• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
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_types.h"
22 #include "xfs_log.h"
23 #include "xfs_inum.h"
24 #include "xfs_trans.h"
25 #include "xfs_sb.h"
26 #include "xfs_ag.h"
27 #include "xfs_dmapi.h"
28 #include "xfs_mount.h"
29 #include "xfs_trans_priv.h"
30 #include "xfs_error.h"
31 
32 STATIC void xfs_ail_insert(struct xfs_ail *, xfs_log_item_t *);
33 STATIC xfs_log_item_t * xfs_ail_delete(struct xfs_ail *, xfs_log_item_t *);
34 STATIC xfs_log_item_t * xfs_ail_min(struct xfs_ail *);
35 STATIC xfs_log_item_t * xfs_ail_next(struct xfs_ail *, xfs_log_item_t *);
36 
37 #ifdef DEBUG
38 STATIC void xfs_ail_check(struct xfs_ail *, xfs_log_item_t *);
39 #else
40 #define	xfs_ail_check(a,l)
41 #endif /* DEBUG */
42 
43 
44 /*
45  * This is called by the log manager code to determine the LSN
46  * of the tail of the log.  This is exactly the LSN of the first
47  * item in the AIL.  If the AIL is empty, then this function
48  * returns 0.
49  *
50  * We need the AIL lock in order to get a coherent read of the
51  * lsn of the last item in the AIL.
52  */
53 xfs_lsn_t
xfs_trans_ail_tail(struct xfs_ail * ailp)54 xfs_trans_ail_tail(
55 	struct xfs_ail	*ailp)
56 {
57 	xfs_lsn_t	lsn;
58 	xfs_log_item_t	*lip;
59 
60 	spin_lock(&ailp->xa_lock);
61 	lip = xfs_ail_min(ailp);
62 	if (lip == NULL) {
63 		lsn = (xfs_lsn_t)0;
64 	} else {
65 		lsn = lip->li_lsn;
66 	}
67 	spin_unlock(&ailp->xa_lock);
68 
69 	return lsn;
70 }
71 
72 /*
73  * xfs_trans_push_ail
74  *
75  * This routine is called to move the tail of the AIL forward.  It does this by
76  * trying to flush items in the AIL whose lsns are below the given
77  * threshold_lsn.
78  *
79  * the push is run asynchronously in a separate thread, so we return the tail
80  * of the log right now instead of the tail after the push. This means we will
81  * either continue right away, or we will sleep waiting on the async thread to
82  * do it's work.
83  *
84  * We do this unlocked - we only need to know whether there is anything in the
85  * AIL at the time we are called. We don't need to access the contents of
86  * any of the objects, so the lock is not needed.
87  */
88 void
xfs_trans_ail_push(struct xfs_ail * ailp,xfs_lsn_t threshold_lsn)89 xfs_trans_ail_push(
90 	struct xfs_ail	*ailp,
91 	xfs_lsn_t	threshold_lsn)
92 {
93 	xfs_log_item_t	*lip;
94 
95 	lip = xfs_ail_min(ailp);
96 	if (lip && !XFS_FORCED_SHUTDOWN(ailp->xa_mount)) {
97 		if (XFS_LSN_CMP(threshold_lsn, ailp->xa_target) > 0)
98 			xfsaild_wakeup(ailp, threshold_lsn);
99 	}
100 }
101 
102 /*
103  * AIL traversal cursor initialisation.
104  *
105  * The cursor keeps track of where our current traversal is up
106  * to by tracking the next ƣtem in the list for us. However, for
107  * this to be safe, removing an object from the AIL needs to invalidate
108  * any cursor that points to it. hence the traversal cursor needs to
109  * be linked to the struct xfs_ail so that deletion can search all the
110  * active cursors for invalidation.
111  *
112  * We don't link the push cursor because it is embedded in the struct
113  * xfs_ail and hence easily findable.
114  */
115 STATIC void
xfs_trans_ail_cursor_init(struct xfs_ail * ailp,struct xfs_ail_cursor * cur)116 xfs_trans_ail_cursor_init(
117 	struct xfs_ail		*ailp,
118 	struct xfs_ail_cursor	*cur)
119 {
120 	cur->item = NULL;
121 	if (cur == &ailp->xa_cursors)
122 		return;
123 
124 	cur->next = ailp->xa_cursors.next;
125 	ailp->xa_cursors.next = cur;
126 }
127 
128 /*
129  * Set the cursor to the next item, because when we look
130  * up the cursor the current item may have been freed.
131  */
132 STATIC void
xfs_trans_ail_cursor_set(struct xfs_ail * ailp,struct xfs_ail_cursor * cur,struct xfs_log_item * lip)133 xfs_trans_ail_cursor_set(
134 	struct xfs_ail		*ailp,
135 	struct xfs_ail_cursor	*cur,
136 	struct xfs_log_item	*lip)
137 {
138 	if (lip)
139 		cur->item = xfs_ail_next(ailp, lip);
140 }
141 
142 /*
143  * Get the next item in the traversal and advance the cursor.
144  * If the cursor was invalidated (inidicated by a lip of 1),
145  * restart the traversal.
146  */
147 struct xfs_log_item *
xfs_trans_ail_cursor_next(struct xfs_ail * ailp,struct xfs_ail_cursor * cur)148 xfs_trans_ail_cursor_next(
149 	struct xfs_ail		*ailp,
150 	struct xfs_ail_cursor	*cur)
151 {
152 	struct xfs_log_item	*lip = cur->item;
153 
154 	if ((__psint_t)lip & 1)
155 		lip = xfs_ail_min(ailp);
156 	xfs_trans_ail_cursor_set(ailp, cur, lip);
157 	return lip;
158 }
159 
160 /*
161  * Now that the traversal is complete, we need to remove the cursor
162  * from the list of traversing cursors. Avoid removing the embedded
163  * push cursor, but use the fact it is alway present to make the
164  * list deletion simple.
165  */
166 void
xfs_trans_ail_cursor_done(struct xfs_ail * ailp,struct xfs_ail_cursor * done)167 xfs_trans_ail_cursor_done(
168 	struct xfs_ail		*ailp,
169 	struct xfs_ail_cursor	*done)
170 {
171 	struct xfs_ail_cursor	*prev = NULL;
172 	struct xfs_ail_cursor	*cur;
173 
174 	done->item = NULL;
175 	if (done == &ailp->xa_cursors)
176 		return;
177 	prev = &ailp->xa_cursors;
178 	for (cur = prev->next; cur; prev = cur, cur = prev->next) {
179 		if (cur == done) {
180 			prev->next = cur->next;
181 			break;
182 		}
183 	}
184 	ASSERT(cur);
185 }
186 
187 /*
188  * Invalidate any cursor that is pointing to this item. This is
189  * called when an item is removed from the AIL. Any cursor pointing
190  * to this object is now invalid and the traversal needs to be
191  * terminated so it doesn't reference a freed object. We set the
192  * cursor item to a value of 1 so we can distinguish between an
193  * invalidation and the end of the list when getting the next item
194  * from the cursor.
195  */
196 STATIC void
xfs_trans_ail_cursor_clear(struct xfs_ail * ailp,struct xfs_log_item * lip)197 xfs_trans_ail_cursor_clear(
198 	struct xfs_ail		*ailp,
199 	struct xfs_log_item	*lip)
200 {
201 	struct xfs_ail_cursor	*cur;
202 
203 	/* need to search all cursors */
204 	for (cur = &ailp->xa_cursors; cur; cur = cur->next) {
205 		if (cur->item == lip)
206 			cur->item = (struct xfs_log_item *)
207 					((__psint_t)cur->item | 1);
208 	}
209 }
210 
211 /*
212  * Return the item in the AIL with the current lsn.
213  * Return the current tree generation number for use
214  * in calls to xfs_trans_next_ail().
215  */
216 xfs_log_item_t *
xfs_trans_ail_cursor_first(struct xfs_ail * ailp,struct xfs_ail_cursor * cur,xfs_lsn_t lsn)217 xfs_trans_ail_cursor_first(
218 	struct xfs_ail		*ailp,
219 	struct xfs_ail_cursor	*cur,
220 	xfs_lsn_t		lsn)
221 {
222 	xfs_log_item_t		*lip;
223 
224 	xfs_trans_ail_cursor_init(ailp, cur);
225 	lip = xfs_ail_min(ailp);
226 	if (lsn == 0)
227 		goto out;
228 
229 	list_for_each_entry(lip, &ailp->xa_ail, li_ail) {
230 		if (XFS_LSN_CMP(lip->li_lsn, lsn) >= 0)
231 			goto out;
232 	}
233 	lip = NULL;
234 out:
235 	xfs_trans_ail_cursor_set(ailp, cur, lip);
236 	return lip;
237 }
238 
239 /*
240  * Function that does the work of pushing on the AIL
241  */
242 long
xfsaild_push(struct xfs_ail * ailp,xfs_lsn_t * last_lsn)243 xfsaild_push(
244 	struct xfs_ail	*ailp,
245 	xfs_lsn_t	*last_lsn)
246 {
247 	long		tout = 1000; /* milliseconds */
248 	xfs_lsn_t	last_pushed_lsn = *last_lsn;
249 	xfs_lsn_t	target =  ailp->xa_target;
250 	xfs_lsn_t	lsn;
251 	xfs_log_item_t	*lip;
252 	int		flush_log, count, stuck;
253 	xfs_mount_t	*mp = ailp->xa_mount;
254 	struct xfs_ail_cursor	*cur = &ailp->xa_cursors;
255 
256 	spin_lock(&ailp->xa_lock);
257 	xfs_trans_ail_cursor_init(ailp, cur);
258 	lip = xfs_trans_ail_cursor_first(ailp, cur, *last_lsn);
259 	if (!lip || XFS_FORCED_SHUTDOWN(mp)) {
260 		/*
261 		 * AIL is empty or our push has reached the end.
262 		 */
263 		xfs_trans_ail_cursor_done(ailp, cur);
264 		spin_unlock(&ailp->xa_lock);
265 		last_pushed_lsn = 0;
266 		return tout;
267 	}
268 
269 	XFS_STATS_INC(xs_push_ail);
270 
271 	/*
272 	 * While the item we are looking at is below the given threshold
273 	 * try to flush it out. We'd like not to stop until we've at least
274 	 * tried to push on everything in the AIL with an LSN less than
275 	 * the given threshold.
276 	 *
277 	 * However, we will stop after a certain number of pushes and wait
278 	 * for a reduced timeout to fire before pushing further. This
279 	 * prevents use from spinning when we can't do anything or there is
280 	 * lots of contention on the AIL lists.
281 	 */
282 	tout = 10;
283 	lsn = lip->li_lsn;
284 	flush_log = stuck = count = 0;
285 	while ((XFS_LSN_CMP(lip->li_lsn, target) < 0)) {
286 		int	lock_result;
287 		/*
288 		 * If we can lock the item without sleeping, unlock the AIL
289 		 * lock and flush the item.  Then re-grab the AIL lock so we
290 		 * can look for the next item on the AIL. List changes are
291 		 * handled by the AIL lookup functions internally
292 		 *
293 		 * If we can't lock the item, either its holder will flush it
294 		 * or it is already being flushed or it is being relogged.  In
295 		 * any of these case it is being taken care of and we can just
296 		 * skip to the next item in the list.
297 		 */
298 		lock_result = IOP_TRYLOCK(lip);
299 		spin_unlock(&ailp->xa_lock);
300 		switch (lock_result) {
301 		case XFS_ITEM_SUCCESS:
302 			XFS_STATS_INC(xs_push_ail_success);
303 			IOP_PUSH(lip);
304 			last_pushed_lsn = lsn;
305 			break;
306 
307 		case XFS_ITEM_PUSHBUF:
308 			XFS_STATS_INC(xs_push_ail_pushbuf);
309 			IOP_PUSHBUF(lip);
310 			last_pushed_lsn = lsn;
311 			break;
312 
313 		case XFS_ITEM_PINNED:
314 			XFS_STATS_INC(xs_push_ail_pinned);
315 			stuck++;
316 			flush_log = 1;
317 			break;
318 
319 		case XFS_ITEM_LOCKED:
320 			XFS_STATS_INC(xs_push_ail_locked);
321 			last_pushed_lsn = lsn;
322 			stuck++;
323 			break;
324 
325 		case XFS_ITEM_FLUSHING:
326 			XFS_STATS_INC(xs_push_ail_flushing);
327 			last_pushed_lsn = lsn;
328 			stuck++;
329 			break;
330 
331 		default:
332 			ASSERT(0);
333 			break;
334 		}
335 
336 		spin_lock(&ailp->xa_lock);
337 		/* should we bother continuing? */
338 		if (XFS_FORCED_SHUTDOWN(mp))
339 			break;
340 		ASSERT(mp->m_log);
341 
342 		count++;
343 
344 		/*
345 		 * Are there too many items we can't do anything with?
346 		 * If we we are skipping too many items because we can't flush
347 		 * them or they are already being flushed, we back off and
348 		 * given them time to complete whatever operation is being
349 		 * done. i.e. remove pressure from the AIL while we can't make
350 		 * progress so traversals don't slow down further inserts and
351 		 * removals to/from the AIL.
352 		 *
353 		 * The value of 100 is an arbitrary magic number based on
354 		 * observation.
355 		 */
356 		if (stuck > 100)
357 			break;
358 
359 		lip = xfs_trans_ail_cursor_next(ailp, cur);
360 		if (lip == NULL)
361 			break;
362 		lsn = lip->li_lsn;
363 	}
364 	xfs_trans_ail_cursor_done(ailp, cur);
365 	spin_unlock(&ailp->xa_lock);
366 
367 	if (flush_log) {
368 		/*
369 		 * If something we need to push out was pinned, then
370 		 * push out the log so it will become unpinned and
371 		 * move forward in the AIL.
372 		 */
373 		XFS_STATS_INC(xs_push_ail_flush);
374 		xfs_log_force(mp, (xfs_lsn_t)0, XFS_LOG_FORCE);
375 	}
376 
377 	if (!count) {
378 		/* We're past our target or empty, so idle */
379 		tout = 1000;
380 	} else if (XFS_LSN_CMP(lsn, target) >= 0) {
381 		/*
382 		 * We reached the target so wait a bit longer for I/O to
383 		 * complete and remove pushed items from the AIL before we
384 		 * start the next scan from the start of the AIL.
385 		 */
386 		tout += 20;
387 		last_pushed_lsn = 0;
388 	} else if ((stuck * 100) / count > 90) {
389 		/*
390 		 * Either there is a lot of contention on the AIL or we
391 		 * are stuck due to operations in progress. "Stuck" in this
392 		 * case is defined as >90% of the items we tried to push
393 		 * were stuck.
394 		 *
395 		 * Backoff a bit more to allow some I/O to complete before
396 		 * continuing from where we were.
397 		 */
398 		tout += 10;
399 	}
400 	*last_lsn = last_pushed_lsn;
401 	return tout;
402 }	/* xfsaild_push */
403 
404 
405 /*
406  * This is to be called when an item is unlocked that may have
407  * been in the AIL.  It will wake up the first member of the AIL
408  * wait list if this item's unlocking might allow it to progress.
409  * If the item is in the AIL, then we need to get the AIL lock
410  * while doing our checking so we don't race with someone going
411  * to sleep waiting for this event in xfs_trans_push_ail().
412  */
413 void
xfs_trans_unlocked_item(struct xfs_ail * ailp,xfs_log_item_t * lip)414 xfs_trans_unlocked_item(
415 	struct xfs_ail	*ailp,
416 	xfs_log_item_t	*lip)
417 {
418 	xfs_log_item_t	*min_lip;
419 
420 	/*
421 	 * If we're forcibly shutting down, we may have
422 	 * unlocked log items arbitrarily. The last thing
423 	 * we want to do is to move the tail of the log
424 	 * over some potentially valid data.
425 	 */
426 	if (!(lip->li_flags & XFS_LI_IN_AIL) ||
427 	    XFS_FORCED_SHUTDOWN(ailp->xa_mount)) {
428 		return;
429 	}
430 
431 	/*
432 	 * This is the one case where we can call into xfs_ail_min()
433 	 * without holding the AIL lock because we only care about the
434 	 * case where we are at the tail of the AIL.  If the object isn't
435 	 * at the tail, it doesn't matter what result we get back.  This
436 	 * is slightly racy because since we were just unlocked, we could
437 	 * go to sleep between the call to xfs_ail_min and the call to
438 	 * xfs_log_move_tail, have someone else lock us, commit to us disk,
439 	 * move us out of the tail of the AIL, and then we wake up.  However,
440 	 * the call to xfs_log_move_tail() doesn't do anything if there's
441 	 * not enough free space to wake people up so we're safe calling it.
442 	 */
443 	min_lip = xfs_ail_min(ailp);
444 
445 	if (min_lip == lip)
446 		xfs_log_move_tail(ailp->xa_mount, 1);
447 }	/* xfs_trans_unlocked_item */
448 
449 
450 /*
451  * Update the position of the item in the AIL with the new
452  * lsn.  If it is not yet in the AIL, add it.  Otherwise, move
453  * it to its new position by removing it and re-adding it.
454  *
455  * Wakeup anyone with an lsn less than the item's lsn.  If the item
456  * we move in the AIL is the minimum one, update the tail lsn in the
457  * log manager.
458  *
459  * This function must be called with the AIL lock held.  The lock
460  * is dropped before returning.
461  */
462 void
xfs_trans_ail_update(struct xfs_ail * ailp,xfs_log_item_t * lip,xfs_lsn_t lsn)463 xfs_trans_ail_update(
464 	struct xfs_ail	*ailp,
465 	xfs_log_item_t	*lip,
466 	xfs_lsn_t	lsn) __releases(ailp->xa_lock)
467 {
468 	xfs_log_item_t		*dlip = NULL;
469 	xfs_log_item_t		*mlip;	/* ptr to minimum lip */
470 
471 	mlip = xfs_ail_min(ailp);
472 
473 	if (lip->li_flags & XFS_LI_IN_AIL) {
474 		dlip = xfs_ail_delete(ailp, lip);
475 		ASSERT(dlip == lip);
476 		xfs_trans_ail_cursor_clear(ailp, dlip);
477 	} else {
478 		lip->li_flags |= XFS_LI_IN_AIL;
479 	}
480 
481 	lip->li_lsn = lsn;
482 	xfs_ail_insert(ailp, lip);
483 
484 	if (mlip == dlip) {
485 		mlip = xfs_ail_min(ailp);
486 		spin_unlock(&ailp->xa_lock);
487 		xfs_log_move_tail(ailp->xa_mount, mlip->li_lsn);
488 	} else {
489 		spin_unlock(&ailp->xa_lock);
490 	}
491 
492 
493 }	/* xfs_trans_update_ail */
494 
495 /*
496  * Delete the given item from the AIL.  It must already be in
497  * the AIL.
498  *
499  * Wakeup anyone with an lsn less than item's lsn.    If the item
500  * we delete in the AIL is the minimum one, update the tail lsn in the
501  * log manager.
502  *
503  * Clear the IN_AIL flag from the item, reset its lsn to 0, and
504  * bump the AIL's generation count to indicate that the tree
505  * has changed.
506  *
507  * This function must be called with the AIL lock held.  The lock
508  * is dropped before returning.
509  */
510 void
xfs_trans_ail_delete(struct xfs_ail * ailp,xfs_log_item_t * lip)511 xfs_trans_ail_delete(
512 	struct xfs_ail	*ailp,
513 	xfs_log_item_t	*lip) __releases(ailp->xa_lock)
514 {
515 	xfs_log_item_t		*dlip;
516 	xfs_log_item_t		*mlip;
517 
518 	if (lip->li_flags & XFS_LI_IN_AIL) {
519 		mlip = xfs_ail_min(ailp);
520 		dlip = xfs_ail_delete(ailp, lip);
521 		ASSERT(dlip == lip);
522 		xfs_trans_ail_cursor_clear(ailp, dlip);
523 
524 
525 		lip->li_flags &= ~XFS_LI_IN_AIL;
526 		lip->li_lsn = 0;
527 
528 		if (mlip == dlip) {
529 			mlip = xfs_ail_min(ailp);
530 			spin_unlock(&ailp->xa_lock);
531 			xfs_log_move_tail(ailp->xa_mount,
532 						(mlip ? mlip->li_lsn : 0));
533 		} else {
534 			spin_unlock(&ailp->xa_lock);
535 		}
536 	}
537 	else {
538 		/*
539 		 * If the file system is not being shutdown, we are in
540 		 * serious trouble if we get to this stage.
541 		 */
542 		struct xfs_mount	*mp = ailp->xa_mount;
543 
544 		spin_unlock(&ailp->xa_lock);
545 		if (!XFS_FORCED_SHUTDOWN(mp)) {
546 			xfs_cmn_err(XFS_PTAG_AILDELETE, CE_ALERT, mp,
547 		"%s: attempting to delete a log item that is not in the AIL",
548 					__func__);
549 			xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
550 		}
551 	}
552 }
553 
554 
555 
556 /*
557  * The active item list (AIL) is a doubly linked list of log
558  * items sorted by ascending lsn.  The base of the list is
559  * a forw/back pointer pair embedded in the xfs mount structure.
560  * The base is initialized with both pointers pointing to the
561  * base.  This case always needs to be distinguished, because
562  * the base has no lsn to look at.  We almost always insert
563  * at the end of the list, so on inserts we search from the
564  * end of the list to find where the new item belongs.
565  */
566 
567 /*
568  * Initialize the doubly linked list to point only to itself.
569  */
570 int
xfs_trans_ail_init(xfs_mount_t * mp)571 xfs_trans_ail_init(
572 	xfs_mount_t	*mp)
573 {
574 	struct xfs_ail	*ailp;
575 	int		error;
576 
577 	ailp = kmem_zalloc(sizeof(struct xfs_ail), KM_MAYFAIL);
578 	if (!ailp)
579 		return ENOMEM;
580 
581 	ailp->xa_mount = mp;
582 	INIT_LIST_HEAD(&ailp->xa_ail);
583 	spin_lock_init(&ailp->xa_lock);
584 	error = xfsaild_start(ailp);
585 	if (error)
586 		goto out_free_ailp;
587 	mp->m_ail = ailp;
588 	return 0;
589 
590 out_free_ailp:
591 	kmem_free(ailp);
592 	return error;
593 }
594 
595 void
xfs_trans_ail_destroy(xfs_mount_t * mp)596 xfs_trans_ail_destroy(
597 	xfs_mount_t	*mp)
598 {
599 	struct xfs_ail	*ailp = mp->m_ail;
600 
601 	xfsaild_stop(ailp);
602 	kmem_free(ailp);
603 }
604 
605 /*
606  * Insert the given log item into the AIL.
607  * We almost always insert at the end of the list, so on inserts
608  * we search from the end of the list to find where the
609  * new item belongs.
610  */
611 STATIC void
xfs_ail_insert(struct xfs_ail * ailp,xfs_log_item_t * lip)612 xfs_ail_insert(
613 	struct xfs_ail	*ailp,
614 	xfs_log_item_t	*lip)
615 /* ARGSUSED */
616 {
617 	xfs_log_item_t	*next_lip;
618 
619 	/*
620 	 * If the list is empty, just insert the item.
621 	 */
622 	if (list_empty(&ailp->xa_ail)) {
623 		list_add(&lip->li_ail, &ailp->xa_ail);
624 		return;
625 	}
626 
627 	list_for_each_entry_reverse(next_lip, &ailp->xa_ail, li_ail) {
628 		if (XFS_LSN_CMP(next_lip->li_lsn, lip->li_lsn) <= 0)
629 			break;
630 	}
631 
632 	ASSERT((&next_lip->li_ail == &ailp->xa_ail) ||
633 	       (XFS_LSN_CMP(next_lip->li_lsn, lip->li_lsn) <= 0));
634 
635 	list_add(&lip->li_ail, &next_lip->li_ail);
636 
637 	xfs_ail_check(ailp, lip);
638 	return;
639 }
640 
641 /*
642  * Delete the given item from the AIL.  Return a pointer to the item.
643  */
644 /*ARGSUSED*/
645 STATIC xfs_log_item_t *
xfs_ail_delete(struct xfs_ail * ailp,xfs_log_item_t * lip)646 xfs_ail_delete(
647 	struct xfs_ail	*ailp,
648 	xfs_log_item_t	*lip)
649 /* ARGSUSED */
650 {
651 	xfs_ail_check(ailp, lip);
652 
653 	list_del(&lip->li_ail);
654 
655 	return lip;
656 }
657 
658 /*
659  * Return a pointer to the first item in the AIL.
660  * If the AIL is empty, then return NULL.
661  */
662 STATIC xfs_log_item_t *
xfs_ail_min(struct xfs_ail * ailp)663 xfs_ail_min(
664 	struct xfs_ail	*ailp)
665 /* ARGSUSED */
666 {
667 	if (list_empty(&ailp->xa_ail))
668 		return NULL;
669 
670 	return list_first_entry(&ailp->xa_ail, xfs_log_item_t, li_ail);
671 }
672 
673 /*
674  * Return a pointer to the item which follows
675  * the given item in the AIL.  If the given item
676  * is the last item in the list, then return NULL.
677  */
678 STATIC xfs_log_item_t *
xfs_ail_next(struct xfs_ail * ailp,xfs_log_item_t * lip)679 xfs_ail_next(
680 	struct xfs_ail	*ailp,
681 	xfs_log_item_t	*lip)
682 /* ARGSUSED */
683 {
684 	if (lip->li_ail.next == &ailp->xa_ail)
685 		return NULL;
686 
687 	return list_first_entry(&lip->li_ail, xfs_log_item_t, li_ail);
688 }
689 
690 #ifdef DEBUG
691 /*
692  * Check that the list is sorted as it should be.
693  */
694 STATIC void
xfs_ail_check(struct xfs_ail * ailp,xfs_log_item_t * lip)695 xfs_ail_check(
696 	struct xfs_ail	*ailp,
697 	xfs_log_item_t	*lip)
698 {
699 	xfs_log_item_t	*prev_lip;
700 
701 	if (list_empty(&ailp->xa_ail))
702 		return;
703 
704 	/*
705 	 * Check the next and previous entries are valid.
706 	 */
707 	ASSERT((lip->li_flags & XFS_LI_IN_AIL) != 0);
708 	prev_lip = list_entry(lip->li_ail.prev, xfs_log_item_t, li_ail);
709 	if (&prev_lip->li_ail != &ailp->xa_ail)
710 		ASSERT(XFS_LSN_CMP(prev_lip->li_lsn, lip->li_lsn) <= 0);
711 
712 	prev_lip = list_entry(lip->li_ail.next, xfs_log_item_t, li_ail);
713 	if (&prev_lip->li_ail != &ailp->xa_ail)
714 		ASSERT(XFS_LSN_CMP(prev_lip->li_lsn, lip->li_lsn) >= 0);
715 
716 
717 #ifdef XFS_TRANS_DEBUG
718 	/*
719 	 * Walk the list checking lsn ordering, and that every entry has the
720 	 * XFS_LI_IN_AIL flag set. This is really expensive, so only do it
721 	 * when specifically debugging the transaction subsystem.
722 	 */
723 	prev_lip = list_entry(&ailp->xa_ail, xfs_log_item_t, li_ail);
724 	list_for_each_entry(lip, &ailp->xa_ail, li_ail) {
725 		if (&prev_lip->li_ail != &ailp->xa_ail)
726 			ASSERT(XFS_LSN_CMP(prev_lip->li_lsn, lip->li_lsn) <= 0);
727 		ASSERT((lip->li_flags & XFS_LI_IN_AIL) != 0);
728 		prev_lip = lip;
729 	}
730 #endif /* XFS_TRANS_DEBUG */
731 }
732 #endif /* DEBUG */
733