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 * The cursor keeps track of where our current traversal is up to by tracking
139 * the next item in the list for us. However, for this to be safe, removing an
140 * object from the AIL needs to invalidate any cursor that points to it. hence
141 * the traversal cursor needs to be linked to the struct xfs_ail so that
142 * deletion can search all the active cursors for invalidation.
143 */
144STATIC void
145xfs_trans_ail_cursor_init(
146	struct xfs_ail		*ailp,
147	struct xfs_ail_cursor	*cur)
148{
149	cur->item = NULL;
150	list_add_tail(&cur->list, &ailp->ail_cursors);
151}
152
153/*
154 * Get the next item in the traversal and advance the cursor.  If the cursor
155 * was invalidated (indicated by a lip of 1), restart the traversal.
156 */
157struct xfs_log_item *
158xfs_trans_ail_cursor_next(
159	struct xfs_ail		*ailp,
160	struct xfs_ail_cursor	*cur)
161{
162	struct xfs_log_item	*lip = cur->item;
163
164	if ((uintptr_t)lip & 1)
165		lip = xfs_ail_min(ailp);
166	if (lip)
167		cur->item = xfs_ail_next(ailp, lip);
168	return lip;
169}
170
171/*
172 * When the traversal is complete, we need to remove the cursor from the list
173 * of traversing cursors.
174 */
175void
176xfs_trans_ail_cursor_done(
177	struct xfs_ail_cursor	*cur)
178{
179	cur->item = NULL;
180	list_del_init(&cur->list);
181}
182
183/*
184 * Invalidate any cursor that is pointing to this item. This is called when an
185 * item is removed from the AIL. Any cursor pointing to this object is now
186 * invalid and the traversal needs to be terminated so it doesn't reference a
187 * freed object. We set the low bit of the cursor item pointer so we can
188 * distinguish between an invalidation and the end of the list when getting the
189 * next item from the cursor.
190 */
191STATIC void
192xfs_trans_ail_cursor_clear(
193	struct xfs_ail		*ailp,
194	struct xfs_log_item	*lip)
195{
196	struct xfs_ail_cursor	*cur;
197
198	list_for_each_entry(cur, &ailp->ail_cursors, list) {
199		if (cur->item == lip)
200			cur->item = (struct xfs_log_item *)
201					((uintptr_t)cur->item | 1);
202	}
203}
204
205/*
206 * Find the first item in the AIL with the given @lsn by searching in ascending
207 * LSN order and initialise the cursor to point to the next item for a
208 * ascending traversal.  Pass a @lsn of zero to initialise the cursor to the
209 * first item in the AIL. Returns NULL if the list is empty.
210 */
211struct xfs_log_item *
212xfs_trans_ail_cursor_first(
213	struct xfs_ail		*ailp,
214	struct xfs_ail_cursor	*cur,
215	xfs_lsn_t		lsn)
216{
217	struct xfs_log_item	*lip;
218
219	xfs_trans_ail_cursor_init(ailp, cur);
220
221	if (lsn == 0) {
222		lip = xfs_ail_min(ailp);
223		goto out;
224	}
225
226	list_for_each_entry(lip, &ailp->ail_head, li_ail) {
227		if (XFS_LSN_CMP(lip->li_lsn, lsn) >= 0)
228			goto out;
229	}
230	return NULL;
231
232out:
233	if (lip)
234		cur->item = xfs_ail_next(ailp, lip);
235	return lip;
236}
237
238static struct xfs_log_item *
239__xfs_trans_ail_cursor_last(
240	struct xfs_ail		*ailp,
241	xfs_lsn_t		lsn)
242{
243	struct xfs_log_item	*lip;
244
245	list_for_each_entry_reverse(lip, &ailp->ail_head, li_ail) {
246		if (XFS_LSN_CMP(lip->li_lsn, lsn) <= 0)
247			return lip;
248	}
249	return NULL;
250}
251
252/*
253 * Find the last item in the AIL with the given @lsn by searching in descending
254 * LSN order and initialise the cursor to point to that item.  If there is no
255 * item with the value of @lsn, then it sets the cursor to the last item with an
256 * LSN lower than @lsn.  Returns NULL if the list is empty.
257 */
258struct xfs_log_item *
259xfs_trans_ail_cursor_last(
260	struct xfs_ail		*ailp,
261	struct xfs_ail_cursor	*cur,
262	xfs_lsn_t		lsn)
263{
264	xfs_trans_ail_cursor_init(ailp, cur);
265	cur->item = __xfs_trans_ail_cursor_last(ailp, lsn);
266	return cur->item;
267}
268
269/*
270 * Splice the log item list into the AIL at the given LSN. We splice to the
271 * tail of the given LSN to maintain insert order for push traversals. The
272 * cursor is optional, allowing repeated updates to the same LSN to avoid
273 * repeated traversals.  This should not be called with an empty list.
274 */
275static void
276xfs_ail_splice(
277	struct xfs_ail		*ailp,
278	struct xfs_ail_cursor	*cur,
279	struct list_head	*list,
280	xfs_lsn_t		lsn)
281{
282	struct xfs_log_item	*lip;
283
284	ASSERT(!list_empty(list));
285
286	/*
287	 * Use the cursor to determine the insertion point if one is
288	 * provided.  If not, or if the one we got is not valid,
289	 * find the place in the AIL where the items belong.
290	 */
291	lip = cur ? cur->item : NULL;
292	if (!lip || (uintptr_t)lip & 1)
293		lip = __xfs_trans_ail_cursor_last(ailp, lsn);
294
295	/*
296	 * If a cursor is provided, we know we're processing the AIL
297	 * in lsn order, and future items to be spliced in will
298	 * follow the last one being inserted now.  Update the
299	 * cursor to point to that last item, now while we have a
300	 * reliable pointer to it.
301	 */
302	if (cur)
303		cur->item = list_entry(list->prev, struct xfs_log_item, li_ail);
304
305	/*
306	 * Finally perform the splice.  Unless the AIL was empty,
307	 * lip points to the item in the AIL _after_ which the new
308	 * items should go.  If lip is null the AIL was empty, so
309	 * the new items go at the head of the AIL.
310	 */
311	if (lip)
312		list_splice(list, &lip->li_ail);
313	else
314		list_splice(list, &ailp->ail_head);
315}
316
317/*
318 * Delete the given item from the AIL.  Return a pointer to the item.
319 */
320static void
321xfs_ail_delete(
322	struct xfs_ail		*ailp,
323	struct xfs_log_item	*lip)
324{
325	xfs_ail_check(ailp, lip);
326	list_del(&lip->li_ail);
327	xfs_trans_ail_cursor_clear(ailp, lip);
328}
329
330/*
331 * Requeue a failed buffer for writeback.
332 *
333 * We clear the log item failed state here as well, but we have to be careful
334 * about reference counts because the only active reference counts on the buffer
335 * may be the failed log items. Hence if we clear the log item failed state
336 * before queuing the buffer for IO we can release all active references to
337 * the buffer and free it, leading to use after free problems in
338 * xfs_buf_delwri_queue. It makes no difference to the buffer or log items which
339 * order we process them in - the buffer is locked, and we own the buffer list
340 * so nothing on them is going to change while we are performing this action.
341 *
342 * Hence we can safely queue the buffer for IO before we clear the failed log
343 * item state, therefore  always having an active reference to the buffer and
344 * avoiding the transient zero-reference state that leads to use-after-free.
345 */
346static inline int
347xfsaild_resubmit_item(
348	struct xfs_log_item	*lip,
349	struct list_head	*buffer_list)
350{
351	struct xfs_buf		*bp = lip->li_buf;
352
353	if (!xfs_buf_trylock(bp))
354		return XFS_ITEM_LOCKED;
355
356	if (!xfs_buf_delwri_queue(bp, buffer_list)) {
357		xfs_buf_unlock(bp);
358		return XFS_ITEM_FLUSHING;
359	}
360
361	/* protected by ail_lock */
362	list_for_each_entry(lip, &bp->b_li_list, li_bio_list) {
363		if (bp->b_flags & (_XBF_INODES | _XBF_DQUOTS))
364			clear_bit(XFS_LI_FAILED, &lip->li_flags);
365		else
366			xfs_clear_li_failed(lip);
367	}
368
369	xfs_buf_unlock(bp);
370	return XFS_ITEM_SUCCESS;
371}
372
373static inline uint
374xfsaild_push_item(
375	struct xfs_ail		*ailp,
376	struct xfs_log_item	*lip)
377{
378	/*
379	 * If log item pinning is enabled, skip the push and track the item as
380	 * pinned. This can help induce head-behind-tail conditions.
381	 */
382	if (XFS_TEST_ERROR(false, ailp->ail_log->l_mp, XFS_ERRTAG_LOG_ITEM_PIN))
383		return XFS_ITEM_PINNED;
384
385	/*
386	 * Consider the item pinned if a push callback is not defined so the
387	 * caller will force the log. This should only happen for intent items
388	 * as they are unpinned once the associated done item is committed to
389	 * the on-disk log.
390	 */
391	if (!lip->li_ops->iop_push)
392		return XFS_ITEM_PINNED;
393	if (test_bit(XFS_LI_FAILED, &lip->li_flags))
394		return xfsaild_resubmit_item(lip, &ailp->ail_buf_list);
395	return lip->li_ops->iop_push(lip, &ailp->ail_buf_list);
396}
397
398/*
399 * Compute the LSN that we'd need to push the log tail towards in order to have
400 * at least 25% of the log space free.  If the log free space already meets this
401 * threshold, this function returns the lowest LSN in the AIL to slowly keep
402 * writeback ticking over and the tail of the log moving forward.
403 */
404static xfs_lsn_t
405xfs_ail_calc_push_target(
406	struct xfs_ail		*ailp)
407{
408	struct xlog		*log = ailp->ail_log;
409	struct xfs_log_item	*lip;
410	xfs_lsn_t		target_lsn;
411	xfs_lsn_t		max_lsn;
412	xfs_lsn_t		min_lsn;
413	int32_t			free_bytes;
414	uint32_t		target_block;
415	uint32_t		target_cycle;
416
417	lockdep_assert_held(&ailp->ail_lock);
418
419	lip = xfs_ail_max(ailp);
420	if (!lip)
421		return NULLCOMMITLSN;
422
423	max_lsn = lip->li_lsn;
424	min_lsn = __xfs_ail_min_lsn(ailp);
425
426	/*
427	 * If we are supposed to push all the items in the AIL, we want to push
428	 * to the current head. We then clear the push flag so that we don't
429	 * keep pushing newly queued items beyond where the push all command was
430	 * run. If the push waiter wants to empty the ail, it should queue
431	 * itself on the ail_empty wait queue.
432	 */
433	if (test_and_clear_bit(XFS_AIL_OPSTATE_PUSH_ALL, &ailp->ail_opstate))
434		return max_lsn;
435
436	/* If someone wants the AIL empty, keep pushing everything we have. */
437	if (waitqueue_active(&ailp->ail_empty))
438		return max_lsn;
439
440	/*
441	 * Background pushing - attempt to keep 25% of the log free and if we
442	 * have that much free retain the existing target.
443	 */
444	free_bytes = log->l_logsize - xlog_lsn_sub(log, max_lsn, min_lsn);
445	if (free_bytes >= log->l_logsize >> 2)
446		return ailp->ail_target;
447
448	target_cycle = CYCLE_LSN(min_lsn);
449	target_block = BLOCK_LSN(min_lsn) + (log->l_logBBsize >> 2);
450	if (target_block >= log->l_logBBsize) {
451		target_block -= log->l_logBBsize;
452		target_cycle += 1;
453	}
454	target_lsn = xlog_assign_lsn(target_cycle, target_block);
455
456	/* Cap the target to the highest LSN known to be in the AIL. */
457	if (XFS_LSN_CMP(target_lsn, max_lsn) > 0)
458		return max_lsn;
459
460	/* If the existing target is higher than the new target, keep it. */
461	if (XFS_LSN_CMP(ailp->ail_target, target_lsn) >= 0)
462		return ailp->ail_target;
463	return target_lsn;
464}
465
466static long
467xfsaild_push(
468	struct xfs_ail		*ailp)
469{
470	struct xfs_mount	*mp = ailp->ail_log->l_mp;
471	struct xfs_ail_cursor	cur;
472	struct xfs_log_item	*lip;
473	xfs_lsn_t		lsn;
 
474	long			tout;
475	int			stuck = 0;
476	int			flushing = 0;
477	int			count = 0;
478
479	/*
480	 * If we encountered pinned items or did not finish writing out all
481	 * buffers the last time we ran, force a background CIL push to get the
482	 * items unpinned in the near future. We do not wait on the CIL push as
483	 * that could stall us for seconds if there is enough background IO
484	 * load. Stalling for that long when the tail of the log is pinned and
485	 * needs flushing will hard stop the transaction subsystem when log
486	 * space runs out.
487	 */
488	if (ailp->ail_log_flush && ailp->ail_last_pushed_lsn == 0 &&
489	    (!list_empty_careful(&ailp->ail_buf_list) ||
490	     xfs_ail_min_lsn(ailp))) {
491		ailp->ail_log_flush = 0;
492
493		XFS_STATS_INC(mp, xs_push_ail_flush);
494		xlog_cil_flush(ailp->ail_log);
495	}
496
497	spin_lock(&ailp->ail_lock);
498	WRITE_ONCE(ailp->ail_target, xfs_ail_calc_push_target(ailp));
499	if (ailp->ail_target == NULLCOMMITLSN)
500		goto out_done;
 
 
501
502	/* we're done if the AIL is empty or our push has reached the end */
503	lip = xfs_trans_ail_cursor_first(ailp, &cur, ailp->ail_last_pushed_lsn);
504	if (!lip)
505		goto out_done_cursor;
506
507	XFS_STATS_INC(mp, xs_push_ail);
508
509	ASSERT(ailp->ail_target != NULLCOMMITLSN);
510
511	lsn = lip->li_lsn;
512	while ((XFS_LSN_CMP(lip->li_lsn, ailp->ail_target) <= 0)) {
513		int	lock_result;
514
515		if (test_bit(XFS_LI_FLUSHING, &lip->li_flags))
516			goto next_item;
517
518		/*
519		 * Note that iop_push may unlock and reacquire the AIL lock.  We
520		 * rely on the AIL cursor implementation to be able to deal with
521		 * the dropped lock.
522		 */
523		lock_result = xfsaild_push_item(ailp, lip);
524		switch (lock_result) {
525		case XFS_ITEM_SUCCESS:
526			XFS_STATS_INC(mp, xs_push_ail_success);
527			trace_xfs_ail_push(lip);
528
529			ailp->ail_last_pushed_lsn = lsn;
530			break;
531
532		case XFS_ITEM_FLUSHING:
533			/*
534			 * The item or its backing buffer is already being
535			 * flushed.  The typical reason for that is that an
536			 * inode buffer is locked because we already pushed the
537			 * updates to it as part of inode clustering.
538			 *
539			 * We do not want to stop flushing just because lots
540			 * of items are already being flushed, but we need to
541			 * re-try the flushing relatively soon if most of the
542			 * AIL is being flushed.
543			 */
544			XFS_STATS_INC(mp, xs_push_ail_flushing);
545			trace_xfs_ail_flushing(lip);
546
547			flushing++;
548			ailp->ail_last_pushed_lsn = lsn;
549			break;
550
551		case XFS_ITEM_PINNED:
552			XFS_STATS_INC(mp, xs_push_ail_pinned);
553			trace_xfs_ail_pinned(lip);
554
555			stuck++;
556			ailp->ail_log_flush++;
557			break;
558		case XFS_ITEM_LOCKED:
559			XFS_STATS_INC(mp, xs_push_ail_locked);
560			trace_xfs_ail_locked(lip);
561
562			stuck++;
563			break;
564		default:
565			ASSERT(0);
566			break;
567		}
568
569		count++;
570
571		/*
572		 * Are there too many items we can't do anything with?
573		 *
574		 * If we are skipping too many items because we can't flush
575		 * them or they are already being flushed, we back off and
576		 * given them time to complete whatever operation is being
577		 * done. i.e. remove pressure from the AIL while we can't make
578		 * progress so traversals don't slow down further inserts and
579		 * removals to/from the AIL.
580		 *
581		 * The value of 100 is an arbitrary magic number based on
582		 * observation.
583		 */
584		if (stuck > 100)
585			break;
586
587next_item:
588		lip = xfs_trans_ail_cursor_next(ailp, &cur);
589		if (lip == NULL)
590			break;
591		if (lip->li_lsn != lsn && count > 1000)
592			break;
593		lsn = lip->li_lsn;
594	}
595
596out_done_cursor:
597	xfs_trans_ail_cursor_done(&cur);
598out_done:
 
599	spin_unlock(&ailp->ail_lock);
600
601	if (xfs_buf_delwri_submit_nowait(&ailp->ail_buf_list))
602		ailp->ail_log_flush++;
603
604	if (!count || XFS_LSN_CMP(lsn, ailp->ail_target) >= 0) {
605		/*
606		 * We reached the target or the AIL is empty, so wait a bit
607		 * longer for I/O to complete and remove pushed items from the
608		 * AIL before we start the next scan from the start of the AIL.
609		 */
610		tout = 50;
611		ailp->ail_last_pushed_lsn = 0;
612	} else if (((stuck + flushing) * 100) / count > 90) {
613		/*
614		 * Either there is a lot of contention on the AIL or we are
615		 * stuck due to operations in progress. "Stuck" in this case
616		 * is defined as >90% of the items we tried to push were stuck.
617		 *
618		 * Backoff a bit more to allow some I/O to complete before
619		 * restarting from the start of the AIL. This prevents us from
620		 * spinning on the same items, and if they are pinned will all
621		 * the restart to issue a log force to unpin the stuck items.
622		 */
623		tout = 20;
624		ailp->ail_last_pushed_lsn = 0;
625	} else {
626		/*
627		 * Assume we have more work to do in a short while.
628		 */
629		tout = 0;
630	}
631
632	return tout;
633}
634
635static int
636xfsaild(
637	void		*data)
638{
639	struct xfs_ail	*ailp = data;
640	long		tout = 0;	/* milliseconds */
641	unsigned int	noreclaim_flag;
642
643	noreclaim_flag = memalloc_noreclaim_save();
644	set_freezable();
645
646	while (1) {
647		/*
648		 * Long waits of 50ms or more occur when we've run out of items
649		 * to push, so we only want uninterruptible state if we're
650		 * actually blocked on something.
651		 */
652		if (tout && tout <= 20)
653			set_current_state(TASK_KILLABLE|TASK_FREEZABLE);
654		else
655			set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
656
657		/*
658		 * Check kthread_should_stop() after we set the task state to
659		 * guarantee that we either see the stop bit and exit or the
660		 * task state is reset to runnable such that it's not scheduled
661		 * out indefinitely and detects the stop bit at next iteration.
662		 * A memory barrier is included in above task state set to
663		 * serialize again kthread_stop().
664		 */
665		if (kthread_should_stop()) {
666			__set_current_state(TASK_RUNNING);
667
668			/*
669			 * The caller forces out the AIL before stopping the
670			 * thread in the common case, which means the delwri
671			 * queue is drained. In the shutdown case, the queue may
672			 * still hold relogged buffers that haven't been
673			 * submitted because they were pinned since added to the
674			 * queue.
675			 *
676			 * Log I/O error processing stales the underlying buffer
677			 * and clears the delwri state, expecting the buf to be
678			 * removed on the next submission attempt. That won't
679			 * happen if we're shutting down, so this is the last
680			 * opportunity to release such buffers from the queue.
681			 */
682			ASSERT(list_empty(&ailp->ail_buf_list) ||
683			       xlog_is_shutdown(ailp->ail_log));
684			xfs_buf_delwri_cancel(&ailp->ail_buf_list);
685			break;
686		}
687
688		/* Idle if the AIL is empty. */
689		spin_lock(&ailp->ail_lock);
690		if (!xfs_ail_min(ailp) && list_empty(&ailp->ail_buf_list)) {
 
 
 
 
 
 
 
 
 
 
 
 
 
691			spin_unlock(&ailp->ail_lock);
692			schedule();
693			tout = 0;
694			continue;
695		}
696		spin_unlock(&ailp->ail_lock);
697
698		if (tout)
699			schedule_timeout(msecs_to_jiffies(tout));
700
701		__set_current_state(TASK_RUNNING);
702
703		try_to_freeze();
704
705		tout = xfsaild_push(ailp);
706	}
707
708	memalloc_noreclaim_restore(noreclaim_flag);
709	return 0;
710}
711
712/*
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
713 * Push out all items in the AIL immediately and wait until the AIL is empty.
714 */
715void
716xfs_ail_push_all_sync(
717	struct xfs_ail  *ailp)
718{
 
719	DEFINE_WAIT(wait);
720
721	spin_lock(&ailp->ail_lock);
722	while (xfs_ail_max(ailp) != NULL) {
723		prepare_to_wait(&ailp->ail_empty, &wait, TASK_UNINTERRUPTIBLE);
 
724		wake_up_process(ailp->ail_task);
725		spin_unlock(&ailp->ail_lock);
726		schedule();
727		spin_lock(&ailp->ail_lock);
728	}
729	spin_unlock(&ailp->ail_lock);
730
731	finish_wait(&ailp->ail_empty, &wait);
732}
733
734void
735__xfs_ail_assign_tail_lsn(
736	struct xfs_ail		*ailp)
737{
738	struct xlog		*log = ailp->ail_log;
739	xfs_lsn_t		tail_lsn;
740
741	assert_spin_locked(&ailp->ail_lock);
742
743	if (xlog_is_shutdown(log))
744		return;
745
746	tail_lsn = __xfs_ail_min_lsn(ailp);
747	if (!tail_lsn)
748		tail_lsn = ailp->ail_head_lsn;
749
750	WRITE_ONCE(log->l_tail_space,
751			xlog_lsn_sub(log, ailp->ail_head_lsn, tail_lsn));
752	trace_xfs_log_assign_tail_lsn(log, tail_lsn);
753	atomic64_set(&log->l_tail_lsn, tail_lsn);
754}
755
756/*
757 * Callers should pass the original tail lsn so that we can detect if the tail
758 * has moved as a result of the operation that was performed. If the caller
759 * needs to force a tail space update, it should pass NULLCOMMITLSN to bypass
760 * the "did the tail LSN change?" checks. If the caller wants to avoid a tail
761 * update (e.g. it knows the tail did not change) it should pass an @old_lsn of
762 * 0.
763 */
764void
765xfs_ail_update_finish(
766	struct xfs_ail		*ailp,
767	xfs_lsn_t		old_lsn) __releases(ailp->ail_lock)
768{
769	struct xlog		*log = ailp->ail_log;
770
771	/* If the tail lsn hasn't changed, don't do updates or wakeups. */
772	if (!old_lsn || old_lsn == __xfs_ail_min_lsn(ailp)) {
773		spin_unlock(&ailp->ail_lock);
774		return;
775	}
776
777	__xfs_ail_assign_tail_lsn(ailp);
 
 
778	if (list_empty(&ailp->ail_head))
779		wake_up_all(&ailp->ail_empty);
780	spin_unlock(&ailp->ail_lock);
781	xfs_log_space_wake(log->l_mp);
782}
783
784/*
785 * xfs_trans_ail_update - bulk AIL insertion operation.
786 *
787 * @xfs_trans_ail_update takes an array of log items that all need to be
788 * positioned at the same LSN in the AIL. If an item is not in the AIL, it will
789 * be added.  Otherwise, it will be repositioned  by removing it and re-adding
790 * it to the AIL. If we move the first item in the AIL, update the log tail to
791 * match the new minimum LSN in the AIL.
792 *
793 * This function takes the AIL lock once to execute the update operations on
794 * all the items in the array, and as such should not be called with the AIL
795 * lock held. As a result, once we have the AIL lock, we need to check each log
796 * item LSN to confirm it needs to be moved forward in the AIL.
797 *
798 * To optimise the insert operation, we delete all the items from the AIL in
799 * the first pass, moving them into a temporary list, then splice the temporary
800 * list into the correct position in the AIL. This avoids needing to do an
801 * insert operation on every item.
802 *
803 * This function must be called with the AIL lock held.  The lock is dropped
804 * before returning.
805 */
806void
807xfs_trans_ail_update_bulk(
808	struct xfs_ail		*ailp,
809	struct xfs_ail_cursor	*cur,
810	struct xfs_log_item	**log_items,
811	int			nr_items,
812	xfs_lsn_t		lsn) __releases(ailp->ail_lock)
813{
814	struct xfs_log_item	*mlip;
815	xfs_lsn_t		tail_lsn = 0;
816	int			i;
817	LIST_HEAD(tmp);
818
819	ASSERT(nr_items > 0);		/* Not required, but true. */
820	mlip = xfs_ail_min(ailp);
821
822	for (i = 0; i < nr_items; i++) {
823		struct xfs_log_item *lip = log_items[i];
824		if (test_and_set_bit(XFS_LI_IN_AIL, &lip->li_flags)) {
825			/* check if we really need to move the item */
826			if (XFS_LSN_CMP(lsn, lip->li_lsn) <= 0)
827				continue;
828
829			trace_xfs_ail_move(lip, lip->li_lsn, lsn);
830			if (mlip == lip && !tail_lsn)
831				tail_lsn = lip->li_lsn;
832
833			xfs_ail_delete(ailp, lip);
834		} else {
835			trace_xfs_ail_insert(lip, 0, lsn);
836		}
837		lip->li_lsn = lsn;
838		list_add_tail(&lip->li_ail, &tmp);
839	}
840
841	if (!list_empty(&tmp))
842		xfs_ail_splice(ailp, cur, &tmp, lsn);
843
844	/*
845	 * If this is the first insert, wake up the push daemon so it can
846	 * actively scan for items to push. We also need to do a log tail
847	 * LSN update to ensure that it is correctly tracked by the log, so
848	 * set the tail_lsn to NULLCOMMITLSN so that xfs_ail_update_finish()
849	 * will see that the tail lsn has changed and will update the tail
850	 * appropriately.
851	 */
852	if (!mlip) {
853		wake_up_process(ailp->ail_task);
854		tail_lsn = NULLCOMMITLSN;
855	}
856
857	xfs_ail_update_finish(ailp, tail_lsn);
858}
859
860/* Insert a log item into the AIL. */
861void
862xfs_trans_ail_insert(
863	struct xfs_ail		*ailp,
864	struct xfs_log_item	*lip,
865	xfs_lsn_t		lsn)
866{
867	spin_lock(&ailp->ail_lock);
868	xfs_trans_ail_update_bulk(ailp, NULL, &lip, 1, lsn);
869}
870
871/*
872 * Delete one log item from the AIL.
873 *
874 * If this item was at the tail of the AIL, return the LSN of the log item so
875 * that we can use it to check if the LSN of the tail of the log has moved
876 * when finishing up the AIL delete process in xfs_ail_update_finish().
877 */
878xfs_lsn_t
879xfs_ail_delete_one(
880	struct xfs_ail		*ailp,
881	struct xfs_log_item	*lip)
882{
883	struct xfs_log_item	*mlip = xfs_ail_min(ailp);
884	xfs_lsn_t		lsn = lip->li_lsn;
885
886	trace_xfs_ail_delete(lip, mlip->li_lsn, lip->li_lsn);
887	xfs_ail_delete(ailp, lip);
888	clear_bit(XFS_LI_IN_AIL, &lip->li_flags);
889	lip->li_lsn = 0;
890
891	if (mlip == lip)
892		return lsn;
893	return 0;
894}
895
896void
897xfs_trans_ail_delete(
898	struct xfs_log_item	*lip,
899	int			shutdown_type)
900{
901	struct xfs_ail		*ailp = lip->li_ailp;
902	struct xlog		*log = ailp->ail_log;
903	xfs_lsn_t		tail_lsn;
904
905	spin_lock(&ailp->ail_lock);
906	if (!test_bit(XFS_LI_IN_AIL, &lip->li_flags)) {
907		spin_unlock(&ailp->ail_lock);
908		if (shutdown_type && !xlog_is_shutdown(log)) {
909			xfs_alert_tag(log->l_mp, XFS_PTAG_AILDELETE,
910	"%s: attempting to delete a log item that is not in the AIL",
911					__func__);
912			xlog_force_shutdown(log, shutdown_type);
913		}
914		return;
915	}
916
917	/* xfs_ail_update_finish() drops the AIL lock */
918	xfs_clear_li_failed(lip);
919	tail_lsn = xfs_ail_delete_one(ailp, lip);
920	xfs_ail_update_finish(ailp, tail_lsn);
921}
922
923int
924xfs_trans_ail_init(
925	xfs_mount_t	*mp)
926{
927	struct xfs_ail	*ailp;
928
929	ailp = kzalloc(sizeof(struct xfs_ail),
930			GFP_KERNEL | __GFP_RETRY_MAYFAIL);
931	if (!ailp)
932		return -ENOMEM;
933
934	ailp->ail_log = mp->m_log;
935	INIT_LIST_HEAD(&ailp->ail_head);
936	INIT_LIST_HEAD(&ailp->ail_cursors);
937	spin_lock_init(&ailp->ail_lock);
938	INIT_LIST_HEAD(&ailp->ail_buf_list);
939	init_waitqueue_head(&ailp->ail_empty);
940
941	ailp->ail_task = kthread_run(xfsaild, ailp, "xfsaild/%s",
942				mp->m_super->s_id);
943	if (IS_ERR(ailp->ail_task))
944		goto out_free_ailp;
945
946	mp->m_ail = ailp;
947	return 0;
948
949out_free_ailp:
950	kfree(ailp);
951	return -ENOMEM;
952}
953
954void
955xfs_trans_ail_destroy(
956	xfs_mount_t	*mp)
957{
958	struct xfs_ail	*ailp = mp->m_ail;
959
960	kthread_stop(ailp->ail_task);
961	kfree(ailp);
962}