From: "Theodore Y. Ts'o" <tytso@mit.edu>
To: Jeff Layton <jlayton@redhat.com>
Cc: "Alan Cox" <gnomes@lxorguk.ukuu.org.uk>,
焦晓冬 <milestonejxd@gmail.com>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
"Rogier Wolff" <R.E.Wolff@BitWizard.nl>,
"Matthew Wilcox" <willy@infradead.org>
Subject: Re: POSIX violation by writeback error
Date: Thu, 27 Sep 2018 10:27:38 -0400 [thread overview]
Message-ID: <20180927142738.GA27040@thunk.org> (raw)
In-Reply-To: <51b401b82356c2d8e124bb8701f310afd98e0838.camel@redhat.com>
On Thu, Sep 27, 2018 at 08:43:10AM -0400, Jeff Layton wrote:
>
> Basically, the problem (as I see it) is that we can end up evicting
> uncleanable data from the cache before you have a chance to call fsync,
> and that means that the results of a read after a write are not
> completely reliable.
Part of the problem is that people don't agree on what the problem is. :-)
The original posting was from someone who claimed it was a "POSIX
violation" if a subsequent read returns *successfully*, but then the
writeback succeeds.
Other people are worried about this problem; yet others are worried
about the system wedging and OOM-killing itself, etc.
The problem is that in the face of I/O errors, it's impossible to keep
everyone happy. (You could make the local storage device completely
reliable, with a multi-million dollar storage array with remote
replication, but then the CFO won't be happy; and other people were
talking about making things work with cheap USB thumb drives and
laptops. This is the very definition of an over-constained problem.)
- Ted
next prev parent reply other threads:[~2018-09-27 14:27 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CAJDTihx2yaR-_-9Ks1PoFcrKNZgUOoLdN-wRTTMV76Jg_dCLrw@mail.gmail.com>
2018-09-04 10:56 ` POSIX violation by writeback error Jeff Layton
2018-09-24 23:30 ` Alan Cox
2018-09-25 11:15 ` Jeff Layton
2018-09-25 15:46 ` Theodore Y. Ts'o
2018-09-25 16:17 ` Rogier Wolff
2018-09-25 16:39 ` Alan Cox
2018-09-25 16:41 ` Jeff Layton
2018-09-25 22:30 ` Theodore Y. Ts'o
2018-09-26 18:10 ` Alan Cox
2018-09-26 21:49 ` Theodore Y. Ts'o
2018-09-27 22:48 ` Alan Cox
2018-09-27 7:18 ` Rogier Wolff
2018-09-27 12:43 ` Jeff Layton
2018-09-27 14:27 ` Theodore Y. Ts'o [this message]
2018-09-25 17:35 ` Adam Borowski
2018-09-25 22:46 ` Theodore Y. Ts'o
2018-09-04 6:32 焦晓冬
2018-09-04 7:53 ` Rogier Wolff
2018-09-04 8:58 ` 焦晓冬
2018-09-04 9:29 ` Rogier Wolff
2018-09-04 10:45 ` 焦晓冬
2018-09-04 11:09 ` Jeff Layton
2018-09-04 14:56 ` 焦晓冬
2018-09-04 15:44 ` Jeff Layton
2018-09-04 16:12 ` J. Bruce Fields
2018-09-04 16:23 ` Rogier Wolff
2018-09-04 18:54 ` J. Bruce Fields
2018-09-04 20:18 ` Jeff Layton
2018-09-04 20:35 ` Vito Caputo
2018-09-04 21:02 ` Matthew Wilcox
2018-09-05 0:51 ` Dave Chinner
2018-09-05 8:24 ` 焦晓冬
2018-09-05 10:55 ` Jeff Layton
2018-09-05 12:07 ` Rogier Wolff
2018-09-06 2:57 ` Dave Chinner
2018-09-06 2:57 ` Dave Chinner
2018-09-06 9:17 ` Rogier Wolff
2018-09-24 23:09 ` Alan Cox
2018-09-05 13:53 ` J. Bruce Fields
2018-09-05 7:08 ` Rogier Wolff
2018-09-05 7:39 ` Martin Steigerwald
2018-09-05 7:39 ` Martin Steigerwald
2018-09-05 8:04 ` Rogier Wolff
2018-09-05 8:04 ` Rogier Wolff
2018-09-05 8:37 ` 焦晓冬
2018-09-05 12:07 ` Austin S. Hemmelgarn
2018-09-05 12:46 ` Rogier Wolff
2018-09-05 9:32 ` Martin Steigerwald
2018-09-05 9:32 ` Martin Steigerwald
2018-09-05 7:37 ` Martin Steigerwald
2018-09-05 11:42 ` Jeff Layton
2018-09-05 8:09 ` 焦晓冬
2018-09-05 13:08 ` Theodore Y. Ts'o
2018-09-24 23:21 ` Alan Cox
2018-09-06 7:28 ` 焦晓冬
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