linux-ext4 - Re: [PATCH] ext4: enable the lazy init thread when remounting read/write

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Date:   Sun, 28 May 2023 13:47:56 -0400
From:   Eric Whitney <enwlinux@...il.com>
To:     Theodore Ts'o <tytso@....edu>
Cc:     Ext4 Developers List <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH] ext4: enable the lazy init thread when remounting
 read/write

* Theodore Ts'o <tytso@....edu>:
> In commit a44be64bbecb ("ext4: don't clear SB_RDONLY when remounting
> r/w until quota is re-enabled") we defer clearing tyhe SB_RDONLY flag
> in struct super.  However, we didn't defer when we checked sb_rdonly()
> to determine the lazy itable init thread should be enabled, with the
> next result that the lazy inode table initialization would not be
> properly started.  This can cause generic/231 to fail in ext4's
> nojournal mode.
> 
> Fix this by moving when we decide to start or stop the lazy itable
> init thread to after we clear the SB_RDONLY flag when we are
> remounting the file system read/write.
> 
> Fixes a44be64bbecb ("ext4: don't clear SB_RDONLY when remounting r/w until...")
> Signed-off-by: Theodore Ts'o <tytso@....edu>
> ---
>  fs/ext4/super.c | 24 ++++++++++++------------
>  1 file changed, 12 insertions(+), 12 deletions(-)
> 
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 9680fe753e59..56a5d1c469fc 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -6588,18 +6588,6 @@ static int __ext4_remount(struct fs_context *fc, struct super_block *sb)
>  		}
>  	}
>  
> -	/*
> -	 * Reinitialize lazy itable initialization thread based on
> -	 * current settings
> -	 */
> -	if (sb_rdonly(sb) || !test_opt(sb, INIT_INODE_TABLE))
> -		ext4_unregister_li_request(sb);
> -	else {
> -		ext4_group_t first_not_zeroed;
> -		first_not_zeroed = ext4_has_uninit_itable(sb);
> -		ext4_register_li_request(sb, first_not_zeroed);
> -	}
> -
>  	/*
>  	 * Handle creation of system zone data early because it can fail.
>  	 * Releasing of existing data is done when we are sure remount will
> @@ -6637,6 +6625,18 @@ static int __ext4_remount(struct fs_context *fc, struct super_block *sb)
>  	if (enable_rw)
>  		sb->s_flags &= ~SB_RDONLY;
>  
> +	/*
> +	 * Reinitialize lazy itable initialization thread based on
> +	 * current settings
> +	 */
> +	if (sb_rdonly(sb) || !test_opt(sb, INIT_INODE_TABLE))
> +		ext4_unregister_li_request(sb);
> +	else {
> +		ext4_group_t first_not_zeroed;
> +		first_not_zeroed = ext4_has_uninit_itable(sb);
> +		ext4_register_li_request(sb, first_not_zeroed);
> +	}
> +
>  	if (!ext4_has_feature_mmp(sb) || sb_rdonly(sb))
>  		ext4_stop_mmpd(sbi);
>  
> -- 
> 2.31.0
>

Hi Ted:

100/100 trials of generic/231 with nojournal passed when I used kvm-xfstests
to run it on a 6.4-rc3 kernel modified with this patch.  A complete run of the
nojournal test case also passed for me without new regressions.

So,
Tested-by: Eric Whitney <enwlinux@...il.com>

Thanks,
Eric