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/sched.h>
22 #include <linux/kthread.h>
23 #include <linux/freezer.h>
24 #include <linux/writeback.h>
25 #include <linux/blkdev.h>
26 #include <linux/backing-dev.h>
27 #include <linux/buffer_head.h>
30 #define inode_to_bdi(inode) ((inode)->i_mapping->backing_dev_info)
33 * Work items for the bdi_writeback threads
36 struct list_head list
;
37 struct list_head wait_list
;
38 struct rcu_head rcu_head
;
43 struct super_block
*sb
;
44 unsigned long nr_pages
;
45 enum writeback_sync_modes sync_mode
;
55 #define WS_USED (1 << WS_USED_B)
56 #define WS_ONSTACK (1 << WS_ONSTACK_B)
58 static inline bool bdi_work_on_stack(struct bdi_work
*work
)
60 return test_bit(WS_ONSTACK_B
, &work
->state
);
63 static inline void bdi_work_init(struct bdi_work
*work
,
64 struct writeback_control
*wbc
)
66 INIT_RCU_HEAD(&work
->rcu_head
);
68 work
->nr_pages
= wbc
->nr_to_write
;
69 work
->sync_mode
= wbc
->sync_mode
;
70 work
->state
= WS_USED
;
73 static inline void bdi_work_init_on_stack(struct bdi_work
*work
,
74 struct writeback_control
*wbc
)
76 bdi_work_init(work
, wbc
);
77 work
->state
|= WS_ONSTACK
;
81 * writeback_in_progress - determine whether there is writeback in progress
82 * @bdi: the device's backing_dev_info structure.
84 * Determine whether there is writeback waiting to be handled against a
87 int writeback_in_progress(struct backing_dev_info
*bdi
)
89 return !list_empty(&bdi
->work_list
);
92 static void bdi_work_clear(struct bdi_work
*work
)
94 clear_bit(WS_USED_B
, &work
->state
);
95 smp_mb__after_clear_bit();
96 wake_up_bit(&work
->state
, WS_USED_B
);
99 static void bdi_work_free(struct rcu_head
*head
)
101 struct bdi_work
*work
= container_of(head
, struct bdi_work
, rcu_head
);
103 if (!bdi_work_on_stack(work
))
106 bdi_work_clear(work
);
109 static void wb_work_complete(struct bdi_work
*work
)
111 const enum writeback_sync_modes sync_mode
= work
->sync_mode
;
114 * For allocated work, we can clear the done/seen bit right here.
115 * For on-stack work, we need to postpone both the clear and free
116 * to after the RCU grace period, since the stack could be invalidated
117 * as soon as bdi_work_clear() has done the wakeup.
119 if (!bdi_work_on_stack(work
))
120 bdi_work_clear(work
);
121 if (sync_mode
== WB_SYNC_NONE
|| bdi_work_on_stack(work
))
122 call_rcu(&work
->rcu_head
, bdi_work_free
);
125 static void wb_clear_pending(struct bdi_writeback
*wb
, struct bdi_work
*work
)
128 * The caller has retrieved the work arguments from this work,
129 * drop our reference. If this is the last ref, delete and free it
131 if (atomic_dec_and_test(&work
->pending
)) {
132 struct backing_dev_info
*bdi
= wb
->bdi
;
134 spin_lock(&bdi
->wb_lock
);
135 list_del_rcu(&work
->list
);
136 spin_unlock(&bdi
->wb_lock
);
138 wb_work_complete(work
);
142 static void bdi_queue_work(struct backing_dev_info
*bdi
, struct bdi_work
*work
)
145 work
->seen
= bdi
->wb_mask
;
147 atomic_set(&work
->pending
, bdi
->wb_cnt
);
148 BUG_ON(!bdi
->wb_cnt
);
151 * Make sure stores are seen before it appears on the list
155 spin_lock(&bdi
->wb_lock
);
156 list_add_tail_rcu(&work
->list
, &bdi
->work_list
);
157 spin_unlock(&bdi
->wb_lock
);
161 * If the default thread isn't there, make sure we add it. When
162 * it gets created and wakes up, we'll run this work.
164 if (unlikely(list_empty_careful(&bdi
->wb_list
)))
165 wake_up_process(default_backing_dev_info
.wb
.task
);
167 struct bdi_writeback
*wb
= &bdi
->wb
;
170 * If we failed allocating the bdi work item, wake up the wb
171 * thread always. As a safety precaution, it'll flush out
174 if (!wb_has_dirty_io(wb
)) {
176 wb_clear_pending(wb
, work
);
178 wake_up_process(wb
->task
);
183 * Used for on-stack allocated work items. The caller needs to wait until
184 * the wb threads have acked the work before it's safe to continue.
186 static void bdi_wait_on_work_clear(struct bdi_work
*work
)
188 wait_on_bit(&work
->state
, WS_USED_B
, bdi_sched_wait
,
189 TASK_UNINTERRUPTIBLE
);
192 static struct bdi_work
*bdi_alloc_work(struct writeback_control
*wbc
)
194 struct bdi_work
*work
;
196 work
= kmalloc(sizeof(*work
), GFP_ATOMIC
);
198 bdi_work_init(work
, wbc
);
203 void bdi_start_writeback(struct writeback_control
*wbc
)
205 const bool must_wait
= wbc
->sync_mode
== WB_SYNC_ALL
;
206 struct bdi_work work_stack
, *work
= NULL
;
209 work
= bdi_alloc_work(wbc
);
213 bdi_work_init_on_stack(work
, wbc
);
216 bdi_queue_work(wbc
->bdi
, work
);
219 * If the sync mode is WB_SYNC_ALL, block waiting for the work to
220 * complete. If not, we only need to wait for the work to be started,
221 * if we allocated it on-stack. We use the same mechanism, if the
222 * wait bit is set in the bdi_work struct, then threads will not
223 * clear pending until after they are done.
225 * Note that work == &work_stack if must_wait is true, so we don't
226 * need to do call_rcu() here ever, since the completion path will
227 * have done that for us.
229 if (must_wait
|| work
== &work_stack
) {
230 bdi_wait_on_work_clear(work
);
231 if (work
!= &work_stack
)
232 call_rcu(&work
->rcu_head
, bdi_work_free
);
237 * Redirty an inode: set its when-it-was dirtied timestamp and move it to the
238 * furthest end of its superblock's dirty-inode list.
240 * Before stamping the inode's ->dirtied_when, we check to see whether it is
241 * already the most-recently-dirtied inode on the b_dirty list. If that is
242 * the case then the inode must have been redirtied while it was being written
243 * out and we don't reset its dirtied_when.
245 static void redirty_tail(struct inode
*inode
)
247 struct bdi_writeback
*wb
= &inode_to_bdi(inode
)->wb
;
249 if (!list_empty(&wb
->b_dirty
)) {
252 tail
= list_entry(wb
->b_dirty
.next
, struct inode
, i_list
);
253 if (time_before(inode
->dirtied_when
, tail
->dirtied_when
))
254 inode
->dirtied_when
= jiffies
;
256 list_move(&inode
->i_list
, &wb
->b_dirty
);
260 * requeue inode for re-scanning after bdi->b_io list is exhausted.
262 static void requeue_io(struct inode
*inode
)
264 struct bdi_writeback
*wb
= &inode_to_bdi(inode
)->wb
;
266 list_move(&inode
->i_list
, &wb
->b_more_io
);
269 static void inode_sync_complete(struct inode
*inode
)
272 * Prevent speculative execution through spin_unlock(&inode_lock);
275 wake_up_bit(&inode
->i_state
, __I_SYNC
);
278 static bool inode_dirtied_after(struct inode
*inode
, unsigned long t
)
280 bool ret
= time_after(inode
->dirtied_when
, t
);
283 * For inodes being constantly redirtied, dirtied_when can get stuck.
284 * It _appears_ to be in the future, but is actually in distant past.
285 * This test is necessary to prevent such wrapped-around relative times
286 * from permanently stopping the whole pdflush writeback.
288 ret
= ret
&& time_before_eq(inode
->dirtied_when
, jiffies
);
294 * Move expired dirty inodes from @delaying_queue to @dispatch_queue.
296 static void move_expired_inodes(struct list_head
*delaying_queue
,
297 struct list_head
*dispatch_queue
,
298 unsigned long *older_than_this
)
300 while (!list_empty(delaying_queue
)) {
301 struct inode
*inode
= list_entry(delaying_queue
->prev
,
302 struct inode
, i_list
);
303 if (older_than_this
&&
304 inode_dirtied_after(inode
, *older_than_this
))
306 list_move(&inode
->i_list
, dispatch_queue
);
311 * Queue all expired dirty inodes for io, eldest first.
313 static void queue_io(struct bdi_writeback
*wb
, unsigned long *older_than_this
)
315 list_splice_init(&wb
->b_more_io
, wb
->b_io
.prev
);
316 move_expired_inodes(&wb
->b_dirty
, &wb
->b_io
, older_than_this
);
319 static int write_inode(struct inode
*inode
, int sync
)
321 if (inode
->i_sb
->s_op
->write_inode
&& !is_bad_inode(inode
))
322 return inode
->i_sb
->s_op
->write_inode(inode
, sync
);
327 * Wait for writeback on an inode to complete.
329 static void inode_wait_for_writeback(struct inode
*inode
)
331 DEFINE_WAIT_BIT(wq
, &inode
->i_state
, __I_SYNC
);
332 wait_queue_head_t
*wqh
;
334 wqh
= bit_waitqueue(&inode
->i_state
, __I_SYNC
);
336 spin_unlock(&inode_lock
);
337 __wait_on_bit(wqh
, &wq
, inode_wait
, TASK_UNINTERRUPTIBLE
);
338 spin_lock(&inode_lock
);
339 } while (inode
->i_state
& I_SYNC
);
343 * Write out an inode's dirty pages. Called under inode_lock. Either the
344 * caller has ref on the inode (either via __iget or via syscall against an fd)
345 * or the inode has I_WILL_FREE set (via generic_forget_inode)
347 * If `wait' is set, wait on the writeout.
349 * The whole writeout design is quite complex and fragile. We want to avoid
350 * starvation of particular inodes when others are being redirtied, prevent
353 * Called under inode_lock.
356 writeback_single_inode(struct inode
*inode
, struct writeback_control
*wbc
)
358 struct address_space
*mapping
= inode
->i_mapping
;
359 int wait
= wbc
->sync_mode
== WB_SYNC_ALL
;
363 if (!atomic_read(&inode
->i_count
))
364 WARN_ON(!(inode
->i_state
& (I_WILL_FREE
|I_FREEING
)));
366 WARN_ON(inode
->i_state
& I_WILL_FREE
);
368 if (inode
->i_state
& I_SYNC
) {
370 * If this inode is locked for writeback and we are not doing
371 * writeback-for-data-integrity, move it to b_more_io so that
372 * writeback can proceed with the other inodes on s_io.
374 * We'll have another go at writing back this inode when we
375 * completed a full scan of b_io.
383 * It's a data-integrity sync. We must wait.
385 inode_wait_for_writeback(inode
);
388 BUG_ON(inode
->i_state
& I_SYNC
);
390 /* Set I_SYNC, reset I_DIRTY */
391 dirty
= inode
->i_state
& I_DIRTY
;
392 inode
->i_state
|= I_SYNC
;
393 inode
->i_state
&= ~I_DIRTY
;
395 spin_unlock(&inode_lock
);
397 ret
= do_writepages(mapping
, wbc
);
399 /* Don't write the inode if only I_DIRTY_PAGES was set */
400 if (dirty
& (I_DIRTY_SYNC
| I_DIRTY_DATASYNC
)) {
401 int err
= write_inode(inode
, wait
);
407 int err
= filemap_fdatawait(mapping
);
412 spin_lock(&inode_lock
);
413 inode
->i_state
&= ~I_SYNC
;
414 if (!(inode
->i_state
& (I_FREEING
| I_CLEAR
))) {
415 if (!(inode
->i_state
& I_DIRTY
) &&
416 mapping_tagged(mapping
, PAGECACHE_TAG_DIRTY
)) {
418 * We didn't write back all the pages. nfs_writepages()
419 * sometimes bales out without doing anything. Redirty
420 * the inode; Move it from b_io onto b_more_io/b_dirty.
423 * akpm: if the caller was the kupdate function we put
424 * this inode at the head of b_dirty so it gets first
425 * consideration. Otherwise, move it to the tail, for
426 * the reasons described there. I'm not really sure
427 * how much sense this makes. Presumably I had a good
428 * reasons for doing it this way, and I'd rather not
429 * muck with it at present.
431 if (wbc
->for_kupdate
) {
433 * For the kupdate function we move the inode
434 * to b_more_io so it will get more writeout as
435 * soon as the queue becomes uncongested.
437 inode
->i_state
|= I_DIRTY_PAGES
;
438 if (wbc
->nr_to_write
<= 0) {
440 * slice used up: queue for next turn
445 * somehow blocked: retry later
451 * Otherwise fully redirty the inode so that
452 * other inodes on this superblock will get some
453 * writeout. Otherwise heavy writing to one
454 * file would indefinitely suspend writeout of
455 * all the other files.
457 inode
->i_state
|= I_DIRTY_PAGES
;
460 } else if (inode
->i_state
& I_DIRTY
) {
462 * Someone redirtied the inode while were writing back
466 } else if (atomic_read(&inode
->i_count
)) {
468 * The inode is clean, inuse
470 list_move(&inode
->i_list
, &inode_in_use
);
473 * The inode is clean, unused
475 list_move(&inode
->i_list
, &inode_unused
);
478 inode_sync_complete(inode
);
483 * For WB_SYNC_NONE writeback, the caller does not have the sb pinned
484 * before calling writeback. So make sure that we do pin it, so it doesn't
485 * go away while we are writing inodes from it.
487 * Returns 0 if the super was successfully pinned (or pinning wasn't needed),
490 static int pin_sb_for_writeback(struct writeback_control
*wbc
,
493 struct super_block
*sb
= inode
->i_sb
;
496 * Caller must already hold the ref for this
498 if (wbc
->sync_mode
== WB_SYNC_ALL
) {
499 WARN_ON(!rwsem_is_locked(&sb
->s_umount
));
505 if (down_read_trylock(&sb
->s_umount
)) {
507 spin_unlock(&sb_lock
);
511 * umounted, drop rwsem again and fall through to failure
513 up_read(&sb
->s_umount
);
517 spin_unlock(&sb_lock
);
521 static void unpin_sb_for_writeback(struct writeback_control
*wbc
,
524 struct super_block
*sb
= inode
->i_sb
;
526 if (wbc
->sync_mode
== WB_SYNC_ALL
)
529 up_read(&sb
->s_umount
);
533 static void writeback_inodes_wb(struct bdi_writeback
*wb
,
534 struct writeback_control
*wbc
)
536 struct super_block
*sb
= wbc
->sb
;
537 const int is_blkdev_sb
= sb_is_blkdev_sb(sb
);
538 const unsigned long start
= jiffies
; /* livelock avoidance */
540 spin_lock(&inode_lock
);
542 if (!wbc
->for_kupdate
|| list_empty(&wb
->b_io
))
543 queue_io(wb
, wbc
->older_than_this
);
545 while (!list_empty(&wb
->b_io
)) {
546 struct inode
*inode
= list_entry(wb
->b_io
.prev
,
547 struct inode
, i_list
);
551 * super block given and doesn't match, skip this inode
553 if (sb
&& sb
!= inode
->i_sb
) {
558 if (!bdi_cap_writeback_dirty(wb
->bdi
)) {
562 * Dirty memory-backed blockdev: the ramdisk
563 * driver does this. Skip just this inode
568 * Dirty memory-backed inode against a filesystem other
569 * than the kernel-internal bdev filesystem. Skip the
575 if (inode
->i_state
& (I_NEW
| I_WILL_FREE
)) {
580 if (wbc
->nonblocking
&& bdi_write_congested(wb
->bdi
)) {
581 wbc
->encountered_congestion
= 1;
583 break; /* Skip a congested fs */
585 continue; /* Skip a congested blockdev */
589 * Was this inode dirtied after sync_sb_inodes was called?
590 * This keeps sync from extra jobs and livelock.
592 if (inode_dirtied_after(inode
, start
))
595 if (pin_sb_for_writeback(wbc
, inode
)) {
600 BUG_ON(inode
->i_state
& (I_FREEING
| I_CLEAR
));
602 pages_skipped
= wbc
->pages_skipped
;
603 writeback_single_inode(inode
, wbc
);
604 unpin_sb_for_writeback(wbc
, inode
);
605 if (wbc
->pages_skipped
!= pages_skipped
) {
607 * writeback is not making progress due to locked
608 * buffers. Skip this inode for now.
612 spin_unlock(&inode_lock
);
615 spin_lock(&inode_lock
);
616 if (wbc
->nr_to_write
<= 0) {
620 if (!list_empty(&wb
->b_more_io
))
624 spin_unlock(&inode_lock
);
625 /* Leave any unwritten inodes on b_io */
628 void writeback_inodes_wbc(struct writeback_control
*wbc
)
630 struct backing_dev_info
*bdi
= wbc
->bdi
;
632 writeback_inodes_wb(&bdi
->wb
, wbc
);
636 * The maximum number of pages to writeout in a single bdi flush/kupdate
637 * operation. We do this so we don't hold I_SYNC against an inode for
638 * enormous amounts of time, which would block a userspace task which has
639 * been forced to throttle against that inode. Also, the code reevaluates
640 * the dirty each time it has written this many pages.
642 #define MAX_WRITEBACK_PAGES 1024
644 static inline bool over_bground_thresh(void)
646 unsigned long background_thresh
, dirty_thresh
;
648 get_dirty_limits(&background_thresh
, &dirty_thresh
, NULL
, NULL
);
650 return (global_page_state(NR_FILE_DIRTY
) +
651 global_page_state(NR_UNSTABLE_NFS
) >= background_thresh
);
655 * Explicit flushing or periodic writeback of "old" data.
657 * Define "old": the first time one of an inode's pages is dirtied, we mark the
658 * dirtying-time in the inode's address_space. So this periodic writeback code
659 * just walks the superblock inode list, writing back any inodes which are
660 * older than a specific point in time.
662 * Try to run once per dirty_writeback_interval. But if a writeback event
663 * takes longer than a dirty_writeback_interval interval, then leave a
666 * older_than_this takes precedence over nr_to_write. So we'll only write back
667 * all dirty pages if they are all attached to "old" mappings.
669 static long wb_writeback(struct bdi_writeback
*wb
, long nr_pages
,
670 struct super_block
*sb
,
671 enum writeback_sync_modes sync_mode
, int for_kupdate
)
673 struct writeback_control wbc
= {
676 .sync_mode
= sync_mode
,
677 .older_than_this
= NULL
,
678 .for_kupdate
= for_kupdate
,
681 unsigned long oldest_jif
;
684 if (wbc
.for_kupdate
) {
685 wbc
.older_than_this
= &oldest_jif
;
686 oldest_jif
= jiffies
-
687 msecs_to_jiffies(dirty_expire_interval
* 10);
692 * Don't flush anything for non-integrity writeback where
693 * no nr_pages was given
695 if (!for_kupdate
&& nr_pages
<= 0 && sync_mode
== WB_SYNC_NONE
)
699 * If no specific pages were given and this is just a
700 * periodic background writeout and we are below the
701 * background dirty threshold, don't do anything
703 if (for_kupdate
&& nr_pages
<= 0 && !over_bground_thresh())
707 wbc
.encountered_congestion
= 0;
708 wbc
.nr_to_write
= MAX_WRITEBACK_PAGES
;
709 wbc
.pages_skipped
= 0;
710 writeback_inodes_wb(wb
, &wbc
);
711 nr_pages
-= MAX_WRITEBACK_PAGES
- wbc
.nr_to_write
;
712 wrote
+= MAX_WRITEBACK_PAGES
- wbc
.nr_to_write
;
715 * If we ran out of stuff to write, bail unless more_io got set
717 if (wbc
.nr_to_write
> 0 || wbc
.pages_skipped
> 0) {
718 if (wbc
.more_io
&& !wbc
.for_kupdate
)
728 * Return the next bdi_work struct that hasn't been processed by this
731 static struct bdi_work
*get_next_work_item(struct backing_dev_info
*bdi
,
732 struct bdi_writeback
*wb
)
734 struct bdi_work
*work
, *ret
= NULL
;
738 list_for_each_entry_rcu(work
, &bdi
->work_list
, list
) {
739 if (!test_and_clear_bit(wb
->nr
, &work
->seen
))
750 static long wb_check_old_data_flush(struct bdi_writeback
*wb
)
752 unsigned long expired
;
755 expired
= wb
->last_old_flush
+
756 msecs_to_jiffies(dirty_writeback_interval
* 10);
757 if (time_before(jiffies
, expired
))
760 wb
->last_old_flush
= jiffies
;
761 nr_pages
= global_page_state(NR_FILE_DIRTY
) +
762 global_page_state(NR_UNSTABLE_NFS
) +
763 (inodes_stat
.nr_inodes
- inodes_stat
.nr_unused
);
766 return wb_writeback(wb
, nr_pages
, NULL
, WB_SYNC_NONE
, 1);
772 * Retrieve work items and do the writeback they describe
774 long wb_do_writeback(struct bdi_writeback
*wb
, int force_wait
)
776 struct backing_dev_info
*bdi
= wb
->bdi
;
777 struct bdi_work
*work
;
778 long nr_pages
, wrote
= 0;
780 while ((work
= get_next_work_item(bdi
, wb
)) != NULL
) {
781 enum writeback_sync_modes sync_mode
;
783 nr_pages
= work
->nr_pages
;
786 * Override sync mode, in case we must wait for completion
789 work
->sync_mode
= sync_mode
= WB_SYNC_ALL
;
791 sync_mode
= work
->sync_mode
;
794 * If this isn't a data integrity operation, just notify
795 * that we have seen this work and we are now starting it.
797 if (sync_mode
== WB_SYNC_NONE
)
798 wb_clear_pending(wb
, work
);
800 wrote
+= wb_writeback(wb
, nr_pages
, work
->sb
, sync_mode
, 0);
803 * This is a data integrity writeback, so only do the
804 * notification when we have completed the work.
806 if (sync_mode
== WB_SYNC_ALL
)
807 wb_clear_pending(wb
, work
);
811 * Check for periodic writeback, kupdated() style
813 wrote
+= wb_check_old_data_flush(wb
);
819 * Handle writeback of dirty data for the device backed by this bdi. Also
820 * wakes up periodically and does kupdated style flushing.
822 int bdi_writeback_task(struct bdi_writeback
*wb
)
824 unsigned long last_active
= jiffies
;
825 unsigned long wait_jiffies
= -1UL;
828 while (!kthread_should_stop()) {
829 pages_written
= wb_do_writeback(wb
, 0);
832 last_active
= jiffies
;
833 else if (wait_jiffies
!= -1UL) {
834 unsigned long max_idle
;
837 * Longest period of inactivity that we tolerate. If we
838 * see dirty data again later, the task will get
839 * recreated automatically.
841 max_idle
= max(5UL * 60 * HZ
, wait_jiffies
);
842 if (time_after(jiffies
, max_idle
+ last_active
))
846 wait_jiffies
= msecs_to_jiffies(dirty_writeback_interval
* 10);
847 set_current_state(TASK_INTERRUPTIBLE
);
848 schedule_timeout(wait_jiffies
);
856 * Schedule writeback for all backing devices. Expensive! If this is a data
857 * integrity operation, writeback will be complete when this returns. If
858 * we are simply called for WB_SYNC_NONE, then writeback will merely be
861 static void bdi_writeback_all(struct writeback_control
*wbc
)
863 const bool must_wait
= wbc
->sync_mode
== WB_SYNC_ALL
;
864 struct backing_dev_info
*bdi
;
865 struct bdi_work
*work
;
869 spin_lock(&bdi_lock
);
871 list_for_each_entry(bdi
, &bdi_list
, bdi_list
) {
872 struct bdi_work
*work
;
874 if (!bdi_has_dirty_io(bdi
))
878 * If work allocation fails, do the writes inline. We drop
879 * the lock and restart the list writeout. This should be OK,
880 * since this happens rarely and because the writeout should
881 * eventually make more free memory available.
883 work
= bdi_alloc_work(wbc
);
885 struct writeback_control __wbc
;
888 * Not a data integrity writeout, just continue
893 spin_unlock(&bdi_lock
);
896 writeback_inodes_wbc(&__wbc
);
900 list_add_tail(&work
->wait_list
, &list
);
902 bdi_queue_work(bdi
, work
);
905 spin_unlock(&bdi_lock
);
908 * If this is for WB_SYNC_ALL, wait for pending work to complete
911 while (!list_empty(&list
)) {
912 work
= list_entry(list
.next
, struct bdi_work
, wait_list
);
913 list_del(&work
->wait_list
);
914 bdi_wait_on_work_clear(work
);
915 call_rcu(&work
->rcu_head
, bdi_work_free
);
920 * Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back
923 void wakeup_flusher_threads(long nr_pages
)
925 struct writeback_control wbc
= {
926 .sync_mode
= WB_SYNC_NONE
,
927 .older_than_this
= NULL
,
932 nr_pages
= global_page_state(NR_FILE_DIRTY
) +
933 global_page_state(NR_UNSTABLE_NFS
);
934 wbc
.nr_to_write
= nr_pages
;
935 bdi_writeback_all(&wbc
);
938 static noinline
void block_dump___mark_inode_dirty(struct inode
*inode
)
940 if (inode
->i_ino
|| strcmp(inode
->i_sb
->s_id
, "bdev")) {
941 struct dentry
*dentry
;
942 const char *name
= "?";
944 dentry
= d_find_alias(inode
);
946 spin_lock(&dentry
->d_lock
);
947 name
= (const char *) dentry
->d_name
.name
;
950 "%s(%d): dirtied inode %lu (%s) on %s\n",
951 current
->comm
, task_pid_nr(current
), inode
->i_ino
,
952 name
, inode
->i_sb
->s_id
);
954 spin_unlock(&dentry
->d_lock
);
961 * __mark_inode_dirty - internal function
962 * @inode: inode to mark
963 * @flags: what kind of dirty (i.e. I_DIRTY_SYNC)
964 * Mark an inode as dirty. Callers should use mark_inode_dirty or
965 * mark_inode_dirty_sync.
967 * Put the inode on the super block's dirty list.
969 * CAREFUL! We mark it dirty unconditionally, but move it onto the
970 * dirty list only if it is hashed or if it refers to a blockdev.
971 * If it was not hashed, it will never be added to the dirty list
972 * even if it is later hashed, as it will have been marked dirty already.
974 * In short, make sure you hash any inodes _before_ you start marking
977 * This function *must* be atomic for the I_DIRTY_PAGES case -
978 * set_page_dirty() is called under spinlock in several places.
980 * Note that for blockdevs, inode->dirtied_when represents the dirtying time of
981 * the block-special inode (/dev/hda1) itself. And the ->dirtied_when field of
982 * the kernel-internal blockdev inode represents the dirtying time of the
983 * blockdev's pages. This is why for I_DIRTY_PAGES we always use
984 * page->mapping->host, so the page-dirtying time is recorded in the internal
987 void __mark_inode_dirty(struct inode
*inode
, int flags
)
989 struct super_block
*sb
= inode
->i_sb
;
992 * Don't do this for I_DIRTY_PAGES - that doesn't actually
993 * dirty the inode itself
995 if (flags
& (I_DIRTY_SYNC
| I_DIRTY_DATASYNC
)) {
996 if (sb
->s_op
->dirty_inode
)
997 sb
->s_op
->dirty_inode(inode
);
1001 * make sure that changes are seen by all cpus before we test i_state
1006 /* avoid the locking if we can */
1007 if ((inode
->i_state
& flags
) == flags
)
1010 if (unlikely(block_dump
))
1011 block_dump___mark_inode_dirty(inode
);
1013 spin_lock(&inode_lock
);
1014 if ((inode
->i_state
& flags
) != flags
) {
1015 const int was_dirty
= inode
->i_state
& I_DIRTY
;
1017 inode
->i_state
|= flags
;
1020 * If the inode is being synced, just update its dirty state.
1021 * The unlocker will place the inode on the appropriate
1022 * superblock list, based upon its state.
1024 if (inode
->i_state
& I_SYNC
)
1028 * Only add valid (hashed) inodes to the superblock's
1029 * dirty list. Add blockdev inodes as well.
1031 if (!S_ISBLK(inode
->i_mode
)) {
1032 if (hlist_unhashed(&inode
->i_hash
))
1035 if (inode
->i_state
& (I_FREEING
|I_CLEAR
))
1039 * If the inode was already on b_dirty/b_io/b_more_io, don't
1040 * reposition it (that would break b_dirty time-ordering).
1043 struct bdi_writeback
*wb
= &inode_to_bdi(inode
)->wb
;
1045 inode
->dirtied_when
= jiffies
;
1046 list_move(&inode
->i_list
, &wb
->b_dirty
);
1050 spin_unlock(&inode_lock
);
1052 EXPORT_SYMBOL(__mark_inode_dirty
);
1055 * Write out a superblock's list of dirty inodes. A wait will be performed
1056 * upon no inodes, all inodes or the final one, depending upon sync_mode.
1058 * If older_than_this is non-NULL, then only write out inodes which
1059 * had their first dirtying at a time earlier than *older_than_this.
1061 * If we're a pdlfush thread, then implement pdflush collision avoidance
1062 * against the entire list.
1064 * If `bdi' is non-zero then we're being asked to writeback a specific queue.
1065 * This function assumes that the blockdev superblock's inodes are backed by
1066 * a variety of queues, so all inodes are searched. For other superblocks,
1067 * assume that all inodes are backed by the same queue.
1069 * The inodes to be written are parked on bdi->b_io. They are moved back onto
1070 * bdi->b_dirty as they are selected for writing. This way, none can be missed
1071 * on the writer throttling path, and we get decent balancing between many
1072 * throttled threads: we don't want them all piling up on inode_sync_wait.
1074 static void wait_sb_inodes(struct writeback_control
*wbc
)
1076 struct inode
*inode
, *old_inode
= NULL
;
1079 * We need to be protected against the filesystem going from
1080 * r/o to r/w or vice versa.
1082 WARN_ON(!rwsem_is_locked(&wbc
->sb
->s_umount
));
1084 spin_lock(&inode_lock
);
1087 * Data integrity sync. Must wait for all pages under writeback,
1088 * because there may have been pages dirtied before our sync
1089 * call, but which had writeout started before we write it out.
1090 * In which case, the inode may not be on the dirty list, but
1091 * we still have to wait for that writeout.
1093 list_for_each_entry(inode
, &wbc
->sb
->s_inodes
, i_sb_list
) {
1094 struct address_space
*mapping
;
1096 if (inode
->i_state
& (I_FREEING
|I_CLEAR
|I_WILL_FREE
|I_NEW
))
1098 mapping
= inode
->i_mapping
;
1099 if (mapping
->nrpages
== 0)
1102 spin_unlock(&inode_lock
);
1104 * We hold a reference to 'inode' so it couldn't have
1105 * been removed from s_inodes list while we dropped the
1106 * inode_lock. We cannot iput the inode now as we can
1107 * be holding the last reference and we cannot iput it
1108 * under inode_lock. So we keep the reference and iput
1114 filemap_fdatawait(mapping
);
1118 spin_lock(&inode_lock
);
1120 spin_unlock(&inode_lock
);
1125 * writeback_inodes_sb - writeback dirty inodes from given super_block
1126 * @sb: the superblock
1128 * Start writeback on some inodes on this super_block. No guarantees are made
1129 * on how many (if any) will be written, and this function does not wait
1130 * for IO completion of submitted IO. The number of pages submitted is
1133 long writeback_inodes_sb(struct super_block
*sb
)
1135 struct writeback_control wbc
= {
1137 .sync_mode
= WB_SYNC_NONE
,
1139 .range_end
= LLONG_MAX
,
1141 unsigned long nr_dirty
= global_page_state(NR_FILE_DIRTY
);
1142 unsigned long nr_unstable
= global_page_state(NR_UNSTABLE_NFS
);
1145 nr_to_write
= nr_dirty
+ nr_unstable
+
1146 (inodes_stat
.nr_inodes
- inodes_stat
.nr_unused
);
1148 wbc
.nr_to_write
= nr_to_write
;
1149 bdi_writeback_all(&wbc
);
1150 return nr_to_write
- wbc
.nr_to_write
;
1152 EXPORT_SYMBOL(writeback_inodes_sb
);
1155 * sync_inodes_sb - sync sb inode pages
1156 * @sb: the superblock
1158 * This function writes and waits on any dirty inode belonging to this
1159 * super_block. The number of pages synced is returned.
1161 long sync_inodes_sb(struct super_block
*sb
)
1163 struct writeback_control wbc
= {
1165 .sync_mode
= WB_SYNC_ALL
,
1167 .range_end
= LLONG_MAX
,
1169 long nr_to_write
= LONG_MAX
; /* doesn't actually matter */
1171 wbc
.nr_to_write
= nr_to_write
;
1172 bdi_writeback_all(&wbc
);
1173 wait_sb_inodes(&wbc
);
1174 return nr_to_write
- wbc
.nr_to_write
;
1176 EXPORT_SYMBOL(sync_inodes_sb
);
1179 * write_inode_now - write an inode to disk
1180 * @inode: inode to write to disk
1181 * @sync: whether the write should be synchronous or not
1183 * This function commits an inode to disk immediately if it is dirty. This is
1184 * primarily needed by knfsd.
1186 * The caller must either have a ref on the inode or must have set I_WILL_FREE.
1188 int write_inode_now(struct inode
*inode
, int sync
)
1191 struct writeback_control wbc
= {
1192 .nr_to_write
= LONG_MAX
,
1193 .sync_mode
= sync
? WB_SYNC_ALL
: WB_SYNC_NONE
,
1195 .range_end
= LLONG_MAX
,
1198 if (!mapping_cap_writeback_dirty(inode
->i_mapping
))
1199 wbc
.nr_to_write
= 0;
1202 spin_lock(&inode_lock
);
1203 ret
= writeback_single_inode(inode
, &wbc
);
1204 spin_unlock(&inode_lock
);
1206 inode_sync_wait(inode
);
1209 EXPORT_SYMBOL(write_inode_now
);
1212 * sync_inode - write an inode and its pages to disk.
1213 * @inode: the inode to sync
1214 * @wbc: controls the writeback mode
1216 * sync_inode() will write an inode and its pages to disk. It will also
1217 * correctly update the inode on its superblock's dirty inode lists and will
1218 * update inode->i_state.
1220 * The caller must have a ref on the inode.
1222 int sync_inode(struct inode
*inode
, struct writeback_control
*wbc
)
1226 spin_lock(&inode_lock
);
1227 ret
= writeback_single_inode(inode
, wbc
);
1228 spin_unlock(&inode_lock
);
1231 EXPORT_SYMBOL(sync_inode
);
1234 * generic_osync_inode - flush all dirty data for a given inode to disk
1235 * @inode: inode to write
1236 * @mapping: the address_space that should be flushed
1237 * @what: what to write and wait upon
1239 * This can be called by file_write functions for files which have the
1240 * O_SYNC flag set, to flush dirty writes to disk.
1242 * @what is a bitmask, specifying which part of the inode's data should be
1243 * written and waited upon.
1245 * OSYNC_DATA: i_mapping's dirty data
1246 * OSYNC_METADATA: the buffers at i_mapping->private_list
1247 * OSYNC_INODE: the inode itself
1250 int generic_osync_inode(struct inode
*inode
, struct address_space
*mapping
, int what
)
1253 int need_write_inode_now
= 0;
1256 if (what
& OSYNC_DATA
)
1257 err
= filemap_fdatawrite(mapping
);
1258 if (what
& (OSYNC_METADATA
|OSYNC_DATA
)) {
1259 err2
= sync_mapping_buffers(mapping
);
1263 if (what
& OSYNC_DATA
) {
1264 err2
= filemap_fdatawait(mapping
);
1269 spin_lock(&inode_lock
);
1270 if ((inode
->i_state
& I_DIRTY
) &&
1271 ((what
& OSYNC_INODE
) || (inode
->i_state
& I_DIRTY_DATASYNC
)))
1272 need_write_inode_now
= 1;
1273 spin_unlock(&inode_lock
);
1275 if (need_write_inode_now
) {
1276 err2
= write_inode_now(inode
, 1);
1281 inode_sync_wait(inode
);
1285 EXPORT_SYMBOL(generic_osync_inode
);