Date:   Fri, 26 Nov 2021 13:03:26 +0800
From:   Chengguang Xu <cgxu519@mykernel.net>
Reply-To: cgxu519@mykernel.net
To:     "Amir Goldstein" <amir73il@gmail.com>
Cc:     "Miklos Szeredi" <miklos@szeredi.hu>, "Jan Kara" <jack@suse.cz>,
        "overlayfs" <linux-unionfs@vger.kernel.org>,
        "linux-fsdevel" <linux-fsdevel@vger.kernel.org>,
        "linux-kernel" <linux-kernel@vger.kernel.org>,
        "Chengguang Xu" <charliecgxu@tencent.com>
Message-ID: <17d5aa0795d.fdfda4a49855.5158536783597235118@mykernel.net>
In-Reply-To: <CAOQ4uxhrg=MAL7sArmP47oyF_QmhG-1b=srs30VNdiT-9s-P0w@mail.gmail.com>
References: <20211122030038.1938875-1-cgxu519@mykernel.net> <20211122030038.1938875-8-cgxu519@mykernel.net> <CAOQ4uxhrg=MAL7sArmP47oyF_QmhG-1b=srs30VNdiT-9s-P0w@mail.gmail.com>
Subject: Re: [RFC PATCH V6 7/7] ovl: implement containerized syncfs for
 overlayfs
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 ---- =E5=9C=A8 =E6=98=9F=E6=9C=9F=E4=B8=80, 2021-11-22 15:40:59 Amir Golds=
tein <amir73il@gmail.com> =E6=92=B0=E5=86=99 ----
 > On Mon, Nov 22, 2021 at 5:01 AM Chengguang Xu <cgxu519@mykernel.net> wro=
te:
 > >
 > > From: Chengguang Xu <charliecgxu@tencent.com>
 > >
 > > Now overlayfs can only sync own dirty inodes during syncfs,
 > > so remove unnecessary sync_filesystem() on upper file system.
 > >
 > > Signed-off-by: Chengguang Xu <charliecgxu@tencent.com>
 > > ---
 > >  fs/overlayfs/super.c | 14 +++++---------
 > >  1 file changed, 5 insertions(+), 9 deletions(-)
 > >
 > > diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
 > > index ccffcd96491d..213b795a6a86 100644
 > > --- a/fs/overlayfs/super.c
 > > +++ b/fs/overlayfs/super.c
 > > @@ -292,18 +292,14 @@ static int ovl_sync_fs(struct super_block *sb, i=
nt wait)
 > >         /*
 > >          * Not called for sync(2) call or an emergency sync (SB_I_SKIP=
_SYNC).
 > >          * All the super blocks will be iterated, including upper_sb.
 > > -        *
 > > -        * If this is a syncfs(2) call, then we do need to call
 > > -        * sync_filesystem() on upper_sb, but enough if we do it when =
being
 > > -        * called with wait =3D=3D 1.
 > >          */
 > > -       if (!wait)
 > > -               return 0;
 > > -
 > >         upper_sb =3D ovl_upper_mnt(ofs)->mnt_sb;
 > > -
 > >         down_read(&upper_sb->s_umount);
 > > -       ret =3D sync_filesystem(upper_sb);
 > > +       if (wait)
 > > +               wait_sb_inodes(upper_sb);
 > > +       if (upper_sb->s_op->sync_fs)
 > > +               upper_sb->s_op->sync_fs(upper_sb, wait);
 > > +       ret =3D ovl_sync_upper_blockdev(upper_sb, wait);
 >=20
 > I think it will be cleaner to use a helper ovl_sync_upper_filesystem()
 > with everything from  upper_sb =3D ... and a comment to explain that
 > this is a variant of __sync_filesystem() where all the dirty inodes writ=
e
 > have already been started.
 >=20
=20
I agree with you.=20

Thanks,
Chengguang