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authorBrian Foster <bfoster@redhat.com>2013-02-11 10:08:21 -0500
committerBen Myers <bpm@sgi.com>2013-02-14 17:23:42 -0600
commit5337fe9b108d602c483fe9d62ffef9227acf3a74 (patch)
tree3f0a022ab4dbd7e60fd0f98778e6602c313d453b /fs/xfs
parenta1e16c26660b301cc8423185924cf1b0b16ea92b (diff)
downloadlinux-5337fe9b108d602c483fe9d62ffef9227acf3a74.tar.gz
xfs: recheck buffer pinned status after push trylock failure
The buffer pinned check and trylock sequence in xfs_buf_item_push() can race with an active transaction on marking the buffer pinned. This can result in the buffer becoming pinned and stale after the initial check and the trylock failure, but before the check in xfs_buf_trylock() that issues a log force. If the log force is issued from this context, a spinlock recursion occurs on xa_lock. Prepare xfs_buf_item_push() to handle the race by detecting a pinned buffer after the trylock failure so xfsaild issues a log force from a safe context. This, along with various previous fixes, renders the log force in xfs_buf_trylock() redundant. Signed-off-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Ben Myers <bpm@sgi.com>
Diffstat (limited to 'fs/xfs')
-rw-r--r--fs/xfs/xfs_buf_item.c12
1 files changed, 11 insertions, 1 deletions
diff --git a/fs/xfs/xfs_buf_item.c b/fs/xfs/xfs_buf_item.c
index 9c4c050e427..cf263476d6b 100644
--- a/fs/xfs/xfs_buf_item.c
+++ b/fs/xfs/xfs_buf_item.c
@@ -469,8 +469,18 @@ xfs_buf_item_push(
if (xfs_buf_ispinned(bp))
return XFS_ITEM_PINNED;
- if (!xfs_buf_trylock(bp))
+ if (!xfs_buf_trylock(bp)) {
+ /*
+ * If we have just raced with a buffer being pinned and it has
+ * been marked stale, we could end up stalling until someone else
+ * issues a log force to unpin the stale buffer. Check for the
+ * race condition here so xfsaild recognizes the buffer is pinned
+ * and queues a log force to move it along.
+ */
+ if (xfs_buf_ispinned(bp))
+ return XFS_ITEM_PINNED;
return XFS_ITEM_LOCKED;
+ }
ASSERT(!(bip->bli_flags & XFS_BLI_STALE));