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1// SPDX-License-Identifier: GPL-2.02/*3 * Copyright (c) 2000-2002,2005 Silicon Graphics, Inc.4 * Copyright (c) 2008 Dave Chinner5 * 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 DEBUG23/*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 it27 * held otherwise we'll lock everything up and won't be able to debug the28 * cause. Hence we sample and check the state under the AIL lock and return if29 * 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 void33xfs_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, then78 * 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. If92 * 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 of107 * the log. This is exactly the LSN of the first item in the AIL. If the AIL108 * 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 last111 * item in the AIL.112 */113static xfs_lsn_t114__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_t125xfs_ail_min_lsn(126 struct xfs_ail *ailp)127{128 xfs_lsn_t lsn;129 130 spin_lock(&ailp->ail_lock);131 lsn = __xfs_ail_min_lsn(ailp);132 spin_unlock(&ailp->ail_lock);133 134 return lsn;135}136 137/*138 * The cursor keeps track of where our current traversal is up to by tracking139 * the next item in the list for us. However, for this to be safe, removing an140 * object from the AIL needs to invalidate any cursor that points to it. hence141 * the traversal cursor needs to be linked to the struct xfs_ail so that142 * deletion can search all the active cursors for invalidation.143 */144STATIC void145xfs_trans_ail_cursor_init(146 struct xfs_ail *ailp,147 struct xfs_ail_cursor *cur)148{149 cur->item = NULL;150 list_add_tail(&cur->list, &ailp->ail_cursors);151}152 153/*154 * Get the next item in the traversal and advance the cursor. If the cursor155 * was invalidated (indicated by a lip of 1), restart the traversal.156 */157struct xfs_log_item *158xfs_trans_ail_cursor_next(159 struct xfs_ail *ailp,160 struct xfs_ail_cursor *cur)161{162 struct xfs_log_item *lip = cur->item;163 164 if ((uintptr_t)lip & 1)165 lip = xfs_ail_min(ailp);166 if (lip)167 cur->item = xfs_ail_next(ailp, lip);168 return lip;169}170 171/*172 * When the traversal is complete, we need to remove the cursor from the list173 * of traversing cursors.174 */175void176xfs_trans_ail_cursor_done(177 struct xfs_ail_cursor *cur)178{179 cur->item = NULL;180 list_del_init(&cur->list);181}182 183/*184 * Invalidate any cursor that is pointing to this item. This is called when an185 * item is removed from the AIL. Any cursor pointing to this object is now186 * invalid and the traversal needs to be terminated so it doesn't reference a187 * freed object. We set the low bit of the cursor item pointer so we can188 * distinguish between an invalidation and the end of the list when getting the189 * next item from the cursor.190 */191STATIC void192xfs_trans_ail_cursor_clear(193 struct xfs_ail *ailp,194 struct xfs_log_item *lip)195{196 struct xfs_ail_cursor *cur;197 198 list_for_each_entry(cur, &ailp->ail_cursors, list) {199 if (cur->item == lip)200 cur->item = (struct xfs_log_item *)201 ((uintptr_t)cur->item | 1);202 }203}204 205/*206 * Find the first item in the AIL with the given @lsn by searching in ascending207 * LSN order and initialise the cursor to point to the next item for a208 * ascending traversal. Pass a @lsn of zero to initialise the cursor to the209 * first item in the AIL. Returns NULL if the list is empty.210 */211struct xfs_log_item *212xfs_trans_ail_cursor_first(213 struct xfs_ail *ailp,214 struct xfs_ail_cursor *cur,215 xfs_lsn_t lsn)216{217 struct xfs_log_item *lip;218 219 xfs_trans_ail_cursor_init(ailp, cur);220 221 if (lsn == 0) {222 lip = xfs_ail_min(ailp);223 goto out;224 }225 226 list_for_each_entry(lip, &ailp->ail_head, li_ail) {227 if (XFS_LSN_CMP(lip->li_lsn, lsn) >= 0)228 goto out;229 }230 return NULL;231 232out:233 if (lip)234 cur->item = xfs_ail_next(ailp, lip);235 return lip;236}237 238static struct xfs_log_item *239__xfs_trans_ail_cursor_last(240 struct xfs_ail *ailp,241 xfs_lsn_t lsn)242{243 struct xfs_log_item *lip;244 245 list_for_each_entry_reverse(lip, &ailp->ail_head, li_ail) {246 if (XFS_LSN_CMP(lip->li_lsn, lsn) <= 0)247 return lip;248 }249 return NULL;250}251 252/*253 * Find the last item in the AIL with the given @lsn by searching in descending254 * LSN order and initialise the cursor to point to that item. If there is no255 * item with the value of @lsn, then it sets the cursor to the last item with an256 * LSN lower than @lsn. Returns NULL if the list is empty.257 */258struct xfs_log_item *259xfs_trans_ail_cursor_last(260 struct xfs_ail *ailp,261 struct xfs_ail_cursor *cur,262 xfs_lsn_t lsn)263{264 xfs_trans_ail_cursor_init(ailp, cur);265 cur->item = __xfs_trans_ail_cursor_last(ailp, lsn);266 return cur->item;267}268 269/*270 * Splice the log item list into the AIL at the given LSN. We splice to the271 * tail of the given LSN to maintain insert order for push traversals. The272 * cursor is optional, allowing repeated updates to the same LSN to avoid273 * repeated traversals. This should not be called with an empty list.274 */275static void276xfs_ail_splice(277 struct xfs_ail *ailp,278 struct xfs_ail_cursor *cur,279 struct list_head *list,280 xfs_lsn_t lsn)281{282 struct xfs_log_item *lip;283 284 ASSERT(!list_empty(list));285 286 /*287 * Use the cursor to determine the insertion point if one is288 * provided. If not, or if the one we got is not valid,289 * find the place in the AIL where the items belong.290 */291 lip = cur ? cur->item : NULL;292 if (!lip || (uintptr_t)lip & 1)293 lip = __xfs_trans_ail_cursor_last(ailp, lsn);294 295 /*296 * If a cursor is provided, we know we're processing the AIL297 * in lsn order, and future items to be spliced in will298 * follow the last one being inserted now. Update the299 * cursor to point to that last item, now while we have a300 * reliable pointer to it.301 */302 if (cur)303 cur->item = list_entry(list->prev, struct xfs_log_item, li_ail);304 305 /*306 * Finally perform the splice. Unless the AIL was empty,307 * lip points to the item in the AIL _after_ which the new308 * items should go. If lip is null the AIL was empty, so309 * the new items go at the head of the AIL.310 */311 if (lip)312 list_splice(list, &lip->li_ail);313 else314 list_splice(list, &ailp->ail_head);315}316 317/*318 * Delete the given item from the AIL. Return a pointer to the item.319 */320static void321xfs_ail_delete(322 struct xfs_ail *ailp,323 struct xfs_log_item *lip)324{325 xfs_ail_check(ailp, lip);326 list_del(&lip->li_ail);327 xfs_trans_ail_cursor_clear(ailp, lip);328}329 330/*331 * Requeue a failed buffer for writeback.332 *333 * We clear the log item failed state here as well, but we have to be careful334 * about reference counts because the only active reference counts on the buffer335 * may be the failed log items. Hence if we clear the log item failed state336 * before queuing the buffer for IO we can release all active references to337 * the buffer and free it, leading to use after free problems in338 * xfs_buf_delwri_queue. It makes no difference to the buffer or log items which339 * order we process them in - the buffer is locked, and we own the buffer list340 * so nothing on them is going to change while we are performing this action.341 *342 * Hence we can safely queue the buffer for IO before we clear the failed log343 * item state, therefore always having an active reference to the buffer and344 * avoiding the transient zero-reference state that leads to use-after-free.345 */346static inline int347xfsaild_resubmit_item(348 struct xfs_log_item *lip,349 struct list_head *buffer_list)350{351 struct xfs_buf *bp = lip->li_buf;352 353 if (!xfs_buf_trylock(bp))354 return XFS_ITEM_LOCKED;355 356 if (!xfs_buf_delwri_queue(bp, buffer_list)) {357 xfs_buf_unlock(bp);358 return XFS_ITEM_FLUSHING;359 }360 361 /* protected by ail_lock */362 list_for_each_entry(lip, &bp->b_li_list, li_bio_list) {363 if (bp->b_flags & _XBF_INODES)364 clear_bit(XFS_LI_FAILED, &lip->li_flags);365 else366 xfs_clear_li_failed(lip);367 }368 369 xfs_buf_unlock(bp);370 return XFS_ITEM_SUCCESS;371}372 373static inline uint374xfsaild_push_item(375 struct xfs_ail *ailp,376 struct xfs_log_item *lip)377{378 /*379 * If log item pinning is enabled, skip the push and track the item as380 * pinned. This can help induce head-behind-tail conditions.381 */382 if (XFS_TEST_ERROR(false, ailp->ail_log->l_mp, XFS_ERRTAG_LOG_ITEM_PIN))383 return XFS_ITEM_PINNED;384 385 /*386 * Consider the item pinned if a push callback is not defined so the387 * caller will force the log. This should only happen for intent items388 * as they are unpinned once the associated done item is committed to389 * the on-disk log.390 */391 if (!lip->li_ops->iop_push)392 return XFS_ITEM_PINNED;393 if (test_bit(XFS_LI_FAILED, &lip->li_flags))394 return xfsaild_resubmit_item(lip, &ailp->ail_buf_list);395 return lip->li_ops->iop_push(lip, &ailp->ail_buf_list);396}397 398/*399 * Compute the LSN that we'd need to push the log tail towards in order to have400 * at least 25% of the log space free. If the log free space already meets this401 * threshold, this function returns the lowest LSN in the AIL to slowly keep402 * writeback ticking over and the tail of the log moving forward.403 */404static xfs_lsn_t405xfs_ail_calc_push_target(406 struct xfs_ail *ailp)407{408 struct xlog *log = ailp->ail_log;409 struct xfs_log_item *lip;410 xfs_lsn_t target_lsn;411 xfs_lsn_t max_lsn;412 xfs_lsn_t min_lsn;413 int32_t free_bytes;414 uint32_t target_block;415 uint32_t target_cycle;416 417 lockdep_assert_held(&ailp->ail_lock);418 419 lip = xfs_ail_max(ailp);420 if (!lip)421 return NULLCOMMITLSN;422 423 max_lsn = lip->li_lsn;424 min_lsn = __xfs_ail_min_lsn(ailp);425 426 /*427 * If we are supposed to push all the items in the AIL, we want to push428 * to the current head. We then clear the push flag so that we don't429 * keep pushing newly queued items beyond where the push all command was430 * run. If the push waiter wants to empty the ail, it should queue431 * itself on the ail_empty wait queue.432 */433 if (test_and_clear_bit(XFS_AIL_OPSTATE_PUSH_ALL, &ailp->ail_opstate))434 return max_lsn;435 436 /* If someone wants the AIL empty, keep pushing everything we have. */437 if (waitqueue_active(&ailp->ail_empty))438 return max_lsn;439 440 /*441 * Background pushing - attempt to keep 25% of the log free and if we442 * have that much free retain the existing target.443 */444 free_bytes = log->l_logsize - xlog_lsn_sub(log, max_lsn, min_lsn);445 if (free_bytes >= log->l_logsize >> 2)446 return ailp->ail_target;447 448 target_cycle = CYCLE_LSN(min_lsn);449 target_block = BLOCK_LSN(min_lsn) + (log->l_logBBsize >> 2);450 if (target_block >= log->l_logBBsize) {451 target_block -= log->l_logBBsize;452 target_cycle += 1;453 }454 target_lsn = xlog_assign_lsn(target_cycle, target_block);455 456 /* Cap the target to the highest LSN known to be in the AIL. */457 if (XFS_LSN_CMP(target_lsn, max_lsn) > 0)458 return max_lsn;459 460 /* If the existing target is higher than the new target, keep it. */461 if (XFS_LSN_CMP(ailp->ail_target, target_lsn) >= 0)462 return ailp->ail_target;463 return target_lsn;464}465 466static long467xfsaild_push(468 struct xfs_ail *ailp)469{470 struct xfs_mount *mp = ailp->ail_log->l_mp;471 struct xfs_ail_cursor cur;472 struct xfs_log_item *lip;473 xfs_lsn_t lsn;474 long tout;475 int stuck = 0;476 int flushing = 0;477 int count = 0;478 479 /*480 * If we encountered pinned items or did not finish writing out all481 * buffers the last time we ran, force a background CIL push to get the482 * items unpinned in the near future. We do not wait on the CIL push as483 * that could stall us for seconds if there is enough background IO484 * load. Stalling for that long when the tail of the log is pinned and485 * needs flushing will hard stop the transaction subsystem when log486 * space runs out.487 */488 if (ailp->ail_log_flush && ailp->ail_last_pushed_lsn == 0 &&489 (!list_empty_careful(&ailp->ail_buf_list) ||490 xfs_ail_min_lsn(ailp))) {491 ailp->ail_log_flush = 0;492 493 XFS_STATS_INC(mp, xs_push_ail_flush);494 xlog_cil_flush(ailp->ail_log);495 }496 497 spin_lock(&ailp->ail_lock);498 WRITE_ONCE(ailp->ail_target, xfs_ail_calc_push_target(ailp));499 if (ailp->ail_target == NULLCOMMITLSN)500 goto out_done;501 502 /* we're done if the AIL is empty or our push has reached the end */503 lip = xfs_trans_ail_cursor_first(ailp, &cur, ailp->ail_last_pushed_lsn);504 if (!lip)505 goto out_done_cursor;506 507 XFS_STATS_INC(mp, xs_push_ail);508 509 ASSERT(ailp->ail_target != NULLCOMMITLSN);510 511 lsn = lip->li_lsn;512 while ((XFS_LSN_CMP(lip->li_lsn, ailp->ail_target) <= 0)) {513 int lock_result;514 515 if (test_bit(XFS_LI_FLUSHING, &lip->li_flags))516 goto next_item;517 518 /*519 * Note that iop_push may unlock and reacquire the AIL lock. We520 * rely on the AIL cursor implementation to be able to deal with521 * the dropped lock.522 */523 lock_result = xfsaild_push_item(ailp, lip);524 switch (lock_result) {525 case XFS_ITEM_SUCCESS:526 XFS_STATS_INC(mp, xs_push_ail_success);527 trace_xfs_ail_push(lip);528 529 ailp->ail_last_pushed_lsn = lsn;530 break;531 532 case XFS_ITEM_FLUSHING:533 /*534 * The item or its backing buffer is already being535 * flushed. The typical reason for that is that an536 * inode buffer is locked because we already pushed the537 * updates to it as part of inode clustering.538 *539 * We do not want to stop flushing just because lots540 * of items are already being flushed, but we need to541 * re-try the flushing relatively soon if most of the542 * AIL is being flushed.543 */544 XFS_STATS_INC(mp, xs_push_ail_flushing);545 trace_xfs_ail_flushing(lip);546 547 flushing++;548 ailp->ail_last_pushed_lsn = lsn;549 break;550 551 case XFS_ITEM_PINNED:552 XFS_STATS_INC(mp, xs_push_ail_pinned);553 trace_xfs_ail_pinned(lip);554 555 stuck++;556 ailp->ail_log_flush++;557 break;558 case XFS_ITEM_LOCKED:559 XFS_STATS_INC(mp, xs_push_ail_locked);560 trace_xfs_ail_locked(lip);561 562 stuck++;563 break;564 default:565 ASSERT(0);566 break;567 }568 569 count++;570 571 /*572 * Are there too many items we can't do anything with?573 *574 * If we are skipping too many items because we can't flush575 * them or they are already being flushed, we back off and576 * given them time to complete whatever operation is being577 * done. i.e. remove pressure from the AIL while we can't make578 * progress so traversals don't slow down further inserts and579 * removals to/from the AIL.580 *581 * The value of 100 is an arbitrary magic number based on582 * observation.583 */584 if (stuck > 100)585 break;586 587next_item:588 lip = xfs_trans_ail_cursor_next(ailp, &cur);589 if (lip == NULL)590 break;591 if (lip->li_lsn != lsn && count > 1000)592 break;593 lsn = lip->li_lsn;594 }595 596out_done_cursor:597 xfs_trans_ail_cursor_done(&cur);598out_done:599 spin_unlock(&ailp->ail_lock);600 601 if (xfs_buf_delwri_submit_nowait(&ailp->ail_buf_list))602 ailp->ail_log_flush++;603 604 if (!count || XFS_LSN_CMP(lsn, ailp->ail_target) >= 0) {605 /*606 * We reached the target or the AIL is empty, so wait a bit607 * longer for I/O to complete and remove pushed items from the608 * AIL before we start the next scan from the start of the AIL.609 */610 tout = 50;611 ailp->ail_last_pushed_lsn = 0;612 } else if (((stuck + flushing) * 100) / count > 90) {613 /*614 * Either there is a lot of contention on the AIL or we are615 * stuck due to operations in progress. "Stuck" in this case616 * is defined as >90% of the items we tried to push were stuck.617 *618 * Backoff a bit more to allow some I/O to complete before619 * restarting from the start of the AIL. This prevents us from620 * spinning on the same items, and if they are pinned will all621 * the restart to issue a log force to unpin the stuck items.622 */623 tout = 20;624 ailp->ail_last_pushed_lsn = 0;625 } else {626 /*627 * Assume we have more work to do in a short while.628 */629 tout = 0;630 }631 632 return tout;633}634 635static int636xfsaild(637 void *data)638{639 struct xfs_ail *ailp = data;640 long tout = 0; /* milliseconds */641 unsigned int noreclaim_flag;642 643 noreclaim_flag = memalloc_noreclaim_save();644 set_freezable();645 646 while (1) {647 /*648 * Long waits of 50ms or more occur when we've run out of items649 * to push, so we only want uninterruptible state if we're650 * actually blocked on something.651 */652 if (tout && tout <= 20)653 set_current_state(TASK_KILLABLE|TASK_FREEZABLE);654 else655 set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);656 657 /*658 * Check kthread_should_stop() after we set the task state to659 * guarantee that we either see the stop bit and exit or the660 * task state is reset to runnable such that it's not scheduled661 * out indefinitely and detects the stop bit at next iteration.662 * A memory barrier is included in above task state set to663 * serialize again kthread_stop().664 */665 if (kthread_should_stop()) {666 __set_current_state(TASK_RUNNING);667 668 /*669 * The caller forces out the AIL before stopping the670 * thread in the common case, which means the delwri671 * queue is drained. In the shutdown case, the queue may672 * still hold relogged buffers that haven't been673 * submitted because they were pinned since added to the674 * queue.675 *676 * Log I/O error processing stales the underlying buffer677 * and clears the delwri state, expecting the buf to be678 * removed on the next submission attempt. That won't679 * happen if we're shutting down, so this is the last680 * opportunity to release such buffers from the queue.681 */682 ASSERT(list_empty(&ailp->ail_buf_list) ||683 xlog_is_shutdown(ailp->ail_log));684 xfs_buf_delwri_cancel(&ailp->ail_buf_list);685 break;686 }687 688 /* Idle if the AIL is empty. */689 spin_lock(&ailp->ail_lock);690 if (!xfs_ail_min(ailp) && list_empty(&ailp->ail_buf_list)) {691 spin_unlock(&ailp->ail_lock);692 schedule();693 tout = 0;694 continue;695 }696 spin_unlock(&ailp->ail_lock);697 698 if (tout)699 schedule_timeout(msecs_to_jiffies(tout));700 701 __set_current_state(TASK_RUNNING);702 703 try_to_freeze();704 705 tout = xfsaild_push(ailp);706 }707 708 memalloc_noreclaim_restore(noreclaim_flag);709 return 0;710}711 712/*713 * Push out all items in the AIL immediately and wait until the AIL is empty.714 */715void716xfs_ail_push_all_sync(717 struct xfs_ail *ailp)718{719 DEFINE_WAIT(wait);720 721 spin_lock(&ailp->ail_lock);722 while (xfs_ail_max(ailp) != NULL) {723 prepare_to_wait(&ailp->ail_empty, &wait, TASK_UNINTERRUPTIBLE);724 wake_up_process(ailp->ail_task);725 spin_unlock(&ailp->ail_lock);726 schedule();727 spin_lock(&ailp->ail_lock);728 }729 spin_unlock(&ailp->ail_lock);730 731 finish_wait(&ailp->ail_empty, &wait);732}733 734void735__xfs_ail_assign_tail_lsn(736 struct xfs_ail *ailp)737{738 struct xlog *log = ailp->ail_log;739 xfs_lsn_t tail_lsn;740 741 assert_spin_locked(&ailp->ail_lock);742 743 if (xlog_is_shutdown(log))744 return;745 746 tail_lsn = __xfs_ail_min_lsn(ailp);747 if (!tail_lsn)748 tail_lsn = ailp->ail_head_lsn;749 750 WRITE_ONCE(log->l_tail_space,751 xlog_lsn_sub(log, ailp->ail_head_lsn, tail_lsn));752 trace_xfs_log_assign_tail_lsn(log, tail_lsn);753 atomic64_set(&log->l_tail_lsn, tail_lsn);754}755 756/*757 * Callers should pass the original tail lsn so that we can detect if the tail758 * has moved as a result of the operation that was performed. If the caller759 * needs to force a tail space update, it should pass NULLCOMMITLSN to bypass760 * the "did the tail LSN change?" checks. If the caller wants to avoid a tail761 * update (e.g. it knows the tail did not change) it should pass an @old_lsn of762 * 0.763 */764void765xfs_ail_update_finish(766 struct xfs_ail *ailp,767 xfs_lsn_t old_lsn) __releases(ailp->ail_lock)768{769 struct xlog *log = ailp->ail_log;770 771 /* If the tail lsn hasn't changed, don't do updates or wakeups. */772 if (!old_lsn || old_lsn == __xfs_ail_min_lsn(ailp)) {773 spin_unlock(&ailp->ail_lock);774 return;775 }776 777 __xfs_ail_assign_tail_lsn(ailp);778 if (list_empty(&ailp->ail_head))779 wake_up_all(&ailp->ail_empty);780 spin_unlock(&ailp->ail_lock);781 xfs_log_space_wake(log->l_mp);782}783 784/*785 * xfs_trans_ail_update - bulk AIL insertion operation.786 *787 * @xfs_trans_ail_update takes an array of log items that all need to be788 * positioned at the same LSN in the AIL. If an item is not in the AIL, it will789 * be added. Otherwise, it will be repositioned by removing it and re-adding790 * it to the AIL. If we move the first item in the AIL, update the log tail to791 * match the new minimum LSN in the AIL.792 *793 * This function takes the AIL lock once to execute the update operations on794 * all the items in the array, and as such should not be called with the AIL795 * lock held. As a result, once we have the AIL lock, we need to check each log796 * item LSN to confirm it needs to be moved forward in the AIL.797 *798 * To optimise the insert operation, we delete all the items from the AIL in799 * the first pass, moving them into a temporary list, then splice the temporary800 * list into the correct position in the AIL. This avoids needing to do an801 * insert operation on every item.802 *803 * This function must be called with the AIL lock held. The lock is dropped804 * before returning.805 */806void807xfs_trans_ail_update_bulk(808 struct xfs_ail *ailp,809 struct xfs_ail_cursor *cur,810 struct xfs_log_item **log_items,811 int nr_items,812 xfs_lsn_t lsn) __releases(ailp->ail_lock)813{814 struct xfs_log_item *mlip;815 xfs_lsn_t tail_lsn = 0;816 int i;817 LIST_HEAD(tmp);818 819 ASSERT(nr_items > 0); /* Not required, but true. */820 mlip = xfs_ail_min(ailp);821 822 for (i = 0; i < nr_items; i++) {823 struct xfs_log_item *lip = log_items[i];824 if (test_and_set_bit(XFS_LI_IN_AIL, &lip->li_flags)) {825 /* check if we really need to move the item */826 if (XFS_LSN_CMP(lsn, lip->li_lsn) <= 0)827 continue;828 829 trace_xfs_ail_move(lip, lip->li_lsn, lsn);830 if (mlip == lip && !tail_lsn)831 tail_lsn = lip->li_lsn;832 833 xfs_ail_delete(ailp, lip);834 } else {835 trace_xfs_ail_insert(lip, 0, lsn);836 }837 lip->li_lsn = lsn;838 list_add_tail(&lip->li_ail, &tmp);839 }840 841 if (!list_empty(&tmp))842 xfs_ail_splice(ailp, cur, &tmp, lsn);843 844 /*845 * If this is the first insert, wake up the push daemon so it can846 * actively scan for items to push. We also need to do a log tail847 * LSN update to ensure that it is correctly tracked by the log, so848 * set the tail_lsn to NULLCOMMITLSN so that xfs_ail_update_finish()849 * will see that the tail lsn has changed and will update the tail850 * appropriately.851 */852 if (!mlip) {853 wake_up_process(ailp->ail_task);854 tail_lsn = NULLCOMMITLSN;855 }856 857 xfs_ail_update_finish(ailp, tail_lsn);858}859 860/* Insert a log item into the AIL. */861void862xfs_trans_ail_insert(863 struct xfs_ail *ailp,864 struct xfs_log_item *lip,865 xfs_lsn_t lsn)866{867 spin_lock(&ailp->ail_lock);868 xfs_trans_ail_update_bulk(ailp, NULL, &lip, 1, lsn);869}870 871/*872 * Delete one log item from the AIL.873 *874 * If this item was at the tail of the AIL, return the LSN of the log item so875 * that we can use it to check if the LSN of the tail of the log has moved876 * when finishing up the AIL delete process in xfs_ail_update_finish().877 */878xfs_lsn_t879xfs_ail_delete_one(880 struct xfs_ail *ailp,881 struct xfs_log_item *lip)882{883 struct xfs_log_item *mlip = xfs_ail_min(ailp);884 xfs_lsn_t lsn = lip->li_lsn;885 886 trace_xfs_ail_delete(lip, mlip->li_lsn, lip->li_lsn);887 xfs_ail_delete(ailp, lip);888 clear_bit(XFS_LI_IN_AIL, &lip->li_flags);889 lip->li_lsn = 0;890 891 if (mlip == lip)892 return lsn;893 return 0;894}895 896void897xfs_trans_ail_delete(898 struct xfs_log_item *lip,899 int shutdown_type)900{901 struct xfs_ail *ailp = lip->li_ailp;902 struct xlog *log = ailp->ail_log;903 xfs_lsn_t tail_lsn;904 905 spin_lock(&ailp->ail_lock);906 if (!test_bit(XFS_LI_IN_AIL, &lip->li_flags)) {907 spin_unlock(&ailp->ail_lock);908 if (shutdown_type && !xlog_is_shutdown(log)) {909 xfs_alert_tag(log->l_mp, XFS_PTAG_AILDELETE,910 "%s: attempting to delete a log item that is not in the AIL",911 __func__);912 xlog_force_shutdown(log, shutdown_type);913 }914 return;915 }916 917 /* xfs_ail_update_finish() drops the AIL lock */918 xfs_clear_li_failed(lip);919 tail_lsn = xfs_ail_delete_one(ailp, lip);920 xfs_ail_update_finish(ailp, tail_lsn);921}922 923int924xfs_trans_ail_init(925 xfs_mount_t *mp)926{927 struct xfs_ail *ailp;928 929 ailp = kzalloc(sizeof(struct xfs_ail),930 GFP_KERNEL | __GFP_RETRY_MAYFAIL);931 if (!ailp)932 return -ENOMEM;933 934 ailp->ail_log = mp->m_log;935 INIT_LIST_HEAD(&ailp->ail_head);936 INIT_LIST_HEAD(&ailp->ail_cursors);937 spin_lock_init(&ailp->ail_lock);938 INIT_LIST_HEAD(&ailp->ail_buf_list);939 init_waitqueue_head(&ailp->ail_empty);940 941 ailp->ail_task = kthread_run(xfsaild, ailp, "xfsaild/%s",942 mp->m_super->s_id);943 if (IS_ERR(ailp->ail_task))944 goto out_free_ailp;945 946 mp->m_ail = ailp;947 return 0;948 949out_free_ailp:950 kfree(ailp);951 return -ENOMEM;952}953 954void955xfs_trans_ail_destroy(956 xfs_mount_t *mp)957{958 struct xfs_ail *ailp = mp->m_ail;959 960 kthread_stop(ailp->ail_task);961 kfree(ailp);962}963