linux-kernel - Re: [PATCH v2 03/10] ext4: don't set EXTENT_STATUS

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Message-ID: <20240806152327.td572f7elpel4aeo@quack3>
Date: Tue, 6 Aug 2024 17:23:27 +0200
From: Jan Kara <jack@...e.cz>
To: Zhang Yi <yi.zhang@...weicloud.com>
Cc: linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org, tytso@....edu,
	adilger.kernel@...ger.ca, jack@...e.cz, ritesh.list@...il.com,
	yi.zhang@...wei.com, chengzhihao1@...wei.com, yukuai3@...wei.com
Subject: Re: [PATCH v2 03/10] ext4: don't set EXTENT_STATUS_DELAYED on
 allocated blocks

On Fri 02-08-24 19:51:13, Zhang Yi wrote:
> From: Zhang Yi <yi.zhang@...wei.com>
> 
> Since we always set EXT4_GET_BLOCKS_DELALLOC_RESERVE when allocating
> delalloc blocks, there is no need to keep delayed flag on the unwritten
> extent status entry, so just drop it after allocation.
> 
> Signed-off-by: Zhang Yi <yi.zhang@...wei.com>

Let me improve the changelog because I was confused for some time before I
understood:

Currently, we release delayed allocation reservation when removing delayed
extent from extent status tree (which also happens when overwriting one
extent with another one). When we allocated unwritten extent under
some delayed allocated extent, we don't need the reservation anymore and
hence we don't need to preserve the EXT4_MAP_DELAYED status bit. Inserting
the new extent into extent status tree will properly release the
reservation.

Otherwise feel free to add:

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

								Honza


> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 91b2610a6dc5..e9ce1e4e6acb 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -558,12 +558,6 @@ static int ext4_map_create_blocks(handle_t *handle, struct inode *inode,
>  
>  	status = map->m_flags & EXT4_MAP_UNWRITTEN ?
>  			EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
> -	if (!(flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE) &&
> -	    !(status & EXTENT_STATUS_WRITTEN) &&
> -	    ext4_es_scan_range(inode, &ext4_es_is_delayed, map->m_lblk,
> -			       map->m_lblk + map->m_len - 1))
> -		status |= EXTENT_STATUS_DELAYED;
> -
>  	ext4_es_insert_extent(inode, map->m_lblk, map->m_len,
>  			      map->m_pblk, status);
>  
> @@ -682,11 +676,6 @@ int ext4_map_blocks(handle_t *handle, struct inode *inode,
>  
>  		status = map->m_flags & EXT4_MAP_UNWRITTEN ?
>  				EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
> -		if (!(flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE) &&
> -		    !(status & EXTENT_STATUS_WRITTEN) &&
> -		    ext4_es_scan_range(inode, &ext4_es_is_delayed, map->m_lblk,
> -				       map->m_lblk + map->m_len - 1))
> -			status |= EXTENT_STATUS_DELAYED;
>  		ext4_es_insert_extent(inode, map->m_lblk, map->m_len,
>  				      map->m_pblk, status);
>  	}
> -- 
> 2.39.2
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR