linux-ext4 - Re: More ext4 acl/xattr corruption

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Message-ID: <m2iqjx5s4n.fsf@vador.mandriva.com>
Date:	Tue, 19 May 2009 12:00:56 +0200
From:	Thierry Vignaud <tvignaud@...driva.com>
To:	Theodore Tso <tytso@....edu>
Cc:	Kevin Shanahan <kmshanah@...b.org.au>,
	Andreas Dilger <adilger@....com>, Alex Tomas <bzzz@....com>,
	linux-ext4@...r.kernel.org
Subject: Re: More ext4 acl/xattr corruption - 4th occurence now

Theodore Tso <tytso@....edu> writes:

> So here's the final fix (it replaces the short circuit i_cached_extent
> patch) which I plan to push to Linus.  It should be much less of a
> performance hit than simply short-circuiting i_cached_extent...
> 
> Thanks so much for helping to find track this down!!!  If ever someone
> deserved an "Ext4 Baker Street Irregulars" T-shirt, it would be
> you....
> 
>        	       	   	      	   	      - Ted
> 
> commit 039ed7a483fdcb2dbbc29f00cd0d74c101ab14c5
> Author: Theodore Ts'o <tytso@....edu>
> Date:   Thu May 14 17:09:37 2009 -0400
> 
>     ext4: Fix race in ext4_inode_info.i_cached_extent
>     
>     If one CPU is reading from a file while another CPU is writing to the
>     same file different locations, there is nothing protecting the
>     i_cached_extent structure from being used and updated at the same
>     time.  This could potentially cause the wrong location on disk to be
>     read or written to, including potentially causing the corruption of
>     the block group descriptors and/or inode table.
>     
>     Many thanks to Ken Shannah for helping to track down this problem.
>     
>     Signed-off-by: "Theodore Ts'o" <tytso@....edu>

I wonder if that would explain the corruption I reported a couple weeks
ago.

Now I remember I wrongly got 2 parallel cp from the same source
directory to the same target directory.
Could this be the cause?
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