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xfs: use a cursor for bulk AIL insertion
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1da177e4 1/*
7b718769 2 * Copyright (c) 2000-2002,2005 Silicon Graphics, Inc.
c7e8f268 3 * Copyright (c) 2008 Dave Chinner
7b718769 4 * All Rights Reserved.
1da177e4 5 *
7b718769
NS
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
1da177e4
LT
8 * published by the Free Software Foundation.
9 *
7b718769
NS
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.
1da177e4 14 *
7b718769
NS
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
1da177e4 18 */
1da177e4 19#include "xfs.h"
a844f451 20#include "xfs_fs.h"
1da177e4 21#include "xfs_types.h"
1da177e4 22#include "xfs_log.h"
a844f451 23#include "xfs_inum.h"
1da177e4
LT
24#include "xfs_trans.h"
25#include "xfs_sb.h"
da353b0d 26#include "xfs_ag.h"
1da177e4
LT
27#include "xfs_mount.h"
28#include "xfs_trans_priv.h"
29#include "xfs_error.h"
30
0bf6a5bd
DC
31struct workqueue_struct *xfs_ail_wq; /* AIL workqueue */
32
1da177e4 33#ifdef DEBUG
cd4a3c50
DC
34/*
35 * Check that the list is sorted as it should be.
36 */
37STATIC void
38xfs_ail_check(
39 struct xfs_ail *ailp,
40 xfs_log_item_t *lip)
41{
42 xfs_log_item_t *prev_lip;
43
44 if (list_empty(&ailp->xa_ail))
45 return;
46
47 /*
48 * Check the next and previous entries are valid.
49 */
50 ASSERT((lip->li_flags & XFS_LI_IN_AIL) != 0);
51 prev_lip = list_entry(lip->li_ail.prev, xfs_log_item_t, li_ail);
52 if (&prev_lip->li_ail != &ailp->xa_ail)
53 ASSERT(XFS_LSN_CMP(prev_lip->li_lsn, lip->li_lsn) <= 0);
54
55 prev_lip = list_entry(lip->li_ail.next, xfs_log_item_t, li_ail);
56 if (&prev_lip->li_ail != &ailp->xa_ail)
57 ASSERT(XFS_LSN_CMP(prev_lip->li_lsn, lip->li_lsn) >= 0);
58
59
60#ifdef XFS_TRANS_DEBUG
61 /*
62 * Walk the list checking lsn ordering, and that every entry has the
63 * XFS_LI_IN_AIL flag set. This is really expensive, so only do it
64 * when specifically debugging the transaction subsystem.
65 */
66 prev_lip = list_entry(&ailp->xa_ail, xfs_log_item_t, li_ail);
67 list_for_each_entry(lip, &ailp->xa_ail, li_ail) {
68 if (&prev_lip->li_ail != &ailp->xa_ail)
69 ASSERT(XFS_LSN_CMP(prev_lip->li_lsn, lip->li_lsn) <= 0);
70 ASSERT((lip->li_flags & XFS_LI_IN_AIL) != 0);
71 prev_lip = lip;
72 }
73#endif /* XFS_TRANS_DEBUG */
74}
75#else /* !DEBUG */
de08dbc1 76#define xfs_ail_check(a,l)
1da177e4
LT
77#endif /* DEBUG */
78
cd4a3c50
DC
79/*
80 * Return a pointer to the first item in the AIL. If the AIL is empty, then
81 * return NULL.
82 */
83static xfs_log_item_t *
84xfs_ail_min(
85 struct xfs_ail *ailp)
86{
87 if (list_empty(&ailp->xa_ail))
88 return NULL;
89
90 return list_first_entry(&ailp->xa_ail, xfs_log_item_t, li_ail);
91}
92
fd074841
DC
93 /*
94 * Return a pointer to the last item in the AIL. If the AIL is empty, then
95 * return NULL.
96 */
97static xfs_log_item_t *
98xfs_ail_max(
99 struct xfs_ail *ailp)
100{
101 if (list_empty(&ailp->xa_ail))
102 return NULL;
103
104 return list_entry(ailp->xa_ail.prev, xfs_log_item_t, li_ail);
105}
106
cd4a3c50
DC
107/*
108 * Return a pointer to the item which follows the given item in the AIL. If
109 * the given item is the last item in the list, then return NULL.
110 */
111static xfs_log_item_t *
112xfs_ail_next(
113 struct xfs_ail *ailp,
114 xfs_log_item_t *lip)
115{
116 if (lip->li_ail.next == &ailp->xa_ail)
117 return NULL;
118
119 return list_first_entry(&lip->li_ail, xfs_log_item_t, li_ail);
120}
1da177e4
LT
121
122/*
cd4a3c50
DC
123 * This is called by the log manager code to determine the LSN of the tail of
124 * the log. This is exactly the LSN of the first item in the AIL. If the AIL
125 * is empty, then this function returns 0.
1da177e4 126 *
cd4a3c50
DC
127 * We need the AIL lock in order to get a coherent read of the lsn of the last
128 * item in the AIL.
1da177e4
LT
129 */
130xfs_lsn_t
fd074841 131xfs_ail_min_lsn(
5b00f14f 132 struct xfs_ail *ailp)
1da177e4 133{
cd4a3c50 134 xfs_lsn_t lsn = 0;
1da177e4 135 xfs_log_item_t *lip;
1da177e4 136
c7e8f268 137 spin_lock(&ailp->xa_lock);
5b00f14f 138 lip = xfs_ail_min(ailp);
cd4a3c50 139 if (lip)
1da177e4 140 lsn = lip->li_lsn;
c7e8f268 141 spin_unlock(&ailp->xa_lock);
1da177e4
LT
142
143 return lsn;
144}
145
fd074841
DC
146/*
147 * Return the maximum lsn held in the AIL, or zero if the AIL is empty.
148 */
149static xfs_lsn_t
150xfs_ail_max_lsn(
151 struct xfs_ail *ailp)
152{
153 xfs_lsn_t lsn = 0;
154 xfs_log_item_t *lip;
155
156 spin_lock(&ailp->xa_lock);
157 lip = xfs_ail_max(ailp);
158 if (lip)
159 lsn = lip->li_lsn;
160 spin_unlock(&ailp->xa_lock);
161
162 return lsn;
163}
164
27d8d5fe
DC
165/*
166 * AIL traversal cursor initialisation.
167 *
168 * The cursor keeps track of where our current traversal is up
169 * to by tracking the next ƣtem in the list for us. However, for
170 * this to be safe, removing an object from the AIL needs to invalidate
171 * any cursor that points to it. hence the traversal cursor needs to
172 * be linked to the struct xfs_ail so that deletion can search all the
173 * active cursors for invalidation.
174 *
175 * We don't link the push cursor because it is embedded in the struct
176 * xfs_ail and hence easily findable.
177 */
5b00f14f 178STATIC void
27d8d5fe
DC
179xfs_trans_ail_cursor_init(
180 struct xfs_ail *ailp,
181 struct xfs_ail_cursor *cur)
182{
183 cur->item = NULL;
184 if (cur == &ailp->xa_cursors)
185 return;
186
187 cur->next = ailp->xa_cursors.next;
188 ailp->xa_cursors.next = cur;
189}
190
191/*
192 * Set the cursor to the next item, because when we look
193 * up the cursor the current item may have been freed.
194 */
195STATIC void
196xfs_trans_ail_cursor_set(
197 struct xfs_ail *ailp,
198 struct xfs_ail_cursor *cur,
199 struct xfs_log_item *lip)
200{
201 if (lip)
202 cur->item = xfs_ail_next(ailp, lip);
203}
204
205/*
206 * Get the next item in the traversal and advance the cursor.
207 * If the cursor was invalidated (inidicated by a lip of 1),
208 * restart the traversal.
209 */
5b00f14f 210struct xfs_log_item *
27d8d5fe
DC
211xfs_trans_ail_cursor_next(
212 struct xfs_ail *ailp,
213 struct xfs_ail_cursor *cur)
214{
215 struct xfs_log_item *lip = cur->item;
216
217 if ((__psint_t)lip & 1)
218 lip = xfs_ail_min(ailp);
219 xfs_trans_ail_cursor_set(ailp, cur, lip);
220 return lip;
221}
222
27d8d5fe
DC
223/*
224 * Now that the traversal is complete, we need to remove the cursor
225 * from the list of traversing cursors. Avoid removing the embedded
9da096fd 226 * push cursor, but use the fact it is always present to make the
27d8d5fe
DC
227 * list deletion simple.
228 */
229void
230xfs_trans_ail_cursor_done(
231 struct xfs_ail *ailp,
232 struct xfs_ail_cursor *done)
233{
234 struct xfs_ail_cursor *prev = NULL;
235 struct xfs_ail_cursor *cur;
236
237 done->item = NULL;
238 if (done == &ailp->xa_cursors)
239 return;
240 prev = &ailp->xa_cursors;
241 for (cur = prev->next; cur; prev = cur, cur = prev->next) {
242 if (cur == done) {
243 prev->next = cur->next;
244 break;
245 }
246 }
247 ASSERT(cur);
248}
249
5b00f14f
DC
250/*
251 * Invalidate any cursor that is pointing to this item. This is
252 * called when an item is removed from the AIL. Any cursor pointing
253 * to this object is now invalid and the traversal needs to be
254 * terminated so it doesn't reference a freed object. We set the
255 * cursor item to a value of 1 so we can distinguish between an
256 * invalidation and the end of the list when getting the next item
257 * from the cursor.
258 */
259STATIC void
260xfs_trans_ail_cursor_clear(
261 struct xfs_ail *ailp,
262 struct xfs_log_item *lip)
263{
264 struct xfs_ail_cursor *cur;
265
266 /* need to search all cursors */
267 for (cur = &ailp->xa_cursors; cur; cur = cur->next) {
268 if (cur->item == lip)
269 cur->item = (struct xfs_log_item *)
270 ((__psint_t)cur->item | 1);
271 }
272}
273
249a8c11 274/*
1d8c95a3
DC
275 * Initialise the cursor to the first item in the AIL with the given @lsn.
276 * This searches the list from lowest LSN to highest. Pass a @lsn of zero
277 * to initialise the cursor to the first item in the AIL.
249a8c11 278 */
5b00f14f
DC
279xfs_log_item_t *
280xfs_trans_ail_cursor_first(
27d8d5fe
DC
281 struct xfs_ail *ailp,
282 struct xfs_ail_cursor *cur,
283 xfs_lsn_t lsn)
249a8c11 284{
27d8d5fe 285 xfs_log_item_t *lip;
249a8c11 286
5b00f14f 287 xfs_trans_ail_cursor_init(ailp, cur);
27d8d5fe 288 lip = xfs_ail_min(ailp);
249a8c11 289 if (lsn == 0)
5b00f14f 290 goto out;
249a8c11 291
27d8d5fe 292 list_for_each_entry(lip, &ailp->xa_ail, li_ail) {
5b00f14f 293 if (XFS_LSN_CMP(lip->li_lsn, lsn) >= 0)
7ee49acf 294 goto out;
535f6b37 295 }
5b00f14f
DC
296 lip = NULL;
297out:
298 xfs_trans_ail_cursor_set(ailp, cur, lip);
299 return lip;
249a8c11
DC
300}
301
cd4a3c50 302/*
1d8c95a3
DC
303 * Initialise the cursor to the last item in the AIL with the given @lsn.
304 * This searches the list from highest LSN to lowest. If there is no item with
305 * the value of @lsn, then it sets the cursor to the last item with an LSN lower
306 * than @lsn.
307 */
308static struct xfs_log_item *
309__xfs_trans_ail_cursor_last(
310 struct xfs_ail *ailp,
311 xfs_lsn_t lsn)
312{
313 xfs_log_item_t *lip;
314
315 list_for_each_entry_reverse(lip, &ailp->xa_ail, li_ail) {
316 if (XFS_LSN_CMP(lip->li_lsn, lsn) <= 0)
317 return lip;
318 }
319 return NULL;
320}
321
322/*
323 * Initialise the cursor to the last item in the AIL with the given @lsn.
324 * This searches the list from highest LSN to lowest.
325 */
326struct xfs_log_item *
327xfs_trans_ail_cursor_last(
328 struct xfs_ail *ailp,
329 struct xfs_ail_cursor *cur,
330 xfs_lsn_t lsn)
331{
332 xfs_trans_ail_cursor_init(ailp, cur);
333 cur->item = __xfs_trans_ail_cursor_last(ailp, lsn);
334 return cur->item;
335}
336
337/*
338 * splice the log item list into the AIL at the given LSN. We splice to the
339 * tail of the given LSN to maintain insert order for push traversals. The
340 * cursor is optional, allowing repeated updates to the same LSN to avoid
341 * repeated traversals.
cd4a3c50
DC
342 */
343static void
344xfs_ail_splice(
1d8c95a3
DC
345 struct xfs_ail *ailp,
346 struct xfs_ail_cursor *cur,
347 struct list_head *list,
348 xfs_lsn_t lsn)
cd4a3c50 349{
1d8c95a3
DC
350 struct xfs_log_item *lip = cur ? cur->item : NULL;
351 struct xfs_log_item *next_lip;
cd4a3c50 352
1d8c95a3
DC
353 /*
354 * Get a new cursor if we don't have a placeholder or the existing one
355 * has been invalidated.
356 */
357 if (!lip || (__psint_t)lip & 1) {
358 lip = __xfs_trans_ail_cursor_last(ailp, lsn);
359
360 if (!lip) {
361 /* The list is empty, so just splice and return. */
362 if (cur)
363 cur->item = NULL;
364 list_splice(list, &ailp->xa_ail);
365 return;
366 }
cd4a3c50
DC
367 }
368
1d8c95a3
DC
369 /*
370 * Our cursor points to the item we want to insert _after_, so we have
371 * to update the cursor to point to the end of the list we are splicing
372 * in so that it points to the correct location for the next splice.
373 * i.e. before the splice
374 *
375 * lsn -> lsn -> lsn + x -> lsn + x ...
376 * ^
377 * | cursor points here
378 *
379 * After the splice we have:
380 *
381 * lsn -> lsn -> lsn -> lsn -> .... -> lsn -> lsn + x -> lsn + x ...
382 * ^ ^
383 * | cursor points here | needs to move here
384 *
385 * So we set the cursor to the last item in the list to be spliced
386 * before we execute the splice, resulting in the cursor pointing to
387 * the correct item after the splice occurs.
388 */
389 if (cur) {
390 next_lip = list_entry(list->prev, struct xfs_log_item, li_ail);
391 cur->item = next_lip;
cd4a3c50 392 }
1d8c95a3 393 list_splice(list, &lip->li_ail);
cd4a3c50
DC
394}
395
396/*
397 * Delete the given item from the AIL. Return a pointer to the item.
398 */
399static void
400xfs_ail_delete(
401 struct xfs_ail *ailp,
402 xfs_log_item_t *lip)
403{
404 xfs_ail_check(ailp, lip);
405 list_del(&lip->li_ail);
406 xfs_trans_ail_cursor_clear(ailp, lip);
407}
408
249a8c11 409/*
0bf6a5bd
DC
410 * xfs_ail_worker does the work of pushing on the AIL. It will requeue itself
411 * to run at a later time if there is more work to do to complete the push.
249a8c11 412 */
0bf6a5bd
DC
413STATIC void
414xfs_ail_worker(
9e7004e7 415 struct work_struct *work)
249a8c11 416{
9e7004e7 417 struct xfs_ail *ailp = container_of(to_delayed_work(work),
0bf6a5bd 418 struct xfs_ail, xa_work);
9e7004e7 419 xfs_mount_t *mp = ailp->xa_mount;
27d8d5fe 420 struct xfs_ail_cursor *cur = &ailp->xa_cursors;
9e7004e7
DC
421 xfs_log_item_t *lip;
422 xfs_lsn_t lsn;
fe0da767 423 xfs_lsn_t target;
9e7004e7
DC
424 long tout = 10;
425 int flush_log = 0;
426 int stuck = 0;
427 int count = 0;
428 int push_xfsbufd = 0;
1da177e4 429
c7e8f268 430 spin_lock(&ailp->xa_lock);
fe0da767 431 target = ailp->xa_target;
27d8d5fe 432 xfs_trans_ail_cursor_init(ailp, cur);
0bf6a5bd 433 lip = xfs_trans_ail_cursor_first(ailp, cur, ailp->xa_last_pushed_lsn);
249a8c11 434 if (!lip || XFS_FORCED_SHUTDOWN(mp)) {
1da177e4 435 /*
249a8c11 436 * AIL is empty or our push has reached the end.
1da177e4 437 */
27d8d5fe 438 xfs_trans_ail_cursor_done(ailp, cur);
c7e8f268 439 spin_unlock(&ailp->xa_lock);
9e7004e7 440 goto out_done;
1da177e4
LT
441 }
442
443 XFS_STATS_INC(xs_push_ail);
444
445 /*
446 * While the item we are looking at is below the given threshold
249a8c11 447 * try to flush it out. We'd like not to stop until we've at least
1da177e4 448 * tried to push on everything in the AIL with an LSN less than
249a8c11
DC
449 * the given threshold.
450 *
451 * However, we will stop after a certain number of pushes and wait
452 * for a reduced timeout to fire before pushing further. This
453 * prevents use from spinning when we can't do anything or there is
454 * lots of contention on the AIL lists.
1da177e4 455 */
249a8c11 456 lsn = lip->li_lsn;
50e86686 457 while ((XFS_LSN_CMP(lip->li_lsn, target) <= 0)) {
249a8c11 458 int lock_result;
1da177e4 459 /*
249a8c11
DC
460 * If we can lock the item without sleeping, unlock the AIL
461 * lock and flush the item. Then re-grab the AIL lock so we
462 * can look for the next item on the AIL. List changes are
463 * handled by the AIL lookup functions internally
1da177e4 464 *
249a8c11
DC
465 * If we can't lock the item, either its holder will flush it
466 * or it is already being flushed or it is being relogged. In
467 * any of these case it is being taken care of and we can just
468 * skip to the next item in the list.
1da177e4
LT
469 */
470 lock_result = IOP_TRYLOCK(lip);
c7e8f268 471 spin_unlock(&ailp->xa_lock);
1da177e4 472 switch (lock_result) {
249a8c11 473 case XFS_ITEM_SUCCESS:
1da177e4
LT
474 XFS_STATS_INC(xs_push_ail_success);
475 IOP_PUSH(lip);
0bf6a5bd 476 ailp->xa_last_pushed_lsn = lsn;
1da177e4
LT
477 break;
478
249a8c11 479 case XFS_ITEM_PUSHBUF:
1da177e4 480 XFS_STATS_INC(xs_push_ail_pushbuf);
1da177e4 481 IOP_PUSHBUF(lip);
0bf6a5bd 482 ailp->xa_last_pushed_lsn = lsn;
d808f617 483 push_xfsbufd = 1;
1da177e4
LT
484 break;
485
249a8c11 486 case XFS_ITEM_PINNED:
1da177e4 487 XFS_STATS_INC(xs_push_ail_pinned);
249a8c11 488 stuck++;
1da177e4
LT
489 flush_log = 1;
490 break;
491
249a8c11 492 case XFS_ITEM_LOCKED:
1da177e4 493 XFS_STATS_INC(xs_push_ail_locked);
0bf6a5bd 494 ailp->xa_last_pushed_lsn = lsn;
249a8c11 495 stuck++;
1da177e4
LT
496 break;
497
249a8c11 498 default:
1da177e4
LT
499 ASSERT(0);
500 break;
501 }
502
c7e8f268 503 spin_lock(&ailp->xa_lock);
249a8c11
DC
504 /* should we bother continuing? */
505 if (XFS_FORCED_SHUTDOWN(mp))
1da177e4 506 break;
249a8c11
DC
507 ASSERT(mp->m_log);
508
509 count++;
1da177e4 510
249a8c11
DC
511 /*
512 * Are there too many items we can't do anything with?
513 * If we we are skipping too many items because we can't flush
514 * them or they are already being flushed, we back off and
515 * given them time to complete whatever operation is being
516 * done. i.e. remove pressure from the AIL while we can't make
517 * progress so traversals don't slow down further inserts and
518 * removals to/from the AIL.
519 *
520 * The value of 100 is an arbitrary magic number based on
521 * observation.
522 */
523 if (stuck > 100)
524 break;
525
27d8d5fe 526 lip = xfs_trans_ail_cursor_next(ailp, cur);
249a8c11
DC
527 if (lip == NULL)
528 break;
249a8c11 529 lsn = lip->li_lsn;
1da177e4 530 }
27d8d5fe 531 xfs_trans_ail_cursor_done(ailp, cur);
c7e8f268 532 spin_unlock(&ailp->xa_lock);
1da177e4
LT
533
534 if (flush_log) {
535 /*
536 * If something we need to push out was pinned, then
537 * push out the log so it will become unpinned and
538 * move forward in the AIL.
539 */
1da177e4 540 XFS_STATS_INC(xs_push_ail_flush);
a14a348b 541 xfs_log_force(mp, 0);
1da177e4
LT
542 }
543
d808f617
DC
544 if (push_xfsbufd) {
545 /* we've got delayed write buffers to flush */
546 wake_up_process(mp->m_ddev_targp->bt_task);
547 }
548
0bf6a5bd 549 /* assume we have more work to do in a short while */
9e7004e7 550out_done:
92d9cd10
DC
551 if (!count) {
552 /* We're past our target or empty, so idle */
0bf6a5bd
DC
553 ailp->xa_last_pushed_lsn = 0;
554
555 /*
7ac95657
DC
556 * We clear the XFS_AIL_PUSHING_BIT first before checking
557 * whether the target has changed. If the target has changed,
558 * this pushes the requeue race directly onto the result of the
559 * atomic test/set bit, so we are guaranteed that either the
560 * the pusher that changed the target or ourselves will requeue
561 * the work (but not both).
0bf6a5bd 562 */
7ac95657 563 clear_bit(XFS_AIL_PUSHING_BIT, &ailp->xa_flags);
0bf6a5bd 564 smp_rmb();
7ac95657
DC
565 if (XFS_LSN_CMP(ailp->xa_target, target) == 0 ||
566 test_and_set_bit(XFS_AIL_PUSHING_BIT, &ailp->xa_flags))
0bf6a5bd 567 return;
7ac95657 568
0bf6a5bd 569 tout = 50;
92d9cd10
DC
570 } else if (XFS_LSN_CMP(lsn, target) >= 0) {
571 /*
572 * We reached the target so wait a bit longer for I/O to
573 * complete and remove pushed items from the AIL before we
574 * start the next scan from the start of the AIL.
575 */
453eac8a 576 tout = 50;
0bf6a5bd 577 ailp->xa_last_pushed_lsn = 0;
27d8d5fe 578 } else if ((stuck * 100) / count > 90) {
249a8c11
DC
579 /*
580 * Either there is a lot of contention on the AIL or we
581 * are stuck due to operations in progress. "Stuck" in this
582 * case is defined as >90% of the items we tried to push
583 * were stuck.
584 *
585 * Backoff a bit more to allow some I/O to complete before
586 * continuing from where we were.
587 */
453eac8a 588 tout = 20;
1da177e4 589 }
0bf6a5bd
DC
590
591 /* There is more to do, requeue us. */
592 queue_delayed_work(xfs_syncd_wq, &ailp->xa_work,
593 msecs_to_jiffies(tout));
453eac8a 594}
1da177e4 595
0bf6a5bd
DC
596/*
597 * This routine is called to move the tail of the AIL forward. It does this by
598 * trying to flush items in the AIL whose lsns are below the given
599 * threshold_lsn.
600 *
601 * The push is run asynchronously in a workqueue, which means the caller needs
602 * to handle waiting on the async flush for space to become available.
603 * We don't want to interrupt any push that is in progress, hence we only queue
604 * work if we set the pushing bit approriately.
605 *
606 * We do this unlocked - we only need to know whether there is anything in the
607 * AIL at the time we are called. We don't need to access the contents of
608 * any of the objects, so the lock is not needed.
609 */
610void
fd074841 611xfs_ail_push(
0bf6a5bd
DC
612 struct xfs_ail *ailp,
613 xfs_lsn_t threshold_lsn)
614{
615 xfs_log_item_t *lip;
616
617 lip = xfs_ail_min(ailp);
618 if (!lip || XFS_FORCED_SHUTDOWN(ailp->xa_mount) ||
619 XFS_LSN_CMP(threshold_lsn, ailp->xa_target) <= 0)
620 return;
621
622 /*
623 * Ensure that the new target is noticed in push code before it clears
624 * the XFS_AIL_PUSHING_BIT.
625 */
626 smp_wmb();
fe0da767 627 xfs_trans_ail_copy_lsn(ailp, &ailp->xa_target, &threshold_lsn);
0bf6a5bd
DC
628 if (!test_and_set_bit(XFS_AIL_PUSHING_BIT, &ailp->xa_flags))
629 queue_delayed_work(xfs_syncd_wq, &ailp->xa_work, 0);
630}
1da177e4 631
fd074841
DC
632/*
633 * Push out all items in the AIL immediately
634 */
635void
636xfs_ail_push_all(
637 struct xfs_ail *ailp)
638{
639 xfs_lsn_t threshold_lsn = xfs_ail_max_lsn(ailp);
640
641 if (threshold_lsn)
642 xfs_ail_push(ailp, threshold_lsn);
643}
644
1da177e4
LT
645/*
646 * This is to be called when an item is unlocked that may have
647 * been in the AIL. It will wake up the first member of the AIL
648 * wait list if this item's unlocking might allow it to progress.
649 * If the item is in the AIL, then we need to get the AIL lock
650 * while doing our checking so we don't race with someone going
651 * to sleep waiting for this event in xfs_trans_push_ail().
652 */
653void
654xfs_trans_unlocked_item(
783a2f65 655 struct xfs_ail *ailp,
1da177e4
LT
656 xfs_log_item_t *lip)
657{
658 xfs_log_item_t *min_lip;
659
660 /*
661 * If we're forcibly shutting down, we may have
662 * unlocked log items arbitrarily. The last thing
663 * we want to do is to move the tail of the log
664 * over some potentially valid data.
665 */
666 if (!(lip->li_flags & XFS_LI_IN_AIL) ||
783a2f65 667 XFS_FORCED_SHUTDOWN(ailp->xa_mount)) {
1da177e4
LT
668 return;
669 }
670
671 /*
672 * This is the one case where we can call into xfs_ail_min()
673 * without holding the AIL lock because we only care about the
674 * case where we are at the tail of the AIL. If the object isn't
675 * at the tail, it doesn't matter what result we get back. This
676 * is slightly racy because since we were just unlocked, we could
677 * go to sleep between the call to xfs_ail_min and the call to
678 * xfs_log_move_tail, have someone else lock us, commit to us disk,
679 * move us out of the tail of the AIL, and then we wake up. However,
680 * the call to xfs_log_move_tail() doesn't do anything if there's
681 * not enough free space to wake people up so we're safe calling it.
682 */
783a2f65 683 min_lip = xfs_ail_min(ailp);
1da177e4
LT
684
685 if (min_lip == lip)
783a2f65 686 xfs_log_move_tail(ailp->xa_mount, 1);
1da177e4
LT
687} /* xfs_trans_unlocked_item */
688
0e57f6a3
DC
689/*
690 * xfs_trans_ail_update - bulk AIL insertion operation.
691 *
692 * @xfs_trans_ail_update takes an array of log items that all need to be
693 * positioned at the same LSN in the AIL. If an item is not in the AIL, it will
694 * be added. Otherwise, it will be repositioned by removing it and re-adding
695 * it to the AIL. If we move the first item in the AIL, update the log tail to
696 * match the new minimum LSN in the AIL.
697 *
698 * This function takes the AIL lock once to execute the update operations on
699 * all the items in the array, and as such should not be called with the AIL
700 * lock held. As a result, once we have the AIL lock, we need to check each log
701 * item LSN to confirm it needs to be moved forward in the AIL.
702 *
703 * To optimise the insert operation, we delete all the items from the AIL in
704 * the first pass, moving them into a temporary list, then splice the temporary
705 * list into the correct position in the AIL. This avoids needing to do an
706 * insert operation on every item.
707 *
708 * This function must be called with the AIL lock held. The lock is dropped
709 * before returning.
710 */
711void
712xfs_trans_ail_update_bulk(
713 struct xfs_ail *ailp,
1d8c95a3 714 struct xfs_ail_cursor *cur,
0e57f6a3
DC
715 struct xfs_log_item **log_items,
716 int nr_items,
717 xfs_lsn_t lsn) __releases(ailp->xa_lock)
718{
719 xfs_log_item_t *mlip;
720 xfs_lsn_t tail_lsn;
721 int mlip_changed = 0;
722 int i;
723 LIST_HEAD(tmp);
724
725 mlip = xfs_ail_min(ailp);
726
727 for (i = 0; i < nr_items; i++) {
728 struct xfs_log_item *lip = log_items[i];
729 if (lip->li_flags & XFS_LI_IN_AIL) {
730 /* check if we really need to move the item */
731 if (XFS_LSN_CMP(lsn, lip->li_lsn) <= 0)
732 continue;
733
734 xfs_ail_delete(ailp, lip);
735 if (mlip == lip)
736 mlip_changed = 1;
737 } else {
738 lip->li_flags |= XFS_LI_IN_AIL;
739 }
740 lip->li_lsn = lsn;
741 list_add(&lip->li_ail, &tmp);
742 }
743
1d8c95a3 744 xfs_ail_splice(ailp, cur, &tmp, lsn);
0e57f6a3
DC
745
746 if (!mlip_changed) {
747 spin_unlock(&ailp->xa_lock);
748 return;
749 }
750
751 /*
752 * It is not safe to access mlip after the AIL lock is dropped, so we
753 * must get a copy of li_lsn before we do so. This is especially
754 * important on 32-bit platforms where accessing and updating 64-bit
755 * values like li_lsn is not atomic.
756 */
757 mlip = xfs_ail_min(ailp);
758 tail_lsn = mlip->li_lsn;
759 spin_unlock(&ailp->xa_lock);
760 xfs_log_move_tail(ailp->xa_mount, tail_lsn);
761}
762
30136832
DC
763/*
764 * xfs_trans_ail_delete_bulk - remove multiple log items from the AIL
765 *
766 * @xfs_trans_ail_delete_bulk takes an array of log items that all need to
767 * removed from the AIL. The caller is already holding the AIL lock, and done
768 * all the checks necessary to ensure the items passed in via @log_items are
769 * ready for deletion. This includes checking that the items are in the AIL.
770 *
771 * For each log item to be removed, unlink it from the AIL, clear the IN_AIL
772 * flag from the item and reset the item's lsn to 0. If we remove the first
773 * item in the AIL, update the log tail to match the new minimum LSN in the
774 * AIL.
775 *
776 * This function will not drop the AIL lock until all items are removed from
777 * the AIL to minimise the amount of lock traffic on the AIL. This does not
778 * greatly increase the AIL hold time, but does significantly reduce the amount
779 * of traffic on the lock, especially during IO completion.
780 *
781 * This function must be called with the AIL lock held. The lock is dropped
782 * before returning.
783 */
784void
785xfs_trans_ail_delete_bulk(
786 struct xfs_ail *ailp,
787 struct xfs_log_item **log_items,
788 int nr_items) __releases(ailp->xa_lock)
789{
790 xfs_log_item_t *mlip;
791 xfs_lsn_t tail_lsn;
792 int mlip_changed = 0;
793 int i;
794
795 mlip = xfs_ail_min(ailp);
796
797 for (i = 0; i < nr_items; i++) {
798 struct xfs_log_item *lip = log_items[i];
799 if (!(lip->li_flags & XFS_LI_IN_AIL)) {
800 struct xfs_mount *mp = ailp->xa_mount;
801
802 spin_unlock(&ailp->xa_lock);
803 if (!XFS_FORCED_SHUTDOWN(mp)) {
6a19d939 804 xfs_alert_tag(mp, XFS_PTAG_AILDELETE,
30136832
DC
805 "%s: attempting to delete a log item that is not in the AIL",
806 __func__);
807 xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
808 }
809 return;
810 }
811
812 xfs_ail_delete(ailp, lip);
813 lip->li_flags &= ~XFS_LI_IN_AIL;
814 lip->li_lsn = 0;
815 if (mlip == lip)
816 mlip_changed = 1;
817 }
818
819 if (!mlip_changed) {
820 spin_unlock(&ailp->xa_lock);
821 return;
822 }
823
824 /*
825 * It is not safe to access mlip after the AIL lock is dropped, so we
826 * must get a copy of li_lsn before we do so. This is especially
827 * important on 32-bit platforms where accessing and updating 64-bit
828 * values like li_lsn is not atomic. It is possible we've emptied the
829 * AIL here, so if that is the case, pass an LSN of 0 to the tail move.
830 */
831 mlip = xfs_ail_min(ailp);
832 tail_lsn = mlip ? mlip->li_lsn : 0;
833 spin_unlock(&ailp->xa_lock);
834 xfs_log_move_tail(ailp->xa_mount, tail_lsn);
835}
1da177e4 836
1da177e4
LT
837/*
838 * The active item list (AIL) is a doubly linked list of log
839 * items sorted by ascending lsn. The base of the list is
840 * a forw/back pointer pair embedded in the xfs mount structure.
841 * The base is initialized with both pointers pointing to the
842 * base. This case always needs to be distinguished, because
843 * the base has no lsn to look at. We almost always insert
844 * at the end of the list, so on inserts we search from the
845 * end of the list to find where the new item belongs.
846 */
847
848/*
849 * Initialize the doubly linked list to point only to itself.
850 */
249a8c11 851int
1da177e4
LT
852xfs_trans_ail_init(
853 xfs_mount_t *mp)
854{
82fa9012
DC
855 struct xfs_ail *ailp;
856
857 ailp = kmem_zalloc(sizeof(struct xfs_ail), KM_MAYFAIL);
858 if (!ailp)
859 return ENOMEM;
860
861 ailp->xa_mount = mp;
862 INIT_LIST_HEAD(&ailp->xa_ail);
c7e8f268 863 spin_lock_init(&ailp->xa_lock);
0bf6a5bd 864 INIT_DELAYED_WORK(&ailp->xa_work, xfs_ail_worker);
27d8d5fe
DC
865 mp->m_ail = ailp;
866 return 0;
249a8c11
DC
867}
868
869void
870xfs_trans_ail_destroy(
871 xfs_mount_t *mp)
872{
82fa9012
DC
873 struct xfs_ail *ailp = mp->m_ail;
874
0bf6a5bd 875 cancel_delayed_work_sync(&ailp->xa_work);
82fa9012 876 kmem_free(ailp);
1da177e4 877}