NFSv4: Recover locks too when returning a delegation

Delegations allow us to cache posix and BSD locks, however when the
 delegation is recalled, we need to "flush the cache" and send
 the cached LOCK requests to the server.

 This patch sets up the mechanism for doing so.

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

fs/nfs/nfs4proc.c

@@ -3124,6 +3124,24 @@ nfs4_proc_lock(struct file *filp, int cmd, struct file_lock *request)
 	return status;
 }
 
+int nfs4_lock_delegation_recall(struct nfs4_state *state, struct file_lock *fl)
+{
+	struct nfs_server *server = NFS_SERVER(state->inode);
+	struct nfs4_exception exception = { };
+	int err;
+
+	err = nfs4_set_lock_state(state, fl);
+	if (err != 0)
+		goto out;
+	do {
+		err = _nfs4_do_setlk(state, F_SETLK, fl, 0);
+		if (err != -NFS4ERR_DELAY)
+			break;
+		err = nfs4_handle_exception(server, err, &exception);
+	} while (exception.retry);
+out:
+	return err;
+}
 
 #define XATTR_NAME_NFSV4_ACL "system.nfs4_acl"