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From: Jamie Lokier <jamie@shareable.org>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: "Jörn Engel" <joern@wohnheim.fh-wedel.de>,
	"Davide Libenzi" <davidel@xmailserver.org>,
	"Patrick J. LoPresti" <patl@users.sourceforge.net>,
	"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] cowlinks v2
Date: Mon, 29 Mar 2004 13:36:58 +0100	[thread overview]
Message-ID: <20040329123658.GA4984@mail.shareable.org> (raw)
In-Reply-To: <m1zna0tp55.fsf@ebiederm.dsl.xmission.com>

Eric W. Biederman wrote:
> The file will become a cow file only after it is modified or it's
> containing directory is modified.

Eh?  The file (or directory) must be labelled as a cowlinked file the
moment you make the cowlink, not when the data is modified.  It's
_breaking_ the cowlink that happens when the data (or directory
contents) are modified.

> Thus you can have data in the
> file that was written after the snapshot operation finished, but
> before the individual file itself is marked cow.

The creation of a cowlink should be atomic w.r.t. writing.

Specifically, the operation which moves the contents of a non-cowlink
inode to a newly created shared inode, and converts the original
non-cowlink inode to a cowlink inode, should be atomic.

Is there an unavoidable race condition?  I don't see one.

-- Jamie

  reply	other threads:[~2004-03-29 12:39 UTC|newest]

Thread overview: 95+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-03-20  8:34 [PATCH] cowlinks v2 Jörn Engel
2004-03-20  8:49 ` Andrew Morton
2004-03-20 11:27   ` Jörn Engel
2004-03-20 19:28     ` Andrew Morton
2004-03-21 12:43       ` Jörn Engel
2004-03-21 18:53       ` Jörn Engel
     [not found] ` <mit.lcs.mail.linux-kernel/20040320083411.GA25934@wohnheim.fh-wedel.de>
2004-03-20 15:03   ` Patrick J. LoPresti
2004-03-20 15:23     ` Jörn Engel
2004-03-29 17:12       ` Pavel Machek
2004-03-29 21:05         ` Patrick J. LoPresti
2004-03-29 23:16           ` Pavel Machek
2004-03-31 14:34             ` Jamie Lokier
2004-03-31 14:45               ` Pavel Machek
2004-03-31 15:20                 ` Jamie Lokier
2004-04-02 11:44                 ` Tim Connors
2004-04-02 16:54             ` Jörn Engel
2004-04-02 18:01               ` Pavel Machek
2004-04-02 18:17                 ` Jörn Engel
2004-04-02 18:23                   ` Pavel Machek
2004-04-02 19:28                     ` Ross Biro
2004-04-02 21:35                       ` Pavel Machek
2004-04-05  8:12                       ` Jörn Engel
2004-04-05  8:19                         ` Pavel Machek
2004-04-05  8:45                           ` Jörn Engel
2004-04-02 20:09                     ` Jamie Lokier
2004-04-02 21:39                       ` Pavel Machek
2004-04-02 22:00                         ` Chris Friesen
2004-04-03  0:49                           ` Jamie Lokier
2004-04-03  8:23                             ` Pavel Machek
2004-04-03 13:15                               ` Jamie Lokier
2004-04-05  8:19                                 ` Jörn Engel
2004-04-05  8:22                                   ` Pavel Machek
2004-04-03  0:46                         ` Jamie Lokier
2004-04-03  1:04                         ` Jamie Lokier
2004-04-03  1:21                           ` Erik Andersen
2004-04-03  1:59                             ` Jamie Lokier
2004-04-03  3:55                               ` Ross Biro
2004-04-03  9:09                               ` Pavel Machek
2004-04-03 13:27                                 ` Jamie Lokier
2004-04-03 18:39                           ` Eric W. Biederman
2004-04-03 19:43                             ` Jamie Lokier
2004-04-03 20:30                               ` Eric W. Biederman
2004-04-03 21:59                                 ` Jamie Lokier
2004-04-04  8:15                                   ` Eric W. Biederman
2004-04-05  8:35                               ` Jörn Engel
2004-04-05  9:15                                 ` Eric W. Biederman
2004-04-05  9:18                                   ` Jörn Engel
2004-04-05 11:43                                   ` Pavel Machek
2004-04-05 12:17                                     ` Jamie Lokier
2004-04-05 12:39                                   ` Jamie Lokier
2004-04-05 12:41                                 ` Jamie Lokier
2004-04-05 18:03                                   ` Jörn Engel
2004-04-05 11:10                         ` jlnance
2004-04-05 11:46                           ` Pavel Machek
2004-04-05 12:35                           ` Jamie Lokier
2004-04-05  8:43                     ` Jörn Engel
2004-04-03 19:47               ` Eric W. Biederman
2004-04-05  8:54                 ` Jörn Engel
2004-04-05  9:07                   ` Eric W. Biederman
2004-03-20 16:48     ` Davide Libenzi
2004-03-21 12:57       ` Jörn Engel
2004-03-21 17:59         ` Davide Libenzi
2004-03-21 18:14           ` Jörn Engel
2004-03-21 20:26             ` Davide Libenzi
2004-03-21 20:35               ` Jörn Engel
2004-03-22  0:18             ` Eric W. Biederman
2004-03-22  0:25               ` Davide Libenzi
2004-03-22  5:07                 ` Eric W. Biederman
2004-03-22  5:11                   ` Davide Libenzi
2004-03-22 11:20                     ` Eric W. Biederman
2004-03-22 16:02                       ` Davide Libenzi
2004-03-25 17:49               ` Jamie Lokier
2004-03-25 18:06                 ` Eric W. Biederman
2004-03-25 19:43                   ` Jamie Lokier
2004-03-25 20:38                     ` Linus Torvalds
2004-03-25 22:16                       ` Eric W. Biederman
2004-04-01 14:53                         ` Jörn Engel
2004-04-02 11:54                         ` Tim Connors
2004-03-25 21:46                     ` Eric W. Biederman
2004-03-27 10:28                       ` Jamie Lokier
2004-03-27 21:00                         ` Eric W. Biederman
2004-03-27 21:42                           ` Jamie Lokier
2004-03-27 23:45                             ` Eric W. Biederman
2004-03-28  0:43                               ` Eric W. Biederman
2004-03-28 12:22                                 ` Jamie Lokier
2004-03-28 20:07                                   ` Eric W. Biederman
2004-03-28 23:55                                     ` Jamie Lokier
2004-03-29  1:31                                       ` Eric W. Biederman
2004-03-29 12:36                                         ` Jamie Lokier [this message]
2004-03-29 19:36                                           ` Eric W. Biederman
2004-03-29 23:05                                             ` Jamie Lokier
2004-03-29 23:58                                               ` Eric W. Biederman
2004-03-29  7:45                                       ` Denis Vlasenko
2004-03-29  9:28                             ` Pavel Machek
2004-03-29 12:40                               ` Jamie Lokier

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