2 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License as
7 * published by the Free Software Foundation.
9 * This program is distributed in the hope that it would be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
20 #include "xfs_types.h"
23 #include "xfs_trans.h"
24 #include "xfs_trans_priv.h"
27 #include "xfs_mount.h"
28 #include "xfs_bmap_btree.h"
29 #include "xfs_inode.h"
30 #include "xfs_dinode.h"
31 #include "xfs_error.h"
32 #include "xfs_filestream.h"
33 #include "xfs_vnodeops.h"
34 #include "xfs_inode_item.h"
35 #include "xfs_quota.h"
36 #include "xfs_trace.h"
37 #include "xfs_fsops.h"
39 #include <linux/kthread.h>
40 #include <linux/freezer.h>
42 struct workqueue_struct
*xfs_syncd_wq
; /* sync workqueue */
45 * The inode lookup is done in batches to keep the amount of lock traffic and
46 * radix tree lookups to a minimum. The batch size is a trade off between
47 * lookup reduction and stack usage. This is in the reclaim path, so we can't
50 #define XFS_LOOKUP_BATCH 32
53 xfs_inode_ag_walk_grab(
56 struct inode
*inode
= VFS_I(ip
);
58 ASSERT(rcu_read_lock_held());
61 * check for stale RCU freed inode
63 * If the inode has been reallocated, it doesn't matter if it's not in
64 * the AG we are walking - we are walking for writeback, so if it
65 * passes all the "valid inode" checks and is dirty, then we'll write
66 * it back anyway. If it has been reallocated and still being
67 * initialised, the XFS_INEW check below will catch it.
69 spin_lock(&ip
->i_flags_lock
);
71 goto out_unlock_noent
;
73 /* avoid new or reclaimable inodes. Leave for reclaim code to flush */
74 if (__xfs_iflags_test(ip
, XFS_INEW
| XFS_IRECLAIMABLE
| XFS_IRECLAIM
))
75 goto out_unlock_noent
;
76 spin_unlock(&ip
->i_flags_lock
);
78 /* nothing to sync during shutdown */
79 if (XFS_FORCED_SHUTDOWN(ip
->i_mount
))
82 /* If we can't grab the inode, it must on it's way to reclaim. */
86 if (is_bad_inode(inode
)) {
95 spin_unlock(&ip
->i_flags_lock
);
101 struct xfs_mount
*mp
,
102 struct xfs_perag
*pag
,
103 int (*execute
)(struct xfs_inode
*ip
,
104 struct xfs_perag
*pag
, int flags
),
107 uint32_t first_index
;
119 struct xfs_inode
*batch
[XFS_LOOKUP_BATCH
];
124 nr_found
= radix_tree_gang_lookup(&pag
->pag_ici_root
,
125 (void **)batch
, first_index
,
133 * Grab the inodes before we drop the lock. if we found
134 * nothing, nr == 0 and the loop will be skipped.
136 for (i
= 0; i
< nr_found
; i
++) {
137 struct xfs_inode
*ip
= batch
[i
];
139 if (done
|| xfs_inode_ag_walk_grab(ip
))
143 * Update the index for the next lookup. Catch
144 * overflows into the next AG range which can occur if
145 * we have inodes in the last block of the AG and we
146 * are currently pointing to the last inode.
148 * Because we may see inodes that are from the wrong AG
149 * due to RCU freeing and reallocation, only update the
150 * index if it lies in this AG. It was a race that lead
151 * us to see this inode, so another lookup from the
152 * same index will not find it again.
154 if (XFS_INO_TO_AGNO(mp
, ip
->i_ino
) != pag
->pag_agno
)
156 first_index
= XFS_INO_TO_AGINO(mp
, ip
->i_ino
+ 1);
157 if (first_index
< XFS_INO_TO_AGINO(mp
, ip
->i_ino
))
161 /* unlock now we've grabbed the inodes. */
164 for (i
= 0; i
< nr_found
; i
++) {
167 error
= execute(batch
[i
], pag
, flags
);
169 if (error
== EAGAIN
) {
173 if (error
&& last_error
!= EFSCORRUPTED
)
177 /* bail out if the filesystem is corrupted. */
178 if (error
== EFSCORRUPTED
)
183 } while (nr_found
&& !done
);
193 xfs_inode_ag_iterator(
194 struct xfs_mount
*mp
,
195 int (*execute
)(struct xfs_inode
*ip
,
196 struct xfs_perag
*pag
, int flags
),
199 struct xfs_perag
*pag
;
205 while ((pag
= xfs_perag_get(mp
, ag
))) {
206 ag
= pag
->pag_agno
+ 1;
207 error
= xfs_inode_ag_walk(mp
, pag
, execute
, flags
);
211 if (error
== EFSCORRUPTED
)
215 return XFS_ERROR(last_error
);
220 struct xfs_inode
*ip
,
221 struct xfs_perag
*pag
,
224 struct inode
*inode
= VFS_I(ip
);
225 struct address_space
*mapping
= inode
->i_mapping
;
228 if (!mapping_tagged(mapping
, PAGECACHE_TAG_DIRTY
))
231 if (!xfs_ilock_nowait(ip
, XFS_IOLOCK_SHARED
)) {
232 if (flags
& SYNC_TRYLOCK
)
234 xfs_ilock(ip
, XFS_IOLOCK_SHARED
);
237 error
= xfs_flush_pages(ip
, 0, -1, (flags
& SYNC_WAIT
) ?
238 0 : XBF_ASYNC
, FI_NONE
);
239 xfs_iunlock(ip
, XFS_IOLOCK_SHARED
);
244 * Write out pagecache data for the whole filesystem.
248 struct xfs_mount
*mp
,
253 ASSERT((flags
& ~(SYNC_TRYLOCK
|SYNC_WAIT
)) == 0);
255 error
= xfs_inode_ag_iterator(mp
, xfs_sync_inode_data
, flags
);
257 return XFS_ERROR(error
);
259 xfs_log_force(mp
, (flags
& SYNC_WAIT
) ? XFS_LOG_SYNC
: 0);
265 struct xfs_mount
*mp
)
271 * If the buffer is pinned then push on the log so we won't get stuck
272 * waiting in the write for someone, maybe ourselves, to flush the log.
274 * Even though we just pushed the log above, we did not have the
275 * superblock buffer locked at that point so it can become pinned in
276 * between there and here.
278 bp
= xfs_getsb(mp
, 0);
279 if (xfs_buf_ispinned(bp
))
280 xfs_log_force(mp
, 0);
281 error
= xfs_bwrite(bp
);
287 * When remounting a filesystem read-only or freezing the filesystem, we have
288 * two phases to execute. This first phase is syncing the data before we
289 * quiesce the filesystem, and the second is flushing all the inodes out after
290 * we've waited for all the transactions created by the first phase to
291 * complete. The second phase ensures that the inodes are written to their
292 * location on disk rather than just existing in transactions in the log. This
293 * means after a quiesce there is no log replay required to write the inodes to
294 * disk (this is the main difference between a sync and a quiesce).
297 * First stage of freeze - no writers will make progress now we are here,
298 * so we flush delwri and delalloc buffers here, then wait for all I/O to
299 * complete. Data is frozen at that point. Metadata is not frozen,
300 * transactions can still occur here so don't bother emptying the AIL
301 * because it'll just get dirty again.
305 struct xfs_mount
*mp
)
307 int error
, error2
= 0;
309 /* force out the log */
310 xfs_log_force(mp
, XFS_LOG_SYNC
);
312 /* write superblock and hoover up shutdown errors */
313 error
= xfs_sync_fsdata(mp
);
315 /* mark the log as covered if needed */
316 if (xfs_log_need_covered(mp
))
317 error2
= xfs_fs_log_dummy(mp
);
319 return error
? error
: error2
;
323 * Second stage of a quiesce. The data is already synced, now we have to take
324 * care of the metadata. New transactions are already blocked, so we need to
325 * wait for any remaining transactions to drain out before proceeding.
329 struct xfs_mount
*mp
)
333 /* wait for all modifications to complete */
334 while (atomic_read(&mp
->m_active_trans
) > 0)
337 /* reclaim inodes to do any IO before the freeze completes */
338 xfs_reclaim_inodes(mp
, 0);
339 xfs_reclaim_inodes(mp
, SYNC_WAIT
);
341 /* flush all pending changes from the AIL */
342 xfs_ail_push_all_sync(mp
->m_ail
);
345 * Just warn here till VFS can correctly support
346 * read-only remount without racing.
348 WARN_ON(atomic_read(&mp
->m_active_trans
) != 0);
350 /* Push the superblock and write an unmount record */
351 error
= xfs_log_sbcount(mp
);
353 xfs_warn(mp
, "xfs_attr_quiesce: failed to log sb changes. "
354 "Frozen image may not be consistent.");
355 xfs_log_unmount_write(mp
);
358 * At this point we might have modified the superblock again and thus
359 * added an item to the AIL, thus flush it again.
361 xfs_ail_push_all_sync(mp
->m_ail
);
364 * The superblock buffer is uncached and xfsaild_push() will lock and
365 * set the XBF_ASYNC flag on the buffer. We cannot do xfs_buf_iowait()
366 * here but a lock on the superblock buffer will block until iodone()
369 xfs_buf_lock(mp
->m_sb_bp
);
370 xfs_buf_unlock(mp
->m_sb_bp
);
374 xfs_syncd_queue_sync(
375 struct xfs_mount
*mp
)
377 queue_delayed_work(xfs_syncd_wq
, &mp
->m_sync_work
,
378 msecs_to_jiffies(xfs_syncd_centisecs
* 10));
382 * Every sync period we need to unpin all items, reclaim inodes and sync
383 * disk quotas. We might need to cover the log to indicate that the
384 * filesystem is idle and not frozen.
388 struct work_struct
*work
)
390 struct xfs_mount
*mp
= container_of(to_delayed_work(work
),
391 struct xfs_mount
, m_sync_work
);
395 * We shouldn't write/force the log if we are in the mount/unmount
396 * process or on a read only filesystem. The workqueue still needs to be
397 * active in both cases, however, because it is used for inode reclaim
398 * during these times. Use the MS_ACTIVE flag to avoid doing anything
399 * during mount. Doing work during unmount is avoided by calling
400 * cancel_delayed_work_sync on this work queue before tearing down
401 * the ail and the log in xfs_log_unmount.
403 if (!(mp
->m_super
->s_flags
& MS_ACTIVE
) &&
404 !(mp
->m_flags
& XFS_MOUNT_RDONLY
)) {
405 /* dgc: errors ignored here */
406 if (mp
->m_super
->s_writers
.frozen
== SB_UNFROZEN
&&
407 xfs_log_need_covered(mp
))
408 error
= xfs_fs_log_dummy(mp
);
410 xfs_log_force(mp
, 0);
412 /* start pushing all the metadata that is currently
414 xfs_ail_push_all(mp
->m_ail
);
417 /* queue us up again */
418 xfs_syncd_queue_sync(mp
);
422 * Queue a new inode reclaim pass if there are reclaimable inodes and there
423 * isn't a reclaim pass already in progress. By default it runs every 5s based
424 * on the xfs syncd work default of 30s. Perhaps this should have it's own
425 * tunable, but that can be done if this method proves to be ineffective or too
429 xfs_syncd_queue_reclaim(
430 struct xfs_mount
*mp
)
434 if (radix_tree_tagged(&mp
->m_perag_tree
, XFS_ICI_RECLAIM_TAG
)) {
435 queue_delayed_work(xfs_syncd_wq
, &mp
->m_reclaim_work
,
436 msecs_to_jiffies(xfs_syncd_centisecs
/ 6 * 10));
442 * This is a fast pass over the inode cache to try to get reclaim moving on as
443 * many inodes as possible in a short period of time. It kicks itself every few
444 * seconds, as well as being kicked by the inode cache shrinker when memory
445 * goes low. It scans as quickly as possible avoiding locked inodes or those
446 * already being flushed, and once done schedules a future pass.
450 struct work_struct
*work
)
452 struct xfs_mount
*mp
= container_of(to_delayed_work(work
),
453 struct xfs_mount
, m_reclaim_work
);
455 xfs_reclaim_inodes(mp
, SYNC_TRYLOCK
);
456 xfs_syncd_queue_reclaim(mp
);
460 * Flush delayed allocate data, attempting to free up reserved space
461 * from existing allocations. At this point a new allocation attempt
462 * has failed with ENOSPC and we are in the process of scratching our
463 * heads, looking about for more room.
465 * Queue a new data flush if there isn't one already in progress and
466 * wait for completion of the flush. This means that we only ever have one
467 * inode flush in progress no matter how many ENOSPC events are occurring and
468 * so will prevent the system from bogging down due to every concurrent
469 * ENOSPC event scanning all the active inodes in the system for writeback.
473 struct xfs_inode
*ip
)
475 struct xfs_mount
*mp
= ip
->i_mount
;
477 queue_work(xfs_syncd_wq
, &mp
->m_flush_work
);
478 flush_work(&mp
->m_flush_work
);
483 struct work_struct
*work
)
485 struct xfs_mount
*mp
= container_of(work
,
486 struct xfs_mount
, m_flush_work
);
488 xfs_sync_data(mp
, SYNC_TRYLOCK
);
489 xfs_sync_data(mp
, SYNC_TRYLOCK
| SYNC_WAIT
);
494 struct xfs_mount
*mp
)
496 INIT_WORK(&mp
->m_flush_work
, xfs_flush_worker
);
497 INIT_DELAYED_WORK(&mp
->m_sync_work
, xfs_sync_worker
);
498 INIT_DELAYED_WORK(&mp
->m_reclaim_work
, xfs_reclaim_worker
);
500 xfs_syncd_queue_sync(mp
);
507 struct xfs_mount
*mp
)
509 cancel_delayed_work_sync(&mp
->m_sync_work
);
510 cancel_delayed_work_sync(&mp
->m_reclaim_work
);
511 cancel_work_sync(&mp
->m_flush_work
);
515 __xfs_inode_set_reclaim_tag(
516 struct xfs_perag
*pag
,
517 struct xfs_inode
*ip
)
519 radix_tree_tag_set(&pag
->pag_ici_root
,
520 XFS_INO_TO_AGINO(ip
->i_mount
, ip
->i_ino
),
521 XFS_ICI_RECLAIM_TAG
);
523 if (!pag
->pag_ici_reclaimable
) {
524 /* propagate the reclaim tag up into the perag radix tree */
525 spin_lock(&ip
->i_mount
->m_perag_lock
);
526 radix_tree_tag_set(&ip
->i_mount
->m_perag_tree
,
527 XFS_INO_TO_AGNO(ip
->i_mount
, ip
->i_ino
),
528 XFS_ICI_RECLAIM_TAG
);
529 spin_unlock(&ip
->i_mount
->m_perag_lock
);
531 /* schedule periodic background inode reclaim */
532 xfs_syncd_queue_reclaim(ip
->i_mount
);
534 trace_xfs_perag_set_reclaim(ip
->i_mount
, pag
->pag_agno
,
537 pag
->pag_ici_reclaimable
++;
541 * We set the inode flag atomically with the radix tree tag.
542 * Once we get tag lookups on the radix tree, this inode flag
546 xfs_inode_set_reclaim_tag(
549 struct xfs_mount
*mp
= ip
->i_mount
;
550 struct xfs_perag
*pag
;
552 pag
= xfs_perag_get(mp
, XFS_INO_TO_AGNO(mp
, ip
->i_ino
));
553 spin_lock(&pag
->pag_ici_lock
);
554 spin_lock(&ip
->i_flags_lock
);
555 __xfs_inode_set_reclaim_tag(pag
, ip
);
556 __xfs_iflags_set(ip
, XFS_IRECLAIMABLE
);
557 spin_unlock(&ip
->i_flags_lock
);
558 spin_unlock(&pag
->pag_ici_lock
);
563 __xfs_inode_clear_reclaim(
567 pag
->pag_ici_reclaimable
--;
568 if (!pag
->pag_ici_reclaimable
) {
569 /* clear the reclaim tag from the perag radix tree */
570 spin_lock(&ip
->i_mount
->m_perag_lock
);
571 radix_tree_tag_clear(&ip
->i_mount
->m_perag_tree
,
572 XFS_INO_TO_AGNO(ip
->i_mount
, ip
->i_ino
),
573 XFS_ICI_RECLAIM_TAG
);
574 spin_unlock(&ip
->i_mount
->m_perag_lock
);
575 trace_xfs_perag_clear_reclaim(ip
->i_mount
, pag
->pag_agno
,
581 __xfs_inode_clear_reclaim_tag(
586 radix_tree_tag_clear(&pag
->pag_ici_root
,
587 XFS_INO_TO_AGINO(mp
, ip
->i_ino
), XFS_ICI_RECLAIM_TAG
);
588 __xfs_inode_clear_reclaim(pag
, ip
);
592 * Grab the inode for reclaim exclusively.
593 * Return 0 if we grabbed it, non-zero otherwise.
596 xfs_reclaim_inode_grab(
597 struct xfs_inode
*ip
,
600 ASSERT(rcu_read_lock_held());
602 /* quick check for stale RCU freed inode */
607 * If we are asked for non-blocking operation, do unlocked checks to
608 * see if the inode already is being flushed or in reclaim to avoid
611 if ((flags
& SYNC_TRYLOCK
) &&
612 __xfs_iflags_test(ip
, XFS_IFLOCK
| XFS_IRECLAIM
))
616 * The radix tree lock here protects a thread in xfs_iget from racing
617 * with us starting reclaim on the inode. Once we have the
618 * XFS_IRECLAIM flag set it will not touch us.
620 * Due to RCU lookup, we may find inodes that have been freed and only
621 * have XFS_IRECLAIM set. Indeed, we may see reallocated inodes that
622 * aren't candidates for reclaim at all, so we must check the
623 * XFS_IRECLAIMABLE is set first before proceeding to reclaim.
625 spin_lock(&ip
->i_flags_lock
);
626 if (!__xfs_iflags_test(ip
, XFS_IRECLAIMABLE
) ||
627 __xfs_iflags_test(ip
, XFS_IRECLAIM
)) {
628 /* not a reclaim candidate. */
629 spin_unlock(&ip
->i_flags_lock
);
632 __xfs_iflags_set(ip
, XFS_IRECLAIM
);
633 spin_unlock(&ip
->i_flags_lock
);
638 * Inodes in different states need to be treated differently. The following
639 * table lists the inode states and the reclaim actions necessary:
641 * inode state iflush ret required action
642 * --------------- ---------- ---------------
644 * shutdown EIO unpin and reclaim
645 * clean, unpinned 0 reclaim
646 * stale, unpinned 0 reclaim
647 * clean, pinned(*) 0 requeue
648 * stale, pinned EAGAIN requeue
649 * dirty, async - requeue
650 * dirty, sync 0 reclaim
652 * (*) dgc: I don't think the clean, pinned state is possible but it gets
653 * handled anyway given the order of checks implemented.
655 * Also, because we get the flush lock first, we know that any inode that has
656 * been flushed delwri has had the flush completed by the time we check that
657 * the inode is clean.
659 * Note that because the inode is flushed delayed write by AIL pushing, the
660 * flush lock may already be held here and waiting on it can result in very
661 * long latencies. Hence for sync reclaims, where we wait on the flush lock,
662 * the caller should push the AIL first before trying to reclaim inodes to
663 * minimise the amount of time spent waiting. For background relaim, we only
664 * bother to reclaim clean inodes anyway.
666 * Hence the order of actions after gaining the locks should be:
668 * shutdown => unpin and reclaim
669 * pinned, async => requeue
670 * pinned, sync => unpin
673 * dirty, async => requeue
674 * dirty, sync => flush, wait and reclaim
678 struct xfs_inode
*ip
,
679 struct xfs_perag
*pag
,
682 struct xfs_buf
*bp
= NULL
;
687 xfs_ilock(ip
, XFS_ILOCK_EXCL
);
688 if (!xfs_iflock_nowait(ip
)) {
689 if (!(sync_mode
& SYNC_WAIT
))
694 if (is_bad_inode(VFS_I(ip
)))
696 if (XFS_FORCED_SHUTDOWN(ip
->i_mount
)) {
698 xfs_iflush_abort(ip
, false);
701 if (xfs_ipincount(ip
)) {
702 if (!(sync_mode
& SYNC_WAIT
))
706 if (xfs_iflags_test(ip
, XFS_ISTALE
))
708 if (xfs_inode_clean(ip
))
712 * Never flush out dirty data during non-blocking reclaim, as it would
713 * just contend with AIL pushing trying to do the same job.
715 if (!(sync_mode
& SYNC_WAIT
))
719 * Now we have an inode that needs flushing.
721 * Note that xfs_iflush will never block on the inode buffer lock, as
722 * xfs_ifree_cluster() can lock the inode buffer before it locks the
723 * ip->i_lock, and we are doing the exact opposite here. As a result,
724 * doing a blocking xfs_imap_to_bp() to get the cluster buffer would
725 * result in an ABBA deadlock with xfs_ifree_cluster().
727 * As xfs_ifree_cluser() must gather all inodes that are active in the
728 * cache to mark them stale, if we hit this case we don't actually want
729 * to do IO here - we want the inode marked stale so we can simply
730 * reclaim it. Hence if we get an EAGAIN error here, just unlock the
731 * inode, back off and try again. Hopefully the next pass through will
732 * see the stale flag set on the inode.
734 error
= xfs_iflush(ip
, &bp
);
735 if (error
== EAGAIN
) {
736 xfs_iunlock(ip
, XFS_ILOCK_EXCL
);
737 /* backoff longer than in xfs_ifree_cluster */
743 error
= xfs_bwrite(bp
);
750 xfs_iunlock(ip
, XFS_ILOCK_EXCL
);
752 XFS_STATS_INC(xs_ig_reclaims
);
754 * Remove the inode from the per-AG radix tree.
756 * Because radix_tree_delete won't complain even if the item was never
757 * added to the tree assert that it's been there before to catch
758 * problems with the inode life time early on.
760 spin_lock(&pag
->pag_ici_lock
);
761 if (!radix_tree_delete(&pag
->pag_ici_root
,
762 XFS_INO_TO_AGINO(ip
->i_mount
, ip
->i_ino
)))
764 __xfs_inode_clear_reclaim(pag
, ip
);
765 spin_unlock(&pag
->pag_ici_lock
);
768 * Here we do an (almost) spurious inode lock in order to coordinate
769 * with inode cache radix tree lookups. This is because the lookup
770 * can reference the inodes in the cache without taking references.
772 * We make that OK here by ensuring that we wait until the inode is
773 * unlocked after the lookup before we go ahead and free it.
775 xfs_ilock(ip
, XFS_ILOCK_EXCL
);
777 xfs_iunlock(ip
, XFS_ILOCK_EXCL
);
785 xfs_iflags_clear(ip
, XFS_IRECLAIM
);
786 xfs_iunlock(ip
, XFS_ILOCK_EXCL
);
788 * We could return EAGAIN here to make reclaim rescan the inode tree in
789 * a short while. However, this just burns CPU time scanning the tree
790 * waiting for IO to complete and xfssyncd never goes back to the idle
791 * state. Instead, return 0 to let the next scheduled background reclaim
792 * attempt to reclaim the inode again.
798 * Walk the AGs and reclaim the inodes in them. Even if the filesystem is
799 * corrupted, we still want to try to reclaim all the inodes. If we don't,
800 * then a shut down during filesystem unmount reclaim walk leak all the
801 * unreclaimed inodes.
804 xfs_reclaim_inodes_ag(
805 struct xfs_mount
*mp
,
809 struct xfs_perag
*pag
;
813 int trylock
= flags
& SYNC_TRYLOCK
;
819 while ((pag
= xfs_perag_get_tag(mp
, ag
, XFS_ICI_RECLAIM_TAG
))) {
820 unsigned long first_index
= 0;
824 ag
= pag
->pag_agno
+ 1;
827 if (!mutex_trylock(&pag
->pag_ici_reclaim_lock
)) {
832 first_index
= pag
->pag_ici_reclaim_cursor
;
834 mutex_lock(&pag
->pag_ici_reclaim_lock
);
837 struct xfs_inode
*batch
[XFS_LOOKUP_BATCH
];
841 nr_found
= radix_tree_gang_lookup_tag(
843 (void **)batch
, first_index
,
845 XFS_ICI_RECLAIM_TAG
);
853 * Grab the inodes before we drop the lock. if we found
854 * nothing, nr == 0 and the loop will be skipped.
856 for (i
= 0; i
< nr_found
; i
++) {
857 struct xfs_inode
*ip
= batch
[i
];
859 if (done
|| xfs_reclaim_inode_grab(ip
, flags
))
863 * Update the index for the next lookup. Catch
864 * overflows into the next AG range which can
865 * occur if we have inodes in the last block of
866 * the AG and we are currently pointing to the
869 * Because we may see inodes that are from the
870 * wrong AG due to RCU freeing and
871 * reallocation, only update the index if it
872 * lies in this AG. It was a race that lead us
873 * to see this inode, so another lookup from
874 * the same index will not find it again.
876 if (XFS_INO_TO_AGNO(mp
, ip
->i_ino
) !=
879 first_index
= XFS_INO_TO_AGINO(mp
, ip
->i_ino
+ 1);
880 if (first_index
< XFS_INO_TO_AGINO(mp
, ip
->i_ino
))
884 /* unlock now we've grabbed the inodes. */
887 for (i
= 0; i
< nr_found
; i
++) {
890 error
= xfs_reclaim_inode(batch
[i
], pag
, flags
);
891 if (error
&& last_error
!= EFSCORRUPTED
)
895 *nr_to_scan
-= XFS_LOOKUP_BATCH
;
899 } while (nr_found
&& !done
&& *nr_to_scan
> 0);
901 if (trylock
&& !done
)
902 pag
->pag_ici_reclaim_cursor
= first_index
;
904 pag
->pag_ici_reclaim_cursor
= 0;
905 mutex_unlock(&pag
->pag_ici_reclaim_lock
);
910 * if we skipped any AG, and we still have scan count remaining, do
911 * another pass this time using blocking reclaim semantics (i.e
912 * waiting on the reclaim locks and ignoring the reclaim cursors). This
913 * ensure that when we get more reclaimers than AGs we block rather
914 * than spin trying to execute reclaim.
916 if (skipped
&& (flags
& SYNC_WAIT
) && *nr_to_scan
> 0) {
920 return XFS_ERROR(last_error
);
928 int nr_to_scan
= INT_MAX
;
930 return xfs_reclaim_inodes_ag(mp
, mode
, &nr_to_scan
);
934 * Scan a certain number of inodes for reclaim.
936 * When called we make sure that there is a background (fast) inode reclaim in
937 * progress, while we will throttle the speed of reclaim via doing synchronous
938 * reclaim of inodes. That means if we come across dirty inodes, we wait for
939 * them to be cleaned, which we hope will not be very long due to the
940 * background walker having already kicked the IO off on those dirty inodes.
943 xfs_reclaim_inodes_nr(
944 struct xfs_mount
*mp
,
947 /* kick background reclaimer and push the AIL */
948 xfs_syncd_queue_reclaim(mp
);
949 xfs_ail_push_all(mp
->m_ail
);
951 xfs_reclaim_inodes_ag(mp
, SYNC_TRYLOCK
| SYNC_WAIT
, &nr_to_scan
);
955 * Return the number of reclaimable inodes in the filesystem for
956 * the shrinker to determine how much to reclaim.
959 xfs_reclaim_inodes_count(
960 struct xfs_mount
*mp
)
962 struct xfs_perag
*pag
;
963 xfs_agnumber_t ag
= 0;
966 while ((pag
= xfs_perag_get_tag(mp
, ag
, XFS_ICI_RECLAIM_TAG
))) {
967 ag
= pag
->pag_agno
+ 1;
968 reclaimable
+= pag
->pag_ici_reclaimable
;