diff options
Diffstat (limited to 'libdde-linux26/libdde_linux26/lib/src/mm/page-writeback.c')
| -rw-r--r-- | libdde-linux26/libdde_linux26/lib/src/mm/page-writeback.c | 1468 |
1 files changed, 0 insertions, 1468 deletions
diff --git a/libdde-linux26/libdde_linux26/lib/src/mm/page-writeback.c b/libdde-linux26/libdde_linux26/lib/src/mm/page-writeback.c deleted file mode 100644 index 8a325e2a..00000000 --- a/libdde-linux26/libdde_linux26/lib/src/mm/page-writeback.c +++ /dev/null @@ -1,1468 +0,0 @@ -/* - * mm/page-writeback.c - * - * Copyright (C) 2002, Linus Torvalds. - * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com> - * - * Contains functions related to writing back dirty pages at the - * address_space level. - * - * 10Apr2002 Andrew Morton - * Initial version - */ - -#include <linux/kernel.h> -#include <linux/module.h> -#include <linux/spinlock.h> -#include <linux/fs.h> -#include <linux/mm.h> -#include <linux/swap.h> -#include <linux/slab.h> -#include <linux/pagemap.h> -#include <linux/writeback.h> -#include <linux/init.h> -#include <linux/backing-dev.h> -#include <linux/task_io_accounting_ops.h> -#include <linux/blkdev.h> -#include <linux/mpage.h> -#include <linux/rmap.h> -#include <linux/percpu.h> -#include <linux/notifier.h> -#include <linux/smp.h> -#include <linux/sysctl.h> -#include <linux/cpu.h> -#include <linux/syscalls.h> -#include <linux/buffer_head.h> -#include <linux/pagevec.h> - -/* - * The maximum number of pages to writeout in a single bdflush/kupdate - * operation. We do this so we don't hold I_SYNC against an inode for - * enormous amounts of time, which would block a userspace task which has - * been forced to throttle against that inode. Also, the code reevaluates - * the dirty each time it has written this many pages. - */ -#define MAX_WRITEBACK_PAGES 1024 - -/* - * After a CPU has dirtied this many pages, balance_dirty_pages_ratelimited - * will look to see if it needs to force writeback or throttling. - */ -static long ratelimit_pages = 32; - -/* - * When balance_dirty_pages decides that the caller needs to perform some - * non-background writeback, this is how many pages it will attempt to write. - * It should be somewhat larger than RATELIMIT_PAGES to ensure that reasonably - * large amounts of I/O are submitted. - */ -static inline long sync_writeback_pages(void) -{ - return ratelimit_pages + ratelimit_pages / 2; -} - -/* The following parameters are exported via /proc/sys/vm */ - -/* - * Start background writeback (via pdflush) at this percentage - */ -int dirty_background_ratio = 5; - -/* - * dirty_background_bytes starts at 0 (disabled) so that it is a function of - * dirty_background_ratio * the amount of dirtyable memory - */ -unsigned long dirty_background_bytes; - -/* - * free highmem will not be subtracted from the total free memory - * for calculating free ratios if vm_highmem_is_dirtyable is true - */ -int vm_highmem_is_dirtyable; - -/* - * The generator of dirty data starts writeback at this percentage - */ -int vm_dirty_ratio = 10; - -/* - * vm_dirty_bytes starts at 0 (disabled) so that it is a function of - * vm_dirty_ratio * the amount of dirtyable memory - */ -unsigned long vm_dirty_bytes; - -/* - * The interval between `kupdate'-style writebacks, in jiffies - */ -#ifndef DDE_LINUX -int dirty_writeback_interval = 5 * HZ; -#else -int dirty_writeback_interval = 1250; -#endif - -#ifndef DDE_LINUX -/* - * The longest number of jiffies for which data is allowed to remain dirty - */ -int dirty_expire_interval = 30 * HZ; -#else -int dirty_expire_interval = 7500; -#endif - -/* - * Flag that makes the machine dump writes/reads and block dirtyings. - */ -int block_dump; - -/* - * Flag that puts the machine in "laptop mode". Doubles as a timeout in jiffies: - * a full sync is triggered after this time elapses without any disk activity. - */ -int laptop_mode; - -EXPORT_SYMBOL(laptop_mode); - -/* End of sysctl-exported parameters */ - - -static void background_writeout(unsigned long _min_pages); - -/* - * Scale the writeback cache size proportional to the relative writeout speeds. - * - * We do this by keeping a floating proportion between BDIs, based on page - * writeback completions [end_page_writeback()]. Those devices that write out - * pages fastest will get the larger share, while the slower will get a smaller - * share. - * - * We use page writeout completions because we are interested in getting rid of - * dirty pages. Having them written out is the primary goal. - * - * We introduce a concept of time, a period over which we measure these events, - * because demand can/will vary over time. The length of this period itself is - * measured in page writeback completions. - * - */ -static struct prop_descriptor vm_completions; -static struct prop_descriptor vm_dirties; - -/* - * couple the period to the dirty_ratio: - * - * period/2 ~ roundup_pow_of_two(dirty limit) - */ -static int calc_period_shift(void) -{ - unsigned long dirty_total; - - if (vm_dirty_bytes) - dirty_total = vm_dirty_bytes / PAGE_SIZE; - else - dirty_total = (vm_dirty_ratio * determine_dirtyable_memory()) / - 100; - return 2 + ilog2(dirty_total - 1); -} - -/* - * update the period when the dirty threshold changes. - */ -static void update_completion_period(void) -{ - int shift = calc_period_shift(); - prop_change_shift(&vm_completions, shift); - prop_change_shift(&vm_dirties, shift); -} - -int dirty_background_ratio_handler(struct ctl_table *table, int write, - struct file *filp, void __user *buffer, size_t *lenp, - loff_t *ppos) -{ - int ret; - - ret = proc_dointvec_minmax(table, write, filp, buffer, lenp, ppos); - if (ret == 0 && write) - dirty_background_bytes = 0; - return ret; -} - -int dirty_background_bytes_handler(struct ctl_table *table, int write, - struct file *filp, void __user *buffer, size_t *lenp, - loff_t *ppos) -{ - int ret; - - ret = proc_doulongvec_minmax(table, write, filp, buffer, lenp, ppos); - if (ret == 0 && write) - dirty_background_ratio = 0; - return ret; -} - -int dirty_ratio_handler(struct ctl_table *table, int write, - struct file *filp, void __user *buffer, size_t *lenp, - loff_t *ppos) -{ - int old_ratio = vm_dirty_ratio; - int ret; - - ret = proc_dointvec_minmax(table, write, filp, buffer, lenp, ppos); - if (ret == 0 && write && vm_dirty_ratio != old_ratio) { - update_completion_period(); - vm_dirty_bytes = 0; - } - return ret; -} - - -int dirty_bytes_handler(struct ctl_table *table, int write, - struct file *filp, void __user *buffer, size_t *lenp, - loff_t *ppos) -{ - unsigned long old_bytes = vm_dirty_bytes; - int ret; - - ret = proc_doulongvec_minmax(table, write, filp, buffer, lenp, ppos); - if (ret == 0 && write && vm_dirty_bytes != old_bytes) { - update_completion_period(); - vm_dirty_ratio = 0; - } - return ret; -} - -/* - * Increment the BDI's writeout completion count and the global writeout - * completion count. Called from test_clear_page_writeback(). - */ -static inline void __bdi_writeout_inc(struct backing_dev_info *bdi) -{ - __prop_inc_percpu_max(&vm_completions, &bdi->completions, - bdi->max_prop_frac); -} - -void bdi_writeout_inc(struct backing_dev_info *bdi) -{ - unsigned long flags; - - local_irq_save(flags); - __bdi_writeout_inc(bdi); - local_irq_restore(flags); -} -EXPORT_SYMBOL_GPL(bdi_writeout_inc); - -void task_dirty_inc(struct task_struct *tsk) -{ - prop_inc_single(&vm_dirties, &tsk->dirties); -} - -/* - * Obtain an accurate fraction of the BDI's portion. - */ -static void bdi_writeout_fraction(struct backing_dev_info *bdi, - long *numerator, long *denominator) -{ - if (bdi_cap_writeback_dirty(bdi)) { - prop_fraction_percpu(&vm_completions, &bdi->completions, - numerator, denominator); - } else { - *numerator = 0; - *denominator = 1; - } -} - -/* - * Clip the earned share of dirty pages to that which is actually available. - * This avoids exceeding the total dirty_limit when the floating averages - * fluctuate too quickly. - */ -static void -clip_bdi_dirty_limit(struct backing_dev_info *bdi, long dirty, long *pbdi_dirty) -{ - long avail_dirty; - - avail_dirty = dirty - - (global_page_state(NR_FILE_DIRTY) + - global_page_state(NR_WRITEBACK) + - global_page_state(NR_UNSTABLE_NFS) + - global_page_state(NR_WRITEBACK_TEMP)); - - if (avail_dirty < 0) - avail_dirty = 0; - - avail_dirty += bdi_stat(bdi, BDI_RECLAIMABLE) + - bdi_stat(bdi, BDI_WRITEBACK); - - *pbdi_dirty = min(*pbdi_dirty, avail_dirty); -} - -static inline void task_dirties_fraction(struct task_struct *tsk, - long *numerator, long *denominator) -{ - prop_fraction_single(&vm_dirties, &tsk->dirties, - numerator, denominator); -} - -/* - * scale the dirty limit - * - * task specific dirty limit: - * - * dirty -= (dirty/8) * p_{t} - */ -static void task_dirty_limit(struct task_struct *tsk, long *pdirty) -{ - long numerator, denominator; - long dirty = *pdirty; - u64 inv = dirty >> 3; - - task_dirties_fraction(tsk, &numerator, &denominator); - inv *= numerator; - do_div(inv, denominator); - - dirty -= inv; - if (dirty < *pdirty/2) - dirty = *pdirty/2; - - *pdirty = dirty; -} - -/* - * - */ -static DEFINE_SPINLOCK(bdi_lock); -static unsigned int bdi_min_ratio; - -int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio) -{ - int ret = 0; - unsigned long flags; - - spin_lock_irqsave(&bdi_lock, flags); - if (min_ratio > bdi->max_ratio) { - ret = -EINVAL; - } else { - min_ratio -= bdi->min_ratio; - if (bdi_min_ratio + min_ratio < 100) { - bdi_min_ratio += min_ratio; - bdi->min_ratio += min_ratio; - } else { - ret = -EINVAL; - } - } - spin_unlock_irqrestore(&bdi_lock, flags); - - return ret; -} - -int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned max_ratio) -{ - unsigned long flags; - int ret = 0; - - if (max_ratio > 100) - return -EINVAL; - - spin_lock_irqsave(&bdi_lock, flags); - if (bdi->min_ratio > max_ratio) { - ret = -EINVAL; - } else { - bdi->max_ratio = max_ratio; - bdi->max_prop_frac = (PROP_FRAC_BASE * max_ratio) / 100; - } - spin_unlock_irqrestore(&bdi_lock, flags); - - return ret; -} -EXPORT_SYMBOL(bdi_set_max_ratio); - -/* - * Work out the current dirty-memory clamping and background writeout - * thresholds. - * - * The main aim here is to lower them aggressively if there is a lot of mapped - * memory around. To avoid stressing page reclaim with lots of unreclaimable - * pages. It is better to clamp down on writers than to start swapping, and - * performing lots of scanning. - * - * We only allow 1/2 of the currently-unmapped memory to be dirtied. - * - * We don't permit the clamping level to fall below 5% - that is getting rather - * excessive. - * - * We make sure that the background writeout level is below the adjusted - * clamping level. - */ - -static unsigned long highmem_dirtyable_memory(unsigned long total) -{ -#ifdef CONFIG_HIGHMEM - int node; - unsigned long x = 0; - - for_each_node_state(node, N_HIGH_MEMORY) { - struct zone *z = - &NODE_DATA(node)->node_zones[ZONE_HIGHMEM]; - - x += zone_page_state(z, NR_FREE_PAGES) + zone_lru_pages(z); - } - /* - * Make sure that the number of highmem pages is never larger - * than the number of the total dirtyable memory. This can only - * occur in very strange VM situations but we want to make sure - * that this does not occur. - */ - return min(x, total); -#else - return 0; -#endif -} - -/** - * determine_dirtyable_memory - amount of memory that may be used - * - * Returns the numebr of pages that can currently be freed and used - * by the kernel for direct mappings. - */ -unsigned long determine_dirtyable_memory(void) -{ - unsigned long x; - - x = global_page_state(NR_FREE_PAGES) + global_lru_pages(); - - if (!vm_highmem_is_dirtyable) - x -= highmem_dirtyable_memory(x); - - return x + 1; /* Ensure that we never return 0 */ -} - -void -get_dirty_limits(unsigned long *pbackground, unsigned long *pdirty, - unsigned long *pbdi_dirty, struct backing_dev_info *bdi) -{ - unsigned long background; - unsigned long dirty; - unsigned long available_memory = determine_dirtyable_memory(); - struct task_struct *tsk; - - if (vm_dirty_bytes) - dirty = DIV_ROUND_UP(vm_dirty_bytes, PAGE_SIZE); - else { - int dirty_ratio; - - dirty_ratio = vm_dirty_ratio; - if (dirty_ratio < 5) - dirty_ratio = 5; - dirty = (dirty_ratio * available_memory) / 100; - } - - if (dirty_background_bytes) - background = DIV_ROUND_UP(dirty_background_bytes, PAGE_SIZE); - else - background = (dirty_background_ratio * available_memory) / 100; - - if (background >= dirty) - background = dirty / 2; - tsk = current; - if (tsk->flags & PF_LESS_THROTTLE || rt_task(tsk)) { - background += background / 4; - dirty += dirty / 4; - } - *pbackground = background; - *pdirty = dirty; - - if (bdi) { - u64 bdi_dirty; - long numerator, denominator; - - /* - * Calculate this BDI's share of the dirty ratio. - */ - bdi_writeout_fraction(bdi, &numerator, &denominator); - - bdi_dirty = (dirty * (100 - bdi_min_ratio)) / 100; - bdi_dirty *= numerator; - do_div(bdi_dirty, denominator); - bdi_dirty += (dirty * bdi->min_ratio) / 100; - if (bdi_dirty > (dirty * bdi->max_ratio) / 100) - bdi_dirty = dirty * bdi->max_ratio / 100; - - *pbdi_dirty = bdi_dirty; - clip_bdi_dirty_limit(bdi, dirty, pbdi_dirty); - task_dirty_limit(current, pbdi_dirty); - } -} - -/* - * balance_dirty_pages() must be called by processes which are generating dirty - * data. It looks at the number of dirty pages in the machine and will force - * the caller to perform writeback if the system is over `vm_dirty_ratio'. - * If we're over `background_thresh' then pdflush is woken to perform some - * writeout. - */ -static void balance_dirty_pages(struct address_space *mapping) -{ - long nr_reclaimable, bdi_nr_reclaimable; - long nr_writeback, bdi_nr_writeback; - unsigned long background_thresh; - unsigned long dirty_thresh; - unsigned long bdi_thresh; - unsigned long pages_written = 0; - unsigned long write_chunk = sync_writeback_pages(); - - struct backing_dev_info *bdi = mapping->backing_dev_info; - - for (;;) { - struct writeback_control wbc = { - .bdi = bdi, - .sync_mode = WB_SYNC_NONE, - .older_than_this = NULL, - .nr_to_write = write_chunk, - .range_cyclic = 1, - }; - - get_dirty_limits(&background_thresh, &dirty_thresh, - &bdi_thresh, bdi); - - nr_reclaimable = global_page_state(NR_FILE_DIRTY) + - global_page_state(NR_UNSTABLE_NFS); - nr_writeback = global_page_state(NR_WRITEBACK); - - bdi_nr_reclaimable = bdi_stat(bdi, BDI_RECLAIMABLE); - bdi_nr_writeback = bdi_stat(bdi, BDI_WRITEBACK); - - if (bdi_nr_reclaimable + bdi_nr_writeback <= bdi_thresh) - break; - - /* - * Throttle it only when the background writeback cannot - * catch-up. This avoids (excessively) small writeouts - * when the bdi limits are ramping up. - */ - if (nr_reclaimable + nr_writeback < - (background_thresh + dirty_thresh) / 2) - break; - - if (!bdi->dirty_exceeded) - bdi->dirty_exceeded = 1; - - /* Note: nr_reclaimable denotes nr_dirty + nr_unstable. - * Unstable writes are a feature of certain networked - * filesystems (i.e. NFS) in which data may have been - * written to the server's write cache, but has not yet - * been flushed to permanent storage. - */ - if (bdi_nr_reclaimable) { - writeback_inodes(&wbc); - pages_written += write_chunk - wbc.nr_to_write; - get_dirty_limits(&background_thresh, &dirty_thresh, - &bdi_thresh, bdi); - } - - /* - * In order to avoid the stacked BDI deadlock we need - * to ensure we accurately count the 'dirty' pages when - * the threshold is low. - * - * Otherwise it would be possible to get thresh+n pages - * reported dirty, even though there are thresh-m pages - * actually dirty; with m+n sitting in the percpu - * deltas. - */ - if (bdi_thresh < 2*bdi_stat_error(bdi)) { - bdi_nr_reclaimable = bdi_stat_sum(bdi, BDI_RECLAIMABLE); - bdi_nr_writeback = bdi_stat_sum(bdi, BDI_WRITEBACK); - } else if (bdi_nr_reclaimable) { - bdi_nr_reclaimable = bdi_stat(bdi, BDI_RECLAIMABLE); - bdi_nr_writeback = bdi_stat(bdi, BDI_WRITEBACK); - } - - if (bdi_nr_reclaimable + bdi_nr_writeback <= bdi_thresh) - break; - if (pages_written >= write_chunk) - break; /* We've done our duty */ - - congestion_wait(WRITE, HZ/10); - } - - if (bdi_nr_reclaimable + bdi_nr_writeback < bdi_thresh && - bdi->dirty_exceeded) - bdi->dirty_exceeded = 0; - - if (writeback_in_progress(bdi)) - return; /* pdflush is already working this queue */ - - /* - * In laptop mode, we wait until hitting the higher threshold before - * starting background writeout, and then write out all the way down - * to the lower threshold. So slow writers cause minimal disk activity. - * - * In normal mode, we start background writeout at the lower - * background_thresh, to keep the amount of dirty memory low. - */ - if ((laptop_mode && pages_written) || - (!laptop_mode && (global_page_state(NR_FILE_DIRTY) - + global_page_state(NR_UNSTABLE_NFS) - > background_thresh))) - pdflush_operation(background_writeout, 0); -} - -void set_page_dirty_balance(struct page *page, int page_mkwrite) -{ - if (set_page_dirty(page) || page_mkwrite) { - struct address_space *mapping = page_mapping(page); - - if (mapping) - balance_dirty_pages_ratelimited(mapping); - } -} - -/** - * balance_dirty_pages_ratelimited_nr - balance dirty memory state - * @mapping: address_space which was dirtied - * @nr_pages_dirtied: number of pages which the caller has just dirtied - * - * Processes which are dirtying memory should call in here once for each page - * which was newly dirtied. The function will periodically check the system's - * dirty state and will initiate writeback if needed. - * - * On really big machines, get_writeback_state is expensive, so try to avoid - * calling it too often (ratelimiting). But once we're over the dirty memory - * limit we decrease the ratelimiting by a lot, to prevent individual processes - * from overshooting the limit by (ratelimit_pages) each. - */ -void balance_dirty_pages_ratelimited_nr(struct address_space *mapping, - unsigned long nr_pages_dirtied) -{ - static DEFINE_PER_CPU(unsigned long, ratelimits) = 0; - unsigned long ratelimit; - unsigned long *p; - - ratelimit = ratelimit_pages; - if (mapping->backing_dev_info->dirty_exceeded) - ratelimit = 8; - - /* - * Check the rate limiting. Also, we do not want to throttle real-time - * tasks in balance_dirty_pages(). Period. - */ - preempt_disable(); - p = &__get_cpu_var(ratelimits); - *p += nr_pages_dirtied; - if (unlikely(*p >= ratelimit)) { - *p = 0; - preempt_enable(); - balance_dirty_pages(mapping); - return; - } - preempt_enable(); -} -EXPORT_SYMBOL(balance_dirty_pages_ratelimited_nr); - -void throttle_vm_writeout(gfp_t gfp_mask) -{ - unsigned long background_thresh; - unsigned long dirty_thresh; - - for ( ; ; ) { - get_dirty_limits(&background_thresh, &dirty_thresh, NULL, NULL); - - /* - * Boost the allowable dirty threshold a bit for page - * allocators so they don't get DoS'ed by heavy writers - */ - dirty_thresh += dirty_thresh / 10; /* wheeee... */ - - if (global_page_state(NR_UNSTABLE_NFS) + - global_page_state(NR_WRITEBACK) <= dirty_thresh) - break; - congestion_wait(WRITE, HZ/10); - - /* - * The caller might hold locks which can prevent IO completion - * or progress in the filesystem. So we cannot just sit here - * waiting for IO to complete. - */ - if ((gfp_mask & (__GFP_FS|__GFP_IO)) != (__GFP_FS|__GFP_IO)) - break; - } -} - -/* - * writeback at least _min_pages, and keep writing until the amount of dirty - * memory is less than the background threshold, or until we're all clean. - */ -static void background_writeout(unsigned long _min_pages) -{ - long min_pages = _min_pages; - struct writeback_control wbc = { - .bdi = NULL, - .sync_mode = WB_SYNC_NONE, - .older_than_this = NULL, - .nr_to_write = 0, - .nonblocking = 1, - .range_cyclic = 1, - }; - - for ( ; ; ) { - unsigned long background_thresh; - unsigned long dirty_thresh; - - get_dirty_limits(&background_thresh, &dirty_thresh, NULL, NULL); - if (global_page_state(NR_FILE_DIRTY) + - global_page_state(NR_UNSTABLE_NFS) < background_thresh - && min_pages <= 0) - break; - wbc.more_io = 0; - wbc.encountered_congestion = 0; - wbc.nr_to_write = MAX_WRITEBACK_PAGES; - wbc.pages_skipped = 0; - writeback_inodes(&wbc); - min_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write; - if (wbc.nr_to_write > 0 || wbc.pages_skipped > 0) { - /* Wrote less than expected */ - if (wbc.encountered_congestion || wbc.more_io) - congestion_wait(WRITE, HZ/10); - else - break; - } - } -} - -/* - * Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back - * the whole world. Returns 0 if a pdflush thread was dispatched. Returns - * -1 if all pdflush threads were busy. - */ -int wakeup_pdflush(long nr_pages) -{ - if (nr_pages == 0) - nr_pages = global_page_state(NR_FILE_DIRTY) + - global_page_state(NR_UNSTABLE_NFS); - return pdflush_operation(background_writeout, nr_pages); -} - -#ifndef DDE_LINUX -static void wb_timer_fn(unsigned long unused); -static void laptop_timer_fn(unsigned long unused); - -static DEFINE_TIMER(wb_timer, wb_timer_fn, 0, 0); -static DEFINE_TIMER(laptop_mode_wb_timer, laptop_timer_fn, 0, 0); - -/* - * Periodic writeback of "old" data. - * - * Define "old": the first time one of an inode's pages is dirtied, we mark the - * dirtying-time in the inode's address_space. So this periodic writeback code - * just walks the superblock inode list, writing back any inodes which are - * older than a specific point in time. - * - * Try to run once per dirty_writeback_interval. But if a writeback event - * takes longer than a dirty_writeback_interval interval, then leave a - * one-second gap. - * - * older_than_this takes precedence over nr_to_write. So we'll only write back - * all dirty pages if they are all attached to "old" mappings. - */ -static void wb_kupdate(unsigned long arg) -{ - unsigned long oldest_jif; - unsigned long start_jif; - unsigned long next_jif; - long nr_to_write; - struct writeback_control wbc = { - .bdi = NULL, - .sync_mode = WB_SYNC_NONE, - .older_than_this = &oldest_jif, - .nr_to_write = 0, - .nonblocking = 1, - .for_kupdate = 1, - .range_cyclic = 1, - }; - - sync_supers(); - - oldest_jif = jiffies - dirty_expire_interval; - start_jif = jiffies; - next_jif = start_jif + dirty_writeback_interval; - nr_to_write = global_page_state(NR_FILE_DIRTY) + - global_page_state(NR_UNSTABLE_NFS) + - (inodes_stat.nr_inodes - inodes_stat.nr_unused); - while (nr_to_write > 0) { - wbc.more_io = 0; - wbc.encountered_congestion = 0; - wbc.nr_to_write = MAX_WRITEBACK_PAGES; - writeback_inodes(&wbc); - if (wbc.nr_to_write > 0) { - if (wbc.encountered_congestion || wbc.more_io) - congestion_wait(WRITE, HZ/10); - else - break; /* All the old data is written */ - } - nr_to_write -= MAX_WRITEBACK_PAGES - wbc.nr_to_write; - } - if (time_before(next_jif, jiffies + HZ)) - next_jif = jiffies + HZ; - if (dirty_writeback_interval) - mod_timer(&wb_timer, next_jif); -} - -/* - * sysctl handler for /proc/sys/vm/dirty_writeback_centisecs - */ -int dirty_writeback_centisecs_handler(ctl_table *table, int write, - struct file *file, void __user *buffer, size_t *length, loff_t *ppos) -{ - proc_dointvec_userhz_jiffies(table, write, file, buffer, length, ppos); - if (dirty_writeback_interval) - mod_timer(&wb_timer, jiffies + dirty_writeback_interval); - else - del_timer(&wb_timer); - return 0; -} - -static void wb_timer_fn(unsigned long unused) -{ - if (pdflush_operation(wb_kupdate, 0) < 0) - mod_timer(&wb_timer, jiffies + HZ); /* delay 1 second */ -} - -static void laptop_flush(unsigned long unused) -{ - sys_sync(); -} - -static void laptop_timer_fn(unsigned long unused) -{ - pdflush_operation(laptop_flush, 0); -} - -/* - * We've spun up the disk and we're in laptop mode: schedule writeback - * of all dirty data a few seconds from now. If the flush is already scheduled - * then push it back - the user is still using the disk. - */ -void laptop_io_completion(void) -{ - mod_timer(&laptop_mode_wb_timer, jiffies + laptop_mode); -} - -/* - * We're in laptop mode and we've just synced. The sync's writes will have - * caused another writeback to be scheduled by laptop_io_completion. - * Nothing needs to be written back anymore, so we unschedule the writeback. - */ -void laptop_sync_completion(void) -{ - del_timer(&laptop_mode_wb_timer); -} -#endif - -/* - * If ratelimit_pages is too high then we can get into dirty-data overload - * if a large number of processes all perform writes at the same time. - * If it is too low then SMP machines will call the (expensive) - * get_writeback_state too often. - * - * Here we set ratelimit_pages to a level which ensures that when all CPUs are - * dirtying in parallel, we cannot go more than 3% (1/32) over the dirty memory - * thresholds before writeback cuts in. - * - * But the limit should not be set too high. Because it also controls the - * amount of memory which the balance_dirty_pages() caller has to write back. - * If this is too large then the caller will block on the IO queue all the - * time. So limit it to four megabytes - the balance_dirty_pages() caller - * will write six megabyte chunks, max. - */ - -void writeback_set_ratelimit(void) -{ - ratelimit_pages = vm_total_pages / (num_online_cpus() * 32); - if (ratelimit_pages < 16) - ratelimit_pages = 16; - if (ratelimit_pages * PAGE_CACHE_SIZE > 4096 * 1024) - ratelimit_pages = (4096 * 1024) / PAGE_CACHE_SIZE; -} - -static int __cpuinit -ratelimit_handler(struct notifier_block *self, unsigned long u, void *v) -{ - writeback_set_ratelimit(); - return NOTIFY_DONE; -} - -static struct notifier_block __cpuinitdata ratelimit_nb = { - .notifier_call = ratelimit_handler, - .next = NULL, -}; - -/* - * Called early on to tune the page writeback dirty limits. - * - * We used to scale dirty pages according to how total memory - * related to pages that could be allocated for buffers (by - * comparing nr_free_buffer_pages() to vm_total_pages. - * - * However, that was when we used "dirty_ratio" to scale with - * all memory, and we don't do that any more. "dirty_ratio" - * is now applied to total non-HIGHPAGE memory (by subtracting - * totalhigh_pages from vm_total_pages), and as such we can't - * get into the old insane situation any more where we had - * large amounts of dirty pages compared to a small amount of - * non-HIGHMEM memory. - * - * But we might still want to scale the dirty_ratio by how - * much memory the box has.. - */ -void __init page_writeback_init(void) -{ - int shift; - -#ifndef DDE_LINUX - mod_timer(&wb_timer, jiffies + dirty_writeback_interval); -#endif - writeback_set_ratelimit(); - register_cpu_notifier(&ratelimit_nb); - - shift = calc_period_shift(); - prop_descriptor_init(&vm_completions, shift); - prop_descriptor_init(&vm_dirties, shift); -} - -/** - * write_cache_pages - walk the list of dirty pages of the given address space and write all of them. - * @mapping: address space structure to write - * @wbc: subtract the number of written pages from *@wbc->nr_to_write - * @writepage: function called for each page - * @data: data passed to writepage function - * - * If a page is already under I/O, write_cache_pages() skips it, even - * if it's dirty. This is desirable behaviour for memory-cleaning writeback, - * but it is INCORRECT for data-integrity system calls such as fsync(). fsync() - * and msync() need to guarantee that all the data which was dirty at the time - * the call was made get new I/O started against them. If wbc->sync_mode is - * WB_SYNC_ALL then we were called for data integrity and we must wait for - * existing IO to complete. - */ -int write_cache_pages(struct address_space *mapping, - struct writeback_control *wbc, writepage_t writepage, - void *data) -{ - struct backing_dev_info *bdi = mapping->backing_dev_info; - int ret = 0; - int done = 0; - struct pagevec pvec; - int nr_pages; - pgoff_t uninitialized_var(writeback_index); - pgoff_t index; - pgoff_t end; /* Inclusive */ - pgoff_t done_index; - int cycled; - int range_whole = 0; - long nr_to_write = wbc->nr_to_write; - - if (wbc->nonblocking && bdi_write_congested(bdi)) { - wbc->encountered_congestion = 1; - return 0; - } - - pagevec_init(&pvec, 0); - if (wbc->range_cyclic) { - writeback_index = mapping->writeback_index; /* prev offset */ - index = writeback_index; - if (index == 0) - cycled = 1; - else - cycled = 0; - end = -1; - } else { - index = wbc->range_start >> PAGE_CACHE_SHIFT; - end = wbc->range_end >> PAGE_CACHE_SHIFT; - if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) - range_whole = 1; - cycled = 1; /* ignore range_cyclic tests */ - } -retry: - done_index = index; - while (!done && (index <= end)) { - int i; - - nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, - PAGECACHE_TAG_DIRTY, - min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1); - if (nr_pages == 0) - break; - - for (i = 0; i < nr_pages; i++) { - struct page *page = pvec.pages[i]; - - /* - * At this point, the page may be truncated or - * invalidated (changing page->mapping to NULL), or - * even swizzled back from swapper_space to tmpfs file - * mapping. However, page->index will not change - * because we have a reference on the page. - */ - if (page->index > end) { - /* - * can't be range_cyclic (1st pass) because - * end == -1 in that case. - */ - done = 1; - break; - } - - done_index = page->index + 1; - - lock_page(page); - - /* - * Page truncated or invalidated. We can freely skip it - * then, even for data integrity operations: the page - * has disappeared concurrently, so there could be no - * real expectation of this data interity operation - * even if there is now a new, dirty page at the same - * pagecache address. - */ - if (unlikely(page->mapping != mapping)) { -continue_unlock: - unlock_page(page); - continue; - } - - if (!PageDirty(page)) { - /* someone wrote it for us */ - goto continue_unlock; - } - - if (PageWriteback(page)) { - if (wbc->sync_mode != WB_SYNC_NONE) - wait_on_page_writeback(page); - else - goto continue_unlock; - } - - BUG_ON(PageWriteback(page)); - if (!clear_page_dirty_for_io(page)) - goto continue_unlock; - - ret = (*writepage)(page, wbc, data); - if (unlikely(ret)) { - if (ret == AOP_WRITEPAGE_ACTIVATE) { - unlock_page(page); - ret = 0; - } else { - /* - * done_index is set past this page, - * so media errors will not choke - * background writeout for the entire - * file. This has consequences for - * range_cyclic semantics (ie. it may - * not be suitable for data integrity - * writeout). - */ - done = 1; - break; - } - } - - if (nr_to_write > 0) { - nr_to_write--; - if (nr_to_write == 0 && - wbc->sync_mode == WB_SYNC_NONE) { - /* - * We stop writing back only if we are - * not doing integrity sync. In case of - * integrity sync we have to keep going - * because someone may be concurrently - * dirtying pages, and we might have - * synced a lot of newly appeared dirty - * pages, but have not synced all of the - * old dirty pages. - */ - done = 1; - break; - } - } - - if (wbc->nonblocking && bdi_write_congested(bdi)) { - wbc->encountered_congestion = 1; - done = 1; - break; - } - } - pagevec_release(&pvec); - cond_resched(); - } - if (!cycled && !done) { - /* - * range_cyclic: - * We hit the last page and there is more work to be done: wrap - * back to the start of the file - */ - cycled = 1; - index = 0; - end = writeback_index - 1; - goto retry; - } - if (!wbc->no_nrwrite_index_update) { - if (wbc->range_cyclic || (range_whole && nr_to_write > 0)) - mapping->writeback_index = done_index; - wbc->nr_to_write = nr_to_write; - } - - return ret; -} -EXPORT_SYMBOL(write_cache_pages); - -#ifndef DDE_LINUX -/* - * Function used by generic_writepages to call the real writepage - * function and set the mapping flags on error - */ -static int __writepage(struct page *page, struct writeback_control *wbc, - void *data) -{ - struct address_space *mapping = data; - int ret = mapping->a_ops->writepage(page, wbc); - mapping_set_error(mapping, ret); - return ret; -} - -/** - * generic_writepages - walk the list of dirty pages of the given address space and writepage() all of them. - * @mapping: address space structure to write - * @wbc: subtract the number of written pages from *@wbc->nr_to_write - * - * This is a library function, which implements the writepages() - * address_space_operation. - */ -int generic_writepages(struct address_space *mapping, - struct writeback_control *wbc) -{ - /* deal with chardevs and other special file */ - if (!mapping->a_ops->writepage) - return 0; - - return write_cache_pages(mapping, wbc, __writepage, mapping); -} - -EXPORT_SYMBOL(generic_writepages); - -int do_writepages(struct address_space *mapping, struct writeback_control *wbc) -{ - int ret; - - if (wbc->nr_to_write <= 0) - return 0; - wbc->for_writepages = 1; - if (mapping->a_ops->writepages) - ret = mapping->a_ops->writepages(mapping, wbc); - else - ret = generic_writepages(mapping, wbc); - wbc->for_writepages = 0; - return ret; -} - -/** - * write_one_page - write out a single page and optionally wait on I/O - * @page: the page to write - * @wait: if true, wait on writeout - * - * The page must be locked by the caller and will be unlocked upon return. - * - * write_one_page() returns a negative error code if I/O failed. - */ -int write_one_page(struct page *page, int wait) -{ - struct address_space *mapping = page->mapping; - int ret = 0; - struct writeback_control wbc = { - .sync_mode = WB_SYNC_ALL, - .nr_to_write = 1, - }; - - BUG_ON(!PageLocked(page)); - - if (wait) - wait_on_page_writeback(page); - - if (clear_page_dirty_for_io(page)) { - page_cache_get(page); - ret = mapping->a_ops->writepage(page, &wbc); - if (ret == 0 && wait) { - wait_on_page_writeback(page); - if (PageError(page)) - ret = -EIO; - } - page_cache_release(page); - } else { - unlock_page(page); - } - return ret; -} -EXPORT_SYMBOL(write_one_page); - -/* - * For address_spaces which do not use buffers nor write back. - */ -int __set_page_dirty_no_writeback(struct page *page) -{ - if (!PageDirty(page)) - SetPageDirty(page); - return 0; -} - -/* - * For address_spaces which do not use buffers. Just tag the page as dirty in - * its radix tree. - * - * This is also used when a single buffer is being dirtied: we want to set the - * page dirty in that case, but not all the buffers. This is a "bottom-up" - * dirtying, whereas __set_page_dirty_buffers() is a "top-down" dirtying. - * - * Most callers have locked the page, which pins the address_space in memory. - * But zap_pte_range() does not lock the page, however in that case the - * mapping is pinned by the vma's ->vm_file reference. - * - * We take care to handle the case where the page was truncated from the - * mapping by re-checking page_mapping() inside tree_lock. - */ -int __set_page_dirty_nobuffers(struct page *page) -{ - if (!TestSetPageDirty(page)) { - struct address_space *mapping = page_mapping(page); - struct address_space *mapping2; - - if (!mapping) - return 1; - - spin_lock_irq(&mapping->tree_lock); - mapping2 = page_mapping(page); - if (mapping2) { /* Race with truncate? */ - BUG_ON(mapping2 != mapping); - WARN_ON_ONCE(!PagePrivate(page) && !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); - if (mapping->host) { - /* !PageAnon && !swapper_space */ - __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); - } - return 1; - } - return 0; -} -EXPORT_SYMBOL(__set_page_dirty_nobuffers); - -/* - * When a writepage implementation decides that it doesn't want to write this - * page for some reason, it should redirty the locked page via - * redirty_page_for_writepage() and it should then unlock the page and return 0 - */ -int redirty_page_for_writepage(struct writeback_control *wbc, struct page *page) -{ - wbc->pages_skipped++; - return __set_page_dirty_nobuffers(page); -} -EXPORT_SYMBOL(redirty_page_for_writepage); - -/* - * If the mapping doesn't provide a set_page_dirty a_op, then - * just fall through and assume that it wants buffer_heads. - */ -int set_page_dirty(struct page *page) -{ - struct address_space *mapping = page_mapping(page); - - if (likely(mapping)) { - int (*spd)(struct page *) = mapping->a_ops->set_page_dirty; -#ifdef CONFIG_BLOCK - if (!spd) - spd = __set_page_dirty_buffers; -#endif - return (*spd)(page); - } - if (!PageDirty(page)) { - if (!TestSetPageDirty(page)) - return 1; - } - return 0; -} -EXPORT_SYMBOL(set_page_dirty); - -/* - * set_page_dirty() is racy if the caller has no reference against - * page->mapping->host, and if the page is unlocked. This is because another - * CPU could truncate the page off the mapping and then free the mapping. - * - * Usually, the page _is_ locked, or the caller is a user-space process which - * holds a reference on the inode by having an open file. - * - * In other cases, the page should be locked before running set_page_dirty(). - */ -int set_page_dirty_lock(struct page *page) -{ - int ret; - - lock_page_nosync(page); - ret = set_page_dirty(page); - unlock_page(page); - return ret; -} -EXPORT_SYMBOL(set_page_dirty_lock); -#endif - -/* - * Clear a page's dirty flag, while caring for dirty memory accounting. - * Returns true if the page was previously dirty. - * - * This is for preparing to put the page under writeout. We leave the page - * tagged as dirty in the radix tree so that a concurrent write-for-sync - * can discover it via a PAGECACHE_TAG_DIRTY walk. The ->writepage - * implementation will run either set_page_writeback() or set_page_dirty(), - * at which stage we bring the page's dirty flag and radix-tree dirty tag - * back into sync. - * - * This incoherency between the page's dirty flag and radix-tree tag is - * unfortunate, but it only exists while the page is locked. - */ -int clear_page_dirty_for_io(struct page *page) -{ - struct address_space *mapping = page_mapping(page); - - BUG_ON(!PageLocked(page)); - - ClearPageReclaim(page); - if (mapping && mapping_cap_account_dirty(mapping)) { - /* - * Yes, Virginia, this is indeed insane. - * - * We use this sequence to make sure that - * (a) we account for dirty stats properly - * (b) we tell the low-level filesystem to - * mark the whole page dirty if it was - * dirty in a pagetable. Only to then - * (c) clean the page again and return 1 to - * cause the writeback. - * - * This way we avoid all nasty races with the - * dirty bit in multiple places and clearing - * them concurrently from different threads. - * - * Note! Normally the "set_page_dirty(page)" - * has no effect on the actual dirty bit - since - * that will already usually be set. But we - * need the side effects, and it can help us - * avoid races. - * - * We basically use the page "master dirty bit" - * as a serialization point for all the different - * threads doing their things. - */ - if (page_mkclean(page)) - set_page_dirty(page); - /* - * We carefully synchronise fault handlers against - * installing a dirty pte and marking the page dirty - * at this point. We do this by having them hold the - * page lock at some point after installing their - * pte, but before marking the page dirty. - * Pages are always locked coming in here, so we get - * the desired exclusion. See mm/memory.c:do_wp_page() - * for more comments. - */ - if (TestClearPageDirty(page)) { - dec_zone_page_state(page, NR_FILE_DIRTY); - dec_bdi_stat(mapping->backing_dev_info, - BDI_RECLAIMABLE); - return 1; - } - return 0; - } - return TestClearPageDirty(page); -} -EXPORT_SYMBOL(clear_page_dirty_for_io); - -int test_clear_page_writeback(struct page *page) -{ - struct address_space *mapping = page_mapping(page); - int ret; - - if (mapping) { - struct backing_dev_info *bdi = mapping->backing_dev_info; - unsigned long flags; - - spin_lock_irqsave(&mapping->tree_lock, flags); - ret = TestClearPageWriteback(page); - if (ret) { - radix_tree_tag_clear(&mapping->page_tree, - page_index(page), - PAGECACHE_TAG_WRITEBACK); - if (bdi_cap_account_writeback(bdi)) { - __dec_bdi_stat(bdi, BDI_WRITEBACK); - __bdi_writeout_inc(bdi); - } - } - spin_unlock_irqrestore(&mapping->tree_lock, flags); - } else { - ret = TestClearPageWriteback(page); - } - if (ret) - dec_zone_page_state(page, NR_WRITEBACK); - return ret; -} - -#ifndef DDE_LINUX -int test_set_page_writeback(struct page *page) -{ - struct address_space *mapping = page_mapping(page); - int ret; - - if (mapping) { - struct backing_dev_info *bdi = mapping->backing_dev_info; - unsigned long flags; - - spin_lock_irqsave(&mapping->tree_lock, flags); - ret = TestSetPageWriteback(page); - if (!ret) { - radix_tree_tag_set(&mapping->page_tree, - page_index(page), - PAGECACHE_TAG_WRITEBACK); - if (bdi_cap_account_writeback(bdi)) - __inc_bdi_stat(bdi, BDI_WRITEBACK); - } - if (!PageDirty(page)) - radix_tree_tag_clear(&mapping->page_tree, - page_index(page), - PAGECACHE_TAG_DIRTY); - spin_unlock_irqrestore(&mapping->tree_lock, flags); - } else { - ret = TestSetPageWriteback(page); - } - if (!ret) - inc_zone_page_state(page, NR_WRITEBACK); - return ret; - -} -EXPORT_SYMBOL(test_set_page_writeback); -#endif /* DDE_LINUX */ - -/* - * Return true if any of the pages in the mapping are marked with the - * passed tag. - */ -int mapping_tagged(struct address_space *mapping, int tag) -{ - int ret; - rcu_read_lock(); - ret = radix_tree_tagged(&mapping->page_tree, tag); - rcu_read_unlock(); - return ret; -} -EXPORT_SYMBOL(mapping_tagged); |