NFSv4: Ensure delegation recall and byte range lock removal don't conflict

Add a mutex to the struct nfs4_state_owner to ensure that delegation
recall doesn't conflict with byte range lock removal.

Note that we nest the new mutex _outside_ the state manager reclaim
protection (nfsi->rwsem) in order to avoid deadlocks.

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

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/nfs/nfs4_fs.h b/fs/nfs/nfs4_fs.h
index b12b73472020..944c9a5c1039 100644
--- a/fs/nfs/nfs4_fs.h
+++ b/fs/nfs/nfs4_fs.h
@@ -93,6 +93,7 @@ struct nfs4_state_owner {
         struct list_head     so_states;
         struct nfs_seqid_counter so_seqid;
         seqcount_t           so_reclaim_seqcount;
+        struct mutex         so_delegreturn_mutex;
 };
 
 enum {