ceph: Update max_len with minimum required size

encode_fh on error should update max_len with minimum required
size, so that caller can redo the call with the reallocated buffer.
This is required with open by handle patch series

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Sage Weil <sage@newdream.net>

fs/ceph/export.c

@@ -62,13 +62,16 @@ static int ceph_encode_fh(struct dentry *dentry, u32 *rawfh, int *max_len,
 		*max_len = connected_handle_length;
 		type = 2;
 	} else if (*max_len >= handle_length) {
-		if (connectable)
+		if (connectable) {
+			*max_len = connected_handle_length;
 			return 255;
+		}
 		dout("encode_fh %p\n", dentry);
 		fh->ino = ceph_ino(dentry->d_inode);
 		*max_len = handle_length;
 		type = 1;
 	} else {
+		*max_len = handle_length;
 		return 255;
 	}
 	return type;