ext4: truncate_inode_pages() in orphan cleanup path

Currently we do not tell mm to zero out tail of the page before truncate
in orphan_cleanup(). This is ok, because the page should not be
uptodate, however this may eventually change and I might cause problems.

Call truncate_inode_pages() as precautionary measure. Thanks Jan Kara
for pointing this out.
Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/super.c

@@ -2170,6 +2170,7 @@ static void ext4_orphan_cleanup(struct super_block *sb,
 			jbd_debug(2, "truncating inode %lu to %lld bytes\n",
 				  inode->i_ino, inode->i_size);
 			mutex_lock(&inode->i_mutex);
+			truncate_inode_pages(inode->i_mapping, inode->i_size);
 			ext4_truncate(inode);
 			mutex_unlock(&inode->i_mutex);
 			nr_truncates++;