Re: [PATCH v2] xen-blkfront: allow discard-* nodes to be optional

From: Jan Beulich
Date: Wed Jan 20 2021 - 09:42:53 EST

On 20.01.2021 15:35, Roger Pau Monné wrote:
> On Wed, Jan 20, 2021 at 03:23:30PM +0100, Arthur Borsboom wrote:
>> Hi Roger,
>> I have set up a test environment based on Linux 5.11.0-rc4.
>> The patch did not apply clean, so I copied/pasted the patch manually.
>> Without the patch the call trace (as reported) is visible in dmesg.
>> With the patch the call trace in dmesg is gone, but ... (there is always a
>> but) ...
>> Now the discard action returns the following.
>> [arthur@test-arch ~]$ sudo fstrim -v /
>> fstrim: /: the discard operation is not supported
>> It might be correct, but of course I was hoping the Xen VM guest would pass
>> on the discard request to the block device in the Xen VM host, which is a
>> disk partition.
>> Any suggestions?
> Hm, that's not what I did see on my testing, the operation worked OK,
> and that's what I would expect to happen in your case also, since I
> know the xenstore keys.

Does discard work on partitions (and not just on entire disks)?
It's been a while since I last had anything to do with this code,
so I may well misremember.