Re: [PATCH v2 9/9] ext4: make ext4_da_map_blocks() buffer_head unaware

Jan Kara
2024-04-29T10:27:39Z

On Wed 10-04-24 11:42:03, Zhang Yi wrote:
> From: Zhang Yi <yi.zhang@huawei.com>
>
> After calling ext4_da_map_blocks(), a delalloc extent state could be
> distinguished through EXT4_MAP_DELAYED flag in map. So factor out
> buffer_head related handles in ext4_da_map_blocks(), make it
> buffer_head unaware, make it become a common helper, it could be used
> for iomap in the future.
>
> Signed-off-by: Zhang Yi <yi.zhang@huawei.com>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

Honza

> - retval = es.es_len - (map->m_lblk - es.es_lblk);
> - if (retval > map->m_len)
> - retval = map->m_len;
> - map->m_len = retval;
> + map->m_len = min_t(unsigned int, map->m_len,
> + es.es_len - (map->m_lblk - es.es_lblk));
>
> if (ext4_es_is_hole(&es))
> goto add_delayed;
> @@ -1785,10 +1778,8 @@ static int ext4_da_map_blocks(struct inode *inode, struct ext4_map_blocks *map,
> * Delayed extent could be allocated by fallocate.
> * So we need to check it.
> */
> - if (ext4_es_is_delayed(&es) && !ext4_es_is_unwritten(&es)) {
> - map_bh(bh, inode->i_sb, invalid_block);
> - set_buffer_new(bh);
> - set_buffer_delay(bh);
> + if (ext4_es_is_delonly(&es)) {
> + map->m_flags |= EXT4_MAP_DELAYED;
> return 0;
> }
>
> @@ -1803,7 +1794,7 @@ static int ext4_da_map_blocks(struct inode *inode, struct ext4_map_blocks *map,
> #ifdef ES_AGGRESSIVE_TEST
> ext4_map_blocks_es_recheck(NULL, inode, map, &orig_map, 0);
> #endif
> - return retval;
> + return 0;
> }
>
> /*
> @@ -1817,7 +1808,7 @@ static int ext4_da_map_blocks(struct inode *inode, struct ext4_map_blocks *map,
> retval = ext4_map_query_blocks(NULL, inode, map);
> up_read(&EXT4_I(inode)->i_data_sem);
> if (retval)
> - return retval;
> + return retval < 0 ? retval : 0;
>
> add_delayed:
> down_write(&EXT4_I(inode)->i_data_sem);
> @@ -1827,10 +1818,8 @@ static int ext4_da_map_blocks(struct inode *inode, struct ext4_map_blocks *map,
> * whitout holding i_rwsem and folio lock.
> */
> if (ext4_es_lookup_extent(inode, map->m_lblk, NULL, &es)) {
> - retval = es.es_len - (map->m_lblk - es.es_lblk);
> - if (retval > map->m_len)
> - retval = map->m_len;
> - map->m_len = retval;
> + map->m_len = min_t(unsigned int, map->m_len,
> + es.es_len - (map->m_lblk - es.es_lblk));
>
> if (!ext4_es_is_hole(&es)) {
> up_write(&EXT4_I(inode)->i_data_sem);
> @@ -1840,18 +1829,14 @@ static int ext4_da_map_blocks(struct inode *inode, struct ext4_map_blocks *map,
> retval = ext4_map_query_blocks(NULL, inode, map);
> if (retval) {
> up_write(&EXT4_I(inode)->i_data_sem);
> - return retval;
> + return retval < 0 ? retval : 0;
> }
> }
>
> + map->m_flags |= EXT4_MAP_DELAYED;
> retval = ext4_insert_delayed_blocks(inode, map->m_lblk, map->m_len);
> up_write(&EXT4_I(inode)->i_data_sem);
> - if (retval)
> - return retval;
>
> - map_bh(bh, inode->i_sb, invalid_block);
> - set_buffer_new(bh);
> - set_buffer_delay(bh);
> return retval;
> }
>
> @@ -1871,11 +1856,15 @@ int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
> struct buffer_head *bh, int create)
> {
> struct ext4_map_blocks map;
> + sector_t invalid_block = ~((sector_t) 0xffff);
> int ret = 0;
>
> BUG_ON(create == 0);
> BUG_ON(bh->b_size != inode->i_sb->s_blocksize);
>
> + if (invalid_block < ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es))
> + invalid_block = ~0;
> +
> map.m_lblk = iblock;
> map.m_len = 1;
>
> @@ -1884,10 +1873,17 @@ int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
> * preallocated blocks are unmapped but should treated
> * the same as allocated blocks.
> */
> - ret = ext4_da_map_blocks(inode, &map, bh);
> - if (ret <= 0)
> + ret = ext4_da_map_blocks(inode, &map);
> + if (ret < 0)
> return ret;
>
> + if (map.m_flags & EXT4_MAP_DELAYED) {
> + map_bh(bh, inode->i_sb, invalid_block);
> + set_buffer_new(bh);
> + set_buffer_delay(bh);
> + return 0;
> + }
> +
> map_bh(bh, inode->i_sb, map.m_pblk);
> ext4_update_bh_state(bh, map.m_flags);
>
> --
> 2.39.2
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR