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}