From: Chengguang Xu <cgxu519@mykernel.net>
To: "Jan Kara" <jack@suse.cz>
Cc: "miklos" <miklos@szeredi.hu>, "amir73il" <amir73il@gmail.com>,
"linux-fsdevel" <linux-fsdevel@vger.kernel.org>,
"linux-unionfs" <linux-unionfs@vger.kernel.org>,
"linux-kernel" <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH v5 06/10] ovl: implement overlayfs' ->write_inode operation
Date: Thu, 07 Oct 2021 22:54:29 +0800 [thread overview]
Message-ID: <17c5b3fa20a.ff02131b26074.9058176981832458952@mykernel.net> (raw)
In-Reply-To: <20211007144156.GK12712@quack2.suse.cz>
---- 在 星期四, 2021-10-07 22:41:56 Jan Kara <jack@suse.cz> 撰写 ----
> On Thu 07-10-21 20:26:36, Chengguang Xu wrote:
> > ---- 在 星期四, 2021-10-07 17:01:57 Jan Kara <jack@suse.cz> 撰写 ----
> > >
> > > > + if (mapping_writably_mapped(upper->i_mapping) ||
> > > > + mapping_tagged(upper->i_mapping, PAGECACHE_TAG_WRITEBACK))
> > > > + iflag |= I_DIRTY_PAGES;
> > > > +
> > > > + iflag |= upper->i_state & I_DIRTY_ALL;
> > >
> > > Also since you call ->write_inode directly upper->i_state won't be updated
> > > to reflect that inode has been written out (I_DIRTY flags get cleared in
> > > __writeback_single_inode()). So it seems to me overlayfs will keep writing
> > > out upper inode until flush worker on upper filesystem also writes the
> > > inode and clears the dirty flags? So you rather need to call something like
> > > write_inode_now() that will handle the flag clearing and do writeback list
> > > handling for you?
> > >
> >
> > Calling ->write_inode directly upper->i_state won't be updated, however,
> > I don't think overlayfs will keep writing out upper inode since
> > ->write_inode will be called when only overlay inode itself marked dirty.
> > Am I missing something?
>
> Well, if upper->i_state is not updated, you are more or less guaranteed
> upper->i_state & I_DIRTY_ALL != 0 and thus even overlay inode stays dirty.
> And thus next time writeback runs you will see dirty overlay inode and
> writeback the upper inode again although it is not necessary.
>
Hi Jan,
Yes, I get the point now. Thanks for the explanation.
Thanks,
Chengguang
next prev parent reply other threads:[~2021-10-07 14:55 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-23 13:08 [RFC PATCH v5 00/10] implement containerized syncfs for overlayfs Chengguang Xu
2021-09-23 13:08 ` [RFC PATCH v5 01/10] ovl: setup overlayfs' private bdi Chengguang Xu
2021-09-23 13:08 ` [RFC PATCH v5 02/10] ovl: implement ->writepages operation Chengguang Xu
2021-09-23 13:08 ` [RFC PATCH v5 03/10] ovl: implement overlayfs' ->evict_inode operation Chengguang Xu
2021-10-06 15:33 ` Miklos Szeredi
2021-10-07 6:08 ` Chengguang Xu
2021-10-07 7:43 ` Miklos Szeredi
2021-09-23 13:08 ` [RFC PATCH v5 04/10] ovl: mark overlayfs' inode dirty on modification Chengguang Xu
2021-10-07 18:43 ` Miklos Szeredi
2021-09-23 13:08 ` [RFC PATCH v5 05/10] ovl: mark overlayfs' inode dirty on shared mmap Chengguang Xu
2021-09-23 13:08 ` [RFC PATCH v5 06/10] ovl: implement overlayfs' ->write_inode operation Chengguang Xu
2021-10-07 9:01 ` Jan Kara
2021-10-07 12:26 ` Chengguang Xu
2021-10-07 14:41 ` Jan Kara
2021-10-07 14:54 ` Chengguang Xu [this message]
2021-10-07 9:23 ` Miklos Szeredi
2021-10-07 12:28 ` Chengguang Xu
2021-10-07 12:45 ` Miklos Szeredi
2021-10-07 13:09 ` Chengguang Xu
2021-10-07 13:34 ` Miklos Szeredi
2021-10-07 14:46 ` Jan Kara
2021-10-07 14:53 ` Chengguang Xu
2021-10-07 18:51 ` Miklos Szeredi
2021-10-08 13:13 ` Jan Kara
2021-11-16 2:20 ` Chengguang Xu
2021-11-16 12:35 ` Miklos Szeredi
2021-11-17 6:11 ` Chengguang Xu
2021-11-18 6:32 ` Chengguang Xu
2021-11-18 11:23 ` Jan Kara
2021-11-18 12:02 ` Chengguang Xu
2021-11-18 16:43 ` Jan Kara
2021-11-19 6:12 ` Chengguang Xu
2021-11-30 11:22 ` Jan Kara
2021-11-30 16:09 ` Chengguang Xu
2021-11-30 19:04 ` Amir Goldstein
2021-12-01 2:37 ` Chengguang Xu
2021-12-01 6:31 ` Chengguang Xu
2021-12-01 7:19 ` Amir Goldstein
2021-12-01 13:46 ` Jan Kara
2021-12-01 14:59 ` Chengguang Xu
2021-12-01 16:24 ` Chengguang Xu
2021-12-01 22:47 ` Amir Goldstein
2021-12-01 23:23 ` ovl_flush() behavior Amir Goldstein
2021-12-02 2:11 ` Chengguang Xu
2021-12-02 15:20 ` Vivek Goyal
2021-12-02 15:59 ` Amir Goldstein
2021-12-02 22:00 ` Vivek Goyal
2021-12-02 15:14 ` Vivek Goyal
2021-12-05 14:06 ` [RFC PATCH v5 06/10] ovl: implement overlayfs' ->write_inode operation Chengguang Xu
2021-12-07 5:33 ` Amir Goldstein
2022-02-05 16:09 ` Chengguang Xu
2022-02-05 16:23 ` Amir Goldstein
2021-09-23 13:08 ` [RFC PATCH v5 07/10] ovl: cache dirty overlayfs' inode Chengguang Xu
2021-10-07 11:09 ` Miklos Szeredi
2021-10-07 12:04 ` Chengguang Xu
2021-10-07 12:27 ` Miklos Szeredi
2021-09-23 13:08 ` [RFC PATCH v5 08/10] fs: export wait_sb_inodes() Chengguang Xu
2021-09-23 13:08 ` [RFC PATCH v5 09/10] fs: introduce new helper sync_fs_and_blockdev() Chengguang Xu
2021-10-19 7:15 ` Amir Goldstein
2021-11-15 11:39 ` Chengguang Xu
2021-09-23 13:08 ` [RFC PATCH v5 10/10] ovl: implement containerized syncfs for overlayfs Chengguang Xu
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