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Re: Loopback device hung [was Re: xfs deadlock on 3.9-rc5 running xfstes

To: Phillip Susi <psusi@xxxxxxxxxx>
Subject: Re: Loopback device hung [was Re: xfs deadlock on 3.9-rc5 running xfstests case #78]
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Tue, 9 Apr 2013 16:55:19 +1000
Cc: Jens Axboe <axboe@xxxxxxxxx>, CAI Qian <caiqian@xxxxxxxxxx>, xfs@xxxxxxxxxxx, LKML <linux-kernel@xxxxxxxxxxxxxxx>
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <515DE2FE.1080201@xxxxxxxxxx>
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User-agent: Mutt/1.5.21 (2010-09-15)
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


Dave Chinner

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