NFS: __nfs_find_lock_context needs to check ctx->lock_context for a match too

Currently, we're forcing an unnecessary duplication of the
initial nfs_lock_context in calls to nfs_get_lock_context, since
__nfs_find_lock_context ignores the ctx->lock_context.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/inode.c

@@ -565,16 +565,17 @@ static void nfs_init_lock_context(struct nfs_lock_context *l_ctx)
 
 static struct nfs_lock_context *__nfs_find_lock_context(struct nfs_open_context *ctx)
 {
-	struct nfs_lock_context *pos;
+	struct nfs_lock_context *head = &ctx->lock_context;
+	struct nfs_lock_context *pos = head;
 
-	list_for_each_entry(pos, &ctx->lock_context.list, list) {
+	do {
 		if (pos->lockowner.l_owner != current->files)
 			continue;
 		if (pos->lockowner.l_pid != current->tgid)
 			continue;
 		atomic_inc(&pos->count);
 		return pos;
-	}
+	} while ((pos = list_entry(pos->list.next, typeof(*pos), list)) != head);
 	return NULL;
 }