Re: [PATCH v2 8/9] ext4: make ext4_insert_delayed_block() insert multi-blocks

Zhang Yi
2024-04-29T12:54:23Z

On 2024/4/29 18:06, Jan Kara wrote:
> On Wed 10-04-24 11:42:02, Zhang Yi wrote:
>> From: Zhang Yi <yi.zhang@huawei.com>
>>
>> Rename ext4_insert_delayed_block() to ext4_insert_delayed_blocks(),
>> pass length parameter to make it insert multi delalloc blocks once a
>> time. For non-bigalloc case, just reserve len blocks and insert delalloc
>> extent. For bigalloc case, we can ensure the middle clusters are not
>> allocated, but need to check whether the start and end clusters are
>> delayed/allocated, if not, we should reserve more space for the start
>> and/or end block(s).
>>
>> Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
>
> Thanks for the patch. Some comments below.
>
>> ---
>> fs/ext4/inode.c | 51 ++++++++++++++++++++++++++++++++++---------------
>> 1 file changed, 36 insertions(+), 15 deletions(-)
>>
>> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
>> index 46c34baa848a..08e2692b7286 100644
>> --- a/fs/ext4/inode.c
>> +++ b/fs/ext4/inode.c
>> @@ -1678,24 +1678,28 @@ static int ext4_da_check_clu_allocated(struct inode *inode, ext4_lblk_t lblk,
>> }
>>
>> /*
>> - * ext4_insert_delayed_block - adds a delayed block to the extents status
>> - * tree, incrementing the reserved cluster/block
>> - * count or making a pending reservation
>> - * where needed
>> + * ext4_insert_delayed_blocks - adds a multiple delayed blocks to the extents
>> + * status tree, incrementing the reserved
>> + * cluster/block count or making pending
>> + * reservations where needed
>> *
>> * @inode - file containing the newly added block
>> - * @lblk - logical block to be added
>> + * @lblk - start logical block to be added
>> + * @len - length of blocks to be added
>> *
>> * Returns 0 on success, negative error code on failure.
>> */
>> -static int ext4_insert_delayed_block(struct inode *inode, ext4_lblk_t lblk)
>> +static int ext4_insert_delayed_blocks(struct inode *inode, ext4_lblk_t lblk,
>> + ext4_lblk_t len)
>> {
>> struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
>> - int ret;
>> - bool allocated = false;
>> + int resv_clu, ret;
> ^^^ this variable is in prinple the length of the extent. Thus
> it should be ext4_lblk_t type.
>
>> + bool lclu_allocated = false;
>> + bool end_allocated = false;
>> + ext4_lblk_t end = lblk + len - 1;
>>
>> /*
>> - * If the cluster containing lblk is shared with a delayed,
>> + * If the cluster containing lblk or end is shared with a delayed,
>> * written, or unwritten extent in a bigalloc file system, it's
>> * already been accounted for and does not need to be reserved.
>> * A pending reservation must be made for the cluster if it's
>> @@ -1706,21 +1710,38 @@ static int ext4_insert_delayed_block(struct inode *inode, ext4_lblk_t lblk)
>> * extents status tree doesn't get a match.
>> */
>> if (sbi->s_cluster_ratio == 1) {
>> - ret = ext4_da_reserve_space(inode, 1);
>> + ret = ext4_da_reserve_space(inode, len);
>> if (ret != 0) /* ENOSPC */
>> return ret;
>> } else { /* bigalloc */
>> - ret = ext4_da_check_clu_allocated(inode, lblk, &allocated);
>> + resv_clu = EXT4_B2C(sbi, end) - EXT4_B2C(sbi, lblk) - 1;
>> + if (resv_clu < 0)
>> + resv_clu = 0;
>
> Here resv_clu going negative is strange I'm not sure the math is 100%
> correct in all the cases. I think it would be more logical as:
>
> resv_clu = EXT4_B2C(sbi, end) - EXT4_B2C(sbi, lblk) + 1;
>> and then update resv_clu below as:
>
>> +
>> + ret = ext4_da_check_clu_allocated(inode, lblk, &lclu_allocated);
>> if (ret < 0)
>> return ret;
>> - if (ret > 0) {
>> - ret = ext4_da_reserve_space(inode, 1);
>> + if (ret > 0)
>> + resv_clu++;
>
> Here we would do:
> if (ret == 0)
> resv_clu--;
>
>> +
>> + if (EXT4_B2C(sbi, lblk) != EXT4_B2C(sbi, end)) {
>> + ret = ext4_da_check_clu_allocated(inode, end,
>> + &end_allocated);
>> + if (ret < 0)
>> + return ret;
>> + if (ret > 0)
>> + resv_clu++;
>
> And similarly here:
> if (ret == 0)
> resv_clu--;

Oh, yes, it is definitely more logical than mine. Thanks for taking time
to review this series, other changelog and comments suggestions in this
series are looks fine to me, I will use them. Besides, Ritesh improved
my changelog in patch 2, I will keep your reviewed tag if you don't have
different opinions.

Thanks,
Yi.

>
>> + }
>> +
>> + if (resv_clu) {
>> + ret = ext4_da_reserve_space(inode, resv_clu);
>> if (ret != 0) /* ENOSPC */
>> return ret;
>> }
>> }
>>
>> - ext4_es_insert_delayed_extent(inode, lblk, 1, allocated, false);
>> + ext4_es_insert_delayed_extent(inode, lblk, len, lclu_allocated,
>> + end_allocated);
>> return 0;
>> }
>>
>> @@ -1823,7 +1844,7 @@ static int ext4_da_map_blocks(struct inode *inode, struct ext4_map_blocks *map,
>> }
>> }
>>
>> - retval = ext4_insert_delayed_block(inode, map->m_lblk);
>> + retval = ext4_insert_delayed_blocks(inode, map->m_lblk, map->m_len);
>> up_write(&EXT4_I(inode)->i_data_sem);
>> if (retval)
>> return retval;
>> --
>> 2.39.2
>>