From: Miklos Szeredi <miklos@szeredi.hu>
To: Vivek Goyal <vgoyal@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Qian Cai <cai@lca.pw>, Hugh Dickins <hughd@google.com>,
Matthew Wilcox <willy@infradead.org>,
"Kirill A . Shutemov" <kirill@shutemov.name>,
Linux-MM <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Amir Goldstein <amir73il@gmail.com>
Subject: Re: Possible deadlock in fuse write path (Was: Re: [PATCH 0/4] Some more lock_page work..)
Date: Wed, 21 Oct 2020 09:40:26 +0200 [thread overview]
Message-ID: <CAJfpegsi8UFiYyPrPbQob2x4X7NKSnciEz-a=5YZtFCgY0wL6w@mail.gmail.com> (raw)
In-Reply-To: <20201020204226.GA376497@redhat.com>
On Tue, Oct 20, 2020 at 10:42 PM Vivek Goyal <vgoyal@redhat.com> wrote:
> As you said, for the full page WRITE, we can probably mark it
> page uptodate write away and drop page lock (Keep reference and
> send WRITE request to fuse server). For the partial page write this will
> not work and there seem to be atleast two options.
>
> A. Either we read the page back from disk first and mark it uptodate.
>
> B. Or we keep track of such partial writes and block any further
> reads/readpage/direct_IO on these pages till partial write is
> complete. After that looks like page will be left notuptodate
> in page cache and reader will read it from disk. We are doing
> something similar for tracking writeback requests. It is much
> more complicated though and we probably can design something
> simpler for these writethrough/synchronous writes.
>
> I am assuming that A. will lead to performance penalty for short
> random writes.
C. Keep partial tail page locked. If write involves a partial and
head AND tail page, then read head page first. I think that would be
a good compromise between performance and simplicity.
WDYT?
Thanks,
Miklos
next prev parent reply other threads:[~2020-10-21 7:40 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-13 19:59 [PATCH 0/4] Some more lock_page work Linus Torvalds
2020-10-13 20:03 ` Linus Torvalds
2020-10-14 13:05 ` Kirill A. Shutemov
2020-10-14 16:53 ` Linus Torvalds
2020-10-14 18:15 ` Matthew Wilcox
2020-10-15 10:41 ` Kirill A. Shutemov
2020-10-15 9:43 ` Kirill A. Shutemov
2020-10-15 16:44 ` Linus Torvalds
2020-10-14 5:50 ` Hugh Dickins
[not found] ` <4794a3fa3742a5e84fb0f934944204b55730829b.camel@lca.pw>
2020-10-15 2:44 ` Linus Torvalds
2020-10-15 15:16 ` Possible deadlock in fuse write path (Was: Re: [PATCH 0/4] Some more lock_page work..) Vivek Goyal
2020-10-15 19:55 ` Vivek Goyal
2020-10-15 21:21 ` Linus Torvalds
2020-10-16 10:02 ` Miklos Szeredi
2020-10-16 12:27 ` Matthew Wilcox
2020-10-20 20:42 ` Vivek Goyal
2020-10-21 7:40 ` Miklos Szeredi [this message]
2020-10-21 20:12 ` Vivek Goyal
2020-10-28 20:29 ` Miklos Szeredi
2021-02-09 10:01 ` Miklos Szeredi
2021-02-09 19:09 ` Vivek Goyal
2020-10-16 18:19 ` Vivek Goyal
2020-10-16 18:24 ` Linus Torvalds
2020-10-16 18:24 ` Linus Torvalds
2020-10-16 23:03 ` Dave Chinner
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