ext4: properly align shifted xattrs when expanding inodes

We did not count with the padding of xattr value when computing desired
shift of xattrs in the inode when expanding i_extra_isize. As a result
we could create unaligned start of inline xattrs. Account for alignment
properly.

CC: stable@vger.kernel.org  # 4.4.x-
Signed-off-by: Jan Kara <jack@suse.cz>

fs/ext4/xattr.c

@@ -1522,7 +1522,7 @@ retry:
 		if (entry_size + EXT4_XATTR_SIZE(size) >= isize_diff)
 			shift_bytes = isize_diff;
 		else
-			shift_bytes = entry_size + size;
+			shift_bytes = entry_size + EXT4_XATTR_SIZE(size);
 		/* Adjust the offsets and shift the remaining entries ahead */
 		ext4_xattr_shift_entries(entry, -shift_bytes,
 			(void *)raw_inode + EXT4_GOOD_OLD_INODE_SIZE +