From: Jan Kara <jack@suse.cz>
To: Amir Goldstein <amir73il@gmail.com>
Cc: Ext4 Developers List <linux-ext4@vger.kernel.org>
Subject: Re: recursive mtime patches
Date: Tue, 12 Apr 2011 17:48:30 +0200 [thread overview]
Message-ID: <20110412154830.GF5246@quack.suse.cz> (raw)
In-Reply-To: <BANLkTim6NYYnr+m4mqawSD4-Mbbzj699hQ@mail.gmail.com>
Hi,
On Mon 11-04-11 16:37:57, Amir Goldstein wrote:
> Do you have an uptodate version of your recursive mtime patches?
> The only version I can find online is the original series from 2007.
I've put latest version (against 2.6.37) to
http://beta.suse.com/private/jack/recursive_mtime/
> I am interested in the patches for indexdb-like application,
> so persistence after crash is also important for my use case.
> Your patches would require the application to perform a full
> directory scan after crash, right?
OK, it depends. Currently, even mtime updates are not reliable (data can
be written to a file while mtime update is not yet committed). Recursive
modification stamps have possibly larger race windows but I haven't really
tried how much (I just know that even mtime races are not that hard to
trigger if you try). So it really depends on how big reliability do you
expect and I personally don't find much value in just rescanning and
checking for mtime after a crash. Reading all the data and doing checksum
certainly has more value but at a high cost.
Honza
--
Jan Kara <jack@suse.cz>
SUSE Labs, CR
next prev parent reply other threads:[~2011-04-12 15:48 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-11 13:37 recursive mtime patches Amir Goldstein
2011-04-12 15:48 ` Jan Kara [this message]
2011-04-13 19:16 ` Amir Goldstein
2011-04-13 21:39 ` Jan Kara
2011-04-14 7:12 ` Amir Goldstein
2011-04-14 9:21 ` Jan Kara
2011-04-14 9:36 ` Amir Goldstein
2011-04-14 9:49 ` Jan Kara
2011-04-14 10:06 ` Amir Goldstein
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