[PATCH 2/2] xfs: another memory barrier before wake_up_bit()

[Alex Elder]

In xfs_inode_item_unpin() there is a call to wake_up_bit() following
an independent test for whether waiters should be awakened.  This
requires a memory barrier in order to guarantee correct operation
(see the comment above wake_up_bit()).

Signed-off-by: Alex Elder <elder at inktank.com>
---
 fs/xfs/xfs_inode_item.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/xfs/xfs_inode_item.c b/fs/xfs/xfs_inode_item.c
index d041d47..a7cacf7 100644
--- a/fs/xfs/xfs_inode_item.c
+++ b/fs/xfs/xfs_inode_item.c
@@ -474,8 +474,10 @@ xfs_inode_item_unpin(

 	trace_xfs_inode_unpin(ip, _RET_IP_);
 	ASSERT(atomic_read(&ip->i_pincount) > 0);
-	if (atomic_dec_and_test(&ip->i_pincount))
-		wake_up_bit(&ip->i_flags, __XFS_IPINNED_BIT);
+	if (!atomic_dec_and_test(&ip->i_pincount))
+		return;
+	smp_mb();
+	wake_up_bit(&ip->i_flags, __XFS_IPINNED_BIT);
 }

 STATIC uint
-- 
1.7.9.5