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Date:   Thu, 07 Oct 2021 22:53:02 +0800
From:   Chengguang Xu <cgxu519@mykernel.net>
Reply-To: cgxu519@mykernel.net
To:     "Jan Kara" <jack@suse.cz>, "Miklos Szeredi" <miklos@szeredi.hu>
Cc:     "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: <17c5b3e4f2b.113dc38cd26071.2800661599712778589@mykernel.net>
In-Reply-To: <20211007144646.GL12712@quack2.suse.cz>
References: <20210923130814.140814-1-cgxu519@mykernel.net>
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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 22:46:46 Jan Kara <=
jack@suse.cz> =E6=92=B0=E5=86=99 ----
 > On Thu 07-10-21 15:34:19, Miklos Szeredi wrote:
 > > On Thu, 7 Oct 2021 at 15:10, Chengguang Xu <cgxu519@mykernel.net> wrot=
e:
 > > >  > However that wasn't what I was asking about.  AFAICS ->write_inod=
e()
 > > >  > won't start write back for dirty pages.   Maybe I'm missing somet=
hing,
 > > >  > but there it looks as if nothing will actually trigger writeback =
for
 > > >  > dirty pages in upper inode.
 > > >  >
 > > >
 > > > Actually, page writeback on upper inode will be triggered by overlay=
fs ->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
 > You could but then you'd have to make sure you have I_DIRTY_SYNC always =
set
 > when I_DIRTY_PAGES is set on the upper inode so that your ->write_inode(=
)
 > callback gets called. Overall I agree the logic would be probably simple=
r.
 >=20

Hi Jan, Miklos

Thnaks for your suggestions. Let me have a try in next version.


Thanks,
Chengguang