From: Hans Reiser <reiser@namesys.com>
To: Andrew Morton <akpm@osdl.org>
Cc: reiserfs-list@namesys.com, linux-kernel@vger.kernel.org
Subject: Re: precise characterization of ext3 atomicity
Date: Thu, 04 Sep 2003 20:25:18 +0400 [thread overview]
Message-ID: <3F57676E.7010804@namesys.com> (raw)
In-Reply-To: <20030904091256.1dca14a5.akpm@osdl.org>
Andrew Morton wrote:
>Hans Reiser <reiser@namesys.com> wrote:
>
>
>> Perhaps the following is correct?
>>
>> By contrast, ext3 in data=journal and data=ordered modes only guarantees the atomicity of a single write
>> that does not span a page boundary, and it guarantees that its internal
>> metadata will not be corrupted even if your application's data is
>> corrupted after the crash (due to the application spreading what should be committed atomically across more than one block).
>>
>>
>
>Correct != comprehensible ;)
>
Touche!
Let's try this then:
Ext3 guarantees that its metadata will be comitted sufficiently
atomically that after a crash it will be consistent with itself.
In data=journal and data=ordered modes ext3 also guarantees that the metadata will be committed atomically with the data they point to. However ext3 does not provide user data atomicity guarantees beyond the scope of a single filesystem disk block (usually 4 kilobytes). If a single write() spans two disk blocks it is possible that a crash partway through the write will result in only one of those blocks appearing in the file after recovery.
--
Hans
next prev parent reply other threads:[~2003-09-04 16:25 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-09-04 14:20 precise characterization of ext3 atomicity Hans Reiser
2003-09-04 15:55 ` Andrew Morton
2003-09-04 15:59 ` Hans Reiser
2003-09-04 16:12 ` Andrew Morton
2003-09-04 16:25 ` Hans Reiser [this message]
2003-09-04 18:15 ` Mike Fedyk
2003-09-04 16:05 ` Antonio Vargas
2003-09-04 18:37 ` Hans Reiser
2003-09-04 19:12 ` Mike Fedyk
2003-09-04 21:03 ` Hans Reiser
2003-09-04 19:28 ` Andreas Dilger
2003-09-04 21:32 ` Hans Reiser
2003-09-04 22:03 ` Andreas Dilger
2003-09-05 13:47 ` Chris Mason
2003-09-09 13:09 ` Pavel Machek
2003-09-09 19:21 ` Gábor Lénárt
2003-09-09 19:43 ` Mike Fedyk
2003-09-04 20:16 ` Daniel Phillips
2003-09-04 20:10 ` Andrew Morton
2003-09-04 21:08 ` Daniel Phillips
2003-09-04 21:39 ` Hans Reiser
2003-09-04 21:59 ` Daniel Phillips
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