[PATCH 5.6 122/177] ceph: flush release queue when handling caps for unknown inode

From: Greg Kroah-Hartman
Date: Mon Jun 01 2020 - 14:38:47 EST

From: Jeff Layton <jlayton@xxxxxxxxxx>

[ Upstream commit fb33c114d3ed5bdac230716f5b0a93b56b92a90d ]

It's possible for the VFS to completely forget about an inode, but for
it to still be sitting on the cap release queue. If the MDS sends the
client a cap message for such an inode, it just ignores it today, which
can lead to a stall of up to 5s until the cap release queue is flushed.

If we get a cap message for an inode that can't be located, then go
ahead and flush the cap release queue.

Cc: stable@xxxxxxxxxxxxxxx
URL: https://tracker.ceph.com/issues/45532
Fixes: 1e9c2eb6811e ("ceph: delete stale dentry when last reference is dropped")
Reported-and-Tested-by: Andrej FilipÄiÄ <andrej.filipcic@xxxxxx>
Suggested-by: Yan, Zheng <zyan@xxxxxxxxxx>
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
fs/ceph/caps.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index f50204380a65..3ae88ca03ccd 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -3952,7 +3952,7 @@ void ceph_handle_caps(struct ceph_mds_session *session,
__ceph_queue_cap_release(session, cap);
- goto done;
+ goto flush_cap_releases;

/* these will work even if we don't have a cap yet */