NLM: Ensure that nlmclnt_cancel_callback() doesn't loop forever

 If the server returns NLM_LCK_DENIED_NOLOCKS, we currently retry the
 entire NLM_CANCEL request. This may end up looping forever unless the
 server changes its mind (why would it do that, though?).

 Ensure that we limit the number of retries (to 3).

 See bug# 5957 in bugzilla.kernel.org.

 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/lockd/clntproc.c b/fs/lockd/clntproc.c
index b8ecfa1168f3..220058d8616d 100644
--- a/fs/lockd/clntproc.c
+++ b/fs/lockd/clntproc.c
@@ -22,6 +22,7 @@
 #define NLMDBG_FACILITY         NLMDBG_CLIENT
 #define NLMCLNT_GRACE_WAIT      (5*HZ)
 #define NLMCLNT_POLL_TIMEOUT    (30*HZ)
+#define NLMCLNT_MAX_RETRIES     3
 
 static int      nlmclnt_test(struct nlm_rqst *, struct file_lock *);
 static int      nlmclnt_lock(struct nlm_rqst *, struct file_lock *);
@@ -802,6 +803,9 @@ die:
         return;
 
 retry_cancel:
+        /* Don't ever retry more than 3 times */
+        if (req->a_retries++ >= NLMCLNT_MAX_RETRIES)
+                goto die;
         nlm_rebind_host(req->a_host);
         rpc_restart_call(task);
         rpc_delay(task, 30 * HZ);