[PATCH 01/10] xfs: log item flags are racy

[Dave Chinner <david@fromorbit.com>]

From: Dave Chinner <dchinner@redhat.com>

The log item flags contain a field that is protected by the AIL
lock - the XFS_LI_IN_AIL flag. We use non-atomic RMW operations to
set and clear these flags, but most of the updates and checks are
not done with the AIL lock held and so are susceptible to update
races.

Fix this by changing the log item flags to use atomic bitops rather
than be reliant on the AIL lock for update serialisation.

Signed-Off-By: Dave Chinner <dchinner@redhat.com>
---
 fs/xfs/xfs_bmap_item.c     |  4 ++--
 fs/xfs/xfs_buf_item.c      |  4 +++-
 fs/xfs/xfs_dquot.c         |  7 +++----
 fs/xfs/xfs_dquot_item.c    |  2 +-
 fs/xfs/xfs_extfree_item.c  |  4 ++--
 fs/xfs/xfs_icache.c        |  3 ++-
 fs/xfs/xfs_icreate_item.c  |  2 +-
 fs/xfs/xfs_inode.c         |  4 ++--
 fs/xfs/xfs_inode_item.c    |  8 ++++----
 fs/xfs/xfs_log.c           |  2 +-
 fs/xfs/xfs_qm.c            |  2 +-
 fs/xfs/xfs_refcount_item.c |  4 ++--
 fs/xfs/xfs_rmap_item.c     |  4 ++--
 fs/xfs/xfs_trace.h         |  6 +++---
 fs/xfs/xfs_trans.c         |  4 ++--
 fs/xfs/xfs_trans.h         | 19 ++++++++++++-------
 fs/xfs/xfs_trans_ail.c     |  9 ++++-----
 fs/xfs/xfs_trans_buf.c     |  2 +-
 fs/xfs/xfs_trans_priv.h    | 10 ++++------
 19 files changed, 52 insertions(+), 48 deletions(-)

diff --git a/fs/xfs/xfs_bmap_item.c b/fs/xfs/xfs_bmap_item.c
index 2203465e63ea..618bb71535c8 100644
--- a/fs/xfs/xfs_bmap_item.c
+++ b/fs/xfs/xfs_bmap_item.c
@@ -160,7 +160,7 @@ STATIC void
 xfs_bui_item_unlock(
 	struct xfs_log_item	*lip)
 {
-	if (lip->li_flags & XFS_LI_ABORTED)
+	if (test_bit(XFS_LI_ABORTED, &lip->li_flags))
 		xfs_bui_release(BUI_ITEM(lip));
 }
 
@@ -305,7 +305,7 @@ xfs_bud_item_unlock(
 {
 	struct xfs_bud_log_item	*budp = BUD_ITEM(lip);
 
-	if (lip->li_flags & XFS_LI_ABORTED) {
+	if (test_bit(XFS_LI_ABORTED, &lip->li_flags)) {
 		xfs_bui_release(budp->bud_buip);
 		kmem_zone_free(xfs_bud_zone, budp);
 	}
diff --git a/fs/xfs/xfs_buf_item.c b/fs/xfs/xfs_buf_item.c
index 76b21f780af8..53c07a7a14fb 100644
--- a/fs/xfs/xfs_buf_item.c
+++ b/fs/xfs/xfs_buf_item.c
@@ -545,13 +545,15 @@ xfs_buf_item_unlock(
 {
 	struct xfs_buf_log_item	*bip = BUF_ITEM(lip);
 	struct xfs_buf		*bp = bip->bli_buf;
-	bool			aborted = !!(lip->li_flags & XFS_LI_ABORTED);
+	bool			aborted;
 	bool			hold = !!(bip->bli_flags & XFS_BLI_HOLD);
 	bool			dirty = !!(bip->bli_flags & XFS_BLI_DIRTY);
 #if defined(DEBUG) || defined(XFS_WARN)
 	bool			ordered = !!(bip->bli_flags & XFS_BLI_ORDERED);
 #endif
 
+	aborted = test_bit(XFS_LI_ABORTED, &lip->li_flags);
+
 	/* Clear the buffer's association with this transaction. */
 	bp->b_transp = NULL;
 
diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c
index a7daef9e16bf..d0b65679baae 100644
--- a/fs/xfs/xfs_dquot.c
+++ b/fs/xfs/xfs_dquot.c
@@ -913,9 +913,9 @@ xfs_qm_dqflush_done(
 	 * since it's cheaper, and then we recheck while
 	 * holding the lock before removing the dquot from the AIL.
 	 */
-	if ((lip->li_flags & XFS_LI_IN_AIL) &&
+	if (test_bit(XFS_LI_IN_AIL, &lip->li_flags) &&
 	    ((lip->li_lsn == qip->qli_flush_lsn) ||
-	     (lip->li_flags & XFS_LI_FAILED))) {
+	     test_bit(XFS_LI_FAILED, &lip->li_flags))) {
 
 		/* xfs_trans_ail_delete() drops the AIL lock. */
 		spin_lock(&ailp->ail_lock);
@@ -926,8 +926,7 @@ xfs_qm_dqflush_done(
 			 * Clear the failed state since we are about to drop the
 			 * flush lock
 			 */
-			if (lip->li_flags & XFS_LI_FAILED)
-				xfs_clear_li_failed(lip);
+			xfs_clear_li_failed(lip);
 			spin_unlock(&ailp->ail_lock);
 		}
 	}
diff --git a/fs/xfs/xfs_dquot_item.c b/fs/xfs/xfs_dquot_item.c
index 4b331e354da7..57df98122156 100644
--- a/fs/xfs/xfs_dquot_item.c
+++ b/fs/xfs/xfs_dquot_item.c
@@ -173,7 +173,7 @@ xfs_qm_dquot_logitem_push(
 	 * The buffer containing this item failed to be written back
 	 * previously. Resubmit the buffer for IO
 	 */
-	if (lip->li_flags & XFS_LI_FAILED) {
+	if (test_bit(XFS_LI_FAILED, &lip->li_flags)) {
 		if (!xfs_buf_trylock(bp))
 			return XFS_ITEM_LOCKED;
 
diff --git a/fs/xfs/xfs_extfree_item.c b/fs/xfs/xfs_extfree_item.c
index b5b1e567b9f4..70b7d48af6d6 100644
--- a/fs/xfs/xfs_extfree_item.c
+++ b/fs/xfs/xfs_extfree_item.c
@@ -168,7 +168,7 @@ STATIC void
 xfs_efi_item_unlock(
 	struct xfs_log_item	*lip)
 {
-	if (lip->li_flags & XFS_LI_ABORTED)
+	if (test_bit(XFS_LI_ABORTED, &lip->li_flags))
 		xfs_efi_release(EFI_ITEM(lip));
 }
 
@@ -402,7 +402,7 @@ xfs_efd_item_unlock(
 {
 	struct xfs_efd_log_item	*efdp = EFD_ITEM(lip);
 
-	if (lip->li_flags & XFS_LI_ABORTED) {
+	if (test_bit(XFS_LI_ABORTED, &lip->li_flags)) {
 		xfs_efi_release(efdp->efd_efip);
 		xfs_efd_item_free(efdp);
 	}
diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
index 8cb2ad1cc2ec..fb37ada55710 100644
--- a/fs/xfs/xfs_icache.c
+++ b/fs/xfs/xfs_icache.c
@@ -107,7 +107,8 @@ xfs_inode_free_callback(
 		xfs_idestroy_fork(ip, XFS_COW_FORK);
 
 	if (ip->i_itemp) {
-		ASSERT(!(ip->i_itemp->ili_item.li_flags & XFS_LI_IN_AIL));
+		ASSERT(!test_bit(XFS_LI_IN_AIL,
+				 &ip->i_itemp->ili_item.li_flags));
 		xfs_inode_item_destroy(ip);
 		ip->i_itemp = NULL;
 	}
diff --git a/fs/xfs/xfs_icreate_item.c b/fs/xfs/xfs_icreate_item.c
index 865ad1373e5e..a99a0f8aa528 100644
--- a/fs/xfs/xfs_icreate_item.c
+++ b/fs/xfs/xfs_icreate_item.c
@@ -91,7 +91,7 @@ xfs_icreate_item_unlock(
 {
 	struct xfs_icreate_item	*icp = ICR_ITEM(lip);
 
-	if (icp->ic_item.li_flags & XFS_LI_ABORTED)
+	if (test_bit(XFS_LI_ABORTED, &lip->li_flags))
 		kmem_zone_free(xfs_icreate_zone, icp);
 	return;
 }
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index bdd92c18a4f3..2cb294e608a0 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -498,7 +498,7 @@ xfs_lock_inodes(
 		if (!try_lock) {
 			for (j = (i - 1); j >= 0 && !try_lock; j--) {
 				lp = (xfs_log_item_t *)ips[j]->i_itemp;
-				if (lp && (lp->li_flags & XFS_LI_IN_AIL))
+				if (lp && test_bit(XFS_LI_IN_AIL, &lp->li_flags))
 					try_lock++;
 			}
 		}
@@ -598,7 +598,7 @@ xfs_lock_two_inodes(
 	 * and try again.
 	 */
 	lp = (xfs_log_item_t *)ip0->i_itemp;
-	if (lp && (lp->li_flags & XFS_LI_IN_AIL)) {
+	if (lp && test_bit(XFS_LI_IN_AIL, &lp->li_flags)) {
 		if (!xfs_ilock_nowait(ip1, xfs_lock_inumorder(ip1_mode, 1))) {
 			xfs_iunlock(ip0, ip0_mode);
 			if ((++attempts % 5) == 0)
diff --git a/fs/xfs/xfs_inode_item.c b/fs/xfs/xfs_inode_item.c
index 34b91b789702..3e5b8574818e 100644
--- a/fs/xfs/xfs_inode_item.c
+++ b/fs/xfs/xfs_inode_item.c
@@ -518,7 +518,7 @@ xfs_inode_item_push(
 	 * The buffer containing this item failed to be written back
 	 * previously. Resubmit the buffer for IO.
 	 */
-	if (lip->li_flags & XFS_LI_FAILED) {
+	if (test_bit(XFS_LI_FAILED, &lip->li_flags)) {
 		if (!xfs_buf_trylock(bp))
 			return XFS_ITEM_LOCKED;
 
@@ -729,14 +729,14 @@ xfs_iflush_done(
 		 */
 		iip = INODE_ITEM(blip);
 		if ((iip->ili_logged && blip->li_lsn == iip->ili_flush_lsn) ||
-		    (blip->li_flags & XFS_LI_FAILED))
+		    test_bit(XFS_LI_FAILED, &blip->li_flags))
 			need_ail++;
 	}
 
 	/* make sure we capture the state of the initial inode. */
 	iip = INODE_ITEM(lip);
 	if ((iip->ili_logged && lip->li_lsn == iip->ili_flush_lsn) ||
-	    lip->li_flags & XFS_LI_FAILED)
+	    test_bit(XFS_LI_FAILED, &lip->li_flags))
 		need_ail++;
 
 	/*
@@ -803,7 +803,7 @@ xfs_iflush_abort(
 	xfs_inode_log_item_t	*iip = ip->i_itemp;
 
 	if (iip) {
-		if (iip->ili_item.li_flags & XFS_LI_IN_AIL) {
+		if (test_bit(XFS_LI_IN_AIL, &iip->ili_item.li_flags)) {
 			xfs_trans_ail_remove(&iip->ili_item,
 					     stale ? SHUTDOWN_LOG_IO_ERROR :
 						     SHUTDOWN_CORRUPT_INCORE);
diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 2fcd9ed5d075..e427864434c1 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -2132,7 +2132,7 @@ xlog_print_trans(
 
 		xfs_warn(mp, "log item: ");
 		xfs_warn(mp, "  type	= 0x%x", lip->li_type);
-		xfs_warn(mp, "  flags	= 0x%x", lip->li_flags);
+		xfs_warn(mp, "  flags	= 0x%lx", lip->li_flags);
 		if (!lv)
 			continue;
 		xfs_warn(mp, "  niovecs	= %d", lv->lv_niovecs);
diff --git a/fs/xfs/xfs_qm.c b/fs/xfs/xfs_qm.c
index aff4924f637f..f93bf427d2da 100644
--- a/fs/xfs/xfs_qm.c
+++ b/fs/xfs/xfs_qm.c
@@ -173,7 +173,7 @@ xfs_qm_dqpurge(
 
 	ASSERT(atomic_read(&dqp->q_pincount) == 0);
 	ASSERT(XFS_FORCED_SHUTDOWN(mp) ||
-	       !(dqp->q_logitem.qli_item.li_flags & XFS_LI_IN_AIL));
+		!test_bit(XFS_LI_IN_AIL, &dqp->q_logitem.qli_item.li_flags));
 
 	xfs_dqfunlock(dqp);
 	xfs_dqunlock(dqp);
diff --git a/fs/xfs/xfs_refcount_item.c b/fs/xfs/xfs_refcount_item.c
index 15c9393dd7a7..e5866b714d5f 100644
--- a/fs/xfs/xfs_refcount_item.c
+++ b/fs/xfs/xfs_refcount_item.c
@@ -159,7 +159,7 @@ STATIC void
 xfs_cui_item_unlock(
 	struct xfs_log_item	*lip)
 {
-	if (lip->li_flags & XFS_LI_ABORTED)
+	if (test_bit(XFS_LI_ABORTED, &lip->li_flags))
 		xfs_cui_release(CUI_ITEM(lip));
 }
 
@@ -310,7 +310,7 @@ xfs_cud_item_unlock(
 {
 	struct xfs_cud_log_item	*cudp = CUD_ITEM(lip);
 
-	if (lip->li_flags & XFS_LI_ABORTED) {
+	if (test_bit(XFS_LI_ABORTED, &lip->li_flags)) {
 		xfs_cui_release(cudp->cud_cuip);
 		kmem_zone_free(xfs_cud_zone, cudp);
 	}
diff --git a/fs/xfs/xfs_rmap_item.c b/fs/xfs/xfs_rmap_item.c
index 06a07846c9b3..e5b5b3e7ef82 100644
--- a/fs/xfs/xfs_rmap_item.c
+++ b/fs/xfs/xfs_rmap_item.c
@@ -158,7 +158,7 @@ STATIC void
 xfs_rui_item_unlock(
 	struct xfs_log_item	*lip)
 {
-	if (lip->li_flags & XFS_LI_ABORTED)
+	if (test_bit(XFS_LI_ABORTED, &lip->li_flags))
 		xfs_rui_release(RUI_ITEM(lip));
 }
 
@@ -331,7 +331,7 @@ xfs_rud_item_unlock(
 {
 	struct xfs_rud_log_item	*rudp = RUD_ITEM(lip);
 
-	if (lip->li_flags & XFS_LI_ABORTED) {
+	if (test_bit(XFS_LI_ABORTED, &lip->li_flags)) {
 		xfs_rui_release(rudp->rud_ruip);
 		kmem_zone_free(xfs_rud_zone, rudp);
 	}
diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index 8955254b900e..7f4d961fae12 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -442,7 +442,7 @@ DECLARE_EVENT_CLASS(xfs_buf_item_class,
 		__field(int, bli_refcount)
 		__field(unsigned, bli_flags)
 		__field(void *, li_desc)
-		__field(unsigned, li_flags)
+		__field(unsigned long, li_flags)
 	),
 	TP_fast_assign(
 		__entry->dev = bip->bli_buf->b_target->bt_dev;
@@ -1018,7 +1018,7 @@ DECLARE_EVENT_CLASS(xfs_log_item_class,
 		__field(dev_t, dev)
 		__field(void *, lip)
 		__field(uint, type)
-		__field(uint, flags)
+		__field(unsigned long, flags)
 		__field(xfs_lsn_t, lsn)
 	),
 	TP_fast_assign(
@@ -1070,7 +1070,7 @@ DECLARE_EVENT_CLASS(xfs_ail_class,
 		__field(dev_t, dev)
 		__field(void *, lip)
 		__field(uint, type)
-		__field(uint, flags)
+		__field(unsigned long, flags)
 		__field(xfs_lsn_t, old_lsn)
 		__field(xfs_lsn_t, new_lsn)
 	),
diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c
index d6d8f9d129a7..c6a2a3cb9df5 100644
--- a/fs/xfs/xfs_trans.c
+++ b/fs/xfs/xfs_trans.c
@@ -790,7 +790,7 @@ xfs_trans_free_items(
 		if (commit_lsn != NULLCOMMITLSN)
 			lip->li_ops->iop_committing(lip, commit_lsn);
 		if (abort)
-			lip->li_flags |= XFS_LI_ABORTED;
+			set_bit(XFS_LI_ABORTED, &lip->li_flags);
 		lip->li_ops->iop_unlock(lip);
 
 		xfs_trans_free_item_desc(lidp);
@@ -861,7 +861,7 @@ xfs_trans_committed_bulk(
 		xfs_lsn_t		item_lsn;
 
 		if (aborted)
-			lip->li_flags |= XFS_LI_ABORTED;
+			set_bit(XFS_LI_ABORTED, &lip->li_flags);
 		item_lsn = lip->li_ops->iop_committed(lip, commit_lsn);
 
 		/* item_lsn of -1 means the item needs no further processing */
diff --git a/fs/xfs/xfs_trans.h b/fs/xfs/xfs_trans.h
index 9d542dfe0052..51145ddf7e5b 100644
--- a/fs/xfs/xfs_trans.h
+++ b/fs/xfs/xfs_trans.h
@@ -48,7 +48,7 @@ typedef struct xfs_log_item {
 	struct xfs_mount		*li_mountp;	/* ptr to fs mount */
 	struct xfs_ail			*li_ailp;	/* ptr to AIL */
 	uint				li_type;	/* item type */
-	uint				li_flags;	/* misc flags */
+	unsigned long			li_flags;	/* misc flags */
 	struct xfs_buf			*li_buf;	/* real buffer pointer */
 	struct list_head		li_bio_list;	/* buffer item list */
 	void				(*li_cb)(struct xfs_buf *,
@@ -64,14 +64,19 @@ typedef struct xfs_log_item {
 	xfs_lsn_t			li_seq;		/* CIL commit seq */
 } xfs_log_item_t;
 
-#define	XFS_LI_IN_AIL	0x1
-#define	XFS_LI_ABORTED	0x2
-#define	XFS_LI_FAILED	0x4
+/*
+ * li_flags use the (set/test/clear)_bit atomic interfaces because updates can
+ * race with each other and we don't want to have to use the AIL lock to
+ * serialise all updates.
+ */
+#define	XFS_LI_IN_AIL	0
+#define	XFS_LI_ABORTED	1
+#define	XFS_LI_FAILED	2
 
 #define XFS_LI_FLAGS \
-	{ XFS_LI_IN_AIL,	"IN_AIL" }, \
-	{ XFS_LI_ABORTED,	"ABORTED" }, \
-	{ XFS_LI_FAILED,	"FAILED" }
+	{ (1 << XFS_LI_IN_AIL),		"IN_AIL" }, \
+	{ (1 << XFS_LI_ABORTED),	"ABORTED" }, \
+	{ (1 << XFS_LI_FAILED),		"FAILED" }
 
 struct xfs_item_ops {
 	void (*iop_size)(xfs_log_item_t *, int *, int *);
diff --git a/fs/xfs/xfs_trans_ail.c b/fs/xfs/xfs_trans_ail.c
index d4a2445215e6..50611d2bcbc2 100644
--- a/fs/xfs/xfs_trans_ail.c
+++ b/fs/xfs/xfs_trans_ail.c
@@ -46,7 +46,7 @@ xfs_ail_check(
 	/*
 	 * Check the next and previous entries are valid.
 	 */
-	ASSERT((lip->li_flags & XFS_LI_IN_AIL) != 0);
+	ASSERT(test_bit(XFS_LI_IN_AIL, &lip->li_flags));
 	prev_lip = list_entry(lip->li_ail.prev, xfs_log_item_t, li_ail);
 	if (&prev_lip->li_ail != &ailp->ail_head)
 		ASSERT(XFS_LSN_CMP(prev_lip->li_lsn, lip->li_lsn) <= 0);
@@ -684,7 +684,7 @@ xfs_trans_ail_update_bulk(
 
 	for (i = 0; i < nr_items; i++) {
 		struct xfs_log_item *lip = log_items[i];
-		if (lip->li_flags & XFS_LI_IN_AIL) {
+		if (test_and_set_bit(XFS_LI_IN_AIL, &lip->li_flags)) {
 			/* check if we really need to move the item */
 			if (XFS_LSN_CMP(lsn, lip->li_lsn) <= 0)
 				continue;
@@ -694,7 +694,6 @@ xfs_trans_ail_update_bulk(
 			if (mlip == lip)
 				mlip_changed = 1;
 		} else {
-			lip->li_flags |= XFS_LI_IN_AIL;
 			trace_xfs_ail_insert(lip, 0, lsn);
 		}
 		lip->li_lsn = lsn;
@@ -725,7 +724,7 @@ xfs_ail_delete_one(
 	trace_xfs_ail_delete(lip, mlip->li_lsn, lip->li_lsn);
 	xfs_ail_delete(ailp, lip);
 	xfs_clear_li_failed(lip);
-	lip->li_flags &= ~XFS_LI_IN_AIL;
+	clear_bit(XFS_LI_IN_AIL, &lip->li_flags);
 	lip->li_lsn = 0;
 
 	return mlip == lip;
@@ -761,7 +760,7 @@ xfs_trans_ail_delete(
 	struct xfs_mount	*mp = ailp->ail_mount;
 	bool			mlip_changed;
 
-	if (!(lip->li_flags & XFS_LI_IN_AIL)) {
+	if (!test_bit(XFS_LI_IN_AIL, &lip->li_flags)) {
 		spin_unlock(&ailp->ail_lock);
 		if (!XFS_FORCED_SHUTDOWN(mp)) {
 			xfs_alert_tag(mp, XFS_PTAG_AILDELETE,
diff --git a/fs/xfs/xfs_trans_buf.c b/fs/xfs/xfs_trans_buf.c
index b26c5973da90..88557dfea21f 100644
--- a/fs/xfs/xfs_trans_buf.c
+++ b/fs/xfs/xfs_trans_buf.c
@@ -442,7 +442,7 @@ xfs_trans_brelse(
 		ASSERT(bp->b_pincount == 0);
 ***/
 		ASSERT(atomic_read(&bip->bli_refcount) == 0);
-		ASSERT(!(bip->bli_item.li_flags & XFS_LI_IN_AIL));
+		ASSERT(!test_bit(XFS_LI_IN_AIL, &bip->bli_item.li_flags));
 		ASSERT(!(bip->bli_flags & XFS_BLI_INODE_ALLOC_BUF));
 		xfs_buf_item_relse(bp);
 	}
diff --git a/fs/xfs/xfs_trans_priv.h b/fs/xfs/xfs_trans_priv.h
index be24b0c8a332..43f773297b9d 100644
--- a/fs/xfs/xfs_trans_priv.h
+++ b/fs/xfs/xfs_trans_priv.h
@@ -119,7 +119,7 @@ xfs_trans_ail_remove(
 
 	spin_lock(&ailp->ail_lock);
 	/* xfs_trans_ail_delete() drops the AIL lock */
-	if (lip->li_flags & XFS_LI_IN_AIL)
+	if (test_bit(XFS_LI_IN_AIL, &lip->li_flags))
 		xfs_trans_ail_delete(ailp, lip, shutdown_type);
 	else
 		spin_unlock(&ailp->ail_lock);
@@ -171,11 +171,10 @@ xfs_clear_li_failed(
 {
 	struct xfs_buf	*bp = lip->li_buf;
 
-	ASSERT(lip->li_flags & XFS_LI_IN_AIL);
+	ASSERT(test_bit(XFS_LI_IN_AIL, &lip->li_flags));
 	lockdep_assert_held(&lip->li_ailp->ail_lock);
 
-	if (lip->li_flags & XFS_LI_FAILED) {
-		lip->li_flags &= ~XFS_LI_FAILED;
+	if (test_and_clear_bit(XFS_LI_FAILED, &lip->li_flags)) {
 		lip->li_buf = NULL;
 		xfs_buf_rele(bp);
 	}
@@ -188,9 +187,8 @@ xfs_set_li_failed(
 {
 	lockdep_assert_held(&lip->li_ailp->ail_lock);
 
-	if (!(lip->li_flags & XFS_LI_FAILED)) {
+	if (!test_and_set_bit(XFS_LI_FAILED, &lip->li_flags)) {
 		xfs_buf_hold(bp);
-		lip->li_flags |= XFS_LI_FAILED;
 		lip->li_buf = bp;
 	}
 }
-- 
2.17.0