}
+
+	/*
+	 * The page straddles i_size.  It must be zeroed out on each and every
+	 * writepage invocation because it may be mmapped.  "A file is mapped
+	 * in multiples of the page size.  For a file that is not a multiple of
+	 * the  page size, the remaining memory is zeroed when mapped, and
+	 * writes to that region are not written out to the file."
+	 */
+	zero_user_segment(page, offset, PAGE_CACHE_SIZE);
+out:
+	ret = mpage_writepage(page, get_block, wbc);
+	if (ret == -EAGAIN)
+		ret = __block_write_full_page(inode, page, get_block, wbc);
+	return ret;
+}
+EXPORT_SYMBOL(nobh_writepage);
+
+int nobh_truncate_page(struct address_space *mapping,
+			loff_t from, get_block_t *get_block)
+{
+	pgoff_t index = from >> PAGE_CACHE_SHIFT;
+	unsigned offset = from & (PAGE_CACHE_SIZE-1);
+	unsigned blocksize;
+	sector_t iblock;
+	unsigned length, pos;
+	struct inode *inode = mapping->host;
+	struct page *page;
+	struct buffer_head map_bh;
+	int err;
+
+	blocksize = 1 << inode->i_blkbits;
+	length = offset & (blocksize - 1);
+
+	/* Block boundary? Nothing to do */
+	if (!length)
+		return 0;
+
+	length = blocksize - length;
+	iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
+
+	page = grab_cache_page(mapping, index);
+	err = -ENOMEM;
+	if (!page)
+		goto out;
+
+	if (page_has_buffers(page)) {
+has_buffers:
+		unlock_page(page);
+		page_cache_release(page);
+		return block_truncate_page(mapping, from, get_block);
+	}
+
+	/* Find the buffer that contains "offset" */
+	pos = blocksize;
+	while (offset >= pos) {
+		iblock++;
+		pos += blocksize;
+	}
+
+	err = get_block(inode, iblock, &map_bh, 0);
+	if (err)
+		goto unlock;
+	/* unmapped? It's a hole - nothing to do */
+	if (!buffer_mapped(&map_bh))
+		goto unlock;
+
+	/* Ok, it's mapped. Make sure it's up-to-date */
+	if (!PageUptodate(page)) {
+		err = mapping->a_ops->readpage(NULL, page);
+		if (err) {
+			page_cache_release(page);
+			goto out;
+		}
+		lock_page(page);
+		if (!PageUptodate(page)) {
+			err = -EIO;
+			goto unlock;
+		}
+		if (page_has_buffers(page))
+			goto has_buffers;
+	}
+	zero_user(page, offset, length);
+	set_page_dirty(page);
+	err = 0;
+
+unlock:
+	unlock_page(page);
+	page_cache_release(page);
+out:
+	return err;
+}
+EXPORT_SYMBOL(nobh_truncate_page);
+
+int block_truncate_page(struct address_space *mapping,
+			loff_t from, get_block_t *get_block)
+{
+	pgoff_t index = from >> PAGE_CACHE_SHIFT;
+	unsigned offset = from & (PAGE_CACHE_SIZE-1);
+	unsigned blocksize;
+	sector_t iblock;
+	unsigned length, pos;
+	struct inode *inode = mapping->host;
+	struct page *page;
+	struct buffer_head *bh;
+	int err;
+
+	blocksize = 1 << inode->i_blkbits;
+	length = offset & (blocksize - 1);
+
+	/* Block boundary? Nothing to do */
+	if (!length)
+		return 0;
+
+	length = blocksize - length;
+	iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
+	
+	page = grab_cache_page(mapping, index);
+	err = -ENOMEM;
+	if (!page)
+		goto out;
+
+	if (!page_has_buffers(page))
+		create_empty_buffers(page, blocksize, 0);
+
+	/* Find the buffer that contains "offset" */
+	bh = page_buffers(page);
+	pos = blocksize;
+	while (offset >= pos) {
+		bh = bh->b_this_page;
+		iblock++;
+		pos += blocksize;
+	}
+
+	err = 0;
+	if (!buffer_mapped(bh)) {
+		WARN_ON(bh->b_size != blocksize);
+		err = get_block(inode, iblock, bh, 0);
+		if (err)
+			goto unlock;
+		/* unmapped? It's a hole - nothing to do */
+		if (!buffer_mapped(bh))
+			goto unlock;
+	}
+
+	/* Ok, it's mapped. Make sure it's up-to-date */
+	if (PageUptodate(page))
+		set_buffer_uptodate(bh);
+
+	if (!buffer_uptodate(bh) && !buffer_delay(bh) && !buffer_unwritten(bh)) {
+		err = -EIO;
+		ll_rw_block(READ, 1, &bh);
+		wait_on_buffer(bh);
+		/* Uhhuh. Read error. Complain and punt. */
+		if (!buffer_uptodate(bh))
+			goto unlock;
+	}
+
+	zero_user(page, offset, length);
+	mark_buffer_dirty(bh);
+	err = 0;
+
+unlock:
+	unlock_page(page);
+	page_cache_release(page);
+out:
+	return err;
+}
+
+/*
+ * The generic ->writepage function for buffer-backed address_spaces
+ */
+int block_write_full_page(struct page *page, get_block_t *get_block,
+			struct writeback_control *wbc)
+{
+	struct inode * const inode = page->mapping->host;
+	loff_t i_size = i_size_read(inode);
+	const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
+	unsigned offset;
+
+	/* Is the page fully inside i_size? */
+	if (page->index < end_index)
+		return __block_write_full_page(inode, page, get_block, wbc);
+
+	/* Is the page fully outside i_size? (truncate in progress) */
+	offset = i_size & (PAGE_CACHE_SIZE-1);
+	if (page->index >= end_index+1 || !offset) {
+		/*
+		 * The page may have dirty, unmapped buffers.  For example,
+		 * they may have been added in ext3_writepage().  Make them
+		 * freeable here, so the page does not leak.
+		 */
+		do_invalidatepage(page, 0);
+		unlock_page(page);
+		return 0; /* don't care */
+	}
+
+	/*
+	 * The page straddles i_size.  It must be zeroed out on each and every
+	 * writepage invokation because it may be mmapped.  "A file is mapped
+	 * in multiples of the page size.  For a file that is not a multiple of
+	 * the  page size, the remaining memory is zeroed when mapped, and
+	 * writes to that region are not written out to the file."
+	 */
+	zero_user_segment(page, offset, PAGE_CACHE_SIZE);
+	return __block_write_full_page(inode, page, get_block, wbc);
+}
+
+sector_t generic_block_bmap(struct address_space *mapping, sector_t block,
+			    get_block_t *get_block)
+{
+	struct buffer_head tmp;
+	struct inode *inode = mapping->host;
+	tmp.b_state = 0;
+	tmp.b_blocknr = 0;
+	tmp.b_size = 1 << inode->i_blkbits;
+	get_block(inode, block, &tmp, 0);
+	return tmp.b_blocknr;
+}
+
+static void end_bio_bh_io_sync(struct bio *bio, int err)
+{
+	struct buffer_head *bh = bio->bi_private;
+
+	if (err == -EOPNOTSUPP) {
+		set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
+		set_bit(BH_Eopnotsupp, &bh->b_state);
+	}
+
+	if (unlikely (test_bit(BIO_QUIET,&bio->bi_flags)))
+		set_bit(BH_Quiet, &bh->b_state);
+
+	bh->b_end_io(bh, test_bit(BIO_UPTODATE, &bio->bi_flags));
+	bio_put(bio);
+}
+
+int submit_bh(int rw, struct buffer_head * bh)
+{
+	struct bio *bio;
+	int ret = 0;
+
+	BUG_ON(!buffer_locked(bh));
+	BUG_ON(!buffer_mapped(bh));
+	BUG_ON(!bh->b_end_io);
+
+	/*
+	 * Mask in barrier bit for a write (could be either a WRITE or a
+	 * WRITE_SYNC
+	 */
+	if (buffer_ordered(bh) && (rw & WRITE))
+		rw |= WRITE_BARRIER;
+
+	/*
+	 * Only clear out a write error when rewriting
+	 */
+	if (test_set_buffer_req(bh) && (rw & WRITE))
+		clear_buffer_write_io_error(bh);
+
+	/*
+	 * from here on down, it's all bio -- do the initial mapping,
+	 * submit_bio -> generic_make_request may further map this bio around
+	 */
+	bio = bio_alloc(GFP_NOIO, 1);
+
+	bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9);
+	bio->bi_bdev = bh->b_bdev;
+	bio->bi_io_vec[0].bv_page = bh->b_page;
+	bio->bi_io_vec[0].bv_len = bh->b_size;
+	bio->bi_io_vec[0].bv_offset = bh_offset(bh);
+
+	bio->bi_vcnt = 1;
+	bio->bi_idx = 0;
+	bio->bi_size = bh->b_size;
+
+	bio->bi_end_io = end_bio_bh_io_sync;
+	bio->bi_private = bh;
+
+	bio_get(bio);
+	submit_bio(rw, bio);
+
+	if (bio_flagged(bio, BIO_EOPNOTSUPP))
+		ret = -EOPNOTSUPP;
+
+	bio_put(bio);
+	return ret;
+}
+
+/**
+ * ll_rw_block: low-level access to block devices (DEPRECATED)
+ * @rw: whether to %READ or %WRITE or %SWRITE or maybe %READA (readahead)
+ * @nr: number of &struct buffer_heads in the array
+ * @bhs: array of pointers to &struct buffer_head
+ *
+ * ll_rw_block() takes an array of pointers to &struct buffer_heads, and
+ * requests an I/O operation on them, either a %READ or a %WRITE.  The third
+ * %SWRITE is like %WRITE only we make sure that the *current* data in buffers
+ * are sent to disk. The fourth %READA option is described in the documentation
+ * for generic_make_request() which ll_rw_block() calls.
+ *
+ * This function drops any buffer that it cannot get a lock on (with the
+ * BH_Lock state bit) unless SWRITE is required, any buffer that appears to be
+ * clean when doing a write request, and any buffer that appears to be
+ * up-to-date when doing read request.  Further it marks as clean buffers that
+ * are processed for writing (the buffer cache won't assume that they are
+ * actually clean until the buffer gets unlocked).
+ *
+ * ll_rw_block sets b_end_io to simple completion handler that marks
+ * the buffer up-to-date (if approriate), unlocks the buffer and wakes
+ * any waiters. 
+ *
+ * All of the buffers must be for the same device, and must also be a
+ * multiple of the current approved size for the device.
+ */
+void ll_rw_block(int rw, int nr, struct buffer_head *bhs[])
+{
+	int i;
+
+	for (i = 0; i < nr; i++) {
+		struct buffer_head *bh = bhs[i];
+
+		if (rw == SWRITE || rw == SWRITE_SYNC)
+			lock_buffer(bh);
+		else if (!trylock_buffer(bh))
+			continue;
+
+		if (rw == WRITE || rw == SWRITE || rw == SWRITE_SYNC) {
+			if (test_clear_buffer_dirty(bh)) {
+				bh->b_end_io = end_buffer_write_sync;
+				get_bh(bh);
+				if (rw == SWRITE_SYNC)
+					submit_bh(WRITE_SYNC, bh);
+				else
+					submit_bh(WRITE, bh);
+				continue;
+			}
+		} else {
+			if (!buffer_uptodate(bh)) {
+				bh->b_end_io = end_buffer_read_sync;
+				get_bh(bh);
+				submit_bh(rw, bh);
+				continue;
+			}
+		}
+		unlock_buffer(bh);
+	}
+}
+
+/*
+ * For a data-integrity writeout, we need to wait upon any in-progress I/O
+ * and then start new I/O and then wait upon it.  The caller must have a ref on
+ * the buffer_head.
+ */
+int sync_dirty_buffer(struct buffer_head *bh)
+{
+	int ret = 0;
+
+	WARN_ON(atomic_read(&bh->b_count) < 1);
+	lock_buffer(bh);
+	if (test_clear_buffer_dirty(bh)) {
+		get_bh(bh);
+		bh->b_end_io = end_buffer_write_sync;
+		ret = submit_bh(WRITE, bh);
+		wait_on_buffer(bh);
+		if (buffer_eopnotsupp(bh)) {
+			clear_buffer_eopnotsupp(bh);
+			ret = -EOPNOTSUPP;
+		}
+		if (!ret && !buffer_uptodate(bh))
+			ret = -EIO;
+	} else {
+		unlock_buffer(bh);
+	}
+	return ret;
+}
+
+/*
+ * try_to_free_buffers() checks if all the buffers on this particular page
+ * are unused, and releases them if so.
+ *
+ * Exclusion against try_to_free_buffers may be obtained by either
+ * locking the page or by holding its mapping's private_lock.
+ *
+ * If the page is dirty but all the buffers are clean then we need to
+ * be sure to mark the page clean as well.  This is because the page
+ * may be against a block device, and a later reattachment of buffers
+ * to a dirty page will set *all* buffers dirty.  Which would corrupt
+ * filesystem data on the same device.
+ *
+ * The same applies to regular filesystem pages: if all the buffers are
+ * clean then we set the page clean and proceed.  To do that, we require
+ * total exclusion from __set_page_dirty_buffers().  That is obtained with
+ * private_lock.
+ *
+ * try_to_free_buffers() is non-blocking.
+ */
+static inline int buffer_busy(struct buffer_head *bh)
+{
+	return atomic_read(&bh->b_count) |
+		(bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock)));
+}
+
+static int
+drop_buffers(struct page *page, struct buffer_head **buffers_to_free)
+{
+	struct buffer_head *head = page_buffers(page);
+	struct buffer_head *bh;
+
+	bh = head;
+	do {
+		if (buffer_write_io_error(bh) && page->mapping)
+			set_bit(AS_EIO, &page->mapping->flags);
+		if (buffer_busy(bh))
+			goto failed;
+		bh = bh->b_this_page;
+	} while (bh != head);
+
+	do {
+		struct buffer_head *next = bh->b_this_page;
+
+		if (bh->b_assoc_map)
+			__remove_assoc_queue(bh);
+		bh = next;
+	} while (bh != head);
+	*buffers_to_free = head;
+	__clear_page_buffers(page);
+	return 1;
+failed:
+	return 0;
+}
+
+int try_to_free_buffers(struct page *page)
+{
+	struct address_space * const mapping = page->mapping;
+	struct buffer_head *buffers_to_free = NULL;
+	int ret = 0;
+
+	BUG_ON(!PageLocked(page));
+	if (PageWriteback(page))
+		return 0;
+
+	if (mapping == NULL) {		/* can this still happen? */
+		ret = drop_buffers(page, &buffers_to_free);
+		goto out;
+	}
+
+	spin_lock(&mapping->private_lock);
+	ret = drop_buffers(page, &buffers_to_free);
+
+	/*
+	 * If the filesystem writes its buffers by hand (eg ext3)
+	 * then we can have clean buffers against a dirty page.  We
+	 * clean the page here; otherwise the VM will never notice
+	 * that the filesystem did any IO at all.
+	 *
+	 * Also, during truncate, discard_buffer will have marked all
+	 * the page's buffers clean.  We discover that here and clean
+	 * the page also.
+	 *
+	 * private_lock must be held over this entire operation in order
+	 * to synchronise against __set_page_dirty_buffers and prevent the
+	 * dirty bit from being lost.
+	 */
+#ifndef DDE_LINUX
+	if (ret)
+		cancel_dirty_page(page, PAGE_CACHE_SIZE);
+#endif
+	spin_unlock(&mapping->private_lock);
+out:
+	if (buffers_to_free) {
+		struct buffer_head *bh = buffers_to_free;
+
+		do {
+			struct buffer_head *next = bh->b_this_page;
+			free_buffer_head(bh);
+			bh = next;
+		} while (bh != buffers_to_free);
+	}
+	return ret;
+}
+EXPORT_SYMBOL(try_to_free_buffers);
+
+void block_sync_page(struct page *page)
+{
+	struct address_space *mapping;
+
+	smp_mb();
+	mapping = page_mapping(page);
+	if (mapping)
+		blk_run_backing_dev(mapping->backing_dev_info, page);
+}
+
+/*
+ * There are no bdflush tunables left.  But distributions are
+ * still running obsolete flush daemons, so we terminate them here.
+ *
+ * Use of bdflush() is deprecated and will be removed in a future kernel.
+ * The `pdflush' kernel threads fully replace bdflush daemons and this call.
+ */
+SYSCALL_DEFINE2(bdflush, int, func, long, data)
+{
+	static int msg_count;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	if (msg_count < 5) {
+		msg_count++;
+		printk(KERN_INFO
+			"warning: process `%s' used the obsolete bdflush"
+			" system call\n", current->comm);
+		printk(KERN_INFO "Fix your initscripts?\n");
+	}
+
+	if (func == 1)
+		do_exit(0);
+	return 0;
+}
+
+/*
+ * Buffer-head allocation
+ */
+static struct kmem_cache *bh_cachep;
+
+/*
+ * Once the number of bh's in the machine exceeds this level, we start
+ * stripping them in writeback.
+ */
+static int max_buffer_heads;
+
+int buffer_heads_over_limit;
+
+struct bh_accounting {
+	int nr;			/* Number of live bh's */
+	int ratelimit;		/* Limit cacheline bouncing */
+};
+
+static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0};
+
+static void recalc_bh_state(void)
+{
+	int i;
+	int tot = 0;
+
+	if (__get_cpu_var(bh_accounting).ratelimit++ < 4096)
+		return;
+	__get_cpu_var(bh_accounting).ratelimit = 0;
+	for_each_online_cpu(i)
+		tot += per_cpu(bh_accounting, i).nr;
+	buffer_heads_over_limit = (tot > max_buffer_heads);
+}
+	
+struct buffer_head *alloc_buffer_head(gfp_t gfp_flags)
+{
+	struct buffer_head *ret = kmem_cache_alloc(bh_cachep, gfp_flags);
+	if (ret) {
+		INIT_LIST_HEAD(&ret->b_assoc_buffers);
+		get_cpu_var(bh_accounting).nr++;
+		recalc_bh_state();
+		put_cpu_var(bh_accounting);
+	}
+	return ret;
+}
+EXPORT_SYMBOL(alloc_buffer_head);
+
+void free_buffer_head(struct buffer_head *bh)
+{
+	BUG_ON(!list_empty(&bh->b_assoc_buffers));
+	kmem_cache_free(bh_cachep, bh);
+	get_cpu_var(bh_accounting).nr--;
+	recalc_bh_state();
+	put_cpu_var(bh_accounting);
+}
+EXPORT_SYMBOL(free_buffer_head);
+
+static void buffer_exit_cpu(int cpu)
+{
+	int i;
+	struct bh_lru *b = &per_cpu(bh_lrus, cpu);
+
+	for (i = 0; i < BH_LRU_SIZE; i++) {
+		brelse(b->bhs[i]);
+		b->bhs[i] = NULL;
+	}
+	get_cpu_var(bh_accounting).nr += per_cpu(bh_accounting, cpu).nr;
+	per_cpu(bh_accounting, cpu).nr = 0;
+	put_cpu_var(bh_accounting);
+}
+
+static int buffer_cpu_notify(struct notifier_block *self,
+			      unsigned long action, void *hcpu)
+{
+	if (action == CPU_DEAD || action == CPU_DEAD_FROZEN)
+		buffer_exit_cpu((unsigned long)hcpu);
+	return NOTIFY_OK;
+}
+
+/**
+ * bh_uptodate_or_lock - Test whether the buffer is uptodate
+ * @bh: struct buffer_head
+ *
+ * Return true if the buffer is up-to-date and false,
+ * with the buffer locked, if not.
+ */
+int bh_uptodate_or_lock(struct buffer_head *bh)
+{
+	if (!buffer_uptodate(bh)) {
+		lock_buffer(bh);
+		if (!buffer_uptodate(bh))
+			return 0;
+		unlock_buffer(bh);
+	}
+	return 1;
+}
+EXPORT_SYMBOL(bh_uptodate_or_lock);
+
+/**
+ * bh_submit_read - Submit a locked buffer for reading
+ * @bh: struct buffer_head
+ *
+ * Returns zero on success and -EIO on error.
+ */
+int bh_submit_read(struct buffer_head *bh)
+{
+	BUG_ON(!buffer_locked(bh));
+
+	if (buffer_uptodate(bh)) {
+		unlock_buffer(bh);
+		return 0;
+	}
+
+	get_bh(bh);
+	bh->b_end_io = end_buffer_read_sync;
+	submit_bh(READ, bh);
+	wait_on_buffer(bh);
+	if (buffer_uptodate(bh))
+		return 0;
+	return -EIO;
+}
+EXPORT_SYMBOL(bh_submit_read);
+
+static void
+init_buffer_head(void *data)
+{
+	struct buffer_head *bh = data;
+
+	memset(bh, 0, sizeof(*bh));
+	INIT_LIST_HEAD(&bh->b_assoc_buffers);
+}
+
+void __init buffer_init(void)
+{
+	int nrpages;
+
+	bh_cachep = kmem_cache_create("buffer_head",
+			sizeof(struct buffer_head), 0,
+				(SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
+				SLAB_MEM_SPREAD),
+				init_buffer_head);
+
+	/*
+	 * Limit the bh occupancy to 10% of ZONE_NORMAL
+	 */
+	nrpages = (nr_free_buffer_pages() * 10) / 100;
+	max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head));
+	hotcpu_notifier(buffer_cpu_notify, 0);
+}
+
+EXPORT_SYMBOL(__bforget);
+EXPORT_SYMBOL(__brelse);
+EXPORT_SYMBOL(__wait_on_buffer);
+EXPORT_SYMBOL(block_commit_write);
+EXPORT_SYMBOL(block_prepare_write);
+EXPORT_SYMBOL(block_page_mkwrite);
+EXPORT_SYMBOL(block_read_full_page);
+EXPORT_SYMBOL(block_sync_page);
+EXPORT_SYMBOL(block_truncate_page);
+EXPORT_SYMBOL(block_write_full_page);
+EXPORT_SYMBOL(cont_write_begin);
+EXPORT_SYMBOL(end_buffer_read_sync);
+EXPORT_SYMBOL(end_buffer_write_sync);
+EXPORT_SYMBOL(file_fsync);
+EXPORT_SYMBOL(fsync_bdev);
+EXPORT_SYMBOL(generic_block_bmap);
+EXPORT_SYMBOL(generic_cont_expand_simple);
+EXPORT_SYMBOL(init_buffer);
+EXPORT_SYMBOL(invalidate_bdev);
+EXPORT_SYMBOL(ll_rw_block);
+EXPORT_SYMBOL(mark_buffer_dirty);
+EXPORT_SYMBOL(submit_bh);
+EXPORT_SYMBOL(sync_dirty_buffer);
+EXPORT_SYMBOL(unlock_buffer);
diff --git a/libdde_linux26/lib/src/fs/char_dev.c b/libdde_linux26/lib/src/fs/char_dev.c
new file mode 100644
index 00000000..3b8e8b3d
--- /dev/null
+++ b/libdde_linux26/lib/src/fs/char_dev.c
@@ -0,0 +1,572 @@
+/*
+ *  linux/fs/char_dev.c
+ *
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ */
+
+#include <linux/init.h>
+#include <linux/fs.h>
+#include <linux/kdev_t.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+
+#include <linux/major.h>
+#include <linux/errno.h>
+#include <linux/module.h>
+#include <linux/smp_lock.h>
+#include <linux/seq_file.h>
+
+#include <linux/kobject.h>
+#include <linux/kobj_map.h>
+#include <linux/cdev.h>
+#include <linux/mutex.h>
+#include <linux/backing-dev.h>
+
+#ifdef CONFIG_KMOD
+#include <linux/kmod.h>
+#endif
+#include "internal.h"
+
+#ifdef DDE_LINUX
+#include "local.h"
+#endif
+
+/*
+ * capabilities for /dev/mem, /dev/kmem and similar directly mappable character
+ * devices
+ * - permits shared-mmap for read, write and/or exec
+ * - does not permit private mmap in NOMMU mode (can't do COW)
+ * - no readahead or I/O queue unplugging required
+ */
+struct backing_dev_info directly_mappable_cdev_bdi = {
+	.capabilities	= (
+#ifdef CONFIG_MMU
+		/* permit private copies of the data to be taken */
+		BDI_CAP_MAP_COPY |
+#endif
+		/* permit direct mmap, for read, write or exec */
+		BDI_CAP_MAP_DIRECT |
+		BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP),
+};
+
+static struct kobj_map *cdev_map;
+
+static DEFINE_MUTEX(chrdevs_lock);
+
+static struct char_device_struct {
+	struct char_device_struct *next;
+	unsigned int major;
+	unsigned int baseminor;
+	int minorct;
+	char name[64];
+	struct cdev *cdev;		/* will die */
+} *chrdevs[CHRDEV_MAJOR_HASH_SIZE];
+
+/* index in the above */
+static inline int major_to_index(int major)
+{
+	return major % CHRDEV_MAJOR_HASH_SIZE;
+}
+
+#ifdef CONFIG_PROC_FS
+
+void chrdev_show(struct seq_file *f, off_t offset)
+{
+	struct char_device_struct *cd;
+
+	if (offset < CHRDEV_MAJOR_HASH_SIZE) {
+		mutex_lock(&chrdevs_lock);
+		for (cd = chrdevs[offset]; cd; cd = cd->next)
+			seq_printf(f, "%3d %s\n", cd->major, cd->name);
+		mutex_unlock(&chrdevs_lock);
+	}
+}
+
+#endif /* CONFIG_PROC_FS */
+
+/*
+ * Register a single major with a specified minor range.
+ *
+ * If major == 0 this functions will dynamically allocate a major and return
+ * its number.
+ *
+ * If major > 0 this function will attempt to reserve the passed range of
+ * minors and will return zero on success.
+ *
+ * Returns a -ve errno on failure.
+ */
+static struct char_device_struct *
+__register_chrdev_region(unsigned int major, unsigned int baseminor,
+			   int minorct, const char *name)
+{
+	struct char_device_struct *cd, **cp;
+	int ret = 0;
+	int i;
+
+	cd = kzalloc(sizeof(struct char_device_struct), GFP_KERNEL);
+	if (cd == NULL)
+		return ERR_PTR(-ENOMEM);
+
+	mutex_lock(&chrdevs_lock);
+
+	/* temporary */
+	if (major == 0) {
+		for (i = ARRAY_SIZE(chrdevs)-1; i > 0; i--) {
+			if (chrdevs[i] == NULL)
+				break;
+		}
+
+		if (i == 0) {
+			ret = -EBUSY;
+			goto out;
+		}
+		major = i;
+		ret = major;
+	}
+
+	cd->major = major;
+	cd->baseminor = baseminor;
+	cd->minorct = minorct;
+	strlcpy(cd->name, name, sizeof(cd->name));
+
+	i = major_to_index(major);
+
+	for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next)
+		if ((*cp)->major > major ||
+		    ((*cp)->major == major &&
+		     (((*cp)->baseminor >= baseminor) ||
+		      ((*cp)->baseminor + (*cp)->minorct > baseminor))))
+			break;
+
+	/* Check for overlapping minor ranges.  */
+	if (*cp && (*cp)->major == major) {
+		int old_min = (*cp)->baseminor;
+		int old_max = (*cp)->baseminor + (*cp)->minorct - 1;
+		int new_min = baseminor;
+		int new_max = baseminor + minorct - 1;
+
+		/* New driver overlaps from the left.  */
+		if (new_max >= old_min && new_max <= old_max) {
+			ret = -EBUSY;
+			goto out;
+		}
+
+		/* New driver overlaps from the right.  */
+		if (new_min <= old_max && new_min >= old_min) {
+			ret = -EBUSY;
+			goto out;
+		}
+	}
+
+	cd->next = *cp;
+	*cp = cd;
+	mutex_unlock(&chrdevs_lock);
+	return cd;
+out:
+	mutex_unlock(&chrdevs_lock);
+	kfree(cd);
+	return ERR_PTR(ret);
+}
+
+static struct char_device_struct *
+__unregister_chrdev_region(unsigned major, unsigned baseminor, int minorct)
+{
+	struct char_device_struct *cd = NULL, **cp;
+	int i = major_to_index(major);
+
+	mutex_lock(&chrdevs_lock);
+	for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next)
+		if ((*cp)->major == major &&
+		    (*cp)->baseminor == baseminor &&
+		    (*cp)->minorct == minorct)
+			break;
+	if (*cp) {
+		cd = *cp;
+		*cp = cd->next;
+	}
+	mutex_unlock(&chrdevs_lock);
+	return cd;
+}
+
+/**
+ * register_chrdev_region() - register a range of device numbers
+ * @from: the first in the desired range of device numbers; must include
+ *        the major number.
+ * @count: the number of consecutive device numbers required
+ * @name: the name of the device or driver.
+ *
+ * Return value is zero on success, a negative error code on failure.
+ */
+int register_chrdev_region(dev_t from, unsigned count, const char *name)
+{
+	struct char_device_struct *cd;
+	dev_t to = from + count;
+	dev_t n, next;
+
+	for (n = from; n < to; n = next) {
+		next = MKDEV(MAJOR(n)+1, 0);
+		if (next > to)
+			next = to;
+		cd = __register_chrdev_region(MAJOR(n), MINOR(n),
+			       next - n, name);
+		if (IS_ERR(cd))
+			goto fail;
+	}
+	return 0;
+fail:
+	to = n;
+	for (n = from; n < to; n = next) {
+		next = MKDEV(MAJOR(n)+1, 0);
+		kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n));
+	}
+	return PTR_ERR(cd);
+}
+
+/**
+ * alloc_chrdev_region() - register a range of char device numbers
+ * @dev: output parameter for first assigned number
+ * @baseminor: first of the requested range of minor numbers
+ * @count: the number of minor numbers required
+ * @name: the name of the associated device or driver
+ *
+ * Allocates a range of char device numbers.  The major number will be
+ * chosen dynamically, and returned (along with the first minor number)
+ * in @dev.  Returns zero or a negative error code.
+ */
+int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count,
+			const char *name)
+{
+	struct char_device_struct *cd;
+	cd = __register_chrdev_region(0, baseminor, count, name);
+	if (IS_ERR(cd))
+		return PTR_ERR(cd);
+	*dev = MKDEV(cd->major, cd->baseminor);
+	return 0;
+}
+
+/**
+ * register_chrdev() - Register a major number for character devices.
+ * @major: major device number or 0 for dynamic allocation
+ * @name: name of this range of devices
+ * @fops: file operations associated with this devices
+ *
+ * If @major == 0 this functions will dynamically allocate a major and return
+ * its number.
+ *
+ * If @major > 0 this function will attempt to reserve a device with the given
+ * major number and will return zero on success.
+ *
+ * Returns a -ve errno on failure.
+ *
+ * The name of this device has nothing to do with the name of the device in
+ * /dev. It only helps to keep track of the different owners of devices. If
+ * your module name has only one type of devices it's ok to use e.g. the name
+ * of the module here.
+ *
+ * This function registers a range of 256 minor numbers. The first minor number
+ * is 0.
+ */
+int register_chrdev(unsigned int major, const char *name,
+		    const struct file_operations *fops)
+{
+	struct char_device_struct *cd;
+	struct cdev *cdev;
+	char *s;
+	int err = -ENOMEM;
+
+	cd = __register_chrdev_region(major, 0, 256, name);
+	if (IS_ERR(cd))
+		return PTR_ERR(cd);
+	
+	cdev = cdev_alloc();
+	if (!cdev)
+		goto out2;
+
+	cdev->owner = fops->owner;
+	cdev->ops = fops;
+	kobject_set_name(&cdev->kobj, "%s", name);
+	for (s = strchr(kobject_name(&cdev->kobj),'/'); s; s = strchr(s, '/'))
+		*s = '!';
+		
+	err = cdev_add(cdev, MKDEV(cd->major, 0), 256);
+	if (err)
+		goto out;
+
+	cd->cdev = cdev;
+
+	return major ? 0 : cd->major;
+out:
+	kobject_put(&cdev->kobj);
+out2:
+	kfree(__unregister_chrdev_region(cd->major, 0, 256));
+	return err;
+}
+
+/**
+ * unregister_chrdev_region() - return a range of device numbers
+ * @from: the first in the range of numbers to unregister
+ * @count: the number of device numbers to unregister
+ *
+ * This function will unregister a range of @count device numbers,
+ * starting with @from.  The caller should normally be the one who
+ * allocated those numbers in the first place...
+ */
+void unregister_chrdev_region(dev_t from, unsigned count)
+{
+	dev_t to = from + count;
+	dev_t n, next;
+
+	for (n = from; n < to; n = next) {
+		next = MKDEV(MAJOR(n)+1, 0);
+		if (next > to)
+			next = to;
+		kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n));
+	}
+}
+
+void unregister_chrdev(unsigned int major, const char *name)
+{
+	struct char_device_struct *cd;
+	cd = __unregister_chrdev_region(major, 0, 256);
+	if (cd && cd->cdev)
+		cdev_del(cd->cdev);
+	kfree(cd);
+}
+
+static DEFINE_SPINLOCK(cdev_lock);
+
+static struct kobject *cdev_get(struct cdev *p)
+{
+	struct module *owner = p->owner;
+	struct kobject *kobj;
+
+	if (owner && !try_module_get(owner))
+		return NULL;
+	kobj = kobject_get(&p->kobj);
+	if (!kobj)
+		module_put(owner);
+	return kobj;
+}
+
+void cdev_put(struct cdev *p)
+{
+	if (p) {
+		struct module *owner = p->owner;
+		kobject_put(&p->kobj);
+		module_put(owner);
+	}
+}
+
+/*
+ * Called every time a character special file is opened
+ */
+static int chrdev_open(struct inode *inode, struct file *filp)
+{
+	struct cdev *p;
+	struct cdev *new = NULL;
+	int ret = 0;
+
+	spin_lock(&cdev_lock);
+	p = inode->i_cdev;
+	if (!p) {
+		struct kobject *kobj;
+		int idx;
+		spin_unlock(&cdev_lock);
+		kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx);
+		if (!kobj)
+			return -ENXIO;
+		new = container_of(kobj, struct cdev, kobj);
+		spin_lock(&cdev_lock);
+		/* Check i_cdev again in case somebody beat us to it while
+		   we dropped the lock. */
+		p = inode->i_cdev;
+		if (!p) {
+			inode->i_cdev = p = new;
+			inode->i_cindex = idx;
+			list_add(&inode->i_devices, &p->list);
+			new = NULL;
+		} else if (!cdev_get(p))
+			ret = -ENXIO;
+	} else if (!cdev_get(p))
+		ret = -ENXIO;
+	spin_unlock(&cdev_lock);
+	cdev_put(new);
+	if (ret)
+		return ret;
+
+	ret = -ENXIO;
+	filp->f_op = fops_get(p->ops);
+	if (!filp->f_op)
+		goto out_cdev_put;
+
+	if (filp->f_op->open) {
+		ret = filp->f_op->open(inode,filp);
+		if (ret)
+			goto out_cdev_put;
+	}
+
+	return 0;
+
+ out_cdev_put:
+	cdev_put(p);
+	return ret;
+}
+
+void cd_forget(struct inode *inode)
+{
+	spin_lock(&cdev_lock);
+	list_del_init(&inode->i_devices);
+	inode->i_cdev = NULL;
+	spin_unlock(&cdev_lock);
+}
+
+static void cdev_purge(struct cdev *cdev)
+{
+	spin_lock(&cdev_lock);
+	while (!list_empty(&cdev->list)) {
+		struct inode *inode;
+		inode = container_of(cdev->list.next, struct inode, i_devices);
+		list_del_init(&inode->i_devices);
+		inode->i_cdev = NULL;
+	}
+	spin_unlock(&cdev_lock);
+}
+
+/*
+ * Dummy default file-operations: the only thing this does
+ * is contain the open that then fills in the correct operations
+ * depending on the special file...
+ */
+const struct file_operations def_chr_fops = {
+	.open = chrdev_open,
+};
+
+static struct kobject *exact_match(dev_t dev, int *part, void *data)
+{
+	struct cdev *p = data;
+	return &p->kobj;
+}
+
+static int exact_lock(dev_t dev, void *data)
+{
+	struct cdev *p = data;
+	return cdev_get(p) ? 0 : -1;
+}
+
+/**
+ * cdev_add() - add a char device to the system
+ * @p: the cdev structure for the device
+ * @dev: the first device number for which this device is responsible
+ * @count: the number of consecutive minor numbers corresponding to this
+ *         device
+ *
+ * cdev_add() adds the device represented by @p to the system, making it
+ * live immediately.  A negative error code is returned on failure.
+ */
+int cdev_add(struct cdev *p, dev_t dev, unsigned count)
+{
+	p->dev = dev;
+	p->count = count;
+	return kobj_map(cdev_map, dev, count, NULL, exact_match, exact_lock, p);
+}
+
+static void cdev_unmap(dev_t dev, unsigned count)
+{
+	kobj_unmap(cdev_map, dev, count);
+}
+
+/**
+ * cdev_del() - remove a cdev from the system
+ * @p: the cdev structure to be removed
+ *
+ * cdev_del() removes @p from the system, possibly freeing the structure
+ * itself.
+ */
+void cdev_del(struct cdev *p)
+{
+	cdev_unmap(p->dev, p->count);
+	kobject_put(&p->kobj);
+}
+
+
+static void cdev_default_release(struct kobject *kobj)
+{
+	struct cdev *p = container_of(kobj, struct cdev, kobj);
+	cdev_purge(p);
+}
+
+static void cdev_dynamic_release(struct kobject *kobj)
+{
+	struct cdev *p = container_of(kobj, struct cdev, kobj);
+	cdev_purge(p);
+	kfree(p);
+}
+
+static struct kobj_type ktype_cdev_default = {
+	.release	= cdev_default_release,
+};
+
+static struct kobj_type ktype_cdev_dynamic = {
+	.release	= cdev_dynamic_release,
+};
+
+/**
+ * cdev_alloc() - allocate a cdev structure
+ *
+ * Allocates and returns a cdev structure, or NULL on failure.
+ */
+struct cdev *cdev_alloc(void)
+{
+	struct cdev *p = kzalloc(sizeof(struct cdev), GFP_KERNEL);
+	if (p) {
+		INIT_LIST_HEAD(&p->list);
+		kobject_init(&p->kobj, &ktype_cdev_dynamic);
+	}
+	return p;
+}
+
+/**
+ * cdev_init() - initialize a cdev structure
+ * @cdev: the structure to initialize
+ * @fops: the file_operations for this device
+ *
+ * Initializes @cdev, remembering @fops, making it ready to add to the
+ * system with cdev_add().
+ */
+void cdev_init(struct cdev *cdev, const struct file_operations *fops)
+{
+	memset(cdev, 0, sizeof *cdev);
+	INIT_LIST_HEAD(&cdev->list);
+	kobject_init(&cdev->kobj, &ktype_cdev_default);
+	cdev->ops = fops;
+}
+
+static struct kobject *base_probe(dev_t dev, int *part, void *data)
+{
+	if (request_module("char-major-%d-%d", MAJOR(dev), MINOR(dev)) > 0)
+		/* Make old-style 2.4 aliases work */
+		request_module("char-major-%d", MAJOR(dev));
+	return NULL;
+}
+
+void __init chrdev_init(void)
+{
+	cdev_map = kobj_map_init(base_probe, &chrdevs_lock);
+	bdi_init(&directly_mappable_cdev_bdi);
+}
+
+#ifndef LIBINPUT
+core_initcall(chrdev_init);
+#endif
+
+/* Let modules do char dev stuff */
+EXPORT_SYMBOL(register_chrdev_region);
+EXPORT_SYMBOL(unregister_chrdev_region);
+EXPORT_SYMBOL(alloc_chrdev_region);
+EXPORT_SYMBOL(cdev_init);
+EXPORT_SYMBOL(cdev_alloc);
+EXPORT_SYMBOL(cdev_del);
+EXPORT_SYMBOL(cdev_add);
+EXPORT_SYMBOL(register_chrdev);
+EXPORT_SYMBOL(unregister_chrdev);
+EXPORT_SYMBOL(directly_mappable_cdev_bdi);