linux-ext4 - Re: [PATCH 2/2] ext4: preserve SB_I

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Message-ID: <6zslpjdu6urzex23d45n47myfzqmksphjz4bin6tpsxi7wqey2@nbmumzwl7255>
Date: Thu, 3 Jul 2025 18:41:48 +0200
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, yi.zhang@...wei.com, 
	yangerkun@...wei.com, libaokun1@...wei.com
Subject: Re: [PATCH 2/2] ext4: preserve SB_I_VERSION on remount

On Thu 03-07-25 15:39:03, libaokun@...weicloud.com wrote:
> From: Baokun Li <libaokun1@...wei.com>
> 
> IMA testing revealed that after an ext4 remount, file accesses triggered
> full measurements even without modifications, instead of skipping as
> expected when i_version is unchanged.
> 
> Debugging showed `SB_I_VERSION` was cleared in reconfigure_super() during
> remount due to commit 1ff20307393e ("ext4: unconditionally enable the
> i_version counter") removing the fix from commit 960e0ab63b2e ("ext4: fix
> i_version handling on remount").
> 
> To rectify this, `SB_I_VERSION` is always set for `fc->sb_flags` in
> ext4_init_fs_context(), instead of `sb->s_flags` in __ext4_fill_super(),
> ensuring it persists across all mounts.
> 
> Fixes: 1ff20307393e ("ext4: unconditionally enable the i_version counter")
> Signed-off-by: Baokun Li <libaokun1@...wei.com>

Looks good. Feel free to add:

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

								Honza

> ---
>  fs/ext4/super.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 9203518786e4..ed1b36bd51c8 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -1998,6 +1998,9 @@ int ext4_init_fs_context(struct fs_context *fc)
>  	fc->fs_private = ctx;
>  	fc->ops = &ext4_context_ops;
>  
> +	/* i_version is always enabled now */
> +	fc->sb_flags |= SB_I_VERSION;
> +
>  	return 0;
>  }
>  
> @@ -5316,9 +5319,6 @@ static int __ext4_fill_super(struct fs_context *fc, struct super_block *sb)
>  	sb->s_flags = (sb->s_flags & ~SB_POSIXACL) |
>  		(test_opt(sb, POSIX_ACL) ? SB_POSIXACL : 0);
>  
> -	/* i_version is always enabled now */
> -	sb->s_flags |= SB_I_VERSION;
> -
>  	/* HSM events are allowed by default. */
>  	sb->s_iflags |= SB_I_ALLOW_HSM;
>  
> -- 
> 2.46.1
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR