ceph: fix multiple mds session shutdown

The use of a completion when waiting for session shutdown during umount is
inappropriate, given the complexity of the condition.  For multiple MDS's,
this resulted in the umount thread spinning, often preventing the session
close message from being processed in some cases.

Switch to a waitqueue and defined a condition helper.  This cleans things
up nicely.

Signed-off-by: Sage Weil <sage@newdream.net>

1 files changed, 2 insertions, 1 deletions

diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h
index ab7e89f5e344..c98267ce6d2a 100644
--- a/fs/ceph/mds_client.h
+++ b/fs/ceph/mds_client.h
@@ -234,7 +234,8 @@ struct ceph_mds_client {
         struct mutex            mutex;         /* all nested structures */
 
         struct ceph_mdsmap      *mdsmap;
-        struct completion       safe_umount_waiters, session_close_waiters;
+        struct completion       safe_umount_waiters;
+        wait_queue_head_t       session_close_wq;
         struct list_head        waiting_for_map;
 
         struct ceph_mds_session **sessions;    /* NULL for mds if no session */