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/include/linux/lockd/lockd.h b/include/linux/lockd/lockd.h
index a6c1a33e5ae3..6b2684763fc7 100644
--- a/include/linux/lockd/lockd.h
+++ b/include/linux/lockd/lockd.h
@@ -50,6 +50,7 @@ struct nlm_host {
                                 h_killed     : 1,
                                 h_monitored  : 1;
         wait_queue_head_t       h_gracewait;    /* wait while reclaiming */
+        struct rw_semaphore     h_rwsem;        /* Reboot recovery lock */
         u32                     h_state;        /* pseudo-state counter */
         u32                     h_nsmstate;     /* true remote NSM state */
         u32                     h_pidcount;     /* Pseudopids */