linux-kernel - Re: [PATCH v2 06/24] ext4: introduce s_min_folio

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Message-ID: <bdc8ea99-f967-4112-b418-f586736da993@pankajraghav.com>
Date: Mon, 10 Nov 2025 13:09:30 +0100
From: Pankaj Raghav <kernel@...kajraghav.com>
To: libaokun@...weicloud.com, linux-ext4@...r.kernel.org
Cc: tytso@....edu, adilger.kernel@...ger.ca, jack@...e.cz,
 linux-kernel@...r.kernel.org, mcgrof@...nel.org, ebiggers@...nel.org,
 willy@...radead.org, yi.zhang@...wei.com, yangerkun@...wei.com,
 chengzhihao1@...wei.com, libaokun1@...wei.com
Subject: Re: [PATCH v2 06/24] ext4: introduce s_min_folio_order for future BS
 > PS support

On 11/7/25 15:42, libaokun@...weicloud.com wrote:
> From: Baokun Li <libaokun1@...wei.com>
> 
> This commit introduces the s_min_folio_order field to the ext4_sb_info
> structure. This field will store the minimum folio order required by the
> current filesystem, laying groundwork for future support of block sizes
> greater than PAGE_SIZE.
> 
> Signed-off-by: Baokun Li <libaokun1@...wei.com>
> Reviewed-by: Zhang Yi <yi.zhang@...wei.com>
> Reviewed-by: Jan Kara <jack@...e.cz>
> ---
Looks good,

Reviewed-by: Pankaj Raghav <p.raghav@...sung.com>

>  fs/ext4/ext4.h  |  3 +++
>  fs/ext4/inode.c |  3 ++-
>  fs/ext4/super.c | 10 +++++-----
>  3 files changed, 10 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 3d18e6bf43cf..6fe8cc3bf9a5 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -1688,6 +1688,9 @@ struct ext4_sb_info {
>  	/* record the last minlen when FITRIM is called. */
>  	unsigned long s_last_trim_minblks;
>  
> +	/* minimum folio order of a page cache allocation */
> +	unsigned int s_min_folio_order;
> +
>  	/* Precomputed FS UUID checksum for seeding other checksums */
>  	__u32 s_csum_seed;
>  
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 6fec3aa2268a..9faa0cf77075 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -5181,7 +5181,8 @@ void ext4_set_inode_mapping_order(struct inode *inode)
>  	if (!ext4_should_enable_large_folio(inode))
>  		return;
>  
> -	mapping_set_folio_order_range(inode->i_mapping, 0,
> +	mapping_set_folio_order_range(inode->i_mapping,
> +				      EXT4_SB(inode->i_sb)->s_min_folio_order,
>  				      EXT4_MAX_PAGECACHE_ORDER(inode));
>  }
>  
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index a9fa824487f9..a6314a3de51d 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -5107,11 +5107,8 @@ static int ext4_load_super(struct super_block *sb, ext4_fsblk_t *lsb,
>  	 * If the default block size is not the same as the real block size,
>  	 * we need to reload it.
>  	 */
> -	if (sb->s_blocksize == blocksize) {
> -		*lsb = logical_sb_block;
> -		sbi->s_sbh = bh;
> -		return 0;
> -	}
> +	if (sb->s_blocksize == blocksize)
> +		goto success;
>  
>  	/*
>  	 * bh must be released before kill_bdev(), otherwise
> @@ -5142,6 +5139,9 @@ static int ext4_load_super(struct super_block *sb, ext4_fsblk_t *lsb,
>  		ext4_msg(sb, KERN_ERR, "Magic mismatch, very weird!");
>  		goto out;
>  	}
> +
> +success:
> +	sbi->s_min_folio_order = get_order(blocksize);
>  	*lsb = logical_sb_block;
>  	sbi->s_sbh = bh;
>  	return 0;