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From: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
To: "Theodore Y. Ts'o" <tytso@mit.edu>
Cc: "Jeff Layton" <jlayton@redhat.com>, 焦晓冬 <milestonejxd@gmail.com>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	"Rogier Wolff" <R.E.Wolff@BitWizard.nl>
Subject: Re: POSIX violation by writeback error
Date: Thu, 27 Sep 2018 23:48:58 +0100	[thread overview]
Message-ID: <20180927234858.507ea60b@alans-desktop> (raw)
In-Reply-To: <20180926214909.GD3688@thunk.org>

On Wed, 26 Sep 2018 17:49:09 -0400
"Theodore Y. Ts'o" <tytso@mit.edu> wrote:

> On Wed, Sep 26, 2018 at 07:10:55PM +0100, Alan Cox wrote:
> > In almost all cases you don't care so you wouldn't use it. In those cases
> > where it might matter it's almost always the case that a reader won't
> > consume it before it hits the media.
> > 
> > That's why I suggested having an fbarrier() so you can explicitly say 'in
> > the even that case does happen then stall and write it'. It's kind of
> > lazy fsync. That can be used with almost no cost by things like mail
> > daemons.  
> 
> How could mail daemons use it?  They *have* to do an fsync() before
> they send a 2xx SMTP return code.

Point - so actually it would be less useful

> > Another way given that this only really makes sense with locks
> > is to add that fbarrier notion as a file locking optional semantic so you
> > can 'unlock with barrier' and 'lock with barrier honoured'  
> 
> I'm not sure what you're suggesting?

If someone has an actual case you could in theory constrain it to a range
specified in a file lock and only between two people who care. That said
seems like a lot of complexity to make a case nobody cares about only
affect people who care about it

Alan

  reply	other threads:[~2018-09-28  5:09 UTC|newest]

Thread overview: 51+ 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 [this message]
2018-09-27  7:18               ` Rogier Wolff
2018-09-27 12:43             ` Jeff Layton
2018-09-27 14:27               ` Theodore Y. Ts'o
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  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  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  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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