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

[Jan Kara <jack@suse.cz>]

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