NLM: Fix reclaim races

Currently it is possible for a task to remove its locks at the same time as
the NLM recovery thread is trying to recover them. This quickly leads to an
Oops.
Protect the locks using an rw semaphore while they are being recovered.

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

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/lockd/host.c b/fs/lockd/host.c
index 5242743c9403..38b0e8a1aec0 100644
--- a/fs/lockd/host.c
+++ b/fs/lockd/host.c
@@ -117,6 +117,7 @@ nlm_lookup_host(int server, struct sockaddr_in *sin,
         host->h_expires    = jiffies + NLM_HOST_EXPIRE;
         atomic_set(&host->h_count, 1);
         init_waitqueue_head(&host->h_gracewait);
+        init_rwsem(&host->h_rwsem);
         host->h_state      = 0;                 /* pseudo NSM state */
         host->h_nsmstate   = 0;                 /* real NSM state */
         host->h_server     = server;