On Thu 29-06-17 06:54:20, Christoph Hellwig wrote:
> @@ -3359,6 +3358,7 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
> unsigned long first_block = offset >> blkbits;
> unsigned long last_block = (offset + length - 1) >> blkbits;
> struct ext4_map_blocks map;
> + bool delalloc = false;
> int ret;
>
> if (WARN_ON_ONCE(ext4_has_inline_data(inode)))
> @@ -3369,6 +3369,27 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
>
> if (!(flags & IOMAP_WRITE)) {
> ret = ext4_map_blocks(NULL, inode, &map, 0);
> + if (!ret) {
> + struct extent_status es = {};
> +
> + ext4_es_find_delayed_extent_range(inode, map.m_lblk,
> + map.m_lblk + map.m_len - 1, &es);
> + /* Is delalloc data before next block in extent tree? */
> + if (es.es_len && es.es_lblk < map.m_lblk + map.m_len) {
> + ext4_lblk_t offset = 0;
> +
> + if (es.es_lblk < map.m_lblk)
> + offset = map.m_lblk - es.es_lblk;
> + map.m_lblk = es.es_lblk + offset;
> + map.m_pblk = ext4_es_pblock(&es) + offset;
This is wrong for delalloc extent - adding offset to some magic block
value...
> + map.m_len = es.es_len - offset;
> + if (ext4_es_status(&es) & EXTENT_STATUS_UNWRITTEN)
> + map.m_flags |= EXT4_MAP_UNWRITTEN;
> + if (ext4_es_status(&es) & EXTENT_STATUS_DELAYED)
> + delalloc = true;
> + ret = 1;
> + }
> + }
Also the delalloc handling seems to be wrong that if we have file as:
HD
where H is hole, D is delalloc block, and iomap is called at offset 0, we
should be getting back "hole at 0" back but instead you will return
"delalloc at 1".
We deal with a similar situation in ext4_da_map_blocks() so it would be
good if we could reuse that one rather than reimplementing it here. But
factoring the necessary functionality out isn't that easy.
Honza
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
