linux-ext4 - Re: [PATCH v3 5/6] ext4: make ext4_map_blocks() distinguish delalloc only extent

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Message-ID: <20240105101823.h5ucbtlhinghhbuk@quack3>
Date: Fri, 5 Jan 2024 11:18:23 +0100
From: Jan Kara <jack@...e.cz>
To: Zhang Yi <yi.zhang@...weicloud.com>
Cc: linux-ext4@...r.kernel.org, tytso@....edu, adilger.kernel@...ger.ca,
	jack@...e.cz, yi.zhang@...wei.com, chengzhihao1@...wei.com,
	yukuai3@...wei.com
Subject: Re: [PATCH v3 5/6] ext4: make ext4_map_blocks() distinguish delalloc
 only extent

On Fri 05-01-24 11:30:17, Zhang Yi wrote:
> From: Zhang Yi <yi.zhang@...wei.com>
> 
> Add a new map flag EXT4_MAP_DELAYED to indicate the mapping range is a
> delayed allocated only (not unwritten) one, and making
> ext4_map_blocks() can distinguish it, no longer mixing it with holes.
> 
> Signed-off-by: Zhang Yi <yi.zhang@...wei.com>

Looks good. Feel free to add:

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

								Honza

> ---
>  fs/ext4/ext4.h    | 4 +++-
>  fs/ext4/extents.c | 7 +++++--
>  fs/ext4/inode.c   | 2 ++
>  3 files changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index a5d784872303..55195909d32f 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -252,8 +252,10 @@ struct ext4_allocation_request {
>  #define EXT4_MAP_MAPPED		BIT(BH_Mapped)
>  #define EXT4_MAP_UNWRITTEN	BIT(BH_Unwritten)
>  #define EXT4_MAP_BOUNDARY	BIT(BH_Boundary)
> +#define EXT4_MAP_DELAYED	BIT(BH_Delay)
>  #define EXT4_MAP_FLAGS		(EXT4_MAP_NEW | EXT4_MAP_MAPPED |\
> -				 EXT4_MAP_UNWRITTEN | EXT4_MAP_BOUNDARY)
> +				 EXT4_MAP_UNWRITTEN | EXT4_MAP_BOUNDARY |\
> +				 EXT4_MAP_DELAYED)
>  
>  struct ext4_map_blocks {
>  	ext4_fsblk_t m_pblk;
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index e0b7e48c4c67..6b64319a7df8 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -4076,8 +4076,11 @@ static ext4_lblk_t ext4_ext_determine_insert_hole(struct inode *inode,
>  		/*
>  		 * The delalloc extent containing lblk, it must have been
>  		 * added after ext4_map_blocks() checked the extent status
> -		 * tree, adjust the length to the delalloc extent's after
> -		 * lblk.
> +		 * tree so we are not holding i_rwsem and delalloc info is
> +		 * only stabilized by i_data_sem we are going to release
> +		 * soon. Don't modify the extent status tree and report
> +		 * extent as a hole, just adjust the length to the delalloc
> +		 * extent's after lblk.
>  		 */
>  		len = es.es_lblk + es.es_len - lblk;
>  		return len;
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 1b5e6409f958..c141bf6d8db2 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -515,6 +515,8 @@ int ext4_map_blocks(handle_t *handle, struct inode *inode,
>  			map->m_len = retval;
>  		} else if (ext4_es_is_delayed(&es) || ext4_es_is_hole(&es)) {
>  			map->m_pblk = 0;
> +			map->m_flags |= ext4_es_is_delayed(&es) ?
> +					EXT4_MAP_DELAYED : 0;
>  			retval = es.es_len - (map->m_lblk - es.es_lblk);
>  			if (retval > map->m_len)
>  				retval = map->m_len;
> -- 
> 2.39.2
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR