Re: Xen VM call trace on fstrim: Error: discard_granularity is 0.

[Arthur Borsboom <arthurborsboom@xxxxxxxxx>]

Find attached the output of xenstore-ls

Best regards,

Arthur Borsboom.

On Mon, 18 Jan 2021 at 11:19, Roger Pau Monné <roger.pau@xxxxxxxxxx> wrote:

On Wed, Jan 13, 2021 at 11:43:50AM +0100, Arthur Borsboom wrote:
> When performing the following command in a Xen VM the call trace below is
> generated.
>
>     sudo fstrim -v /
>
> Xen VM host: Xen 4.14.0
> Xen Dom0: Linux 4.19.14
> Xen DomX: Linux 5.10.6
>
> The code in the kernel triggering this trace is the following.
>
>         /* In case the discard granularity isn't set by buggy device driver
> */
>         if (WARN_ON_ONCE(!q->limits.discard_granularity)) {
>                 char dev_name[BDEVNAME_SIZE];
>
>                 bdevname(bdev, dev_name);
>                 pr_err_ratelimited("%s: Error: discard_granularity is
> 0.\n", dev_name);
>                 return -EOPNOTSUPP;
>         }

So it seems like the underlying storage in dom0 doesn't support
discard, and hence the feature don't get setup on the frontend?

Can you print the output of `xenstore-ls -fp` executed from dom0 when
the guest is running? That way I could see which features the backend
is exposing.

Thanks, Roger.

--

Arthur Borsboom

Attachment: xenstore-ls.txt
Description: Text document