Date:   Tue, 16 Nov 2021 10:20:25 +0800
From:   Chengguang Xu <cgxu519@mykernel.net>
Reply-To: cgxu519@mykernel.net
To:     "Miklos Szeredi" <miklos@szeredi.hu>
Cc:     "Jan Kara" <jack@suse.cz>, "Amir Goldstein" <amir73il@gmail.com>,
        "linux-fsdevel" <linux-fsdevel@vger.kernel.org>,
        "overlayfs" <linux-unionfs@vger.kernel.org>,
        "linux-kernel" <linux-kernel@vger.kernel.org>
Message-ID: <17d268ba3ce.1199800543649.1713755891767595962@mykernel.net>
In-Reply-To: <CAJfpegt4jZpSCXGFk2ieqUXVm3m=ng7QtSzZp2bXVs07bfrbXg@mail.gmail.com>
References: <20210923130814.140814-1-cgxu519@mykernel.net> <20210923130814.140814-7-cgxu519@mykernel.net>
 <CAJfpeguqj2vst4Zj5EovSktJkXiDSCSWY=X12X0Yrz4M8gPRmQ@mail.gmail.com>
 <17c5aba1fef.c5c03d5825886.6577730832510234905@mykernel.net>
 <CAJfpegtr1NkOiY9YWd1meU1yiD-LFX-aB55UVJs94FrX0VNEJQ@mail.gmail.com> <17c5adfe5ea.12f1be94625921.4478415437452327206@mykernel.net> <CAJfpegt4jZpSCXGFk2ieqUXVm3m=ng7QtSzZp2bXVs07bfrbXg@mail.gmail.com>
Subject: Re: [RFC PATCH v5 06/10] ovl: implement overlayfs' ->write_inode
 operation
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 ---- =E5=9C=A8 =E6=98=9F=E6=9C=9F=E5=9B=9B, 2021-10-07 21:34:19 Miklos Sze=
redi <miklos@szeredi.hu> =E6=92=B0=E5=86=99 ----
 > On Thu, 7 Oct 2021 at 15:10, Chengguang Xu <cgxu519@mykernel.net> wrote:
 > >  > However that wasn't what I was asking about.  AFAICS ->write_inode(=
)
 > >  > won't start write back for dirty pages.   Maybe I'm missing somethi=
ng,
 > >  > but there it looks as if nothing will actually trigger writeback fo=
r
 > >  > dirty pages in upper inode.
 > >  >
 > >
 > > Actually, page writeback on upper inode will be triggered by overlayfs=
 ->writepages and
 > > overlayfs' ->writepages will be called by vfs writeback function (i.e =
writeback_sb_inodes).
 >=20
 > Right.
 >=20
 > But wouldn't it be simpler to do this from ->write_inode()?
 >=20
 > I.e. call write_inode_now() as suggested by Jan.
 >=20
 > Also could just call mark_inode_dirty() on the overlay inode
 > regardless of the dirty flags on the upper inode since it shouldn't
 > matter and results in simpler logic.
 >=20

Hi Miklos=EF=BC=8C

Sorry for delayed response for this, I've been busy with another project.

I agree with your suggesion above and further more how about just mark over=
lay inode dirty
when it has upper inode? This approach will make marking dirtiness simple e=
nough.

Thanks,
Chengguang