davinci: cp_intc: provide set_wake function
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / fs / xfs / xfs_trans_ail.c
blob2ffc570679bef017199f59fafa64b9e9c9433797
1 /*
2 * Copyright (c) 2000-2002,2005 Silicon Graphics, Inc.
3 * Copyright (c) 2008 Dave Chinner
4 * All Rights Reserved.
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.
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.
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
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"
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 *);
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 */
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.
50 * We need the AIL lock in order to get a coherent read of the
51 * lsn of the last item in the AIL.
53 xfs_lsn_t
54 xfs_trans_ail_tail(
55 struct xfs_ail *ailp)
57 xfs_lsn_t lsn;
58 xfs_log_item_t *lip;
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;
67 spin_unlock(&ailp->xa_lock);
69 return lsn;
73 * xfs_trans_push_ail
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.
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 its work.
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.
88 void
89 xfs_trans_ail_push(
90 struct xfs_ail *ailp,
91 xfs_lsn_t threshold_lsn)
93 xfs_log_item_t *lip;
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);
103 * AIL traversal cursor initialisation.
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.
112 * We don't link the push cursor because it is embedded in the struct
113 * xfs_ail and hence easily findable.
115 STATIC void
116 xfs_trans_ail_cursor_init(
117 struct xfs_ail *ailp,
118 struct xfs_ail_cursor *cur)
120 cur->item = NULL;
121 if (cur == &ailp->xa_cursors)
122 return;
124 cur->next = ailp->xa_cursors.next;
125 ailp->xa_cursors.next = cur;
129 * Set the cursor to the next item, because when we look
130 * up the cursor the current item may have been freed.
132 STATIC void
133 xfs_trans_ail_cursor_set(
134 struct xfs_ail *ailp,
135 struct xfs_ail_cursor *cur,
136 struct xfs_log_item *lip)
138 if (lip)
139 cur->item = xfs_ail_next(ailp, lip);
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.
147 struct xfs_log_item *
148 xfs_trans_ail_cursor_next(
149 struct xfs_ail *ailp,
150 struct xfs_ail_cursor *cur)
152 struct xfs_log_item *lip = cur->item;
154 if ((__psint_t)lip & 1)
155 lip = xfs_ail_min(ailp);
156 xfs_trans_ail_cursor_set(ailp, cur, lip);
157 return lip;
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 always present to make the
164 * list deletion simple.
166 void
167 xfs_trans_ail_cursor_done(
168 struct xfs_ail *ailp,
169 struct xfs_ail_cursor *done)
171 struct xfs_ail_cursor *prev = NULL;
172 struct xfs_ail_cursor *cur;
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;
184 ASSERT(cur);
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.
196 STATIC void
197 xfs_trans_ail_cursor_clear(
198 struct xfs_ail *ailp,
199 struct xfs_log_item *lip)
201 struct xfs_ail_cursor *cur;
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);
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().
216 xfs_log_item_t *
217 xfs_trans_ail_cursor_first(
218 struct xfs_ail *ailp,
219 struct xfs_ail_cursor *cur,
220 xfs_lsn_t lsn)
222 xfs_log_item_t *lip;
224 xfs_trans_ail_cursor_init(ailp, cur);
225 lip = xfs_ail_min(ailp);
226 if (lsn == 0)
227 goto out;
229 list_for_each_entry(lip, &ailp->xa_ail, li_ail) {
230 if (XFS_LSN_CMP(lip->li_lsn, lsn) >= 0)
231 goto out;
233 lip = NULL;
234 out:
235 xfs_trans_ail_cursor_set(ailp, cur, lip);
236 return lip;
240 * Function that does the work of pushing on the AIL
242 long
243 xfsaild_push(
244 struct xfs_ail *ailp,
245 xfs_lsn_t *last_lsn)
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;
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)) {
261 * AIL is empty or our push has reached the end.
263 xfs_trans_ail_cursor_done(ailp, cur);
264 spin_unlock(&ailp->xa_lock);
265 last_pushed_lsn = 0;
266 return tout;
269 XFS_STATS_INC(xs_push_ail);
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.
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.
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;
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
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.
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;
307 case XFS_ITEM_PUSHBUF:
308 XFS_STATS_INC(xs_push_ail_pushbuf);
309 IOP_PUSHBUF(lip);
310 last_pushed_lsn = lsn;
311 break;
313 case XFS_ITEM_PINNED:
314 XFS_STATS_INC(xs_push_ail_pinned);
315 stuck++;
316 flush_log = 1;
317 break;
319 case XFS_ITEM_LOCKED:
320 XFS_STATS_INC(xs_push_ail_locked);
321 last_pushed_lsn = lsn;
322 stuck++;
323 break;
325 case XFS_ITEM_FLUSHING:
326 XFS_STATS_INC(xs_push_ail_flushing);
327 last_pushed_lsn = lsn;
328 stuck++;
329 break;
331 default:
332 ASSERT(0);
333 break;
336 spin_lock(&ailp->xa_lock);
337 /* should we bother continuing? */
338 if (XFS_FORCED_SHUTDOWN(mp))
339 break;
340 ASSERT(mp->m_log);
342 count++;
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.
353 * The value of 100 is an arbitrary magic number based on
354 * observation.
356 if (stuck > 100)
357 break;
359 lip = xfs_trans_ail_cursor_next(ailp, cur);
360 if (lip == NULL)
361 break;
362 lsn = lip->li_lsn;
364 xfs_trans_ail_cursor_done(ailp, cur);
365 spin_unlock(&ailp->xa_lock);
367 if (flush_log) {
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.
373 XFS_STATS_INC(xs_push_ail_flush);
374 xfs_log_force(mp, (xfs_lsn_t)0, XFS_LOG_FORCE);
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) {
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.
386 tout += 20;
387 last_pushed_lsn = 0;
388 } else if ((stuck * 100) / count > 90) {
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.
395 * Backoff a bit more to allow some I/O to complete before
396 * continuing from where we were.
398 tout += 10;
400 *last_lsn = last_pushed_lsn;
401 return tout;
402 } /* xfsaild_push */
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().
413 void
414 xfs_trans_unlocked_item(
415 struct xfs_ail *ailp,
416 xfs_log_item_t *lip)
418 xfs_log_item_t *min_lip;
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.
426 if (!(lip->li_flags & XFS_LI_IN_AIL) ||
427 XFS_FORCED_SHUTDOWN(ailp->xa_mount)) {
428 return;
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.
443 min_lip = xfs_ail_min(ailp);
445 if (min_lip == lip)
446 xfs_log_move_tail(ailp->xa_mount, 1);
447 } /* xfs_trans_unlocked_item */
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.
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.
459 * This function must be called with the AIL lock held. The lock
460 * is dropped before returning.
462 void
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)
468 xfs_log_item_t *dlip = NULL;
469 xfs_log_item_t *mlip; /* ptr to minimum lip */
470 xfs_lsn_t tail_lsn;
472 mlip = xfs_ail_min(ailp);
474 if (lip->li_flags & XFS_LI_IN_AIL) {
475 dlip = xfs_ail_delete(ailp, lip);
476 ASSERT(dlip == lip);
477 xfs_trans_ail_cursor_clear(ailp, dlip);
478 } else {
479 lip->li_flags |= XFS_LI_IN_AIL;
482 lip->li_lsn = lsn;
483 xfs_ail_insert(ailp, lip);
485 if (mlip == dlip) {
486 mlip = xfs_ail_min(ailp);
488 * It is not safe to access mlip after the AIL lock is
489 * dropped, so we must get a copy of li_lsn before we do
490 * so. This is especially important on 32-bit platforms
491 * where accessing and updating 64-bit values like li_lsn
492 * is not atomic.
494 tail_lsn = mlip->li_lsn;
495 spin_unlock(&ailp->xa_lock);
496 xfs_log_move_tail(ailp->xa_mount, tail_lsn);
497 } else {
498 spin_unlock(&ailp->xa_lock);
502 } /* xfs_trans_update_ail */
505 * Delete the given item from the AIL. It must already be in
506 * the AIL.
508 * Wakeup anyone with an lsn less than item's lsn. If the item
509 * we delete in the AIL is the minimum one, update the tail lsn in the
510 * log manager.
512 * Clear the IN_AIL flag from the item, reset its lsn to 0, and
513 * bump the AIL's generation count to indicate that the tree
514 * has changed.
516 * This function must be called with the AIL lock held. The lock
517 * is dropped before returning.
519 void
520 xfs_trans_ail_delete(
521 struct xfs_ail *ailp,
522 xfs_log_item_t *lip) __releases(ailp->xa_lock)
524 xfs_log_item_t *dlip;
525 xfs_log_item_t *mlip;
526 xfs_lsn_t tail_lsn;
528 if (lip->li_flags & XFS_LI_IN_AIL) {
529 mlip = xfs_ail_min(ailp);
530 dlip = xfs_ail_delete(ailp, lip);
531 ASSERT(dlip == lip);
532 xfs_trans_ail_cursor_clear(ailp, dlip);
535 lip->li_flags &= ~XFS_LI_IN_AIL;
536 lip->li_lsn = 0;
538 if (mlip == dlip) {
539 mlip = xfs_ail_min(ailp);
541 * It is not safe to access mlip after the AIL lock
542 * is dropped, so we must get a copy of li_lsn
543 * before we do so. This is especially important
544 * on 32-bit platforms where accessing and updating
545 * 64-bit values like li_lsn is not atomic.
547 tail_lsn = mlip ? mlip->li_lsn : 0;
548 spin_unlock(&ailp->xa_lock);
549 xfs_log_move_tail(ailp->xa_mount, tail_lsn);
550 } else {
551 spin_unlock(&ailp->xa_lock);
554 else {
556 * If the file system is not being shutdown, we are in
557 * serious trouble if we get to this stage.
559 struct xfs_mount *mp = ailp->xa_mount;
561 spin_unlock(&ailp->xa_lock);
562 if (!XFS_FORCED_SHUTDOWN(mp)) {
563 xfs_cmn_err(XFS_PTAG_AILDELETE, CE_ALERT, mp,
564 "%s: attempting to delete a log item that is not in the AIL",
565 __func__);
566 xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
574 * The active item list (AIL) is a doubly linked list of log
575 * items sorted by ascending lsn. The base of the list is
576 * a forw/back pointer pair embedded in the xfs mount structure.
577 * The base is initialized with both pointers pointing to the
578 * base. This case always needs to be distinguished, because
579 * the base has no lsn to look at. We almost always insert
580 * at the end of the list, so on inserts we search from the
581 * end of the list to find where the new item belongs.
585 * Initialize the doubly linked list to point only to itself.
588 xfs_trans_ail_init(
589 xfs_mount_t *mp)
591 struct xfs_ail *ailp;
592 int error;
594 ailp = kmem_zalloc(sizeof(struct xfs_ail), KM_MAYFAIL);
595 if (!ailp)
596 return ENOMEM;
598 ailp->xa_mount = mp;
599 INIT_LIST_HEAD(&ailp->xa_ail);
600 spin_lock_init(&ailp->xa_lock);
601 error = xfsaild_start(ailp);
602 if (error)
603 goto out_free_ailp;
604 mp->m_ail = ailp;
605 return 0;
607 out_free_ailp:
608 kmem_free(ailp);
609 return error;
612 void
613 xfs_trans_ail_destroy(
614 xfs_mount_t *mp)
616 struct xfs_ail *ailp = mp->m_ail;
618 xfsaild_stop(ailp);
619 kmem_free(ailp);
623 * Insert the given log item into the AIL.
624 * We almost always insert at the end of the list, so on inserts
625 * we search from the end of the list to find where the
626 * new item belongs.
628 STATIC void
629 xfs_ail_insert(
630 struct xfs_ail *ailp,
631 xfs_log_item_t *lip)
632 /* ARGSUSED */
634 xfs_log_item_t *next_lip;
637 * If the list is empty, just insert the item.
639 if (list_empty(&ailp->xa_ail)) {
640 list_add(&lip->li_ail, &ailp->xa_ail);
641 return;
644 list_for_each_entry_reverse(next_lip, &ailp->xa_ail, li_ail) {
645 if (XFS_LSN_CMP(next_lip->li_lsn, lip->li_lsn) <= 0)
646 break;
649 ASSERT((&next_lip->li_ail == &ailp->xa_ail) ||
650 (XFS_LSN_CMP(next_lip->li_lsn, lip->li_lsn) <= 0));
652 list_add(&lip->li_ail, &next_lip->li_ail);
654 xfs_ail_check(ailp, lip);
655 return;
659 * Delete the given item from the AIL. Return a pointer to the item.
661 /*ARGSUSED*/
662 STATIC xfs_log_item_t *
663 xfs_ail_delete(
664 struct xfs_ail *ailp,
665 xfs_log_item_t *lip)
666 /* ARGSUSED */
668 xfs_ail_check(ailp, lip);
670 list_del(&lip->li_ail);
672 return lip;
676 * Return a pointer to the first item in the AIL.
677 * If the AIL is empty, then return NULL.
679 STATIC xfs_log_item_t *
680 xfs_ail_min(
681 struct xfs_ail *ailp)
682 /* ARGSUSED */
684 if (list_empty(&ailp->xa_ail))
685 return NULL;
687 return list_first_entry(&ailp->xa_ail, xfs_log_item_t, li_ail);
691 * Return a pointer to the item which follows
692 * the given item in the AIL. If the given item
693 * is the last item in the list, then return NULL.
695 STATIC xfs_log_item_t *
696 xfs_ail_next(
697 struct xfs_ail *ailp,
698 xfs_log_item_t *lip)
699 /* ARGSUSED */
701 if (lip->li_ail.next == &ailp->xa_ail)
702 return NULL;
704 return list_first_entry(&lip->li_ail, xfs_log_item_t, li_ail);
707 #ifdef DEBUG
709 * Check that the list is sorted as it should be.
711 STATIC void
712 xfs_ail_check(
713 struct xfs_ail *ailp,
714 xfs_log_item_t *lip)
716 xfs_log_item_t *prev_lip;
718 if (list_empty(&ailp->xa_ail))
719 return;
722 * Check the next and previous entries are valid.
724 ASSERT((lip->li_flags & XFS_LI_IN_AIL) != 0);
725 prev_lip = list_entry(lip->li_ail.prev, xfs_log_item_t, li_ail);
726 if (&prev_lip->li_ail != &ailp->xa_ail)
727 ASSERT(XFS_LSN_CMP(prev_lip->li_lsn, lip->li_lsn) <= 0);
729 prev_lip = list_entry(lip->li_ail.next, xfs_log_item_t, li_ail);
730 if (&prev_lip->li_ail != &ailp->xa_ail)
731 ASSERT(XFS_LSN_CMP(prev_lip->li_lsn, lip->li_lsn) >= 0);
734 #ifdef XFS_TRANS_DEBUG
736 * Walk the list checking lsn ordering, and that every entry has the
737 * XFS_LI_IN_AIL flag set. This is really expensive, so only do it
738 * when specifically debugging the transaction subsystem.
740 prev_lip = list_entry(&ailp->xa_ail, xfs_log_item_t, li_ail);
741 list_for_each_entry(lip, &ailp->xa_ail, li_ail) {
742 if (&prev_lip->li_ail != &ailp->xa_ail)
743 ASSERT(XFS_LSN_CMP(prev_lip->li_lsn, lip->li_lsn) <= 0);
744 ASSERT((lip->li_flags & XFS_LI_IN_AIL) != 0);
745 prev_lip = lip;
747 #endif /* XFS_TRANS_DEBUG */
749 #endif /* DEBUG */