ceph: don't skip updating wanted caps when cap is stale

[ Upstream commit 0aa971b6fd3f92afef6afe24ef78d9bb14471519 ]

1. try_get_cap_refs() fails to get caps and finds that mds_wanted
   does not include what it wants. It returns -ESTALE.
2. ceph_get_caps() calls ceph_renew_caps(). ceph_renew_caps() finds
   that inode has cap, so it calls ceph_check_caps().
3. ceph_check_caps() finds that issued caps (without checking if it's
   stale) already includes caps wanted by open file, so it skips
   updating wanted caps.

Above events can cause an infinite loop inside ceph_get_caps().

Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index f5a38910a82bfb94d71ceab28af196b3d0165c6f..703945cce0e5d9ec4b0200127346e63c8d6ae6c9 100644 (file)
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -1976,8 +1976,12 @@ retry_locked:
                }
 
                /* want more caps from mds? */
-               if (want & ~(cap->mds_wanted | cap->issued))
-                       goto ack;
+               if (want & ~cap->mds_wanted) {
+                       if (want & ~(cap->mds_wanted | cap->issued))
+                               goto ack;
+                       if (!__cap_is_valid(cap))
+                               goto ack;
+               }
 
                /* things we might delay */
                if ((cap->issued & ~retain) == 0)