Re: Loopback device hung [was Re: xfs deadlock on 3.9-rc5 runningxfstests case #78]

From: Phillip Susi
Date: Wed Apr 03 2013 - 11:41:30 EST


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On 4/3/2013 7:41 AM, Jens Axboe wrote:
>> Thanks for testing! I don't particularly like this stuff in
>> loop, though. It's quite nasty and depends on other behaviour. It
>> would be prettier if we just had rescan_partitions() do the right
>> thing, and only drop partitions and not rescan if NO_PART_SCAN is
>> set.
>>
>> Ala the below, dropping the loop change and implementing that
>> change in the core code. Phillip, can you check whether this does
>> the right thing for your bug too?
>
> Phillip? I'm going to revert the loop change asap, so if you want
> this fixed for 3.10, it's about that time to test it out.

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.


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