Re: [PATCH v4 08/12] ext4: using nofail preallocation in ext4_es_insert_extent()

Jan Kara
2023-05-03T14:32:30Z

On Mon 24-04-23 11:38:42, Baokun Li wrote:
> Similar to in ext4_es_insert_delayed_block(), we use preallocations that
> do not fail to avoid inconsistencies, but we do not care about es that are
> not must be kept, and we return 0 even if such es memory allocation fails.
>
> Suggested-by: Jan Kara <jack@suse.cz>
> Signed-off-by: Baokun Li <libaokun1@huawei.com>

Looks good to me. Feel free to add:

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

Honza

> ---
> fs/ext4/extents_status.c | 38 ++++++++++++++++++++++++++------------
> 1 file changed, 26 insertions(+), 12 deletions(-)
>
> diff --git a/fs/ext4/extents_status.c b/fs/ext4/extents_status.c
> index f892277155fa..91828cf7395b 100644
> --- a/fs/ext4/extents_status.c
> +++ b/fs/ext4/extents_status.c
> @@ -840,8 +840,11 @@ int ext4_es_insert_extent(struct inode *inode, ext4_lblk_t lblk,
> {
> struct extent_status newes;
> ext4_lblk_t end = lblk + len - 1;
> - int err = 0;
> + int err1 = 0;
> + int err2 = 0;
> struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
> + struct extent_status *es1 = NULL;
> + struct extent_status *es2 = NULL;
>
> if (EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY)
> return 0;
> @@ -869,29 +872,40 @@ int ext4_es_insert_extent(struct inode *inode, ext4_lblk_t lblk,
>
> ext4_es_insert_extent_check(inode, &newes);
>
> +retry:
> + if (err1 && !es1)
> + es1 = __es_alloc_extent(true);
> + if ((err1 || err2) && !es2)
> + es2 = __es_alloc_extent(true);
> write_lock(&EXT4_I(inode)->i_es_lock);
> - err = __es_remove_extent(inode, lblk, end, NULL, NULL);
> - if (err != 0)
> +
> + err1 = __es_remove_extent(inode, lblk, end, NULL, es1);
> + if (err1 != 0)
> + goto error;
> +
> + err2 = __es_insert_extent(inode, &newes, es2);
> + if (err2 == -ENOMEM && !ext4_es_must_keep(&newes))
> + err2 = 0;
> + if (err2 != 0)
> goto error;
> -retry:
> - err = __es_insert_extent(inode, &newes, NULL);
> - if (err == -ENOMEM && __es_shrink(EXT4_SB(inode->i_sb),
> - 128, EXT4_I(inode)))
> - goto retry;
> - if (err == -ENOMEM && !ext4_es_must_keep(&newes))
> - err = 0;
>
> if (sbi->s_cluster_ratio > 1 && test_opt(inode->i_sb, DELALLOC) &&
> (status & EXTENT_STATUS_WRITTEN ||
> status & EXTENT_STATUS_UNWRITTEN))
> __revise_pending(inode, lblk, len);
>
> + /* es is pre-allocated but not used, free it. */
> + if (es1 && !es1->es_len)
> + __es_free_extent(es1);
> + if (es2 && !es2->es_len)
> + __es_free_extent(es2);
> error:
> write_unlock(&EXT4_I(inode)->i_es_lock);
> + if (err1 || err2)
> + goto retry;
>
> ext4_es_print_tree(inode);
> -
> - return err;
> + return 0;
> }
>
> /*
> --
> 2.31.1
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR