ceph: handle race between cap reconnect and cap release

When a cap get released while composing the cap reconnect message.
We should skip queuing the release message if the cap hasn't been
added to the cap reconnect message.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: Sage Weil <sage@inktank.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index d2d6e40e7345..3c0a4bd74996 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -909,7 +909,13 @@ void __ceph_remove_cap(struct ceph_cap *cap, bool queue_release)
 
         /* remove from session list */
         spin_lock(&session->s_cap_lock);
-        if (queue_release)
+        /*
+         * s_cap_reconnect is protected by s_cap_lock. no one changes
+         * s_cap_gen while session is in the reconnect state.
+         */
+        if (queue_release &&
+            (!session->s_cap_reconnect ||
+             cap->cap_gen == session->s_cap_gen))
                 __queue_cap_release(session, ci->i_vino.ino, cap->cap_id,
                                     cap->mseq, cap->issue_seq);