From: Jan Kara <jack@suse.cz>
Subject: Re: [PATCH] ext4: fix incorrect quotaoff if the quota feature is
 enabled
Date: Tue, 22 Aug 2017 11:22:05 +0200
Message-ID: <20170822092205.GA4909@quack2.suse.cz>
References: <1503384097-19206-1-git-send-email-yi.zhang@huawei.com>
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Cc: linux-ext4@vger.kernel.org, tytso@mit.edu,
        adilger.kernel@dilger.ca, miaoxie@huawei.com, jack@suse.cz
To: "zhangyi (F)" <yi.zhang@huawei.com>
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In-Reply-To: <1503384097-19206-1-git-send-email-yi.zhang@huawei.com>
Sender: linux-ext4-owner@vger.kernel.org

On Tue 22-08-17 14:41:37, zhangyi (F) wrote:
> Current ext4 quota should always "usage enabled" if the
> quota feautre is enabled. But in ext4_orphan_cleanup(), it
> turn quota off directly (used for the older quota), so
> we cannot turn it on again via "quotaon" unless umount and
> remount ext4.
> 
> Simple reproduce:
> 
>   mkfs.ext4 -O project,quota /dev/vdb1
>   mount -o prjquota /dev/vdb1 /mnt
>   chattr -p 123 /mnt
>   chattr +P /mnt
>   touch /mnt/aa /mnt/bb
>   exec 100<>/mnt/aa
>   rm -f /mnt/aa
>   sync
>   echo c > /proc/sysrq-trigger
> 
>   #reboot and mount
>   mount -o prjquota /dev/vdb1 /mnt
>   #query status
>   quotaon -Ppv /dev/vdb1
>   #output
>   quotaon: Cannot find mountpoint for device /dev/vdb1
>   quotaon: No correct mountpoint specified.
> 
> This patch avoid incorrect quotaoff when ext4 has quota
> feautre. We also take care about the "quota on" part in
> ext4_orphan_cleanup(), it is used for journalled quota
> and not invoked if quota feature is enabled, so it's not
> affected.
> 
> Signed-off-by: zhangyi (F) <yi.zhang@huawei.com>
> ---
>  fs/ext4/super.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index d61a70e2..c1b23b1 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -2510,10 +2510,12 @@ static void ext4_orphan_cleanup(struct super_block *sb,
>  		ext4_msg(sb, KERN_INFO, "%d truncate%s cleaned up",
>  		       PLURAL(nr_truncates));
>  #ifdef CONFIG_QUOTA
> -	/* Turn quotas off */
> -	for (i = 0; i < EXT4_MAXQUOTAS; i++) {
> -		if (sb_dqopt(sb)->files[i])
> -			dquot_quota_off(sb, i);
> +	if (!ext4_has_feature_quota(sb)) {
> +		/* Turn quotas off */
> +		for (i = 0; i < EXT4_MAXQUOTAS; i++) {
> +			if (sb_dqopt(sb)->files[i])
> +				dquot_quota_off(sb, i);
> +		}

So this should work however I'd prefer if we kept the test symmetric to the
place where we turn quotas on for orphan cleanup. I.e. something like:

	for (i = 0; i < EXT4_MAXQUOTAS; i++) {
		/* Old style journalled quotas enabled for orphan cleanup? */
		if (EXT4_SB(sb)->s_qf_names[i] && sb_dqopt(sb)->files[i])
			dquot_quota_off(sb, i);
	}

Also when looking at this code I've noticed that quota does not get enabled
if we use quota feature and we do orphan replay on read-only filesystem.
Could you fix that by handling this case in ext4_orphan_cleanup() as well?
Thanks!

								Honza

>  	}
>  #endif
>  	sb->s_flags = s_flags; /* Restore MS_RDONLY status */
> -- 
> 2.5.0
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR