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/* Fetching and storing the hypermetadata (superblock and bg summary info).
Copyright (C) 1994, 1995 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2, or (at
your option) any later version.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
#include <string.h>
#include <stdio.h>
#include "ext2fs.h"
error_t
get_hypermetadata (void)
{
error_t err = diskfs_catch_exception ();
if (err)
return err;
sblock = (struct ext2_super_block *)boffs_ptr (SBLOCK_OFFS);
if (sblock->s_magic != EXT2_SUPER_MAGIC
#ifdef EXT2FS_PRE_02B_COMPAT
&& sblock->s_magic != EXT2_PRE_02B_MAGIC
#endif
)
ext2_panic("get_hypermetadata",
"Bad magic number %#x (should be %#x)",
sblock->s_magic, EXT2_SUPER_MAGIC);
block_size = EXT2_MIN_BLOCK_SIZE << sblock->s_log_block_size;
if (block_size > 8192)
ext2_panic("get_hypermetadata",
"Block size %ld is too big (max is 8192 bytes)", block_size);
log2_dev_blocks_per_fs_block = 0;
while ((device_block_size << log2_dev_blocks_per_fs_block) < block_size)
log2_dev_blocks_per_fs_block++;
if ((device_block_size << log2_dev_blocks_per_fs_block) != block_size)
ext2_panic("get_hypermetadata",
"Block size %ld isn't a power-of-two multiple of the device"
" block size (%d)!",
block_size, device_block_size);
log2_block_size = 0;
while ((1 << log2_block_size) < block_size)
log2_block_size++;
if ((1 << log2_block_size) != block_size)
ext2_panic("get_hypermetadata",
"Block size %ld isn't a power of two!", block_size);
if (!diskfs_readonly && block_size < vm_page_size)
/* If the block size is too small, we have to take extra care when
writing out pages from the global pager, to make sure we don't stomp
on any file pager blocks. In this case use a bitmap to record which
global blocks are actually modified so the pager can write only them.
Since small block sizes are probably used on smaller media (to save
space), this shouldn't be too much of a problem. */
{
/* One bit per filesystem block. */
vm_allocate (mach_task_self (), (vm_address_t *)&modified_global_blocks,
(sblock->s_blocks_count >> log2_block_size) >> 3, 1);
}
else
modified_global_blocks = 0;
/* Set these handy variables. */
inodes_per_block = block_size / sizeof (struct ext2_inode);
frag_size = EXT2_MIN_FRAG_SIZE << sblock->s_log_frag_size;
if (frag_size)
frags_per_block = block_size / frag_size;
else
ext2_panic("get_hypermetadata", "Frag size is zero!");
groups_count =
((sblock->s_blocks_count - sblock->s_first_data_block +
sblock->s_blocks_per_group - 1)
/ sblock->s_blocks_per_group);
itb_per_group = sblock->s_inodes_per_group / inodes_per_block;
desc_per_block = block_size / sizeof (struct ext2_group_desc);
addr_per_block = block_size / sizeof (u32);
db_per_group = (groups_count + desc_per_block - 1) / desc_per_block;
diskfs_end_catch_exception ();
return 0;
}
void
diskfs_set_hypermetadata (int wait, int clean)
{
if (clean && !(sblock->s_state & EXT2_VALID_FS))
/* The filesystem is clean, so we need to set the clean flag. We
just write the superblock directly, without using the paged copy. */
{
vm_address_t page_buf = get_page_buf ();
bcopy (sblock, (void *)page_buf, SBLOCK_SIZE);
((struct ext2_super_block *)page_buf)->s_state |= EXT2_VALID_FS;
dev_write_sync (SBLOCK_OFFS / device_block_size, page_buf, block_size);
free_page_buf (page_buf);
}
}
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