Date: Tue, 9 Apr 2013 16:55:19 +1000
From: Dave Chinner <david@fromorbit.com>
To: Phillip Susi <psusi@ubuntu.com>
Cc: Jens Axboe <axboe@kernel.dk>, CAI Qian <caiqian@redhat.com>,
        xfs@oss.sgi.com, LKML <linux-kernel@vger.kernel.org>
Subject: Re: Loopback device hung [was Re: xfs deadlock on 3.9-rc5 running
 xfstests case #78]
Message-ID: <20130409065519.GH17758@dastard>
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On Thu, Apr 04, 2013 at 04:30:54PM -0400, Phillip Susi wrote:
> > I have not tested it yet, but I am pretty sure it won't work.  It
> > looks like the patch changes the BLKRRPART path to go ahead and remove
> > existing partitions when GENHD_FL_NO_PARTSCAN is set.  loop doesn't
> > issue the BLKRRPART ioctl when !LO_FLAGS_PARTSCAN so this won't help.
> >  I think loop needs to set GENHD_FL_NO_PARTSCAN and then issue the
> > ioctl regardless of the LO_FLAGS_PARTSCAN flag to get the partitions
> > to be removed.  I will try to test tonight.
> 
> After testing, my initial thoughts appeared to have been correct.  I had
> to modify the patch as follows.  To test, simply do:
> 
> truncate -s 10m img
> losetup /dev/loop0 img
> parted /dev/loop0
> mklabel msdos
> mkpart primary ext2 1m 2m
> quit
> ls /dev/loop0*
> 
> Note the /dev/loop0p1 node.  Run losetup -d /dev/loop0 and see if it is
> still there.

Jens, can we get one of these fixes merged quickly? xfstests is
unusable on any kernel more recent than 3.9-rc4 because of these
problems....

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com
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