4 * Copyright (C) 2002, Linus Torvalds.
6 * Contains all the functions related to writing back and waiting
7 * upon dirty inodes against superblocks, and writing back dirty
8 * pages against inodes. ie: data writeback. Writeout of the
9 * inode itself is not handled here.
11 * 10Apr2002 Andrew Morton
12 * Split out of fs/inode.c
13 * Additions for address_space-based writeback
16 #include <linux/kernel.h>
17 #include <linux/module.h>
18 #include <linux/spinlock.h>
19 #include <linux/slab.h>
20 #include <linux/sched.h>
23 #include <linux/kthread.h>
24 #include <linux/freezer.h>
25 #include <linux/writeback.h>
26 #include <linux/blkdev.h>
27 #include <linux/backing-dev.h>
28 #include <linux/buffer_head.h>
29 #include <linux/tracepoint.h>
33 * Passed into wb_writeback(), essentially a subset of writeback_control
35 struct wb_writeback_work
{
37 struct super_block
*sb
;
38 enum writeback_sync_modes sync_mode
;
39 unsigned int for_kupdate
:1;
40 unsigned int range_cyclic
:1;
41 unsigned int for_background
:1;
43 struct list_head list
; /* pending work list */
44 struct completion
*done
; /* set if the caller waits */
48 * Include the creation of the trace points after defining the
49 * wb_writeback_work structure so that the definition remains local to this
52 #define CREATE_TRACE_POINTS
53 #include <trace/events/writeback.h>
56 * We don't actually have pdflush, but this one is exported though /proc...
58 int nr_pdflush_threads
;
61 * writeback_in_progress - determine whether there is writeback in progress
62 * @bdi: the device's backing_dev_info structure.
64 * Determine whether there is writeback waiting to be handled against a
67 int writeback_in_progress(struct backing_dev_info
*bdi
)
69 return test_bit(BDI_writeback_running
, &bdi
->state
);
72 static inline struct backing_dev_info
*inode_to_bdi(struct inode
*inode
)
74 struct super_block
*sb
= inode
->i_sb
;
76 if (strcmp(sb
->s_type
->name
, "bdev") == 0)
77 return inode
->i_mapping
->backing_dev_info
;
82 static inline struct inode
*wb_inode(struct list_head
*head
)
84 return list_entry(head
, struct inode
, i_wb_list
);
87 static void bdi_queue_work(struct backing_dev_info
*bdi
,
88 struct wb_writeback_work
*work
)
90 trace_writeback_queue(bdi
, work
);
92 spin_lock_bh(&bdi
->wb_lock
);
93 list_add_tail(&work
->list
, &bdi
->work_list
);
95 wake_up_process(bdi
->wb
.task
);
98 * The bdi thread isn't there, wake up the forker thread which
99 * will create and run it.
101 trace_writeback_nothread(bdi
, work
);
102 wake_up_process(default_backing_dev_info
.wb
.task
);
104 spin_unlock_bh(&bdi
->wb_lock
);
108 __bdi_start_writeback(struct backing_dev_info
*bdi
, long nr_pages
,
109 bool range_cyclic
, bool for_background
)
111 struct wb_writeback_work
*work
;
114 * This is WB_SYNC_NONE writeback, so if allocation fails just
115 * wakeup the thread for old dirty data writeback
117 work
= kzalloc(sizeof(*work
), GFP_ATOMIC
);
120 trace_writeback_nowork(bdi
);
121 wake_up_process(bdi
->wb
.task
);
126 work
->sync_mode
= WB_SYNC_NONE
;
127 work
->nr_pages
= nr_pages
;
128 work
->range_cyclic
= range_cyclic
;
129 work
->for_background
= for_background
;
131 bdi_queue_work(bdi
, work
);
135 * bdi_start_writeback - start writeback
136 * @bdi: the backing device to write from
137 * @nr_pages: the number of pages to write
140 * This does WB_SYNC_NONE opportunistic writeback. The IO is only
141 * started when this function returns, we make no guarentees on
142 * completion. Caller need not hold sb s_umount semaphore.
145 void bdi_start_writeback(struct backing_dev_info
*bdi
, long nr_pages
)
147 __bdi_start_writeback(bdi
, nr_pages
, true, false);
151 * bdi_start_background_writeback - start background writeback
152 * @bdi: the backing device to write from
155 * This does WB_SYNC_NONE background writeback. The IO is only
156 * started when this function returns, we make no guarentees on
157 * completion. Caller need not hold sb s_umount semaphore.
159 void bdi_start_background_writeback(struct backing_dev_info
*bdi
)
161 __bdi_start_writeback(bdi
, LONG_MAX
, true, true);
165 * Redirty an inode: set its when-it-was dirtied timestamp and move it to the
166 * furthest end of its superblock's dirty-inode list.
168 * Before stamping the inode's ->dirtied_when, we check to see whether it is
169 * already the most-recently-dirtied inode on the b_dirty list. If that is
170 * the case then the inode must have been redirtied while it was being written
171 * out and we don't reset its dirtied_when.
173 static void redirty_tail(struct inode
*inode
)
175 struct bdi_writeback
*wb
= &inode_to_bdi(inode
)->wb
;
177 if (!list_empty(&wb
->b_dirty
)) {
180 tail
= wb_inode(wb
->b_dirty
.next
);
181 if (time_before(inode
->dirtied_when
, tail
->dirtied_when
))
182 inode
->dirtied_when
= jiffies
;
184 list_move(&inode
->i_wb_list
, &wb
->b_dirty
);
188 * requeue inode for re-scanning after bdi->b_io list is exhausted.
190 static void requeue_io(struct inode
*inode
)
192 struct bdi_writeback
*wb
= &inode_to_bdi(inode
)->wb
;
194 list_move(&inode
->i_wb_list
, &wb
->b_more_io
);
197 static void inode_sync_complete(struct inode
*inode
)
200 * Prevent speculative execution through spin_unlock(&inode_lock);
203 wake_up_bit(&inode
->i_state
, __I_SYNC
);
206 static bool inode_dirtied_after(struct inode
*inode
, unsigned long t
)
208 bool ret
= time_after(inode
->dirtied_when
, t
);
211 * For inodes being constantly redirtied, dirtied_when can get stuck.
212 * It _appears_ to be in the future, but is actually in distant past.
213 * This test is necessary to prevent such wrapped-around relative times
214 * from permanently stopping the whole bdi writeback.
216 ret
= ret
&& time_before_eq(inode
->dirtied_when
, jiffies
);
222 * Move expired dirty inodes from @delaying_queue to @dispatch_queue.
224 static void move_expired_inodes(struct list_head
*delaying_queue
,
225 struct list_head
*dispatch_queue
,
226 unsigned long *older_than_this
)
229 struct list_head
*pos
, *node
;
230 struct super_block
*sb
= NULL
;
234 while (!list_empty(delaying_queue
)) {
235 inode
= wb_inode(delaying_queue
->prev
);
236 if (older_than_this
&&
237 inode_dirtied_after(inode
, *older_than_this
))
239 if (sb
&& sb
!= inode
->i_sb
)
242 list_move(&inode
->i_wb_list
, &tmp
);
245 /* just one sb in list, splice to dispatch_queue and we're done */
247 list_splice(&tmp
, dispatch_queue
);
251 /* Move inodes from one superblock together */
252 while (!list_empty(&tmp
)) {
253 sb
= wb_inode(tmp
.prev
)->i_sb
;
254 list_for_each_prev_safe(pos
, node
, &tmp
) {
255 inode
= wb_inode(pos
);
256 if (inode
->i_sb
== sb
)
257 list_move(&inode
->i_wb_list
, dispatch_queue
);
263 * Queue all expired dirty inodes for io, eldest first.
265 * newly dirtied b_dirty b_io b_more_io
266 * =============> gf edc BA
268 * newly dirtied b_dirty b_io b_more_io
269 * =============> g fBAedc
271 * +--> dequeue for IO
273 static void queue_io(struct bdi_writeback
*wb
, unsigned long *older_than_this
)
275 list_splice_init(&wb
->b_more_io
, &wb
->b_io
);
276 move_expired_inodes(&wb
->b_dirty
, &wb
->b_io
, older_than_this
);
279 static int write_inode(struct inode
*inode
, struct writeback_control
*wbc
)
281 if (inode
->i_sb
->s_op
->write_inode
&& !is_bad_inode(inode
))
282 return inode
->i_sb
->s_op
->write_inode(inode
, wbc
);
287 * Wait for writeback on an inode to complete.
289 static void inode_wait_for_writeback(struct inode
*inode
)
291 DEFINE_WAIT_BIT(wq
, &inode
->i_state
, __I_SYNC
);
292 wait_queue_head_t
*wqh
;
294 wqh
= bit_waitqueue(&inode
->i_state
, __I_SYNC
);
295 while (inode
->i_state
& I_SYNC
) {
296 spin_unlock(&inode_lock
);
297 __wait_on_bit(wqh
, &wq
, inode_wait
, TASK_UNINTERRUPTIBLE
);
298 spin_lock(&inode_lock
);
303 * Write out an inode's dirty pages. Called under inode_lock. Either the
304 * caller has ref on the inode (either via __iget or via syscall against an fd)
305 * or the inode has I_WILL_FREE set (via generic_forget_inode)
307 * If `wait' is set, wait on the writeout.
309 * The whole writeout design is quite complex and fragile. We want to avoid
310 * starvation of particular inodes when others are being redirtied, prevent
313 * Called under inode_lock.
316 writeback_single_inode(struct inode
*inode
, struct writeback_control
*wbc
)
318 struct address_space
*mapping
= inode
->i_mapping
;
322 if (!atomic_read(&inode
->i_count
))
323 WARN_ON(!(inode
->i_state
& (I_WILL_FREE
|I_FREEING
)));
325 WARN_ON(inode
->i_state
& I_WILL_FREE
);
327 if (inode
->i_state
& I_SYNC
) {
329 * If this inode is locked for writeback and we are not doing
330 * writeback-for-data-integrity, move it to b_more_io so that
331 * writeback can proceed with the other inodes on s_io.
333 * We'll have another go at writing back this inode when we
334 * completed a full scan of b_io.
336 if (wbc
->sync_mode
!= WB_SYNC_ALL
) {
342 * It's a data-integrity sync. We must wait.
344 inode_wait_for_writeback(inode
);
347 BUG_ON(inode
->i_state
& I_SYNC
);
349 /* Set I_SYNC, reset I_DIRTY_PAGES */
350 inode
->i_state
|= I_SYNC
;
351 inode
->i_state
&= ~I_DIRTY_PAGES
;
352 spin_unlock(&inode_lock
);
354 ret
= do_writepages(mapping
, wbc
);
357 * Make sure to wait on the data before writing out the metadata.
358 * This is important for filesystems that modify metadata on data
361 if (wbc
->sync_mode
== WB_SYNC_ALL
) {
362 int err
= filemap_fdatawait(mapping
);
368 * Some filesystems may redirty the inode during the writeback
369 * due to delalloc, clear dirty metadata flags right before
372 spin_lock(&inode_lock
);
373 dirty
= inode
->i_state
& I_DIRTY
;
374 inode
->i_state
&= ~(I_DIRTY_SYNC
| I_DIRTY_DATASYNC
);
375 spin_unlock(&inode_lock
);
376 /* Don't write the inode if only I_DIRTY_PAGES was set */
377 if (dirty
& (I_DIRTY_SYNC
| I_DIRTY_DATASYNC
)) {
378 int err
= write_inode(inode
, wbc
);
383 spin_lock(&inode_lock
);
384 inode
->i_state
&= ~I_SYNC
;
385 if (!(inode
->i_state
& I_FREEING
)) {
386 if (mapping_tagged(mapping
, PAGECACHE_TAG_DIRTY
)) {
388 * We didn't write back all the pages. nfs_writepages()
389 * sometimes bales out without doing anything.
391 inode
->i_state
|= I_DIRTY_PAGES
;
392 if (wbc
->nr_to_write
<= 0) {
394 * slice used up: queue for next turn
399 * Writeback blocked by something other than
400 * congestion. Delay the inode for some time to
401 * avoid spinning on the CPU (100% iowait)
402 * retrying writeback of the dirty page/inode
403 * that cannot be performed immediately.
407 } else if (inode
->i_state
& I_DIRTY
) {
409 * Filesystems can dirty the inode during writeback
410 * operations, such as delayed allocation during
411 * submission or metadata updates after data IO
417 * The inode is clean. At this point we either have
418 * a reference to the inode or it's on it's way out.
419 * No need to add it back to the LRU.
421 list_del_init(&inode
->i_wb_list
);
424 inode_sync_complete(inode
);
429 * For background writeback the caller does not have the sb pinned
430 * before calling writeback. So make sure that we do pin it, so it doesn't
431 * go away while we are writing inodes from it.
433 static bool pin_sb_for_writeback(struct super_block
*sb
)
436 if (list_empty(&sb
->s_instances
)) {
437 spin_unlock(&sb_lock
);
442 spin_unlock(&sb_lock
);
444 if (down_read_trylock(&sb
->s_umount
)) {
447 up_read(&sb
->s_umount
);
455 * Write a portion of b_io inodes which belong to @sb.
457 * If @only_this_sb is true, then find and write all such
458 * inodes. Otherwise write only ones which go sequentially
461 * Return 1, if the caller writeback routine should be
462 * interrupted. Otherwise return 0.
464 static int writeback_sb_inodes(struct super_block
*sb
, struct bdi_writeback
*wb
,
465 struct writeback_control
*wbc
, bool only_this_sb
)
467 while (!list_empty(&wb
->b_io
)) {
469 struct inode
*inode
= wb_inode(wb
->b_io
.prev
);
471 if (inode
->i_sb
!= sb
) {
474 * We only want to write back data for this
475 * superblock, move all inodes not belonging
476 * to it back onto the dirty list.
483 * The inode belongs to a different superblock.
484 * Bounce back to the caller to unpin this and
485 * pin the next superblock.
490 if (inode
->i_state
& (I_NEW
| I_WILL_FREE
)) {
495 * Was this inode dirtied after sync_sb_inodes was called?
496 * This keeps sync from extra jobs and livelock.
498 if (inode_dirtied_after(inode
, wbc
->wb_start
))
501 BUG_ON(inode
->i_state
& I_FREEING
);
503 pages_skipped
= wbc
->pages_skipped
;
504 writeback_single_inode(inode
, wbc
);
505 if (wbc
->pages_skipped
!= pages_skipped
) {
507 * writeback is not making progress due to locked
508 * buffers. Skip this inode for now.
512 spin_unlock(&inode_lock
);
515 spin_lock(&inode_lock
);
516 if (wbc
->nr_to_write
<= 0) {
520 if (!list_empty(&wb
->b_more_io
))
527 void writeback_inodes_wb(struct bdi_writeback
*wb
,
528 struct writeback_control
*wbc
)
533 wbc
->wb_start
= jiffies
; /* livelock avoidance */
534 spin_lock(&inode_lock
);
535 if (!wbc
->for_kupdate
|| list_empty(&wb
->b_io
))
536 queue_io(wb
, wbc
->older_than_this
);
538 while (!list_empty(&wb
->b_io
)) {
539 struct inode
*inode
= wb_inode(wb
->b_io
.prev
);
540 struct super_block
*sb
= inode
->i_sb
;
542 if (!pin_sb_for_writeback(sb
)) {
546 ret
= writeback_sb_inodes(sb
, wb
, wbc
, false);
552 spin_unlock(&inode_lock
);
553 /* Leave any unwritten inodes on b_io */
556 static void __writeback_inodes_sb(struct super_block
*sb
,
557 struct bdi_writeback
*wb
, struct writeback_control
*wbc
)
559 WARN_ON(!rwsem_is_locked(&sb
->s_umount
));
561 spin_lock(&inode_lock
);
562 if (!wbc
->for_kupdate
|| list_empty(&wb
->b_io
))
563 queue_io(wb
, wbc
->older_than_this
);
564 writeback_sb_inodes(sb
, wb
, wbc
, true);
565 spin_unlock(&inode_lock
);
569 * The maximum number of pages to writeout in a single bdi flush/kupdate
570 * operation. We do this so we don't hold I_SYNC against an inode for
571 * enormous amounts of time, which would block a userspace task which has
572 * been forced to throttle against that inode. Also, the code reevaluates
573 * the dirty each time it has written this many pages.
575 #define MAX_WRITEBACK_PAGES 1024
577 static inline bool over_bground_thresh(void)
579 unsigned long background_thresh
, dirty_thresh
;
581 global_dirty_limits(&background_thresh
, &dirty_thresh
);
583 return (global_page_state(NR_FILE_DIRTY
) +
584 global_page_state(NR_UNSTABLE_NFS
) >= background_thresh
);
588 * Explicit flushing or periodic writeback of "old" data.
590 * Define "old": the first time one of an inode's pages is dirtied, we mark the
591 * dirtying-time in the inode's address_space. So this periodic writeback code
592 * just walks the superblock inode list, writing back any inodes which are
593 * older than a specific point in time.
595 * Try to run once per dirty_writeback_interval. But if a writeback event
596 * takes longer than a dirty_writeback_interval interval, then leave a
599 * older_than_this takes precedence over nr_to_write. So we'll only write back
600 * all dirty pages if they are all attached to "old" mappings.
602 static long wb_writeback(struct bdi_writeback
*wb
,
603 struct wb_writeback_work
*work
)
605 struct writeback_control wbc
= {
606 .sync_mode
= work
->sync_mode
,
607 .older_than_this
= NULL
,
608 .for_kupdate
= work
->for_kupdate
,
609 .for_background
= work
->for_background
,
610 .range_cyclic
= work
->range_cyclic
,
612 unsigned long oldest_jif
;
616 if (wbc
.for_kupdate
) {
617 wbc
.older_than_this
= &oldest_jif
;
618 oldest_jif
= jiffies
-
619 msecs_to_jiffies(dirty_expire_interval
* 10);
621 if (!wbc
.range_cyclic
) {
623 wbc
.range_end
= LLONG_MAX
;
626 wbc
.wb_start
= jiffies
; /* livelock avoidance */
629 * Stop writeback when nr_pages has been consumed
631 if (work
->nr_pages
<= 0)
635 * For background writeout, stop when we are below the
636 * background dirty threshold
638 if (work
->for_background
&& !over_bground_thresh())
642 wbc
.nr_to_write
= MAX_WRITEBACK_PAGES
;
643 wbc
.pages_skipped
= 0;
645 trace_wbc_writeback_start(&wbc
, wb
->bdi
);
647 __writeback_inodes_sb(work
->sb
, wb
, &wbc
);
649 writeback_inodes_wb(wb
, &wbc
);
650 trace_wbc_writeback_written(&wbc
, wb
->bdi
);
652 work
->nr_pages
-= MAX_WRITEBACK_PAGES
- wbc
.nr_to_write
;
653 wrote
+= MAX_WRITEBACK_PAGES
- wbc
.nr_to_write
;
656 * If we consumed everything, see if we have more
658 if (wbc
.nr_to_write
<= 0)
661 * Didn't write everything and we don't have more IO, bail
666 * Did we write something? Try for more
668 if (wbc
.nr_to_write
< MAX_WRITEBACK_PAGES
)
671 * Nothing written. Wait for some inode to
672 * become available for writeback. Otherwise
673 * we'll just busyloop.
675 spin_lock(&inode_lock
);
676 if (!list_empty(&wb
->b_more_io
)) {
677 inode
= wb_inode(wb
->b_more_io
.prev
);
678 trace_wbc_writeback_wait(&wbc
, wb
->bdi
);
679 inode_wait_for_writeback(inode
);
681 spin_unlock(&inode_lock
);
688 * Return the next wb_writeback_work struct that hasn't been processed yet.
690 static struct wb_writeback_work
*
691 get_next_work_item(struct backing_dev_info
*bdi
)
693 struct wb_writeback_work
*work
= NULL
;
695 spin_lock_bh(&bdi
->wb_lock
);
696 if (!list_empty(&bdi
->work_list
)) {
697 work
= list_entry(bdi
->work_list
.next
,
698 struct wb_writeback_work
, list
);
699 list_del_init(&work
->list
);
701 spin_unlock_bh(&bdi
->wb_lock
);
705 static long wb_check_old_data_flush(struct bdi_writeback
*wb
)
707 unsigned long expired
;
711 * When set to zero, disable periodic writeback
713 if (!dirty_writeback_interval
)
716 expired
= wb
->last_old_flush
+
717 msecs_to_jiffies(dirty_writeback_interval
* 10);
718 if (time_before(jiffies
, expired
))
721 wb
->last_old_flush
= jiffies
;
722 nr_pages
= global_page_state(NR_FILE_DIRTY
) +
723 global_page_state(NR_UNSTABLE_NFS
) +
724 get_nr_dirty_inodes();
727 struct wb_writeback_work work
= {
728 .nr_pages
= nr_pages
,
729 .sync_mode
= WB_SYNC_NONE
,
734 return wb_writeback(wb
, &work
);
741 * Retrieve work items and do the writeback they describe
743 long wb_do_writeback(struct bdi_writeback
*wb
, int force_wait
)
745 struct backing_dev_info
*bdi
= wb
->bdi
;
746 struct wb_writeback_work
*work
;
749 set_bit(BDI_writeback_running
, &wb
->bdi
->state
);
750 while ((work
= get_next_work_item(bdi
)) != NULL
) {
752 * Override sync mode, in case we must wait for completion
753 * because this thread is exiting now.
756 work
->sync_mode
= WB_SYNC_ALL
;
758 trace_writeback_exec(bdi
, work
);
760 wrote
+= wb_writeback(wb
, work
);
763 * Notify the caller of completion if this is a synchronous
764 * work item, otherwise just free it.
767 complete(work
->done
);
773 * Check for periodic writeback, kupdated() style
775 wrote
+= wb_check_old_data_flush(wb
);
776 clear_bit(BDI_writeback_running
, &wb
->bdi
->state
);
782 * Handle writeback of dirty data for the device backed by this bdi. Also
783 * wakes up periodically and does kupdated style flushing.
785 int bdi_writeback_thread(void *data
)
787 struct bdi_writeback
*wb
= data
;
788 struct backing_dev_info
*bdi
= wb
->bdi
;
791 current
->flags
|= PF_FLUSHER
| PF_SWAPWRITE
;
793 wb
->last_active
= jiffies
;
796 * Our parent may run at a different priority, just set us to normal
798 set_user_nice(current
, 0);
800 trace_writeback_thread_start(bdi
);
802 while (!kthread_should_stop()) {
804 * Remove own delayed wake-up timer, since we are already awake
805 * and we'll take care of the preriodic write-back.
807 del_timer(&wb
->wakeup_timer
);
809 pages_written
= wb_do_writeback(wb
, 0);
811 trace_writeback_pages_written(pages_written
);
814 wb
->last_active
= jiffies
;
816 set_current_state(TASK_INTERRUPTIBLE
);
817 if (!list_empty(&bdi
->work_list
) || kthread_should_stop()) {
818 __set_current_state(TASK_RUNNING
);
822 if (wb_has_dirty_io(wb
) && dirty_writeback_interval
)
823 schedule_timeout(msecs_to_jiffies(dirty_writeback_interval
* 10));
826 * We have nothing to do, so can go sleep without any
827 * timeout and save power. When a work is queued or
828 * something is made dirty - we will be woken up.
836 /* Flush any work that raced with us exiting */
837 if (!list_empty(&bdi
->work_list
))
838 wb_do_writeback(wb
, 1);
840 trace_writeback_thread_stop(bdi
);
846 * Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back
849 void wakeup_flusher_threads(long nr_pages
)
851 struct backing_dev_info
*bdi
;
854 nr_pages
= global_page_state(NR_FILE_DIRTY
) +
855 global_page_state(NR_UNSTABLE_NFS
);
859 list_for_each_entry_rcu(bdi
, &bdi_list
, bdi_list
) {
860 if (!bdi_has_dirty_io(bdi
))
862 __bdi_start_writeback(bdi
, nr_pages
, false, false);
867 static noinline
void block_dump___mark_inode_dirty(struct inode
*inode
)
869 if (inode
->i_ino
|| strcmp(inode
->i_sb
->s_id
, "bdev")) {
870 struct dentry
*dentry
;
871 const char *name
= "?";
873 dentry
= d_find_alias(inode
);
875 spin_lock(&dentry
->d_lock
);
876 name
= (const char *) dentry
->d_name
.name
;
879 "%s(%d): dirtied inode %lu (%s) on %s\n",
880 current
->comm
, task_pid_nr(current
), inode
->i_ino
,
881 name
, inode
->i_sb
->s_id
);
883 spin_unlock(&dentry
->d_lock
);
890 * __mark_inode_dirty - internal function
891 * @inode: inode to mark
892 * @flags: what kind of dirty (i.e. I_DIRTY_SYNC)
893 * Mark an inode as dirty. Callers should use mark_inode_dirty or
894 * mark_inode_dirty_sync.
896 * Put the inode on the super block's dirty list.
898 * CAREFUL! We mark it dirty unconditionally, but move it onto the
899 * dirty list only if it is hashed or if it refers to a blockdev.
900 * If it was not hashed, it will never be added to the dirty list
901 * even if it is later hashed, as it will have been marked dirty already.
903 * In short, make sure you hash any inodes _before_ you start marking
906 * This function *must* be atomic for the I_DIRTY_PAGES case -
907 * set_page_dirty() is called under spinlock in several places.
909 * Note that for blockdevs, inode->dirtied_when represents the dirtying time of
910 * the block-special inode (/dev/hda1) itself. And the ->dirtied_when field of
911 * the kernel-internal blockdev inode represents the dirtying time of the
912 * blockdev's pages. This is why for I_DIRTY_PAGES we always use
913 * page->mapping->host, so the page-dirtying time is recorded in the internal
916 void __mark_inode_dirty(struct inode
*inode
, int flags
)
918 struct super_block
*sb
= inode
->i_sb
;
919 struct backing_dev_info
*bdi
= NULL
;
920 bool wakeup_bdi
= false;
923 * Don't do this for I_DIRTY_PAGES - that doesn't actually
924 * dirty the inode itself
926 if (flags
& (I_DIRTY_SYNC
| I_DIRTY_DATASYNC
)) {
927 if (sb
->s_op
->dirty_inode
)
928 sb
->s_op
->dirty_inode(inode
);
932 * make sure that changes are seen by all cpus before we test i_state
937 /* avoid the locking if we can */
938 if ((inode
->i_state
& flags
) == flags
)
941 if (unlikely(block_dump
))
942 block_dump___mark_inode_dirty(inode
);
944 spin_lock(&inode_lock
);
945 if ((inode
->i_state
& flags
) != flags
) {
946 const int was_dirty
= inode
->i_state
& I_DIRTY
;
948 inode
->i_state
|= flags
;
951 * If the inode is being synced, just update its dirty state.
952 * The unlocker will place the inode on the appropriate
953 * superblock list, based upon its state.
955 if (inode
->i_state
& I_SYNC
)
959 * Only add valid (hashed) inodes to the superblock's
960 * dirty list. Add blockdev inodes as well.
962 if (!S_ISBLK(inode
->i_mode
)) {
963 if (inode_unhashed(inode
))
966 if (inode
->i_state
& I_FREEING
)
970 * If the inode was already on b_dirty/b_io/b_more_io, don't
971 * reposition it (that would break b_dirty time-ordering).
974 bdi
= inode_to_bdi(inode
);
976 if (bdi_cap_writeback_dirty(bdi
)) {
977 WARN(!test_bit(BDI_registered
, &bdi
->state
),
978 "bdi-%s not registered\n", bdi
->name
);
981 * If this is the first dirty inode for this
982 * bdi, we have to wake-up the corresponding
983 * bdi thread to make sure background
984 * write-back happens later.
986 if (!wb_has_dirty_io(&bdi
->wb
))
990 inode
->dirtied_when
= jiffies
;
991 list_move(&inode
->i_wb_list
, &bdi
->wb
.b_dirty
);
995 spin_unlock(&inode_lock
);
998 bdi_wakeup_thread_delayed(bdi
);
1000 EXPORT_SYMBOL(__mark_inode_dirty
);
1003 * Write out a superblock's list of dirty inodes. A wait will be performed
1004 * upon no inodes, all inodes or the final one, depending upon sync_mode.
1006 * If older_than_this is non-NULL, then only write out inodes which
1007 * had their first dirtying at a time earlier than *older_than_this.
1009 * If `bdi' is non-zero then we're being asked to writeback a specific queue.
1010 * This function assumes that the blockdev superblock's inodes are backed by
1011 * a variety of queues, so all inodes are searched. For other superblocks,
1012 * assume that all inodes are backed by the same queue.
1014 * The inodes to be written are parked on bdi->b_io. They are moved back onto
1015 * bdi->b_dirty as they are selected for writing. This way, none can be missed
1016 * on the writer throttling path, and we get decent balancing between many
1017 * throttled threads: we don't want them all piling up on inode_sync_wait.
1019 static void wait_sb_inodes(struct super_block
*sb
)
1021 struct inode
*inode
, *old_inode
= NULL
;
1024 * We need to be protected against the filesystem going from
1025 * r/o to r/w or vice versa.
1027 WARN_ON(!rwsem_is_locked(&sb
->s_umount
));
1029 spin_lock(&inode_lock
);
1032 * Data integrity sync. Must wait for all pages under writeback,
1033 * because there may have been pages dirtied before our sync
1034 * call, but which had writeout started before we write it out.
1035 * In which case, the inode may not be on the dirty list, but
1036 * we still have to wait for that writeout.
1038 list_for_each_entry(inode
, &sb
->s_inodes
, i_sb_list
) {
1039 struct address_space
*mapping
;
1041 if (inode
->i_state
& (I_FREEING
|I_WILL_FREE
|I_NEW
))
1043 mapping
= inode
->i_mapping
;
1044 if (mapping
->nrpages
== 0)
1047 spin_unlock(&inode_lock
);
1049 * We hold a reference to 'inode' so it couldn't have
1050 * been removed from s_inodes list while we dropped the
1051 * inode_lock. We cannot iput the inode now as we can
1052 * be holding the last reference and we cannot iput it
1053 * under inode_lock. So we keep the reference and iput
1059 filemap_fdatawait(mapping
);
1063 spin_lock(&inode_lock
);
1065 spin_unlock(&inode_lock
);
1070 * writeback_inodes_sb - writeback dirty inodes from given super_block
1071 * @sb: the superblock
1073 * Start writeback on some inodes on this super_block. No guarantees are made
1074 * on how many (if any) will be written, and this function does not wait
1075 * for IO completion of submitted IO. The number of pages submitted is
1078 void writeback_inodes_sb(struct super_block
*sb
)
1080 unsigned long nr_dirty
= global_page_state(NR_FILE_DIRTY
);
1081 unsigned long nr_unstable
= global_page_state(NR_UNSTABLE_NFS
);
1082 DECLARE_COMPLETION_ONSTACK(done
);
1083 struct wb_writeback_work work
= {
1085 .sync_mode
= WB_SYNC_NONE
,
1089 WARN_ON(!rwsem_is_locked(&sb
->s_umount
));
1091 work
.nr_pages
= nr_dirty
+ nr_unstable
+ get_nr_dirty_inodes();
1093 bdi_queue_work(sb
->s_bdi
, &work
);
1094 wait_for_completion(&done
);
1096 EXPORT_SYMBOL(writeback_inodes_sb
);
1099 * writeback_inodes_sb_if_idle - start writeback if none underway
1100 * @sb: the superblock
1102 * Invoke writeback_inodes_sb if no writeback is currently underway.
1103 * Returns 1 if writeback was started, 0 if not.
1105 int writeback_inodes_sb_if_idle(struct super_block
*sb
)
1107 if (!writeback_in_progress(sb
->s_bdi
)) {
1108 down_read(&sb
->s_umount
);
1109 writeback_inodes_sb(sb
);
1110 up_read(&sb
->s_umount
);
1115 EXPORT_SYMBOL(writeback_inodes_sb_if_idle
);
1118 * sync_inodes_sb - sync sb inode pages
1119 * @sb: the superblock
1121 * This function writes and waits on any dirty inode belonging to this
1122 * super_block. The number of pages synced is returned.
1124 void sync_inodes_sb(struct super_block
*sb
)
1126 DECLARE_COMPLETION_ONSTACK(done
);
1127 struct wb_writeback_work work
= {
1129 .sync_mode
= WB_SYNC_ALL
,
1130 .nr_pages
= LONG_MAX
,
1135 WARN_ON(!rwsem_is_locked(&sb
->s_umount
));
1137 bdi_queue_work(sb
->s_bdi
, &work
);
1138 wait_for_completion(&done
);
1142 EXPORT_SYMBOL(sync_inodes_sb
);
1145 * write_inode_now - write an inode to disk
1146 * @inode: inode to write to disk
1147 * @sync: whether the write should be synchronous or not
1149 * This function commits an inode to disk immediately if it is dirty. This is
1150 * primarily needed by knfsd.
1152 * The caller must either have a ref on the inode or must have set I_WILL_FREE.
1154 int write_inode_now(struct inode
*inode
, int sync
)
1157 struct writeback_control wbc
= {
1158 .nr_to_write
= LONG_MAX
,
1159 .sync_mode
= sync
? WB_SYNC_ALL
: WB_SYNC_NONE
,
1161 .range_end
= LLONG_MAX
,
1164 if (!mapping_cap_writeback_dirty(inode
->i_mapping
))
1165 wbc
.nr_to_write
= 0;
1168 spin_lock(&inode_lock
);
1169 ret
= writeback_single_inode(inode
, &wbc
);
1170 spin_unlock(&inode_lock
);
1172 inode_sync_wait(inode
);
1175 EXPORT_SYMBOL(write_inode_now
);
1178 * sync_inode - write an inode and its pages to disk.
1179 * @inode: the inode to sync
1180 * @wbc: controls the writeback mode
1182 * sync_inode() will write an inode and its pages to disk. It will also
1183 * correctly update the inode on its superblock's dirty inode lists and will
1184 * update inode->i_state.
1186 * The caller must have a ref on the inode.
1188 int sync_inode(struct inode
*inode
, struct writeback_control
*wbc
)
1192 spin_lock(&inode_lock
);
1193 ret
= writeback_single_inode(inode
, wbc
);
1194 spin_unlock(&inode_lock
);
1197 EXPORT_SYMBOL(sync_inode
);
1200 * sync_inode - write an inode to disk
1201 * @inode: the inode to sync
1202 * @wait: wait for I/O to complete.
1204 * Write an inode to disk and adjust it's dirty state after completion.
1206 * Note: only writes the actual inode, no associated data or other metadata.
1208 int sync_inode_metadata(struct inode
*inode
, int wait
)
1210 struct writeback_control wbc
= {
1211 .sync_mode
= wait
? WB_SYNC_ALL
: WB_SYNC_NONE
,
1212 .nr_to_write
= 0, /* metadata-only */
1215 return sync_inode(inode
, &wbc
);
1217 EXPORT_SYMBOL(sync_inode_metadata
);