From: Matthew Wilcox <willy@infradead.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: David Howells <dhowells@redhat.com>,
Steve French <stfrench@microsoft.com>,
Vishal Moola <vishal.moola@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Jan Kara <jack@suse.cz>, Paulo Alcantara <pc@cjr.nz>,
Huang Ying <ying.huang@intel.com>,
Baolin Wang <baolin.wang@linux.alibaba.com>,
Xin Hao <xhao@linux.alibaba.com>,
linux-mm@kvack.org, mm-commits@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [RFC][PATCH] cifs: Fix cifs_writepages_region()
Date: Fri, 24 Feb 2023 20:45:36 +0000 [thread overview]
Message-ID: <Y/kh8P4oSjunIU7T@casper.infradead.org> (raw)
In-Reply-To: <CAHk-=wgpjrdcs_aFvdHdH6TpOsOmN9S5rXDqCZTB8WqXsZH8Qw@mail.gmail.com>
On Fri, Feb 24, 2023 at 12:16:49PM -0800, Linus Torvalds wrote:
> On Fri, Feb 24, 2023 at 12:14 PM David Howells <dhowells@redhat.com> wrote:
> >
> > Then why do we have to wait for PG_writeback to complete?
>
> At least for PG_writeback, it's about "the _previous_ dirty write is
> still under way, but - since PG_dirty is set again - the page has been
> dirtied since".
>
> So we have to start _another_ writeback, because while the current
> writeback *might* have written the updated data, that is not at all
> certain or clear.
also, we only have a writeback bit, not a writeback count. And when
the current writeback completes, it'll clear that bit. We're also
being kind to our backing store and not writing to the same block twice
at the same time.
> I'm not sure what the fscache rules are.
My understanding is that the fscache bit is set under several
circumstances, but if the folio is dirty _and_ the fscache bit
is set, it means the folio is currently being written to the cache
device. I don't see a conflict there; we can write to the backing
store and the cache device at the same time.
next prev parent reply other threads:[~2023-02-24 20:46 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-20 21:52 [GIT PULL] MM updates for 6.3-rc1 Andrew Morton
2023-02-21 23:36 ` Andrew Morton
2023-02-24 1:33 ` pr-tracker-bot
2023-02-24 1:33 ` Linus Torvalds
2023-02-24 1:56 ` Andrew Morton
2023-02-24 3:01 ` Huang, Ying
2023-02-24 9:04 ` David Howells
2023-02-24 12:12 ` David Howells
2023-02-24 14:31 ` [RFC][PATCH] cifs: Fix cifs_writepages_region() David Howells
2023-02-24 16:06 ` Linus Torvalds
2023-02-24 16:11 ` Matthew Wilcox
2023-02-24 17:15 ` David Howells
2023-02-24 18:44 ` Matthew Wilcox
2023-02-24 20:13 ` David Howells
2023-02-24 20:16 ` Linus Torvalds
2023-02-24 20:45 ` Matthew Wilcox [this message]
2023-02-27 13:20 ` David Howells
2023-02-24 20:58 ` David Howells
2023-02-24 17:19 ` David Howells
2023-02-24 18:58 ` Linus Torvalds
2023-02-24 19:05 ` Linus Torvalds
2023-02-24 22:11 ` [EXTERNAL] " Steven French
2023-03-01 18:32 ` Steven French
2023-02-24 14:48 ` [RFC][PATCH] cifs, afs: Revert changes to {cifs,afs}_writepages_region() David Howells
2023-02-24 16:13 ` Linus Torvalds
2023-02-24 15:13 ` [RFC][PATCH] cifs: Improve use of filemap_get_folios_tag() David Howells
2023-02-24 16:22 ` Linus Torvalds
2023-02-24 17:22 ` David Howells
2023-02-26 2:43 ` [GIT PULL] MM updates for 6.3-rc1 Linus Torvalds
2023-02-26 3:27 ` Linus Torvalds
2023-02-26 3:53 ` Linus Torvalds
2023-02-26 3:57 ` Andrew Morton
2023-02-26 4:03 ` Linus Torvalds
2023-02-26 4:12 ` Linus Torvalds
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=Y/kh8P4oSjunIU7T@casper.infradead.org \
--to=willy@infradead.org \
--cc=akpm@linux-foundation.org \
--cc=baolin.wang@linux.alibaba.com \
--cc=dhowells@redhat.com \
--cc=jack@suse.cz \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mm-commits@vger.kernel.org \
--cc=pc@cjr.nz \
--cc=stfrench@microsoft.com \
--cc=torvalds@linux-foundation.org \
--cc=vishal.moola@gmail.com \
--cc=xhao@linux.alibaba.com \
--cc=ying.huang@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).