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