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2024-02-20 ea08eeccae9297f7aabd2ef7f0c2517ac4549acc 
 kernel/fs/xfs/xfs_trans_ail.c
....@@ -6,6 +6,7 @@
66  */
77 #include "xfs.h"
88 #include "xfs_fs.h"
9
+#include "xfs_shared.h"
910 #include "xfs_format.h"
1011 #include "xfs_log_format.h"
1112 #include "xfs_trans_resv.h"
....@@ -31,6 +32,7 @@
3132 xfs_ail_check(
3233 	struct xfs_ail		*ailp,
3334 	struct xfs_log_item	*lip)
35
+	__must_hold(&ailp->ail_lock)
3436 {
3537 	struct xfs_log_item	*prev_lip;
3638 	struct xfs_log_item	*next_lip;
....@@ -74,29 +76,29 @@
7476  * Return a pointer to the last item in the AIL.  If the AIL is empty, then
7577  * return NULL.
7678  */
77
-static xfs_log_item_t *
79
+static struct xfs_log_item *
7880 xfs_ail_max(
7981 	struct xfs_ail  *ailp)
8082 {
8183 	if (list_empty(&ailp->ail_head))
8284 		return NULL;
8385 
84
-	return list_entry(ailp->ail_head.prev, xfs_log_item_t, li_ail);
86
+	return list_entry(ailp->ail_head.prev, struct xfs_log_item, li_ail);
8587 }
8688 
8789 /*
8890  * Return a pointer to the item which follows the given item in the AIL.  If
8991  * the given item is the last item in the list, then return NULL.
9092  */
91
-static xfs_log_item_t *
93
+static struct xfs_log_item *
9294 xfs_ail_next(
93
-	struct xfs_ail  *ailp,
94
-	xfs_log_item_t  *lip)
95
+	struct xfs_ail		*ailp,
96
+	struct xfs_log_item	*lip)
9597 {
9698 	if (lip->li_ail.next == &ailp->ail_head)
9799 		return NULL;
98100 
99
-	return list_first_entry(&lip->li_ail, xfs_log_item_t, li_ail);
101
+	return list_first_entry(&lip->li_ail, struct xfs_log_item, li_ail);
100102 }
101103 
102104 /*
....@@ -107,17 +109,25 @@
107109  * We need the AIL lock in order to get a coherent read of the lsn of the last
108110  * item in the AIL.
109111  */
112
+static xfs_lsn_t
113
+__xfs_ail_min_lsn(
114
+	struct xfs_ail		*ailp)
115
+{
116
+	struct xfs_log_item	*lip = xfs_ail_min(ailp);
117
+
118
+	if (lip)
119
+		return lip->li_lsn;
120
+	return 0;
121
+}
122
+
110123 xfs_lsn_t
111124 xfs_ail_min_lsn(
112
-	struct xfs_ail	*ailp)
125
+	struct xfs_ail		*ailp)
113126 {
114
-	xfs_lsn_t	lsn = 0;
115
-	xfs_log_item_t	*lip;
127
+	xfs_lsn_t		lsn;
116128 
117129 	spin_lock(&ailp->ail_lock);
118
-	lip = xfs_ail_min(ailp);
119
-	if (lip)
120
-		lsn = lip->li_lsn;
130
+	lsn = __xfs_ail_min_lsn(ailp);
121131 	spin_unlock(&ailp->ail_lock);
122132 
123133 	return lsn;
....@@ -128,10 +138,10 @@
128138  */
129139 static xfs_lsn_t
130140 xfs_ail_max_lsn(
131
-	struct xfs_ail  *ailp)
141
+	struct xfs_ail		*ailp)
132142 {
133
-	xfs_lsn_t       lsn = 0;
134
-	xfs_log_item_t  *lip;
143
+	xfs_lsn_t       	lsn = 0;
144
+	struct xfs_log_item	*lip;
135145 
136146 	spin_lock(&ailp->ail_lock);
137147 	lip = xfs_ail_max(ailp);
....@@ -216,13 +226,13 @@
216226  * ascending traversal.  Pass a @lsn of zero to initialise the cursor to the
217227  * first item in the AIL. Returns NULL if the list is empty.
218228  */
219
-xfs_log_item_t *
229
+struct xfs_log_item *
220230 xfs_trans_ail_cursor_first(
221231 	struct xfs_ail		*ailp,
222232 	struct xfs_ail_cursor	*cur,
223233 	xfs_lsn_t		lsn)
224234 {
225
-	xfs_log_item_t		*lip;
235
+	struct xfs_log_item	*lip;
226236 
227237 	xfs_trans_ail_cursor_init(ailp, cur);
228238 
....@@ -248,7 +258,7 @@
248258 	struct xfs_ail		*ailp,
249259 	xfs_lsn_t		lsn)
250260 {
251
-	xfs_log_item_t		*lip;
261
+	struct xfs_log_item	*lip;
252262 
253263 	list_for_each_entry_reverse(lip, &ailp->ail_head, li_ail) {
254264 		if (XFS_LSN_CMP(lip->li_lsn, lsn) <= 0)
....@@ -327,12 +337,55 @@
327337  */
328338 static void
329339 xfs_ail_delete(
330
-	struct xfs_ail  *ailp,
331
-	xfs_log_item_t  *lip)
340
+	struct xfs_ail		*ailp,
341
+	struct xfs_log_item	*lip)
332342 {
333343 	xfs_ail_check(ailp, lip);
334344 	list_del(&lip->li_ail);
335345 	xfs_trans_ail_cursor_clear(ailp, lip);
346
+}
347
+
348
+/*
349
+ * Requeue a failed buffer for writeback.
350
+ *
351
+ * We clear the log item failed state here as well, but we have to be careful
352
+ * about reference counts because the only active reference counts on the buffer
353
+ * may be the failed log items. Hence if we clear the log item failed state
354
+ * before queuing the buffer for IO we can release all active references to
355
+ * the buffer and free it, leading to use after free problems in
356
+ * xfs_buf_delwri_queue. It makes no difference to the buffer or log items which
357
+ * order we process them in - the buffer is locked, and we own the buffer list
358
+ * so nothing on them is going to change while we are performing this action.
359
+ *
360
+ * Hence we can safely queue the buffer for IO before we clear the failed log
361
+ * item state, therefore  always having an active reference to the buffer and
362
+ * avoiding the transient zero-reference state that leads to use-after-free.
363
+ */
364
+static inline int
365
+xfsaild_resubmit_item(
366
+	struct xfs_log_item	*lip,
367
+	struct list_head	*buffer_list)
368
+{
369
+	struct xfs_buf		*bp = lip->li_buf;
370
+
371
+	if (!xfs_buf_trylock(bp))
372
+		return XFS_ITEM_LOCKED;
373
+
374
+	if (!xfs_buf_delwri_queue(bp, buffer_list)) {
375
+		xfs_buf_unlock(bp);
376
+		return XFS_ITEM_FLUSHING;
377
+	}
378
+
379
+	/* protected by ail_lock */
380
+	list_for_each_entry(lip, &bp->b_li_list, li_bio_list) {
381
+		if (bp->b_flags & _XBF_INODES)
382
+			clear_bit(XFS_LI_FAILED, &lip->li_flags);
383
+		else
384
+			xfs_clear_li_failed(lip);
385
+	}
386
+
387
+	xfs_buf_unlock(bp);
388
+	return XFS_ITEM_SUCCESS;
336389 }
337390 
338391 static inline uint
....@@ -347,6 +400,16 @@
347400 	if (XFS_TEST_ERROR(false, ailp->ail_mount, XFS_ERRTAG_LOG_ITEM_PIN))
348401 		return XFS_ITEM_PINNED;
349402 
403
+	/*
404
+	 * Consider the item pinned if a push callback is not defined so the
405
+	 * caller will force the log. This should only happen for intent items
406
+	 * as they are unpinned once the associated done item is committed to
407
+	 * the on-disk log.
408
+	 */
409
+	if (!lip->li_ops->iop_push)
410
+		return XFS_ITEM_PINNED;
411
+	if (test_bit(XFS_LI_FAILED, &lip->li_flags))
412
+		return xfsaild_resubmit_item(lip, &ailp->ail_buf_list);
350413 	return lip->li_ops->iop_push(lip, &ailp->ail_buf_list);
351414 }
352415 
....@@ -356,7 +419,7 @@
356419 {
357420 	xfs_mount_t		*mp = ailp->ail_mount;
358421 	struct xfs_ail_cursor	cur;
359
-	xfs_log_item_t		*lip;
422
+	struct xfs_log_item	*lip;
360423 	xfs_lsn_t		lsn;
361424 	xfs_lsn_t		target;
362425 	long			tout;
....@@ -385,16 +448,10 @@
385448 	target = ailp->ail_target;
386449 	ailp->ail_target_prev = target;
387450 
451
+	/* we're done if the AIL is empty or our push has reached the end */
388452 	lip = xfs_trans_ail_cursor_first(ailp, &cur, ailp->ail_last_pushed_lsn);
389
-	if (!lip) {
390
-		/*
391
-		 * If the AIL is empty or our push has reached the end we are
392
-		 * done now.
393
-		 */
394
-		xfs_trans_ail_cursor_done(&cur);
395
-		spin_unlock(&ailp->ail_lock);
453
+	if (!lip)
396454 		goto out_done;
397
-	}
398455 
399456 	XFS_STATS_INC(mp, xs_push_ail);
400457 
....@@ -418,15 +475,15 @@
418475 
419476 		case XFS_ITEM_FLUSHING:
420477 			/*
421
-			 * The item or its backing buffer is already beeing
478
+			 * The item or its backing buffer is already being
422479 			 * flushed.  The typical reason for that is that an
423480 			 * inode buffer is locked because we already pushed the
424481 			 * updates to it as part of inode clustering.
425482 			 *
426
-			 * We do not want to to stop flushing just because lots
427
-			 * of items are already beeing flushed, but we need to
483
+			 * We do not want to stop flushing just because lots
484
+			 * of items are already being flushed, but we need to
428485 			 * re-try the flushing relatively soon if most of the
429
-			 * AIL is beeing flushed.
486
+			 * AIL is being flushed.
430487 			 */
431488 			XFS_STATS_INC(mp, xs_push_ail_flushing);
432489 			trace_xfs_ail_flushing(lip);
....@@ -458,7 +515,7 @@
458515 		/*
459516 		 * Are there too many items we can't do anything with?
460517 		 *
461
-		 * If we we are skipping too many items because we can't flush
518
+		 * If we are skipping too many items because we can't flush
462519 		 * them or they are already being flushed, we back off and
463520 		 * given them time to complete whatever operation is being
464521 		 * done. i.e. remove pressure from the AIL while we can't make
....@@ -476,6 +533,8 @@
476533 			break;
477534 		lsn = lip->li_lsn;
478535 	}
536
+
537
+out_done:
479538 	xfs_trans_ail_cursor_done(&cur);
480539 	spin_unlock(&ailp->ail_lock);
481540 
....@@ -483,7 +542,6 @@
483542 		ailp->ail_log_flush++;
484543 
485544 	if (!count || XFS_LSN_CMP(lsn, target) >= 0) {
486
-out_done:
487545 		/*
488546 		 * We reached the target or the AIL is empty, so wait a bit
489547 		 * longer for I/O to complete and remove pushed items from the
....@@ -575,7 +633,8 @@
575633 		 */
576634 		smp_rmb();
577635 		if (!xfs_ail_min(ailp) &&
578
-		    ailp->ail_target == ailp->ail_target_prev) {
636
+		    ailp->ail_target == ailp->ail_target_prev &&
637
+		    list_empty(&ailp->ail_buf_list)) {
579638 			spin_unlock(&ailp->ail_lock);
580639 			freezable_schedule();
581640 			tout = 0;
....@@ -605,7 +664,7 @@
605664  * The push is run asynchronously in a workqueue, which means the caller needs
606665  * to handle waiting on the async flush for space to become available.
607666  * We don't want to interrupt any push that is in progress, hence we only queue
608
- * work if we set the pushing bit approriately.
667
+ * work if we set the pushing bit appropriately.
609668  *
610669  * We do this unlocked - we only need to know whether there is anything in the
611670  * AIL at the time we are called. We don't need to access the contents of
....@@ -613,10 +672,10 @@
613672  */
614673 void
615674 xfs_ail_push(
616
-	struct xfs_ail	*ailp,
617
-	xfs_lsn_t	threshold_lsn)
675
+	struct xfs_ail		*ailp,
676
+	xfs_lsn_t		threshold_lsn)
618677 {
619
-	xfs_log_item_t	*lip;
678
+	struct xfs_log_item	*lip;
620679 
621680 	lip = xfs_ail_min(ailp);
622681 	if (!lip || XFS_FORCED_SHUTDOWN(ailp->ail_mount) ||
....@@ -671,6 +730,28 @@
671730 	finish_wait(&ailp->ail_empty, &wait);
672731 }
673732 
733
+void
734
+xfs_ail_update_finish(
735
+	struct xfs_ail		*ailp,
736
+	xfs_lsn_t		old_lsn) __releases(ailp->ail_lock)
737
+{
738
+	struct xfs_mount	*mp = ailp->ail_mount;
739
+
740
+	/* if the tail lsn hasn't changed, don't do updates or wakeups. */
741
+	if (!old_lsn || old_lsn == __xfs_ail_min_lsn(ailp)) {
742
+		spin_unlock(&ailp->ail_lock);
743
+		return;
744
+	}
745
+
746
+	if (!XFS_FORCED_SHUTDOWN(mp))
747
+		xlog_assign_tail_lsn_locked(mp);
748
+
749
+	if (list_empty(&ailp->ail_head))
750
+		wake_up_all(&ailp->ail_empty);
751
+	spin_unlock(&ailp->ail_lock);
752
+	xfs_log_space_wake(mp);
753
+}
754
+
674755 /*
675756  * xfs_trans_ail_update - bulk AIL insertion operation.
676757  *
....@@ -701,8 +782,8 @@
701782 	int			nr_items,
702783 	xfs_lsn_t		lsn) __releases(ailp->ail_lock)
703784 {
704
-	xfs_log_item_t		*mlip;
705
-	int			mlip_changed = 0;
785
+	struct xfs_log_item	*mlip;
786
+	xfs_lsn_t		tail_lsn = 0;
706787 	int			i;
707788 	LIST_HEAD(tmp);
708789 
....@@ -717,9 +798,10 @@
717798 				continue;
718799 
719800 			trace_xfs_ail_move(lip, lip->li_lsn, lsn);
801
+			if (mlip == lip && !tail_lsn)
802
+				tail_lsn = lip->li_lsn;
803
+
720804 			xfs_ail_delete(ailp, lip);
721
-			if (mlip == lip)
722
-				mlip_changed = 1;
723805 		} else {
724806 			trace_xfs_ail_insert(lip, 0, lsn);
725807 		}
....@@ -730,66 +812,58 @@
730812 	if (!list_empty(&tmp))
731813 		xfs_ail_splice(ailp, cur, &tmp, lsn);
732814 
733
-	if (mlip_changed) {
734
-		if (!XFS_FORCED_SHUTDOWN(ailp->ail_mount))
735
-			xlog_assign_tail_lsn_locked(ailp->ail_mount);
736
-		spin_unlock(&ailp->ail_lock);
737
-
738
-		xfs_log_space_wake(ailp->ail_mount);
739
-	} else {
740
-		spin_unlock(&ailp->ail_lock);
741
-	}
815
+	xfs_ail_update_finish(ailp, tail_lsn);
742816 }
743817 
744
-bool
818
+/* Insert a log item into the AIL. */
819
+void
820
+xfs_trans_ail_insert(
821
+	struct xfs_ail		*ailp,
822
+	struct xfs_log_item	*lip,
823
+	xfs_lsn_t		lsn)
824
+{
825
+	spin_lock(&ailp->ail_lock);
826
+	xfs_trans_ail_update_bulk(ailp, NULL, &lip, 1, lsn);
827
+}
828
+
829
+/*
830
+ * Delete one log item from the AIL.
831
+ *
832
+ * If this item was at the tail of the AIL, return the LSN of the log item so
833
+ * that we can use it to check if the LSN of the tail of the log has moved
834
+ * when finishing up the AIL delete process in xfs_ail_update_finish().
835
+ */
836
+xfs_lsn_t
745837 xfs_ail_delete_one(
746838 	struct xfs_ail		*ailp,
747839 	struct xfs_log_item	*lip)
748840 {
749841 	struct xfs_log_item	*mlip = xfs_ail_min(ailp);
842
+	xfs_lsn_t		lsn = lip->li_lsn;
750843 
751844 	trace_xfs_ail_delete(lip, mlip->li_lsn, lip->li_lsn);
752845 	xfs_ail_delete(ailp, lip);
753
-	xfs_clear_li_failed(lip);
754846 	clear_bit(XFS_LI_IN_AIL, &lip->li_flags);
755847 	lip->li_lsn = 0;
756848 
757
-	return mlip == lip;
849
+	if (mlip == lip)
850
+		return lsn;
851
+	return 0;
758852 }
759853 
760
-/**
761
- * Remove a log items from the AIL
762
- *
763
- * @xfs_trans_ail_delete_bulk takes an array of log items that all need to
764
- * removed from the AIL. The caller is already holding the AIL lock, and done
765
- * all the checks necessary to ensure the items passed in via @log_items are
766
- * ready for deletion. This includes checking that the items are in the AIL.
767
- *
768
- * For each log item to be removed, unlink it  from the AIL, clear the IN_AIL
769
- * flag from the item and reset the item's lsn to 0. If we remove the first
770
- * item in the AIL, update the log tail to match the new minimum LSN in the
771
- * AIL.
772
- *
773
- * This function will not drop the AIL lock until all items are removed from
774
- * the AIL to minimise the amount of lock traffic on the AIL. This does not
775
- * greatly increase the AIL hold time, but does significantly reduce the amount
776
- * of traffic on the lock, especially during IO completion.
777
- *
778
- * This function must be called with the AIL lock held.  The lock is dropped
779
- * before returning.
780
- */
781854 void
782855 xfs_trans_ail_delete(
783
-	struct xfs_ail		*ailp,
784856 	struct xfs_log_item	*lip,
785
-	int			shutdown_type) __releases(ailp->ail_lock)
857
+	int			shutdown_type)
786858 {
859
+	struct xfs_ail		*ailp = lip->li_ailp;
787860 	struct xfs_mount	*mp = ailp->ail_mount;
788
-	bool			mlip_changed;
861
+	xfs_lsn_t		tail_lsn;
789862 
863
+	spin_lock(&ailp->ail_lock);
790864 	if (!test_bit(XFS_LI_IN_AIL, &lip->li_flags)) {
791865 		spin_unlock(&ailp->ail_lock);
792
-		if (!XFS_FORCED_SHUTDOWN(mp)) {
866
+		if (shutdown_type && !XFS_FORCED_SHUTDOWN(mp)) {
793867 			xfs_alert_tag(mp, XFS_PTAG_AILDELETE,
794868 	"%s: attempting to delete a log item that is not in the AIL",
795869 					__func__);
....@@ -798,17 +872,10 @@
798872 		return;
799873 	}
800874 
801
-	mlip_changed = xfs_ail_delete_one(ailp, lip);
802
-	if (mlip_changed) {
803
-		if (!XFS_FORCED_SHUTDOWN(mp))
804
-			xlog_assign_tail_lsn_locked(mp);
805
-		if (list_empty(&ailp->ail_head))
806
-			wake_up_all(&ailp->ail_empty);
807
-	}
808
-
809
-	spin_unlock(&ailp->ail_lock);
810
-	if (mlip_changed)
811
-		xfs_log_space_wake(ailp->ail_mount);
875
+	/* xfs_ail_update_finish() drops the AIL lock */
876
+	xfs_clear_li_failed(lip);
877
+	tail_lsn = xfs_ail_delete_one(ailp, lip);
878
+	xfs_ail_update_finish(ailp, tail_lsn);
812879 }
813880 
814881 int
....@@ -829,7 +896,7 @@
829896 	init_waitqueue_head(&ailp->ail_empty);
830897 
831898 	ailp->ail_task = kthread_run(xfsaild, ailp, "xfsaild/%s",
832
-			ailp->ail_mount->m_fsname);
899
+			ailp->ail_mount->m_super->s_id);
833900 	if (IS_ERR(ailp->ail_task))
834901 		goto out_free_ailp;
835902