linux-ext4 - Re: [bug report] ext4: Set flags on quota files directly

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Message-ID: <20211215115927.GN14044@quack2.suse.cz>
Date:   Wed, 15 Dec 2021 12:59:27 +0100
From:   Jan Kara <jack@...e.cz>
To:     Dan Carpenter <dan.carpenter@...cle.com>
Cc:     jack@...e.cz, linux-ext4@...r.kernel.org
Subject: Re: [bug report] ext4: Set flags on quota files directly

Hello Dan!

On Wed 15-12-21 14:42:31, Dan Carpenter wrote:
> The patch 957153fce8d2: "ext4: Set flags on quota files directly"
> from Apr 6, 2017, leads to the following Smatch static checker
> warning:
> 
> 	fs/ext4/super.c:6779 ext4_quota_on()
> 	warn: missing error code here? 'IS_ERR()' failed. 'err' = '0'
> 
> fs/ext4/super.c
>     6761 
>     6762         lockdep_set_quota_inode(path->dentry->d_inode, I_DATA_SEM_QUOTA);
>     6763         err = dquot_quota_on(sb, type, format_id, path);
>     6764         if (err) {
>     6765                 lockdep_set_quota_inode(path->dentry->d_inode,
>     6766                                              I_DATA_SEM_NORMAL);
>     6767         } else {
>     6768                 struct inode *inode = d_inode(path->dentry);
>     6769                 handle_t *handle;
>     6770 
>     6771                 /*
>     6772                  * Set inode flags to prevent userspace from messing with quota
>     6773                  * files. If this fails, we return success anyway since quotas
>     6774                  * are already enabled and this is not a hard failure.
>     6775                  */
>     6776                 inode_lock(inode);
>     6777                 handle = ext4_journal_start(inode, EXT4_HT_QUOTA, 1);
>     6778                 if (IS_ERR(handle))
> --> 6779                         goto unlock_inode;
> 
> This should set "err = PTR_ERR(handle)" right?

The comment above explains it I guess. We don't want to return error if
ext4_journal_start() fails because it is a "soft" failure we can absorb.

								Honza


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