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.
> Otherwise the patch looks good so after fixing up these small issues feel
> free to add:
>
> Reviewed-by: Jan Kara <jack@xxxxxxx>
Thanks,
Andreas
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