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);