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From: Dave Chinner <david@fromorbit.com>
To: Lukas Czerner <lczerner@redhat.com>
Cc: Jayashree Mohan <jayashree2912@gmail.com>,
	linux-xfs@vger.kernel.org,
	Vijaychidambaram Velayudhan Pillai <vijay@cs.utexas.edu>,
	Ashlie Martinez <ashmrtn@utexas.edu>,
	fstests@vger.kernel.org, Theodore Ts'o <tytso@mit.edu>
Subject: Re: XFS crash consistency bug : Loss of fsynced metadata operation
Date: Fri, 16 Mar 2018 11:19:55 +1100	[thread overview]
Message-ID: <20180316001955.GN18129@dastard> (raw)
In-Reply-To: <20180315103207.scrm5e4cvkj26m4k@rh_laptop>

On Thu, Mar 15, 2018 at 11:32:07AM +0100, Lukas Czerner wrote:
> 
> And where the "cdcd" data is comming from ? Not from the
> 
> "pwrite -S 1 0 64k"
> 
> that's producing "0101".

Ah, too much context switching. Makes me look like the village
idiot...

Ok, I just spent some time looking at this in detail (event traces,
etc) and it is indeed as the test describes - an whole delalloc
extent allocation on partial overwrite. THe partial overwrite is
triggered by the fpunch/fzero code, and it appears the delalloc
converison is not paying attention to the start offset of the
writeback:

xfs_writepage:        dev 7:0 ino 0x7603 pgoff 0xf000 size 0x10000 delalloc 1
.....
xfs_alloc_near_greater: dev 7:0 agno 0 agbno 3784 minlen 16 maxlen 16
.....
xfs_write_extent:     dev 7:0 ino 0x7603 offset 0 block 3784 count 16 flag 0

IOWs, as I've said from the start (based on the test description)
this has nothing to do with the corruption issue CrashMonkey is
creating.

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

  reply	other threads:[~2018-03-16  0:21 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-13  2:15 XFS crash consistency bug : Loss of fsynced metadata operation Jayashree Mohan
2018-03-13  4:21 ` Dave Chinner
2018-03-13  6:36   ` Amir Goldstein
2018-03-13 18:05     ` Jayashree Mohan
2018-03-13 16:57   ` Jayashree Mohan
2018-03-13 22:45     ` Dave Chinner
2018-03-14 13:16       ` Lukas Czerner
2018-03-14 13:32         ` Dave Chinner
2018-03-14 13:57           ` Lukas Czerner
2018-03-14 21:24             ` Dave Chinner
2018-03-15  6:15               ` Lukas Czerner
2018-03-15 10:06                 ` Dave Chinner
2018-03-15 10:32                   ` Lukas Czerner
2018-03-16  0:19                     ` Dave Chinner [this message]
2018-03-16  5:45                       ` Lukas Czerner
2018-03-17  3:16                         ` Dave Chinner

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