On Thu 14-09-17 14:47:28, Andreas Grünbacher wrote:
> 2017-09-14 14:02 GMT+02:00 Jan Kara <jack@xxxxxxx>:
> > On Thu 14-09-17 11:50:47, Andreas Gruenbacher wrote:
> >> @@ -3422,9 +3422,38 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
> >> map.m_lblk = first_block;
> >> map.m_len = last_block - first_block + 1;
> >>
> >> - if (!(flags & IOMAP_WRITE)) {
> >> + if (flags & IOMAP_REPORT) {
> >> ret = ext4_map_blocks(NULL, inode, &map, 0);
> >> - } else {
> >> + if (ret < 0)
> >> + return ret;
> >> +
> >> + if (ret == 0) {
> >> + ext4_lblk_t end = map.m_lblk + map.m_len - 1;
> >> + struct extent_status es;
> >> +
> >> + ext4_es_find_delayed_extent_range(inode, map.m_lblk, end, &es);
> >> +
> >> + if (!es.es_len || es.es_lblk > end) {
> >> + /* entire range is a hole */
> >> + } else if (es.es_lblk > map.m_lblk) {
> >> + /* range starts with a hole */
> >> + map.m_len = es.es_lblk - map.m_lblk;
> >> + } else {
> >> + ext4_lblk_t offs = 0;
> >> +
> >> + if (es.es_lblk < map.m_lblk)
> >> + offs = map.m_lblk - es.es_lblk;
> >> + map.m_lblk = es.es_lblk + offs;
> >> + map.m_pblk = ext4_es_pblock(&es) + offs;
> >> + map.m_len = es.es_len - offs;
> >> + if (ext4_es_is_unwritten(&es))
> >> + map.m_flags |= EXT4_MAP_UNWRITTEN;
> >
> > This is not possible. If there is unwritten extent at map->m_lblk, then
> > ext4_map_blocks() could not have possibly returned 0. So just delete this
> > condition and set map.m_pblk to 0 since delalloc extent has no physical
> > position.
> >
> >> + if (ext4_es_is_delayed(&es))
> >> + delalloc = true;
> >
> > Also ext4_es_is_delayed(&es) is guaranteed to be true since you've looked
> > it up by ext4_es_find_delayed_extent_range(). So just set delalloc = true
> > unconditionally.
>
> Since map.m_pblk is never used in the delalloc case, we can leave it
> undefined above as well.
Yeah, that's fine by me as well.
Honza
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
