Merge tag 'for-linus-v3.6-rc1' of git://oss.sgi.com/xfs/xfs
[GitHub/mt8127/android_kernel_alcatel_ttab.git] / fs / xfs / xfs_sync.c
1 /*
2 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
3 * All Rights Reserved.
4 *
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.
8 *
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.
13 *
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
17 */
18 #include "xfs.h"
19 #include "xfs_fs.h"
20 #include "xfs_types.h"
21 #include "xfs_log.h"
22 #include "xfs_inum.h"
23 #include "xfs_trans.h"
24 #include "xfs_trans_priv.h"
25 #include "xfs_sb.h"
26 #include "xfs_ag.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"
38
39 #include <linux/kthread.h>
40 #include <linux/freezer.h>
41
42 struct workqueue_struct *xfs_syncd_wq; /* sync workqueue */
43
44 /*
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
48 * be too greedy.
49 */
50 #define XFS_LOOKUP_BATCH 32
51
52 STATIC int
53 xfs_inode_ag_walk_grab(
54 struct xfs_inode *ip)
55 {
56 struct inode *inode = VFS_I(ip);
57
58 ASSERT(rcu_read_lock_held());
59
60 /*
61 * check for stale RCU freed inode
62 *
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.
68 */
69 spin_lock(&ip->i_flags_lock);
70 if (!ip->i_ino)
71 goto out_unlock_noent;
72
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);
77
78 /* nothing to sync during shutdown */
79 if (XFS_FORCED_SHUTDOWN(ip->i_mount))
80 return EFSCORRUPTED;
81
82 /* If we can't grab the inode, it must on it's way to reclaim. */
83 if (!igrab(inode))
84 return ENOENT;
85
86 if (is_bad_inode(inode)) {
87 IRELE(ip);
88 return ENOENT;
89 }
90
91 /* inode is valid */
92 return 0;
93
94 out_unlock_noent:
95 spin_unlock(&ip->i_flags_lock);
96 return ENOENT;
97 }
98
99 STATIC int
100 xfs_inode_ag_walk(
101 struct xfs_mount *mp,
102 struct xfs_perag *pag,
103 int (*execute)(struct xfs_inode *ip,
104 struct xfs_perag *pag, int flags),
105 int flags)
106 {
107 uint32_t first_index;
108 int last_error = 0;
109 int skipped;
110 int done;
111 int nr_found;
112
113 restart:
114 done = 0;
115 skipped = 0;
116 first_index = 0;
117 nr_found = 0;
118 do {
119 struct xfs_inode *batch[XFS_LOOKUP_BATCH];
120 int error = 0;
121 int i;
122
123 rcu_read_lock();
124 nr_found = radix_tree_gang_lookup(&pag->pag_ici_root,
125 (void **)batch, first_index,
126 XFS_LOOKUP_BATCH);
127 if (!nr_found) {
128 rcu_read_unlock();
129 break;
130 }
131
132 /*
133 * Grab the inodes before we drop the lock. if we found
134 * nothing, nr == 0 and the loop will be skipped.
135 */
136 for (i = 0; i < nr_found; i++) {
137 struct xfs_inode *ip = batch[i];
138
139 if (done || xfs_inode_ag_walk_grab(ip))
140 batch[i] = NULL;
141
142 /*
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.
147 *
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.
153 */
154 if (XFS_INO_TO_AGNO(mp, ip->i_ino) != pag->pag_agno)
155 continue;
156 first_index = XFS_INO_TO_AGINO(mp, ip->i_ino + 1);
157 if (first_index < XFS_INO_TO_AGINO(mp, ip->i_ino))
158 done = 1;
159 }
160
161 /* unlock now we've grabbed the inodes. */
162 rcu_read_unlock();
163
164 for (i = 0; i < nr_found; i++) {
165 if (!batch[i])
166 continue;
167 error = execute(batch[i], pag, flags);
168 IRELE(batch[i]);
169 if (error == EAGAIN) {
170 skipped++;
171 continue;
172 }
173 if (error && last_error != EFSCORRUPTED)
174 last_error = error;
175 }
176
177 /* bail out if the filesystem is corrupted. */
178 if (error == EFSCORRUPTED)
179 break;
180
181 cond_resched();
182
183 } while (nr_found && !done);
184
185 if (skipped) {
186 delay(1);
187 goto restart;
188 }
189 return last_error;
190 }
191
192 int
193 xfs_inode_ag_iterator(
194 struct xfs_mount *mp,
195 int (*execute)(struct xfs_inode *ip,
196 struct xfs_perag *pag, int flags),
197 int flags)
198 {
199 struct xfs_perag *pag;
200 int error = 0;
201 int last_error = 0;
202 xfs_agnumber_t ag;
203
204 ag = 0;
205 while ((pag = xfs_perag_get(mp, ag))) {
206 ag = pag->pag_agno + 1;
207 error = xfs_inode_ag_walk(mp, pag, execute, flags);
208 xfs_perag_put(pag);
209 if (error) {
210 last_error = error;
211 if (error == EFSCORRUPTED)
212 break;
213 }
214 }
215 return XFS_ERROR(last_error);
216 }
217
218 STATIC int
219 xfs_sync_inode_data(
220 struct xfs_inode *ip,
221 struct xfs_perag *pag,
222 int flags)
223 {
224 struct inode *inode = VFS_I(ip);
225 struct address_space *mapping = inode->i_mapping;
226 int error = 0;
227
228 if (!mapping_tagged(mapping, PAGECACHE_TAG_DIRTY))
229 return 0;
230
231 if (!xfs_ilock_nowait(ip, XFS_IOLOCK_SHARED)) {
232 if (flags & SYNC_TRYLOCK)
233 return 0;
234 xfs_ilock(ip, XFS_IOLOCK_SHARED);
235 }
236
237 error = xfs_flush_pages(ip, 0, -1, (flags & SYNC_WAIT) ?
238 0 : XBF_ASYNC, FI_NONE);
239 xfs_iunlock(ip, XFS_IOLOCK_SHARED);
240 return error;
241 }
242
243 /*
244 * Write out pagecache data for the whole filesystem.
245 */
246 STATIC int
247 xfs_sync_data(
248 struct xfs_mount *mp,
249 int flags)
250 {
251 int error;
252
253 ASSERT((flags & ~(SYNC_TRYLOCK|SYNC_WAIT)) == 0);
254
255 error = xfs_inode_ag_iterator(mp, xfs_sync_inode_data, flags);
256 if (error)
257 return XFS_ERROR(error);
258
259 xfs_log_force(mp, (flags & SYNC_WAIT) ? XFS_LOG_SYNC : 0);
260 return 0;
261 }
262
263 STATIC int
264 xfs_sync_fsdata(
265 struct xfs_mount *mp)
266 {
267 struct xfs_buf *bp;
268 int error;
269
270 /*
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.
273 *
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.
277 */
278 bp = xfs_getsb(mp, 0);
279 if (xfs_buf_ispinned(bp))
280 xfs_log_force(mp, 0);
281 error = xfs_bwrite(bp);
282 xfs_buf_relse(bp);
283 return error;
284 }
285
286 /*
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).
295 */
296 /*
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.
302 */
303 int
304 xfs_quiesce_data(
305 struct xfs_mount *mp)
306 {
307 int error, error2 = 0;
308
309 /* force out the log */
310 xfs_log_force(mp, XFS_LOG_SYNC);
311
312 /* write superblock and hoover up shutdown errors */
313 error = xfs_sync_fsdata(mp);
314
315 /* mark the log as covered if needed */
316 if (xfs_log_need_covered(mp))
317 error2 = xfs_fs_log_dummy(mp);
318
319 return error ? error : error2;
320 }
321
322 /*
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.
326 */
327 void
328 xfs_quiesce_attr(
329 struct xfs_mount *mp)
330 {
331 int error = 0;
332
333 /* wait for all modifications to complete */
334 while (atomic_read(&mp->m_active_trans) > 0)
335 delay(100);
336
337 /* reclaim inodes to do any IO before the freeze completes */
338 xfs_reclaim_inodes(mp, 0);
339 xfs_reclaim_inodes(mp, SYNC_WAIT);
340
341 /* flush all pending changes from the AIL */
342 xfs_ail_push_all_sync(mp->m_ail);
343
344 /*
345 * Just warn here till VFS can correctly support
346 * read-only remount without racing.
347 */
348 WARN_ON(atomic_read(&mp->m_active_trans) != 0);
349
350 /* Push the superblock and write an unmount record */
351 error = xfs_log_sbcount(mp);
352 if (error)
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);
356
357 /*
358 * At this point we might have modified the superblock again and thus
359 * added an item to the AIL, thus flush it again.
360 */
361 xfs_ail_push_all_sync(mp->m_ail);
362
363 /*
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()
367 * has completed.
368 */
369 xfs_buf_lock(mp->m_sb_bp);
370 xfs_buf_unlock(mp->m_sb_bp);
371 }
372
373 static void
374 xfs_syncd_queue_sync(
375 struct xfs_mount *mp)
376 {
377 queue_delayed_work(xfs_syncd_wq, &mp->m_sync_work,
378 msecs_to_jiffies(xfs_syncd_centisecs * 10));
379 }
380
381 /*
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.
385 */
386 STATIC void
387 xfs_sync_worker(
388 struct work_struct *work)
389 {
390 struct xfs_mount *mp = container_of(to_delayed_work(work),
391 struct xfs_mount, m_sync_work);
392 int error;
393
394 /*
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.
402 */
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_frozen == SB_UNFROZEN &&
407 xfs_log_need_covered(mp))
408 error = xfs_fs_log_dummy(mp);
409 else
410 xfs_log_force(mp, 0);
411
412 /* start pushing all the metadata that is currently
413 * dirty */
414 xfs_ail_push_all(mp->m_ail);
415 }
416
417 /* queue us up again */
418 xfs_syncd_queue_sync(mp);
419 }
420
421 /*
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
426 * aggressive.
427 */
428 static void
429 xfs_syncd_queue_reclaim(
430 struct xfs_mount *mp)
431 {
432
433 rcu_read_lock();
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));
437 }
438 rcu_read_unlock();
439 }
440
441 /*
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.
447 */
448 STATIC void
449 xfs_reclaim_worker(
450 struct work_struct *work)
451 {
452 struct xfs_mount *mp = container_of(to_delayed_work(work),
453 struct xfs_mount, m_reclaim_work);
454
455 xfs_reclaim_inodes(mp, SYNC_TRYLOCK);
456 xfs_syncd_queue_reclaim(mp);
457 }
458
459 /*
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.
464 *
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.
470 */
471 void
472 xfs_flush_inodes(
473 struct xfs_inode *ip)
474 {
475 struct xfs_mount *mp = ip->i_mount;
476
477 queue_work(xfs_syncd_wq, &mp->m_flush_work);
478 flush_work_sync(&mp->m_flush_work);
479 }
480
481 STATIC void
482 xfs_flush_worker(
483 struct work_struct *work)
484 {
485 struct xfs_mount *mp = container_of(work,
486 struct xfs_mount, m_flush_work);
487
488 xfs_sync_data(mp, SYNC_TRYLOCK);
489 xfs_sync_data(mp, SYNC_TRYLOCK | SYNC_WAIT);
490 }
491
492 int
493 xfs_syncd_init(
494 struct xfs_mount *mp)
495 {
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);
499
500 xfs_syncd_queue_sync(mp);
501
502 return 0;
503 }
504
505 void
506 xfs_syncd_stop(
507 struct xfs_mount *mp)
508 {
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);
512 }
513
514 void
515 __xfs_inode_set_reclaim_tag(
516 struct xfs_perag *pag,
517 struct xfs_inode *ip)
518 {
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);
522
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);
530
531 /* schedule periodic background inode reclaim */
532 xfs_syncd_queue_reclaim(ip->i_mount);
533
534 trace_xfs_perag_set_reclaim(ip->i_mount, pag->pag_agno,
535 -1, _RET_IP_);
536 }
537 pag->pag_ici_reclaimable++;
538 }
539
540 /*
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
543 * can go away.
544 */
545 void
546 xfs_inode_set_reclaim_tag(
547 xfs_inode_t *ip)
548 {
549 struct xfs_mount *mp = ip->i_mount;
550 struct xfs_perag *pag;
551
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);
559 xfs_perag_put(pag);
560 }
561
562 STATIC void
563 __xfs_inode_clear_reclaim(
564 xfs_perag_t *pag,
565 xfs_inode_t *ip)
566 {
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,
576 -1, _RET_IP_);
577 }
578 }
579
580 void
581 __xfs_inode_clear_reclaim_tag(
582 xfs_mount_t *mp,
583 xfs_perag_t *pag,
584 xfs_inode_t *ip)
585 {
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);
589 }
590
591 /*
592 * Grab the inode for reclaim exclusively.
593 * Return 0 if we grabbed it, non-zero otherwise.
594 */
595 STATIC int
596 xfs_reclaim_inode_grab(
597 struct xfs_inode *ip,
598 int flags)
599 {
600 ASSERT(rcu_read_lock_held());
601
602 /* quick check for stale RCU freed inode */
603 if (!ip->i_ino)
604 return 1;
605
606 /*
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
609 * lock traffic.
610 */
611 if ((flags & SYNC_TRYLOCK) &&
612 __xfs_iflags_test(ip, XFS_IFLOCK | XFS_IRECLAIM))
613 return 1;
614
615 /*
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.
619 *
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.
624 */
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);
630 return 1;
631 }
632 __xfs_iflags_set(ip, XFS_IRECLAIM);
633 spin_unlock(&ip->i_flags_lock);
634 return 0;
635 }
636
637 /*
638 * Inodes in different states need to be treated differently. The following
639 * table lists the inode states and the reclaim actions necessary:
640 *
641 * inode state iflush ret required action
642 * --------------- ---------- ---------------
643 * bad - reclaim
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
651 *
652 * (*) dgc: I don't think the clean, pinned state is possible but it gets
653 * handled anyway given the order of checks implemented.
654 *
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.
658 *
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.
665 *
666 * Hence the order of actions after gaining the locks should be:
667 * bad => reclaim
668 * shutdown => unpin and reclaim
669 * pinned, async => requeue
670 * pinned, sync => unpin
671 * stale => reclaim
672 * clean => reclaim
673 * dirty, async => requeue
674 * dirty, sync => flush, wait and reclaim
675 */
676 STATIC int
677 xfs_reclaim_inode(
678 struct xfs_inode *ip,
679 struct xfs_perag *pag,
680 int sync_mode)
681 {
682 struct xfs_buf *bp = NULL;
683 int error;
684
685 restart:
686 error = 0;
687 xfs_ilock(ip, XFS_ILOCK_EXCL);
688 if (!xfs_iflock_nowait(ip)) {
689 if (!(sync_mode & SYNC_WAIT))
690 goto out;
691 xfs_iflock(ip);
692 }
693
694 if (is_bad_inode(VFS_I(ip)))
695 goto reclaim;
696 if (XFS_FORCED_SHUTDOWN(ip->i_mount)) {
697 xfs_iunpin_wait(ip);
698 xfs_iflush_abort(ip, false);
699 goto reclaim;
700 }
701 if (xfs_ipincount(ip)) {
702 if (!(sync_mode & SYNC_WAIT))
703 goto out_ifunlock;
704 xfs_iunpin_wait(ip);
705 }
706 if (xfs_iflags_test(ip, XFS_ISTALE))
707 goto reclaim;
708 if (xfs_inode_clean(ip))
709 goto reclaim;
710
711 /*
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.
714 */
715 if (!(sync_mode & SYNC_WAIT))
716 goto out_ifunlock;
717
718 /*
719 * Now we have an inode that needs flushing.
720 *
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().
726 *
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.
733 */
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 */
738 delay(2);
739 goto restart;
740 }
741
742 if (!error) {
743 error = xfs_bwrite(bp);
744 xfs_buf_relse(bp);
745 }
746
747 xfs_iflock(ip);
748 reclaim:
749 xfs_ifunlock(ip);
750 xfs_iunlock(ip, XFS_ILOCK_EXCL);
751
752 XFS_STATS_INC(xs_ig_reclaims);
753 /*
754 * Remove the inode from the per-AG radix tree.
755 *
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.
759 */
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)))
763 ASSERT(0);
764 __xfs_inode_clear_reclaim(pag, ip);
765 spin_unlock(&pag->pag_ici_lock);
766
767 /*
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.
771 *
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.
774 */
775 xfs_ilock(ip, XFS_ILOCK_EXCL);
776 xfs_qm_dqdetach(ip);
777 xfs_iunlock(ip, XFS_ILOCK_EXCL);
778
779 xfs_inode_free(ip);
780 return error;
781
782 out_ifunlock:
783 xfs_ifunlock(ip);
784 out:
785 xfs_iflags_clear(ip, XFS_IRECLAIM);
786 xfs_iunlock(ip, XFS_ILOCK_EXCL);
787 /*
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.
793 */
794 return 0;
795 }
796
797 /*
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.
802 */
803 int
804 xfs_reclaim_inodes_ag(
805 struct xfs_mount *mp,
806 int flags,
807 int *nr_to_scan)
808 {
809 struct xfs_perag *pag;
810 int error = 0;
811 int last_error = 0;
812 xfs_agnumber_t ag;
813 int trylock = flags & SYNC_TRYLOCK;
814 int skipped;
815
816 restart:
817 ag = 0;
818 skipped = 0;
819 while ((pag = xfs_perag_get_tag(mp, ag, XFS_ICI_RECLAIM_TAG))) {
820 unsigned long first_index = 0;
821 int done = 0;
822 int nr_found = 0;
823
824 ag = pag->pag_agno + 1;
825
826 if (trylock) {
827 if (!mutex_trylock(&pag->pag_ici_reclaim_lock)) {
828 skipped++;
829 xfs_perag_put(pag);
830 continue;
831 }
832 first_index = pag->pag_ici_reclaim_cursor;
833 } else
834 mutex_lock(&pag->pag_ici_reclaim_lock);
835
836 do {
837 struct xfs_inode *batch[XFS_LOOKUP_BATCH];
838 int i;
839
840 rcu_read_lock();
841 nr_found = radix_tree_gang_lookup_tag(
842 &pag->pag_ici_root,
843 (void **)batch, first_index,
844 XFS_LOOKUP_BATCH,
845 XFS_ICI_RECLAIM_TAG);
846 if (!nr_found) {
847 done = 1;
848 rcu_read_unlock();
849 break;
850 }
851
852 /*
853 * Grab the inodes before we drop the lock. if we found
854 * nothing, nr == 0 and the loop will be skipped.
855 */
856 for (i = 0; i < nr_found; i++) {
857 struct xfs_inode *ip = batch[i];
858
859 if (done || xfs_reclaim_inode_grab(ip, flags))
860 batch[i] = NULL;
861
862 /*
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
867 * last inode.
868 *
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.
875 */
876 if (XFS_INO_TO_AGNO(mp, ip->i_ino) !=
877 pag->pag_agno)
878 continue;
879 first_index = XFS_INO_TO_AGINO(mp, ip->i_ino + 1);
880 if (first_index < XFS_INO_TO_AGINO(mp, ip->i_ino))
881 done = 1;
882 }
883
884 /* unlock now we've grabbed the inodes. */
885 rcu_read_unlock();
886
887 for (i = 0; i < nr_found; i++) {
888 if (!batch[i])
889 continue;
890 error = xfs_reclaim_inode(batch[i], pag, flags);
891 if (error && last_error != EFSCORRUPTED)
892 last_error = error;
893 }
894
895 *nr_to_scan -= XFS_LOOKUP_BATCH;
896
897 cond_resched();
898
899 } while (nr_found && !done && *nr_to_scan > 0);
900
901 if (trylock && !done)
902 pag->pag_ici_reclaim_cursor = first_index;
903 else
904 pag->pag_ici_reclaim_cursor = 0;
905 mutex_unlock(&pag->pag_ici_reclaim_lock);
906 xfs_perag_put(pag);
907 }
908
909 /*
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.
915 */
916 if (skipped && (flags & SYNC_WAIT) && *nr_to_scan > 0) {
917 trylock = 0;
918 goto restart;
919 }
920 return XFS_ERROR(last_error);
921 }
922
923 int
924 xfs_reclaim_inodes(
925 xfs_mount_t *mp,
926 int mode)
927 {
928 int nr_to_scan = INT_MAX;
929
930 return xfs_reclaim_inodes_ag(mp, mode, &nr_to_scan);
931 }
932
933 /*
934 * Scan a certain number of inodes for reclaim.
935 *
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.
941 */
942 void
943 xfs_reclaim_inodes_nr(
944 struct xfs_mount *mp,
945 int nr_to_scan)
946 {
947 /* kick background reclaimer and push the AIL */
948 xfs_syncd_queue_reclaim(mp);
949 xfs_ail_push_all(mp->m_ail);
950
951 xfs_reclaim_inodes_ag(mp, SYNC_TRYLOCK | SYNC_WAIT, &nr_to_scan);
952 }
953
954 /*
955 * Return the number of reclaimable inodes in the filesystem for
956 * the shrinker to determine how much to reclaim.
957 */
958 int
959 xfs_reclaim_inodes_count(
960 struct xfs_mount *mp)
961 {
962 struct xfs_perag *pag;
963 xfs_agnumber_t ag = 0;
964 int reclaimable = 0;
965
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;
969 xfs_perag_put(pag);
970 }
971 return reclaimable;
972 }
973