linux-kernel - Re: [PATCH v1] fs/ext4/xattr: check the return value of ext4_xattr_inode_dec

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Message-ID: <CAMEuxRqbLuVeC_daXjGEAVEBi9_ikSC=Bf2PFea_GeMtDvCEHw@mail.gmail.com>
Date:   Fri, 16 Sep 2022 17:25:44 -0700
From:   Li Zhong <floridsleeves@...il.com>
To:     Ojaswin Mujoo <ojaswin@...ux.ibm.com>
Cc:     linux-kernel@...r.kernel.org, linux-ext4@...r.kernel.org,
        adilger.kernel@...ger.ca, tytso@....edu
Subject: Re: [PATCH v1] fs/ext4/xattr: check the return value of ext4_xattr_inode_dec_ref()

On Sat, Sep 10, 2022 at 2:55 AM Ojaswin Mujoo <ojaswin@...ux.ibm.com> wrote:
>
> On Thu, Sep 08, 2022 at 09:47:27PM -0700, Li Zhong wrote:
> > Check the return value of ext4_xattr_inode_dec_ref(), which could return
> > error code and need to be warned.
> >
> > Signed-off-by: Li Zhong <floridsleeves@...il.com>
> > ---
> >  fs/ext4/xattr.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
> > index 533216e80fa2..76141ed12bc2 100644
> > --- a/fs/ext4/xattr.c
> > +++ b/fs/ext4/xattr.c
> > @@ -1540,7 +1540,9 @@ static int ext4_xattr_inode_lookup_create(handle_t *handle, struct inode *inode,
> >
> >       err = ext4_xattr_inode_write(handle, ea_inode, value, value_len);
> >       if (err) {
> > -             ext4_xattr_inode_dec_ref(handle, ea_inode);
> > +             err = ext4_xattr_inode_dec_ref(handle, ea_inode);
> Hey Li,
>
> My only concern here is in case ext4_xattr_inode_dec_ref() fails, we
> overwrite the err value and the actual err from ext4_xattr_inode_write()
> is lost.
>
> I feel the ext4_xattr_inode_write() error code would be more valuable
> for the calling function hence that is the one we should propogate.
> Maybe we can just print the warning without overwriting err?
>
Thanks for pointing this out! I'll fix it in v2 patch.
>
> Regards,
> Ojaswin
> > +             if (err)
> > +                     ext4_warning_inode(ea_inode, "cleanup dec ref error %d", err);
> >               iput(ea_inode);
> >               return err;
> >       }
> > --
> > 2.25.1
> >