linux-kernel - Re: [PATCH 16/25] ext4: support large block size in ext4_mpage

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Message-ID: <svvbzbdnlvd5bvcbale6xe2qtdaf4ddr3rlrphqv3spcy6dxpt@cynxzantfcmu>
Date: Wed, 5 Nov 2025 10:26:42 +0100
From: Jan Kara <jack@...e.cz>
To: libaokun@...weicloud.com
Cc: linux-ext4@...r.kernel.org, tytso@....edu, adilger.kernel@...ger.ca, 
	jack@...e.cz, linux-kernel@...r.kernel.org, kernel@...kajraghav.com, 
	mcgrof@...nel.org, linux-fsdevel@...r.kernel.org, linux-mm@...ck.org, 
	yi.zhang@...wei.com, yangerkun@...wei.com, chengzhihao1@...wei.com, 
	libaokun1@...wei.com
Subject: Re: [PATCH 16/25] ext4: support large block size in
 ext4_mpage_readpages()

On Sat 25-10-25 11:22:12, libaokun@...weicloud.com wrote:
> From: Baokun Li <libaokun1@...wei.com>
> 
> Use the EXT4_P_TO_LBLK() macro to convert folio indexes to blocks to avoid
> negative left shifts after supporting blocksize greater than PAGE_SIZE.
> 
> Signed-off-by: Baokun Li <libaokun1@...wei.com>
> Reviewed-by: Zhang Yi <yi.zhang@...wei.com>

Looks good. Feel free to add:

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

								Honza

> ---
>  fs/ext4/readpage.c | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/ext4/readpage.c b/fs/ext4/readpage.c
> index f329daf6e5c7..8c8ec9d60b90 100644
> --- a/fs/ext4/readpage.c
> +++ b/fs/ext4/readpage.c
> @@ -213,9 +213,7 @@ int ext4_mpage_readpages(struct inode *inode,
>  {
>  	struct bio *bio = NULL;
>  	sector_t last_block_in_bio = 0;
> -
>  	const unsigned blkbits = inode->i_blkbits;
> -	const unsigned blocks_per_page = PAGE_SIZE >> blkbits;
>  	const unsigned blocksize = 1 << blkbits;
>  	sector_t next_block;
>  	sector_t block_in_file;
> @@ -251,9 +249,8 @@ int ext4_mpage_readpages(struct inode *inode,
>  
>  		blocks_per_folio = folio_size(folio) >> blkbits;
>  		first_hole = blocks_per_folio;
> -		block_in_file = next_block =
> -			(sector_t)folio->index << (PAGE_SHIFT - blkbits);
> -		last_block = block_in_file + nr_pages * blocks_per_page;
> +		block_in_file = next_block = EXT4_P_TO_LBLK(inode, folio->index);
> +		last_block = EXT4_P_TO_LBLK(inode, folio->index + nr_pages);
>  		last_block_in_file = (ext4_readpage_limit(inode) +
>  				      blocksize - 1) >> blkbits;
>  		if (last_block > last_block_in_file)
> -- 
> 2.46.1
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR