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1/*
2 * Copyright (c) 2000-2002,2005 Silicon Graphics, Inc.
3 * Copyright (c) 2008 Dave Chinner
4 * All Rights Reserved.
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License as
8 * published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it would be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
18 */
19#include "xfs.h"
20#include "xfs_fs.h"
21#include "xfs_format.h"
22#include "xfs_log_format.h"
23#include "xfs_trans_resv.h"
24#include "xfs_mount.h"
25#include "xfs_trans.h"
26#include "xfs_trans_priv.h"
27#include "xfs_trace.h"
28#include "xfs_error.h"
29#include "xfs_log.h"
30
31#ifdef DEBUG
32/*
33 * Check that the list is sorted as it should be.
34 */
35STATIC void
36xfs_ail_check(
37 struct xfs_ail *ailp,
38 xfs_log_item_t *lip)
39{
40 xfs_log_item_t *prev_lip;
41
42 if (list_empty(&ailp->xa_ail))
43 return;
44
45 /*
46 * Check the next and previous entries are valid.
47 */
48 ASSERT((lip->li_flags & XFS_LI_IN_AIL) != 0);
49 prev_lip = list_entry(lip->li_ail.prev, xfs_log_item_t, li_ail);
50 if (&prev_lip->li_ail != &ailp->xa_ail)
51 ASSERT(XFS_LSN_CMP(prev_lip->li_lsn, lip->li_lsn) <= 0);
52
53 prev_lip = list_entry(lip->li_ail.next, xfs_log_item_t, li_ail);
54 if (&prev_lip->li_ail != &ailp->xa_ail)
55 ASSERT(XFS_LSN_CMP(prev_lip->li_lsn, lip->li_lsn) >= 0);
56
57
58}
59#else /* !DEBUG */
60#define xfs_ail_check(a,l)
61#endif /* DEBUG */
62
63/*
64 * Return a pointer to the last item in the AIL. If the AIL is empty, then
65 * return NULL.
66 */
67static xfs_log_item_t *
68xfs_ail_max(
69 struct xfs_ail *ailp)
70{
71 if (list_empty(&ailp->xa_ail))
72 return NULL;
73
74 return list_entry(ailp->xa_ail.prev, xfs_log_item_t, li_ail);
75}
76
77/*
78 * Return a pointer to the item which follows the given item in the AIL. If
79 * the given item is the last item in the list, then return NULL.
80 */
81static xfs_log_item_t *
82xfs_ail_next(
83 struct xfs_ail *ailp,
84 xfs_log_item_t *lip)
85{
86 if (lip->li_ail.next == &ailp->xa_ail)
87 return NULL;
88
89 return list_first_entry(&lip->li_ail, xfs_log_item_t, li_ail);
90}
91
92/*
93 * This is called by the log manager code to determine the LSN of the tail of
94 * the log. This is exactly the LSN of the first item in the AIL. If the AIL
95 * is empty, then this function returns 0.
96 *
97 * We need the AIL lock in order to get a coherent read of the lsn of the last
98 * item in the AIL.
99 */
100xfs_lsn_t
101xfs_ail_min_lsn(
102 struct xfs_ail *ailp)
103{
104 xfs_lsn_t lsn = 0;
105 xfs_log_item_t *lip;
106
107 spin_lock(&ailp->xa_lock);
108 lip = xfs_ail_min(ailp);
109 if (lip)
110 lsn = lip->li_lsn;
111 spin_unlock(&ailp->xa_lock);
112
113 return lsn;
114}
115
116/*
117 * Return the maximum lsn held in the AIL, or zero if the AIL is empty.
118 */
119static xfs_lsn_t
120xfs_ail_max_lsn(
121 struct xfs_ail *ailp)
122{
123 xfs_lsn_t lsn = 0;
124 xfs_log_item_t *lip;
125
126 spin_lock(&ailp->xa_lock);
127 lip = xfs_ail_max(ailp);
128 if (lip)
129 lsn = lip->li_lsn;
130 spin_unlock(&ailp->xa_lock);
131
132 return lsn;
133}
134
135/*
136 * The cursor keeps track of where our current traversal is up to by tracking
137 * the next item in the list for us. However, for this to be safe, removing an
138 * object from the AIL needs to invalidate any cursor that points to it. hence
139 * the traversal cursor needs to be linked to the struct xfs_ail so that
140 * deletion can search all the active cursors for invalidation.
141 */
142STATIC void
143xfs_trans_ail_cursor_init(
144 struct xfs_ail *ailp,
145 struct xfs_ail_cursor *cur)
146{
147 cur->item = NULL;
148 list_add_tail(&cur->list, &ailp->xa_cursors);
149}
150
151/*
152 * Get the next item in the traversal and advance the cursor. If the cursor
153 * was invalidated (indicated by a lip of 1), restart the traversal.
154 */
155struct xfs_log_item *
156xfs_trans_ail_cursor_next(
157 struct xfs_ail *ailp,
158 struct xfs_ail_cursor *cur)
159{
160 struct xfs_log_item *lip = cur->item;
161
162 if ((uintptr_t)lip & 1)
163 lip = xfs_ail_min(ailp);
164 if (lip)
165 cur->item = xfs_ail_next(ailp, lip);
166 return lip;
167}
168
169/*
170 * When the traversal is complete, we need to remove the cursor from the list
171 * of traversing cursors.
172 */
173void
174xfs_trans_ail_cursor_done(
175 struct xfs_ail_cursor *cur)
176{
177 cur->item = NULL;
178 list_del_init(&cur->list);
179}
180
181/*
182 * Invalidate any cursor that is pointing to this item. This is called when an
183 * item is removed from the AIL. Any cursor pointing to this object is now
184 * invalid and the traversal needs to be terminated so it doesn't reference a
185 * freed object. We set the low bit of the cursor item pointer so we can
186 * distinguish between an invalidation and the end of the list when getting the
187 * next item from the cursor.
188 */
189STATIC void
190xfs_trans_ail_cursor_clear(
191 struct xfs_ail *ailp,
192 struct xfs_log_item *lip)
193{
194 struct xfs_ail_cursor *cur;
195
196 list_for_each_entry(cur, &ailp->xa_cursors, list) {
197 if (cur->item == lip)
198 cur->item = (struct xfs_log_item *)
199 ((uintptr_t)cur->item | 1);
200 }
201}
202
203/*
204 * Find the first item in the AIL with the given @lsn by searching in ascending
205 * LSN order and initialise the cursor to point to the next item for a
206 * ascending traversal. Pass a @lsn of zero to initialise the cursor to the
207 * first item in the AIL. Returns NULL if the list is empty.
208 */
209xfs_log_item_t *
210xfs_trans_ail_cursor_first(
211 struct xfs_ail *ailp,
212 struct xfs_ail_cursor *cur,
213 xfs_lsn_t lsn)
214{
215 xfs_log_item_t *lip;
216
217 xfs_trans_ail_cursor_init(ailp, cur);
218
219 if (lsn == 0) {
220 lip = xfs_ail_min(ailp);
221 goto out;
222 }
223
224 list_for_each_entry(lip, &ailp->xa_ail, li_ail) {
225 if (XFS_LSN_CMP(lip->li_lsn, lsn) >= 0)
226 goto out;
227 }
228 return NULL;
229
230out:
231 if (lip)
232 cur->item = xfs_ail_next(ailp, lip);
233 return lip;
234}
235
236static struct xfs_log_item *
237__xfs_trans_ail_cursor_last(
238 struct xfs_ail *ailp,
239 xfs_lsn_t lsn)
240{
241 xfs_log_item_t *lip;
242
243 list_for_each_entry_reverse(lip, &ailp->xa_ail, li_ail) {
244 if (XFS_LSN_CMP(lip->li_lsn, lsn) <= 0)
245 return lip;
246 }
247 return NULL;
248}
249
250/*
251 * Find the last item in the AIL with the given @lsn by searching in descending
252 * LSN order and initialise the cursor to point to that item. If there is no
253 * item with the value of @lsn, then it sets the cursor to the last item with an
254 * LSN lower than @lsn. Returns NULL if the list is empty.
255 */
256struct xfs_log_item *
257xfs_trans_ail_cursor_last(
258 struct xfs_ail *ailp,
259 struct xfs_ail_cursor *cur,
260 xfs_lsn_t lsn)
261{
262 xfs_trans_ail_cursor_init(ailp, cur);
263 cur->item = __xfs_trans_ail_cursor_last(ailp, lsn);
264 return cur->item;
265}
266
267/*
268 * Splice the log item list into the AIL at the given LSN. We splice to the
269 * tail of the given LSN to maintain insert order for push traversals. The
270 * cursor is optional, allowing repeated updates to the same LSN to avoid
271 * repeated traversals. This should not be called with an empty list.
272 */
273static void
274xfs_ail_splice(
275 struct xfs_ail *ailp,
276 struct xfs_ail_cursor *cur,
277 struct list_head *list,
278 xfs_lsn_t lsn)
279{
280 struct xfs_log_item *lip;
281
282 ASSERT(!list_empty(list));
283
284 /*
285 * Use the cursor to determine the insertion point if one is
286 * provided. If not, or if the one we got is not valid,
287 * find the place in the AIL where the items belong.
288 */
289 lip = cur ? cur->item : NULL;
290 if (!lip || (uintptr_t)lip & 1)
291 lip = __xfs_trans_ail_cursor_last(ailp, lsn);
292
293 /*
294 * If a cursor is provided, we know we're processing the AIL
295 * in lsn order, and future items to be spliced in will
296 * follow the last one being inserted now. Update the
297 * cursor to point to that last item, now while we have a
298 * reliable pointer to it.
299 */
300 if (cur)
301 cur->item = list_entry(list->prev, struct xfs_log_item, li_ail);
302
303 /*
304 * Finally perform the splice. Unless the AIL was empty,
305 * lip points to the item in the AIL _after_ which the new
306 * items should go. If lip is null the AIL was empty, so
307 * the new items go at the head of the AIL.
308 */
309 if (lip)
310 list_splice(list, &lip->li_ail);
311 else
312 list_splice(list, &ailp->xa_ail);
313}
314
315/*
316 * Delete the given item from the AIL. Return a pointer to the item.
317 */
318static void
319xfs_ail_delete(
320 struct xfs_ail *ailp,
321 xfs_log_item_t *lip)
322{
323 xfs_ail_check(ailp, lip);
324 list_del(&lip->li_ail);
325 xfs_trans_ail_cursor_clear(ailp, lip);
326}
327
328static long
329xfsaild_push(
330 struct xfs_ail *ailp)
331{
332 xfs_mount_t *mp = ailp->xa_mount;
333 struct xfs_ail_cursor cur;
334 xfs_log_item_t *lip;
335 xfs_lsn_t lsn;
336 xfs_lsn_t target;
337 long tout;
338 int stuck = 0;
339 int flushing = 0;
340 int count = 0;
341
342 /*
343 * If we encountered pinned items or did not finish writing out all
344 * buffers the last time we ran, force the log first and wait for it
345 * before pushing again.
346 */
347 if (ailp->xa_log_flush && ailp->xa_last_pushed_lsn == 0 &&
348 (!list_empty_careful(&ailp->xa_buf_list) ||
349 xfs_ail_min_lsn(ailp))) {
350 ailp->xa_log_flush = 0;
351
352 XFS_STATS_INC(mp, xs_push_ail_flush);
353 xfs_log_force(mp, XFS_LOG_SYNC);
354 }
355
356 spin_lock(&ailp->xa_lock);
357
358 /* barrier matches the xa_target update in xfs_ail_push() */
359 smp_rmb();
360 target = ailp->xa_target;
361 ailp->xa_target_prev = target;
362
363 lip = xfs_trans_ail_cursor_first(ailp, &cur, ailp->xa_last_pushed_lsn);
364 if (!lip) {
365 /*
366 * If the AIL is empty or our push has reached the end we are
367 * done now.
368 */
369 xfs_trans_ail_cursor_done(&cur);
370 spin_unlock(&ailp->xa_lock);
371 goto out_done;
372 }
373
374 XFS_STATS_INC(mp, xs_push_ail);
375
376 lsn = lip->li_lsn;
377 while ((XFS_LSN_CMP(lip->li_lsn, target) <= 0)) {
378 int lock_result;
379
380 /*
381 * Note that iop_push may unlock and reacquire the AIL lock. We
382 * rely on the AIL cursor implementation to be able to deal with
383 * the dropped lock.
384 */
385 lock_result = lip->li_ops->iop_push(lip, &ailp->xa_buf_list);
386 switch (lock_result) {
387 case XFS_ITEM_SUCCESS:
388 XFS_STATS_INC(mp, xs_push_ail_success);
389 trace_xfs_ail_push(lip);
390
391 ailp->xa_last_pushed_lsn = lsn;
392 break;
393
394 case XFS_ITEM_FLUSHING:
395 /*
396 * The item or its backing buffer is already beeing
397 * flushed. The typical reason for that is that an
398 * inode buffer is locked because we already pushed the
399 * updates to it as part of inode clustering.
400 *
401 * We do not want to to stop flushing just because lots
402 * of items are already beeing flushed, but we need to
403 * re-try the flushing relatively soon if most of the
404 * AIL is beeing flushed.
405 */
406 XFS_STATS_INC(mp, xs_push_ail_flushing);
407 trace_xfs_ail_flushing(lip);
408
409 flushing++;
410 ailp->xa_last_pushed_lsn = lsn;
411 break;
412
413 case XFS_ITEM_PINNED:
414 XFS_STATS_INC(mp, xs_push_ail_pinned);
415 trace_xfs_ail_pinned(lip);
416
417 stuck++;
418 ailp->xa_log_flush++;
419 break;
420 case XFS_ITEM_LOCKED:
421 XFS_STATS_INC(mp, xs_push_ail_locked);
422 trace_xfs_ail_locked(lip);
423
424 stuck++;
425 break;
426 default:
427 ASSERT(0);
428 break;
429 }
430
431 count++;
432
433 /*
434 * Are there too many items we can't do anything with?
435 *
436 * If we we are skipping too many items because we can't flush
437 * them or they are already being flushed, we back off and
438 * given them time to complete whatever operation is being
439 * done. i.e. remove pressure from the AIL while we can't make
440 * progress so traversals don't slow down further inserts and
441 * removals to/from the AIL.
442 *
443 * The value of 100 is an arbitrary magic number based on
444 * observation.
445 */
446 if (stuck > 100)
447 break;
448
449 lip = xfs_trans_ail_cursor_next(ailp, &cur);
450 if (lip == NULL)
451 break;
452 lsn = lip->li_lsn;
453 }
454 xfs_trans_ail_cursor_done(&cur);
455 spin_unlock(&ailp->xa_lock);
456
457 if (xfs_buf_delwri_submit_nowait(&ailp->xa_buf_list))
458 ailp->xa_log_flush++;
459
460 if (!count || XFS_LSN_CMP(lsn, target) >= 0) {
461out_done:
462 /*
463 * We reached the target or the AIL is empty, so wait a bit
464 * longer for I/O to complete and remove pushed items from the
465 * AIL before we start the next scan from the start of the AIL.
466 */
467 tout = 50;
468 ailp->xa_last_pushed_lsn = 0;
469 } else if (((stuck + flushing) * 100) / count > 90) {
470 /*
471 * Either there is a lot of contention on the AIL or we are
472 * stuck due to operations in progress. "Stuck" in this case
473 * is defined as >90% of the items we tried to push were stuck.
474 *
475 * Backoff a bit more to allow some I/O to complete before
476 * restarting from the start of the AIL. This prevents us from
477 * spinning on the same items, and if they are pinned will all
478 * the restart to issue a log force to unpin the stuck items.
479 */
480 tout = 20;
481 ailp->xa_last_pushed_lsn = 0;
482 } else {
483 /*
484 * Assume we have more work to do in a short while.
485 */
486 tout = 10;
487 }
488
489 return tout;
490}
491
492static int
493xfsaild(
494 void *data)
495{
496 struct xfs_ail *ailp = data;
497 long tout = 0; /* milliseconds */
498
499 current->flags |= PF_MEMALLOC;
500 set_freezable();
501
502 while (!kthread_should_stop()) {
503 if (tout && tout <= 20)
504 __set_current_state(TASK_KILLABLE);
505 else
506 __set_current_state(TASK_INTERRUPTIBLE);
507
508 spin_lock(&ailp->xa_lock);
509
510 /*
511 * Idle if the AIL is empty and we are not racing with a target
512 * update. We check the AIL after we set the task to a sleep
513 * state to guarantee that we either catch an xa_target update
514 * or that a wake_up resets the state to TASK_RUNNING.
515 * Otherwise, we run the risk of sleeping indefinitely.
516 *
517 * The barrier matches the xa_target update in xfs_ail_push().
518 */
519 smp_rmb();
520 if (!xfs_ail_min(ailp) &&
521 ailp->xa_target == ailp->xa_target_prev) {
522 spin_unlock(&ailp->xa_lock);
523 freezable_schedule();
524 tout = 0;
525 continue;
526 }
527 spin_unlock(&ailp->xa_lock);
528
529 if (tout)
530 freezable_schedule_timeout(msecs_to_jiffies(tout));
531
532 __set_current_state(TASK_RUNNING);
533
534 try_to_freeze();
535
536 tout = xfsaild_push(ailp);
537 }
538
539 return 0;
540}
541
542/*
543 * This routine is called to move the tail of the AIL forward. It does this by
544 * trying to flush items in the AIL whose lsns are below the given
545 * threshold_lsn.
546 *
547 * The push is run asynchronously in a workqueue, which means the caller needs
548 * to handle waiting on the async flush for space to become available.
549 * We don't want to interrupt any push that is in progress, hence we only queue
550 * work if we set the pushing bit approriately.
551 *
552 * We do this unlocked - we only need to know whether there is anything in the
553 * AIL at the time we are called. We don't need to access the contents of
554 * any of the objects, so the lock is not needed.
555 */
556void
557xfs_ail_push(
558 struct xfs_ail *ailp,
559 xfs_lsn_t threshold_lsn)
560{
561 xfs_log_item_t *lip;
562
563 lip = xfs_ail_min(ailp);
564 if (!lip || XFS_FORCED_SHUTDOWN(ailp->xa_mount) ||
565 XFS_LSN_CMP(threshold_lsn, ailp->xa_target) <= 0)
566 return;
567
568 /*
569 * Ensure that the new target is noticed in push code before it clears
570 * the XFS_AIL_PUSHING_BIT.
571 */
572 smp_wmb();
573 xfs_trans_ail_copy_lsn(ailp, &ailp->xa_target, &threshold_lsn);
574 smp_wmb();
575
576 wake_up_process(ailp->xa_task);
577}
578
579/*
580 * Push out all items in the AIL immediately
581 */
582void
583xfs_ail_push_all(
584 struct xfs_ail *ailp)
585{
586 xfs_lsn_t threshold_lsn = xfs_ail_max_lsn(ailp);
587
588 if (threshold_lsn)
589 xfs_ail_push(ailp, threshold_lsn);
590}
591
592/*
593 * Push out all items in the AIL immediately and wait until the AIL is empty.
594 */
595void
596xfs_ail_push_all_sync(
597 struct xfs_ail *ailp)
598{
599 struct xfs_log_item *lip;
600 DEFINE_WAIT(wait);
601
602 spin_lock(&ailp->xa_lock);
603 while ((lip = xfs_ail_max(ailp)) != NULL) {
604 prepare_to_wait(&ailp->xa_empty, &wait, TASK_UNINTERRUPTIBLE);
605 ailp->xa_target = lip->li_lsn;
606 wake_up_process(ailp->xa_task);
607 spin_unlock(&ailp->xa_lock);
608 schedule();
609 spin_lock(&ailp->xa_lock);
610 }
611 spin_unlock(&ailp->xa_lock);
612
613 finish_wait(&ailp->xa_empty, &wait);
614}
615
616/*
617 * xfs_trans_ail_update - bulk AIL insertion operation.
618 *
619 * @xfs_trans_ail_update takes an array of log items that all need to be
620 * positioned at the same LSN in the AIL. If an item is not in the AIL, it will
621 * be added. Otherwise, it will be repositioned by removing it and re-adding
622 * it to the AIL. If we move the first item in the AIL, update the log tail to
623 * match the new minimum LSN in the AIL.
624 *
625 * This function takes the AIL lock once to execute the update operations on
626 * all the items in the array, and as such should not be called with the AIL
627 * lock held. As a result, once we have the AIL lock, we need to check each log
628 * item LSN to confirm it needs to be moved forward in the AIL.
629 *
630 * To optimise the insert operation, we delete all the items from the AIL in
631 * the first pass, moving them into a temporary list, then splice the temporary
632 * list into the correct position in the AIL. This avoids needing to do an
633 * insert operation on every item.
634 *
635 * This function must be called with the AIL lock held. The lock is dropped
636 * before returning.
637 */
638void
639xfs_trans_ail_update_bulk(
640 struct xfs_ail *ailp,
641 struct xfs_ail_cursor *cur,
642 struct xfs_log_item **log_items,
643 int nr_items,
644 xfs_lsn_t lsn) __releases(ailp->xa_lock)
645{
646 xfs_log_item_t *mlip;
647 int mlip_changed = 0;
648 int i;
649 LIST_HEAD(tmp);
650
651 ASSERT(nr_items > 0); /* Not required, but true. */
652 mlip = xfs_ail_min(ailp);
653
654 for (i = 0; i < nr_items; i++) {
655 struct xfs_log_item *lip = log_items[i];
656 if (lip->li_flags & XFS_LI_IN_AIL) {
657 /* check if we really need to move the item */
658 if (XFS_LSN_CMP(lsn, lip->li_lsn) <= 0)
659 continue;
660
661 trace_xfs_ail_move(lip, lip->li_lsn, lsn);
662 xfs_ail_delete(ailp, lip);
663 if (mlip == lip)
664 mlip_changed = 1;
665 } else {
666 lip->li_flags |= XFS_LI_IN_AIL;
667 trace_xfs_ail_insert(lip, 0, lsn);
668 }
669 lip->li_lsn = lsn;
670 list_add(&lip->li_ail, &tmp);
671 }
672
673 if (!list_empty(&tmp))
674 xfs_ail_splice(ailp, cur, &tmp, lsn);
675
676 if (mlip_changed) {
677 if (!XFS_FORCED_SHUTDOWN(ailp->xa_mount))
678 xlog_assign_tail_lsn_locked(ailp->xa_mount);
679 spin_unlock(&ailp->xa_lock);
680
681 xfs_log_space_wake(ailp->xa_mount);
682 } else {
683 spin_unlock(&ailp->xa_lock);
684 }
685}
686
687/*
688 * xfs_trans_ail_delete_bulk - remove multiple log items from the AIL
689 *
690 * @xfs_trans_ail_delete_bulk takes an array of log items that all need to
691 * removed from the AIL. The caller is already holding the AIL lock, and done
692 * all the checks necessary to ensure the items passed in via @log_items are
693 * ready for deletion. This includes checking that the items are in the AIL.
694 *
695 * For each log item to be removed, unlink it from the AIL, clear the IN_AIL
696 * flag from the item and reset the item's lsn to 0. If we remove the first
697 * item in the AIL, update the log tail to match the new minimum LSN in the
698 * AIL.
699 *
700 * This function will not drop the AIL lock until all items are removed from
701 * the AIL to minimise the amount of lock traffic on the AIL. This does not
702 * greatly increase the AIL hold time, but does significantly reduce the amount
703 * of traffic on the lock, especially during IO completion.
704 *
705 * This function must be called with the AIL lock held. The lock is dropped
706 * before returning.
707 */
708void
709xfs_trans_ail_delete_bulk(
710 struct xfs_ail *ailp,
711 struct xfs_log_item **log_items,
712 int nr_items,
713 int shutdown_type) __releases(ailp->xa_lock)
714{
715 xfs_log_item_t *mlip;
716 int mlip_changed = 0;
717 int i;
718
719 mlip = xfs_ail_min(ailp);
720
721 for (i = 0; i < nr_items; i++) {
722 struct xfs_log_item *lip = log_items[i];
723 if (!(lip->li_flags & XFS_LI_IN_AIL)) {
724 struct xfs_mount *mp = ailp->xa_mount;
725
726 spin_unlock(&ailp->xa_lock);
727 if (!XFS_FORCED_SHUTDOWN(mp)) {
728 xfs_alert_tag(mp, XFS_PTAG_AILDELETE,
729 "%s: attempting to delete a log item that is not in the AIL",
730 __func__);
731 xfs_force_shutdown(mp, shutdown_type);
732 }
733 return;
734 }
735
736 trace_xfs_ail_delete(lip, mlip->li_lsn, lip->li_lsn);
737 xfs_ail_delete(ailp, lip);
738 lip->li_flags &= ~XFS_LI_IN_AIL;
739 lip->li_lsn = 0;
740 if (mlip == lip)
741 mlip_changed = 1;
742 }
743
744 if (mlip_changed) {
745 if (!XFS_FORCED_SHUTDOWN(ailp->xa_mount))
746 xlog_assign_tail_lsn_locked(ailp->xa_mount);
747 if (list_empty(&ailp->xa_ail))
748 wake_up_all(&ailp->xa_empty);
749 spin_unlock(&ailp->xa_lock);
750
751 xfs_log_space_wake(ailp->xa_mount);
752 } else {
753 spin_unlock(&ailp->xa_lock);
754 }
755}
756
757int
758xfs_trans_ail_init(
759 xfs_mount_t *mp)
760{
761 struct xfs_ail *ailp;
762
763 ailp = kmem_zalloc(sizeof(struct xfs_ail), KM_MAYFAIL);
764 if (!ailp)
765 return -ENOMEM;
766
767 ailp->xa_mount = mp;
768 INIT_LIST_HEAD(&ailp->xa_ail);
769 INIT_LIST_HEAD(&ailp->xa_cursors);
770 spin_lock_init(&ailp->xa_lock);
771 INIT_LIST_HEAD(&ailp->xa_buf_list);
772 init_waitqueue_head(&ailp->xa_empty);
773
774 ailp->xa_task = kthread_run(xfsaild, ailp, "xfsaild/%s",
775 ailp->xa_mount->m_fsname);
776 if (IS_ERR(ailp->xa_task))
777 goto out_free_ailp;
778
779 mp->m_ail = ailp;
780 return 0;
781
782out_free_ailp:
783 kmem_free(ailp);
784 return -ENOMEM;
785}
786
787void
788xfs_trans_ail_destroy(
789 xfs_mount_t *mp)
790{
791 struct xfs_ail *ailp = mp->m_ail;
792
793 kthread_stop(ailp->xa_task);
794 kmem_free(ailp);
795}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (c) 2000-2002,2005 Silicon Graphics, Inc.
4 * Copyright (c) 2008 Dave Chinner
5 * All Rights Reserved.
6 */
7#include "xfs.h"
8#include "xfs_fs.h"
9#include "xfs_shared.h"
10#include "xfs_format.h"
11#include "xfs_log_format.h"
12#include "xfs_trans_resv.h"
13#include "xfs_mount.h"
14#include "xfs_trans.h"
15#include "xfs_trans_priv.h"
16#include "xfs_trace.h"
17#include "xfs_errortag.h"
18#include "xfs_error.h"
19#include "xfs_log.h"
20#include "xfs_log_priv.h"
21
22#ifdef DEBUG
23/*
24 * Check that the list is sorted as it should be.
25 *
26 * Called with the ail lock held, but we don't want to assert fail with it
27 * held otherwise we'll lock everything up and won't be able to debug the
28 * cause. Hence we sample and check the state under the AIL lock and return if
29 * everything is fine, otherwise we drop the lock and run the ASSERT checks.
30 * Asserts may not be fatal, so pick the lock back up and continue onwards.
31 */
32STATIC void
33xfs_ail_check(
34 struct xfs_ail *ailp,
35 struct xfs_log_item *lip)
36 __must_hold(&ailp->ail_lock)
37{
38 struct xfs_log_item *prev_lip;
39 struct xfs_log_item *next_lip;
40 xfs_lsn_t prev_lsn = NULLCOMMITLSN;
41 xfs_lsn_t next_lsn = NULLCOMMITLSN;
42 xfs_lsn_t lsn;
43 bool in_ail;
44
45
46 if (list_empty(&ailp->ail_head))
47 return;
48
49 /*
50 * Sample then check the next and previous entries are valid.
51 */
52 in_ail = test_bit(XFS_LI_IN_AIL, &lip->li_flags);
53 prev_lip = list_entry(lip->li_ail.prev, struct xfs_log_item, li_ail);
54 if (&prev_lip->li_ail != &ailp->ail_head)
55 prev_lsn = prev_lip->li_lsn;
56 next_lip = list_entry(lip->li_ail.next, struct xfs_log_item, li_ail);
57 if (&next_lip->li_ail != &ailp->ail_head)
58 next_lsn = next_lip->li_lsn;
59 lsn = lip->li_lsn;
60
61 if (in_ail &&
62 (prev_lsn == NULLCOMMITLSN || XFS_LSN_CMP(prev_lsn, lsn) <= 0) &&
63 (next_lsn == NULLCOMMITLSN || XFS_LSN_CMP(next_lsn, lsn) >= 0))
64 return;
65
66 spin_unlock(&ailp->ail_lock);
67 ASSERT(in_ail);
68 ASSERT(prev_lsn == NULLCOMMITLSN || XFS_LSN_CMP(prev_lsn, lsn) <= 0);
69 ASSERT(next_lsn == NULLCOMMITLSN || XFS_LSN_CMP(next_lsn, lsn) >= 0);
70 spin_lock(&ailp->ail_lock);
71}
72#else /* !DEBUG */
73#define xfs_ail_check(a,l)
74#endif /* DEBUG */
75
76/*
77 * Return a pointer to the last item in the AIL. If the AIL is empty, then
78 * return NULL.
79 */
80static struct xfs_log_item *
81xfs_ail_max(
82 struct xfs_ail *ailp)
83{
84 if (list_empty(&ailp->ail_head))
85 return NULL;
86
87 return list_entry(ailp->ail_head.prev, struct xfs_log_item, li_ail);
88}
89
90/*
91 * Return a pointer to the item which follows the given item in the AIL. If
92 * the given item is the last item in the list, then return NULL.
93 */
94static struct xfs_log_item *
95xfs_ail_next(
96 struct xfs_ail *ailp,
97 struct xfs_log_item *lip)
98{
99 if (lip->li_ail.next == &ailp->ail_head)
100 return NULL;
101
102 return list_first_entry(&lip->li_ail, struct xfs_log_item, li_ail);
103}
104
105/*
106 * This is called by the log manager code to determine the LSN of the tail of
107 * the log. This is exactly the LSN of the first item in the AIL. If the AIL
108 * is empty, then this function returns 0.
109 *
110 * We need the AIL lock in order to get a coherent read of the lsn of the last
111 * item in the AIL.
112 */
113static xfs_lsn_t
114__xfs_ail_min_lsn(
115 struct xfs_ail *ailp)
116{
117 struct xfs_log_item *lip = xfs_ail_min(ailp);
118
119 if (lip)
120 return lip->li_lsn;
121 return 0;
122}
123
124xfs_lsn_t
125xfs_ail_min_lsn(
126 struct xfs_ail *ailp)
127{
128 xfs_lsn_t lsn;
129
130 spin_lock(&ailp->ail_lock);
131 lsn = __xfs_ail_min_lsn(ailp);
132 spin_unlock(&ailp->ail_lock);
133
134 return lsn;
135}
136
137/*
138 * Return the maximum lsn held in the AIL, or zero if the AIL is empty.
139 */
140static xfs_lsn_t
141xfs_ail_max_lsn(
142 struct xfs_ail *ailp)
143{
144 xfs_lsn_t lsn = 0;
145 struct xfs_log_item *lip;
146
147 spin_lock(&ailp->ail_lock);
148 lip = xfs_ail_max(ailp);
149 if (lip)
150 lsn = lip->li_lsn;
151 spin_unlock(&ailp->ail_lock);
152
153 return lsn;
154}
155
156/*
157 * The cursor keeps track of where our current traversal is up to by tracking
158 * the next item in the list for us. However, for this to be safe, removing an
159 * object from the AIL needs to invalidate any cursor that points to it. hence
160 * the traversal cursor needs to be linked to the struct xfs_ail so that
161 * deletion can search all the active cursors for invalidation.
162 */
163STATIC void
164xfs_trans_ail_cursor_init(
165 struct xfs_ail *ailp,
166 struct xfs_ail_cursor *cur)
167{
168 cur->item = NULL;
169 list_add_tail(&cur->list, &ailp->ail_cursors);
170}
171
172/*
173 * Get the next item in the traversal and advance the cursor. If the cursor
174 * was invalidated (indicated by a lip of 1), restart the traversal.
175 */
176struct xfs_log_item *
177xfs_trans_ail_cursor_next(
178 struct xfs_ail *ailp,
179 struct xfs_ail_cursor *cur)
180{
181 struct xfs_log_item *lip = cur->item;
182
183 if ((uintptr_t)lip & 1)
184 lip = xfs_ail_min(ailp);
185 if (lip)
186 cur->item = xfs_ail_next(ailp, lip);
187 return lip;
188}
189
190/*
191 * When the traversal is complete, we need to remove the cursor from the list
192 * of traversing cursors.
193 */
194void
195xfs_trans_ail_cursor_done(
196 struct xfs_ail_cursor *cur)
197{
198 cur->item = NULL;
199 list_del_init(&cur->list);
200}
201
202/*
203 * Invalidate any cursor that is pointing to this item. This is called when an
204 * item is removed from the AIL. Any cursor pointing to this object is now
205 * invalid and the traversal needs to be terminated so it doesn't reference a
206 * freed object. We set the low bit of the cursor item pointer so we can
207 * distinguish between an invalidation and the end of the list when getting the
208 * next item from the cursor.
209 */
210STATIC void
211xfs_trans_ail_cursor_clear(
212 struct xfs_ail *ailp,
213 struct xfs_log_item *lip)
214{
215 struct xfs_ail_cursor *cur;
216
217 list_for_each_entry(cur, &ailp->ail_cursors, list) {
218 if (cur->item == lip)
219 cur->item = (struct xfs_log_item *)
220 ((uintptr_t)cur->item | 1);
221 }
222}
223
224/*
225 * Find the first item in the AIL with the given @lsn by searching in ascending
226 * LSN order and initialise the cursor to point to the next item for a
227 * ascending traversal. Pass a @lsn of zero to initialise the cursor to the
228 * first item in the AIL. Returns NULL if the list is empty.
229 */
230struct xfs_log_item *
231xfs_trans_ail_cursor_first(
232 struct xfs_ail *ailp,
233 struct xfs_ail_cursor *cur,
234 xfs_lsn_t lsn)
235{
236 struct xfs_log_item *lip;
237
238 xfs_trans_ail_cursor_init(ailp, cur);
239
240 if (lsn == 0) {
241 lip = xfs_ail_min(ailp);
242 goto out;
243 }
244
245 list_for_each_entry(lip, &ailp->ail_head, li_ail) {
246 if (XFS_LSN_CMP(lip->li_lsn, lsn) >= 0)
247 goto out;
248 }
249 return NULL;
250
251out:
252 if (lip)
253 cur->item = xfs_ail_next(ailp, lip);
254 return lip;
255}
256
257static struct xfs_log_item *
258__xfs_trans_ail_cursor_last(
259 struct xfs_ail *ailp,
260 xfs_lsn_t lsn)
261{
262 struct xfs_log_item *lip;
263
264 list_for_each_entry_reverse(lip, &ailp->ail_head, li_ail) {
265 if (XFS_LSN_CMP(lip->li_lsn, lsn) <= 0)
266 return lip;
267 }
268 return NULL;
269}
270
271/*
272 * Find the last item in the AIL with the given @lsn by searching in descending
273 * LSN order and initialise the cursor to point to that item. If there is no
274 * item with the value of @lsn, then it sets the cursor to the last item with an
275 * LSN lower than @lsn. Returns NULL if the list is empty.
276 */
277struct xfs_log_item *
278xfs_trans_ail_cursor_last(
279 struct xfs_ail *ailp,
280 struct xfs_ail_cursor *cur,
281 xfs_lsn_t lsn)
282{
283 xfs_trans_ail_cursor_init(ailp, cur);
284 cur->item = __xfs_trans_ail_cursor_last(ailp, lsn);
285 return cur->item;
286}
287
288/*
289 * Splice the log item list into the AIL at the given LSN. We splice to the
290 * tail of the given LSN to maintain insert order for push traversals. The
291 * cursor is optional, allowing repeated updates to the same LSN to avoid
292 * repeated traversals. This should not be called with an empty list.
293 */
294static void
295xfs_ail_splice(
296 struct xfs_ail *ailp,
297 struct xfs_ail_cursor *cur,
298 struct list_head *list,
299 xfs_lsn_t lsn)
300{
301 struct xfs_log_item *lip;
302
303 ASSERT(!list_empty(list));
304
305 /*
306 * Use the cursor to determine the insertion point if one is
307 * provided. If not, or if the one we got is not valid,
308 * find the place in the AIL where the items belong.
309 */
310 lip = cur ? cur->item : NULL;
311 if (!lip || (uintptr_t)lip & 1)
312 lip = __xfs_trans_ail_cursor_last(ailp, lsn);
313
314 /*
315 * If a cursor is provided, we know we're processing the AIL
316 * in lsn order, and future items to be spliced in will
317 * follow the last one being inserted now. Update the
318 * cursor to point to that last item, now while we have a
319 * reliable pointer to it.
320 */
321 if (cur)
322 cur->item = list_entry(list->prev, struct xfs_log_item, li_ail);
323
324 /*
325 * Finally perform the splice. Unless the AIL was empty,
326 * lip points to the item in the AIL _after_ which the new
327 * items should go. If lip is null the AIL was empty, so
328 * the new items go at the head of the AIL.
329 */
330 if (lip)
331 list_splice(list, &lip->li_ail);
332 else
333 list_splice(list, &ailp->ail_head);
334}
335
336/*
337 * Delete the given item from the AIL. Return a pointer to the item.
338 */
339static void
340xfs_ail_delete(
341 struct xfs_ail *ailp,
342 struct xfs_log_item *lip)
343{
344 xfs_ail_check(ailp, lip);
345 list_del(&lip->li_ail);
346 xfs_trans_ail_cursor_clear(ailp, lip);
347}
348
349/*
350 * Requeue a failed buffer for writeback.
351 *
352 * We clear the log item failed state here as well, but we have to be careful
353 * about reference counts because the only active reference counts on the buffer
354 * may be the failed log items. Hence if we clear the log item failed state
355 * before queuing the buffer for IO we can release all active references to
356 * the buffer and free it, leading to use after free problems in
357 * xfs_buf_delwri_queue. It makes no difference to the buffer or log items which
358 * order we process them in - the buffer is locked, and we own the buffer list
359 * so nothing on them is going to change while we are performing this action.
360 *
361 * Hence we can safely queue the buffer for IO before we clear the failed log
362 * item state, therefore always having an active reference to the buffer and
363 * avoiding the transient zero-reference state that leads to use-after-free.
364 */
365static inline int
366xfsaild_resubmit_item(
367 struct xfs_log_item *lip,
368 struct list_head *buffer_list)
369{
370 struct xfs_buf *bp = lip->li_buf;
371
372 if (!xfs_buf_trylock(bp))
373 return XFS_ITEM_LOCKED;
374
375 if (!xfs_buf_delwri_queue(bp, buffer_list)) {
376 xfs_buf_unlock(bp);
377 return XFS_ITEM_FLUSHING;
378 }
379
380 /* protected by ail_lock */
381 list_for_each_entry(lip, &bp->b_li_list, li_bio_list) {
382 if (bp->b_flags & _XBF_INODES)
383 clear_bit(XFS_LI_FAILED, &lip->li_flags);
384 else
385 xfs_clear_li_failed(lip);
386 }
387
388 xfs_buf_unlock(bp);
389 return XFS_ITEM_SUCCESS;
390}
391
392static inline uint
393xfsaild_push_item(
394 struct xfs_ail *ailp,
395 struct xfs_log_item *lip)
396{
397 /*
398 * If log item pinning is enabled, skip the push and track the item as
399 * pinned. This can help induce head-behind-tail conditions.
400 */
401 if (XFS_TEST_ERROR(false, ailp->ail_log->l_mp, XFS_ERRTAG_LOG_ITEM_PIN))
402 return XFS_ITEM_PINNED;
403
404 /*
405 * Consider the item pinned if a push callback is not defined so the
406 * caller will force the log. This should only happen for intent items
407 * as they are unpinned once the associated done item is committed to
408 * the on-disk log.
409 */
410 if (!lip->li_ops->iop_push)
411 return XFS_ITEM_PINNED;
412 if (test_bit(XFS_LI_FAILED, &lip->li_flags))
413 return xfsaild_resubmit_item(lip, &ailp->ail_buf_list);
414 return lip->li_ops->iop_push(lip, &ailp->ail_buf_list);
415}
416
417static long
418xfsaild_push(
419 struct xfs_ail *ailp)
420{
421 struct xfs_mount *mp = ailp->ail_log->l_mp;
422 struct xfs_ail_cursor cur;
423 struct xfs_log_item *lip;
424 xfs_lsn_t lsn;
425 xfs_lsn_t target = NULLCOMMITLSN;
426 long tout;
427 int stuck = 0;
428 int flushing = 0;
429 int count = 0;
430
431 /*
432 * If we encountered pinned items or did not finish writing out all
433 * buffers the last time we ran, force a background CIL push to get the
434 * items unpinned in the near future. We do not wait on the CIL push as
435 * that could stall us for seconds if there is enough background IO
436 * load. Stalling for that long when the tail of the log is pinned and
437 * needs flushing will hard stop the transaction subsystem when log
438 * space runs out.
439 */
440 if (ailp->ail_log_flush && ailp->ail_last_pushed_lsn == 0 &&
441 (!list_empty_careful(&ailp->ail_buf_list) ||
442 xfs_ail_min_lsn(ailp))) {
443 ailp->ail_log_flush = 0;
444
445 XFS_STATS_INC(mp, xs_push_ail_flush);
446 xlog_cil_flush(ailp->ail_log);
447 }
448
449 spin_lock(&ailp->ail_lock);
450
451 /*
452 * If we have a sync push waiter, we always have to push till the AIL is
453 * empty. Update the target to point to the end of the AIL so that
454 * capture updates that occur after the sync push waiter has gone to
455 * sleep.
456 */
457 if (waitqueue_active(&ailp->ail_empty)) {
458 lip = xfs_ail_max(ailp);
459 if (lip)
460 target = lip->li_lsn;
461 } else {
462 /* barrier matches the ail_target update in xfs_ail_push() */
463 smp_rmb();
464 target = ailp->ail_target;
465 ailp->ail_target_prev = target;
466 }
467
468 /* we're done if the AIL is empty or our push has reached the end */
469 lip = xfs_trans_ail_cursor_first(ailp, &cur, ailp->ail_last_pushed_lsn);
470 if (!lip)
471 goto out_done;
472
473 XFS_STATS_INC(mp, xs_push_ail);
474
475 ASSERT(target != NULLCOMMITLSN);
476
477 lsn = lip->li_lsn;
478 while ((XFS_LSN_CMP(lip->li_lsn, target) <= 0)) {
479 int lock_result;
480
481 /*
482 * Note that iop_push may unlock and reacquire the AIL lock. We
483 * rely on the AIL cursor implementation to be able to deal with
484 * the dropped lock.
485 */
486 lock_result = xfsaild_push_item(ailp, lip);
487 switch (lock_result) {
488 case XFS_ITEM_SUCCESS:
489 XFS_STATS_INC(mp, xs_push_ail_success);
490 trace_xfs_ail_push(lip);
491
492 ailp->ail_last_pushed_lsn = lsn;
493 break;
494
495 case XFS_ITEM_FLUSHING:
496 /*
497 * The item or its backing buffer is already being
498 * flushed. The typical reason for that is that an
499 * inode buffer is locked because we already pushed the
500 * updates to it as part of inode clustering.
501 *
502 * We do not want to stop flushing just because lots
503 * of items are already being flushed, but we need to
504 * re-try the flushing relatively soon if most of the
505 * AIL is being flushed.
506 */
507 XFS_STATS_INC(mp, xs_push_ail_flushing);
508 trace_xfs_ail_flushing(lip);
509
510 flushing++;
511 ailp->ail_last_pushed_lsn = lsn;
512 break;
513
514 case XFS_ITEM_PINNED:
515 XFS_STATS_INC(mp, xs_push_ail_pinned);
516 trace_xfs_ail_pinned(lip);
517
518 stuck++;
519 ailp->ail_log_flush++;
520 break;
521 case XFS_ITEM_LOCKED:
522 XFS_STATS_INC(mp, xs_push_ail_locked);
523 trace_xfs_ail_locked(lip);
524
525 stuck++;
526 break;
527 default:
528 ASSERT(0);
529 break;
530 }
531
532 count++;
533
534 /*
535 * Are there too many items we can't do anything with?
536 *
537 * If we are skipping too many items because we can't flush
538 * them or they are already being flushed, we back off and
539 * given them time to complete whatever operation is being
540 * done. i.e. remove pressure from the AIL while we can't make
541 * progress so traversals don't slow down further inserts and
542 * removals to/from the AIL.
543 *
544 * The value of 100 is an arbitrary magic number based on
545 * observation.
546 */
547 if (stuck > 100)
548 break;
549
550 lip = xfs_trans_ail_cursor_next(ailp, &cur);
551 if (lip == NULL)
552 break;
553 lsn = lip->li_lsn;
554 }
555
556out_done:
557 xfs_trans_ail_cursor_done(&cur);
558 spin_unlock(&ailp->ail_lock);
559
560 if (xfs_buf_delwri_submit_nowait(&ailp->ail_buf_list))
561 ailp->ail_log_flush++;
562
563 if (!count || XFS_LSN_CMP(lsn, target) >= 0) {
564 /*
565 * We reached the target or the AIL is empty, so wait a bit
566 * longer for I/O to complete and remove pushed items from the
567 * AIL before we start the next scan from the start of the AIL.
568 */
569 tout = 50;
570 ailp->ail_last_pushed_lsn = 0;
571 } else if (((stuck + flushing) * 100) / count > 90) {
572 /*
573 * Either there is a lot of contention on the AIL or we are
574 * stuck due to operations in progress. "Stuck" in this case
575 * is defined as >90% of the items we tried to push were stuck.
576 *
577 * Backoff a bit more to allow some I/O to complete before
578 * restarting from the start of the AIL. This prevents us from
579 * spinning on the same items, and if they are pinned will all
580 * the restart to issue a log force to unpin the stuck items.
581 */
582 tout = 20;
583 ailp->ail_last_pushed_lsn = 0;
584 } else {
585 /*
586 * Assume we have more work to do in a short while.
587 */
588 tout = 10;
589 }
590
591 return tout;
592}
593
594static int
595xfsaild(
596 void *data)
597{
598 struct xfs_ail *ailp = data;
599 long tout = 0; /* milliseconds */
600 unsigned int noreclaim_flag;
601
602 noreclaim_flag = memalloc_noreclaim_save();
603 set_freezable();
604
605 while (1) {
606 if (tout && tout <= 20)
607 set_current_state(TASK_KILLABLE|TASK_FREEZABLE);
608 else
609 set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
610
611 /*
612 * Check kthread_should_stop() after we set the task state to
613 * guarantee that we either see the stop bit and exit or the
614 * task state is reset to runnable such that it's not scheduled
615 * out indefinitely and detects the stop bit at next iteration.
616 * A memory barrier is included in above task state set to
617 * serialize again kthread_stop().
618 */
619 if (kthread_should_stop()) {
620 __set_current_state(TASK_RUNNING);
621
622 /*
623 * The caller forces out the AIL before stopping the
624 * thread in the common case, which means the delwri
625 * queue is drained. In the shutdown case, the queue may
626 * still hold relogged buffers that haven't been
627 * submitted because they were pinned since added to the
628 * queue.
629 *
630 * Log I/O error processing stales the underlying buffer
631 * and clears the delwri state, expecting the buf to be
632 * removed on the next submission attempt. That won't
633 * happen if we're shutting down, so this is the last
634 * opportunity to release such buffers from the queue.
635 */
636 ASSERT(list_empty(&ailp->ail_buf_list) ||
637 xlog_is_shutdown(ailp->ail_log));
638 xfs_buf_delwri_cancel(&ailp->ail_buf_list);
639 break;
640 }
641
642 spin_lock(&ailp->ail_lock);
643
644 /*
645 * Idle if the AIL is empty and we are not racing with a target
646 * update. We check the AIL after we set the task to a sleep
647 * state to guarantee that we either catch an ail_target update
648 * or that a wake_up resets the state to TASK_RUNNING.
649 * Otherwise, we run the risk of sleeping indefinitely.
650 *
651 * The barrier matches the ail_target update in xfs_ail_push().
652 */
653 smp_rmb();
654 if (!xfs_ail_min(ailp) &&
655 ailp->ail_target == ailp->ail_target_prev &&
656 list_empty(&ailp->ail_buf_list)) {
657 spin_unlock(&ailp->ail_lock);
658 schedule();
659 tout = 0;
660 continue;
661 }
662 spin_unlock(&ailp->ail_lock);
663
664 if (tout)
665 schedule_timeout(msecs_to_jiffies(tout));
666
667 __set_current_state(TASK_RUNNING);
668
669 try_to_freeze();
670
671 tout = xfsaild_push(ailp);
672 }
673
674 memalloc_noreclaim_restore(noreclaim_flag);
675 return 0;
676}
677
678/*
679 * This routine is called to move the tail of the AIL forward. It does this by
680 * trying to flush items in the AIL whose lsns are below the given
681 * threshold_lsn.
682 *
683 * The push is run asynchronously in a workqueue, which means the caller needs
684 * to handle waiting on the async flush for space to become available.
685 * We don't want to interrupt any push that is in progress, hence we only queue
686 * work if we set the pushing bit appropriately.
687 *
688 * We do this unlocked - we only need to know whether there is anything in the
689 * AIL at the time we are called. We don't need to access the contents of
690 * any of the objects, so the lock is not needed.
691 */
692void
693xfs_ail_push(
694 struct xfs_ail *ailp,
695 xfs_lsn_t threshold_lsn)
696{
697 struct xfs_log_item *lip;
698
699 lip = xfs_ail_min(ailp);
700 if (!lip || xlog_is_shutdown(ailp->ail_log) ||
701 XFS_LSN_CMP(threshold_lsn, ailp->ail_target) <= 0)
702 return;
703
704 /*
705 * Ensure that the new target is noticed in push code before it clears
706 * the XFS_AIL_PUSHING_BIT.
707 */
708 smp_wmb();
709 xfs_trans_ail_copy_lsn(ailp, &ailp->ail_target, &threshold_lsn);
710 smp_wmb();
711
712 wake_up_process(ailp->ail_task);
713}
714
715/*
716 * Push out all items in the AIL immediately
717 */
718void
719xfs_ail_push_all(
720 struct xfs_ail *ailp)
721{
722 xfs_lsn_t threshold_lsn = xfs_ail_max_lsn(ailp);
723
724 if (threshold_lsn)
725 xfs_ail_push(ailp, threshold_lsn);
726}
727
728/*
729 * Push out all items in the AIL immediately and wait until the AIL is empty.
730 */
731void
732xfs_ail_push_all_sync(
733 struct xfs_ail *ailp)
734{
735 DEFINE_WAIT(wait);
736
737 spin_lock(&ailp->ail_lock);
738 while (xfs_ail_max(ailp) != NULL) {
739 prepare_to_wait(&ailp->ail_empty, &wait, TASK_UNINTERRUPTIBLE);
740 wake_up_process(ailp->ail_task);
741 spin_unlock(&ailp->ail_lock);
742 schedule();
743 spin_lock(&ailp->ail_lock);
744 }
745 spin_unlock(&ailp->ail_lock);
746
747 finish_wait(&ailp->ail_empty, &wait);
748}
749
750void
751xfs_ail_update_finish(
752 struct xfs_ail *ailp,
753 xfs_lsn_t old_lsn) __releases(ailp->ail_lock)
754{
755 struct xlog *log = ailp->ail_log;
756
757 /* if the tail lsn hasn't changed, don't do updates or wakeups. */
758 if (!old_lsn || old_lsn == __xfs_ail_min_lsn(ailp)) {
759 spin_unlock(&ailp->ail_lock);
760 return;
761 }
762
763 if (!xlog_is_shutdown(log))
764 xlog_assign_tail_lsn_locked(log->l_mp);
765
766 if (list_empty(&ailp->ail_head))
767 wake_up_all(&ailp->ail_empty);
768 spin_unlock(&ailp->ail_lock);
769 xfs_log_space_wake(log->l_mp);
770}
771
772/*
773 * xfs_trans_ail_update - bulk AIL insertion operation.
774 *
775 * @xfs_trans_ail_update takes an array of log items that all need to be
776 * positioned at the same LSN in the AIL. If an item is not in the AIL, it will
777 * be added. Otherwise, it will be repositioned by removing it and re-adding
778 * it to the AIL. If we move the first item in the AIL, update the log tail to
779 * match the new minimum LSN in the AIL.
780 *
781 * This function takes the AIL lock once to execute the update operations on
782 * all the items in the array, and as such should not be called with the AIL
783 * lock held. As a result, once we have the AIL lock, we need to check each log
784 * item LSN to confirm it needs to be moved forward in the AIL.
785 *
786 * To optimise the insert operation, we delete all the items from the AIL in
787 * the first pass, moving them into a temporary list, then splice the temporary
788 * list into the correct position in the AIL. This avoids needing to do an
789 * insert operation on every item.
790 *
791 * This function must be called with the AIL lock held. The lock is dropped
792 * before returning.
793 */
794void
795xfs_trans_ail_update_bulk(
796 struct xfs_ail *ailp,
797 struct xfs_ail_cursor *cur,
798 struct xfs_log_item **log_items,
799 int nr_items,
800 xfs_lsn_t lsn) __releases(ailp->ail_lock)
801{
802 struct xfs_log_item *mlip;
803 xfs_lsn_t tail_lsn = 0;
804 int i;
805 LIST_HEAD(tmp);
806
807 ASSERT(nr_items > 0); /* Not required, but true. */
808 mlip = xfs_ail_min(ailp);
809
810 for (i = 0; i < nr_items; i++) {
811 struct xfs_log_item *lip = log_items[i];
812 if (test_and_set_bit(XFS_LI_IN_AIL, &lip->li_flags)) {
813 /* check if we really need to move the item */
814 if (XFS_LSN_CMP(lsn, lip->li_lsn) <= 0)
815 continue;
816
817 trace_xfs_ail_move(lip, lip->li_lsn, lsn);
818 if (mlip == lip && !tail_lsn)
819 tail_lsn = lip->li_lsn;
820
821 xfs_ail_delete(ailp, lip);
822 } else {
823 trace_xfs_ail_insert(lip, 0, lsn);
824 }
825 lip->li_lsn = lsn;
826 list_add(&lip->li_ail, &tmp);
827 }
828
829 if (!list_empty(&tmp))
830 xfs_ail_splice(ailp, cur, &tmp, lsn);
831
832 xfs_ail_update_finish(ailp, tail_lsn);
833}
834
835/* Insert a log item into the AIL. */
836void
837xfs_trans_ail_insert(
838 struct xfs_ail *ailp,
839 struct xfs_log_item *lip,
840 xfs_lsn_t lsn)
841{
842 spin_lock(&ailp->ail_lock);
843 xfs_trans_ail_update_bulk(ailp, NULL, &lip, 1, lsn);
844}
845
846/*
847 * Delete one log item from the AIL.
848 *
849 * If this item was at the tail of the AIL, return the LSN of the log item so
850 * that we can use it to check if the LSN of the tail of the log has moved
851 * when finishing up the AIL delete process in xfs_ail_update_finish().
852 */
853xfs_lsn_t
854xfs_ail_delete_one(
855 struct xfs_ail *ailp,
856 struct xfs_log_item *lip)
857{
858 struct xfs_log_item *mlip = xfs_ail_min(ailp);
859 xfs_lsn_t lsn = lip->li_lsn;
860
861 trace_xfs_ail_delete(lip, mlip->li_lsn, lip->li_lsn);
862 xfs_ail_delete(ailp, lip);
863 clear_bit(XFS_LI_IN_AIL, &lip->li_flags);
864 lip->li_lsn = 0;
865
866 if (mlip == lip)
867 return lsn;
868 return 0;
869}
870
871void
872xfs_trans_ail_delete(
873 struct xfs_log_item *lip,
874 int shutdown_type)
875{
876 struct xfs_ail *ailp = lip->li_ailp;
877 struct xlog *log = ailp->ail_log;
878 xfs_lsn_t tail_lsn;
879
880 spin_lock(&ailp->ail_lock);
881 if (!test_bit(XFS_LI_IN_AIL, &lip->li_flags)) {
882 spin_unlock(&ailp->ail_lock);
883 if (shutdown_type && !xlog_is_shutdown(log)) {
884 xfs_alert_tag(log->l_mp, XFS_PTAG_AILDELETE,
885 "%s: attempting to delete a log item that is not in the AIL",
886 __func__);
887 xlog_force_shutdown(log, shutdown_type);
888 }
889 return;
890 }
891
892 /* xfs_ail_update_finish() drops the AIL lock */
893 xfs_clear_li_failed(lip);
894 tail_lsn = xfs_ail_delete_one(ailp, lip);
895 xfs_ail_update_finish(ailp, tail_lsn);
896}
897
898int
899xfs_trans_ail_init(
900 xfs_mount_t *mp)
901{
902 struct xfs_ail *ailp;
903
904 ailp = kmem_zalloc(sizeof(struct xfs_ail), KM_MAYFAIL);
905 if (!ailp)
906 return -ENOMEM;
907
908 ailp->ail_log = mp->m_log;
909 INIT_LIST_HEAD(&ailp->ail_head);
910 INIT_LIST_HEAD(&ailp->ail_cursors);
911 spin_lock_init(&ailp->ail_lock);
912 INIT_LIST_HEAD(&ailp->ail_buf_list);
913 init_waitqueue_head(&ailp->ail_empty);
914
915 ailp->ail_task = kthread_run(xfsaild, ailp, "xfsaild/%s",
916 mp->m_super->s_id);
917 if (IS_ERR(ailp->ail_task))
918 goto out_free_ailp;
919
920 mp->m_ail = ailp;
921 return 0;
922
923out_free_ailp:
924 kmem_free(ailp);
925 return -ENOMEM;
926}
927
928void
929xfs_trans_ail_destroy(
930 xfs_mount_t *mp)
931{
932 struct xfs_ail *ailp = mp->m_ail;
933
934 kthread_stop(ailp->ail_task);
935 kmem_free(ailp);
936}