[dm-devel] fstrim discarding too many or wrong blocks on Linux 5.1, leading to data loss

Michael Laß bevan at bi-co.net
Tue May 21 19:59:50 UTC 2019

> Am 21.05.2019 um 21:00 schrieb Andrea Gelmini <andrea.gelmini at linux.it>:
> On Tue, May 21, 2019 at 06:46:20PM +0200, Michael Laß wrote:
>>> I finished bisecting. Here’s the responsible commit:
>>> commit 61697a6abd24acba941359c6268a94f4afe4a53d
>>> Author: Mike Snitzer <snitzer at redhat.com>
>>> Date:   Fri Jan 18 14:19:26 2019 -0500
>>>   dm: eliminate 'split_discard_bios' flag from DM target interface
>>>   There is no need to have DM core split discards on behalf of a DM target
>>>   now that blk_queue_split() handles splitting discards based on the
>>>   queue_limits.  A DM target just needs to set max_discard_sectors,
>>>   discard_granularity, etc, in queue_limits.
>>>   Signed-off-by: Mike Snitzer <snitzer at redhat.com>
>> Reverting that commit solves the issue for me on Linux 5.1.3. Would that be an option until the root cause has been identified? I’d rather not let more people run into this issue.
> Thanks a lot Michael, for your time/work.
> This kind of bisecting are very boring and time consuming.

I just sent a patch to dm-devel which fixes the issue for me. Maybe you can test that in your environment?


PS: Sorry if the patch was sent multiple times. I had some issues with git send-email.

> I CC: also the patch author.
> Thanks again,
> Andrea

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