linux-kernel - Re: [PATCH v2 22/24] ext4: support verifying data from large folios with fs-verity

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Message-ID: <tyeh5ds2dezr4hrqxs46riwi3ps7ugwhcx46fqmpzarughiokz@q26eyruagm6v>
Date: Mon, 10 Nov 2025 10:54:21 +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, ebiggers@...nel.org, willy@...radead.org, yi.zhang@...wei.com, 
	yangerkun@...wei.com, chengzhihao1@...wei.com, libaokun1@...wei.com
Subject: Re: [PATCH v2 22/24] ext4: support verifying data from large folios
 with fs-verity

On Fri 07-11-25 22:42:47, libaokun@...weicloud.com wrote:
> From: Baokun Li <libaokun1@...wei.com>
> 
> Eric Biggers already added support for verifying data from large folios
> several years ago in commit 5d0f0e57ed90 ("fsverity: support verifying
> data from large folios").
> 
> With ext4 now supporting large block sizes, the fs-verity tests
> `kvm-xfstests -c ext4/64k -g verity -x encrypt` pass without issues.
> 
> Therefore, remove the restriction and allow LBS to be enabled together
> with fs-verity.
> 
> Cc: Eric Biggers <ebiggers@...nel.org>
> Signed-off-by: Baokun Li <libaokun1@...wei.com>

Nice!

> @@ -5175,7 +5173,8 @@ void ext4_set_inode_mapping_order(struct inode *inode)
>  		return;
>  
>  	if (test_opt(inode->i_sb, DATA_FLAGS) == EXT4_MOUNT_JOURNAL_DATA ||
> -	    ext4_test_inode_flag(inode, EXT4_INODE_JOURNAL_DATA))
> +	    ext4_test_inode_flag(inode, EXT4_INODE_JOURNAL_DATA) ||
> +	    ext4_has_feature_verity(inode->i_sb))
>  		max_order = EXT4_SB(inode->i_sb)->s_min_folio_order;
>  	else
>  		max_order = EXT4_MAX_PAGECACHE_ORDER(inode);

Is there a reason why fsverity needs the folio order to match the block
size? I didn't find any by a quick glance. If yes, please state it in
the changelog. If no, then I'd just use EXT4_MAX_PAGECACHE_ORDER() because
it will give us some performance e.g. for mmapped executables protected by
fsverify...

								Honza

-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR