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

From: Arthur Borsboom <arthurborsboom@gmail.com>
To: "Roger Pau Monné" <roger.pau@citrix.com>
Cc: linux-kernel@vger.kernel.org,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	Juergen Gross <jgross@suse.com>,
	Stefano Stabellini <sstabellini@kernel.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	Jens Axboe <axboe@kernel.dk>,
	xen-devel@lists.xenproject.org, linux-block@vger.kernel.org
Subject: Re: [PATCH v2] xen-blkfront: allow discard-* nodes to be optional
Date: Fri, 22 Jan 2021 21:29:01 +0100	[thread overview]
Message-ID: <CALUcmUmBz76p_kHy2yA1v-F_vuTtMwORsqH4gtS04wvV4nQosw@mail.gmail.com> (raw)
In-Reply-To: <CALUcmU=6aAUrkg8KkJQvsQvNr1yL3E88Uy5xsD+u+XOrbUAhCQ@mail.gmail.com>

Any chance of getting this backported to stable?
I believe the previous attempt by CC-ing stable was not following the
correct procedure and probably rejected.

https://lkml.org/lkml/2021/1/19/543

On Wed, 20 Jan 2021 at 16:17, Arthur Borsboom <arthurborsboom@gmail.com> wrote:
>
> This time the patch applied cleanly.
>
> The trim command seems to work as well, meaning no error messages and
> a certain amount of blocks (5GB) is trimmed.
> The trimming did consume a bit of time (10-20 seconds), assuming it is
> actually discarding the blocks at the host.
>
> First run:
>
> [arthur@test-arch ~]$ sudo fstrim -v /
> /: 5.7 GiB (6074368000 bytes) trimmed
>
> Second run:
>
> [arthur@test-arch ~]$ sudo fstrim -v /
> /: 0 B (0 bytes) trimmed
>
> No errors were reported in the dmesg of the VM; no errors in Dom0 and
> no errors in dmesg of Xen (xl dmesg).
>
> Based on this single test, it seems to work.
> You can add me as Tested-By.
>
> On Wed, 20 Jan 2021 at 15:35, Roger Pau Monné <roger.pau@citrix.com> 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.
> >
> > I think it's possible your email client has mangled the patch, I'm
> > attaching the same patch to this email, could you try to apply it
> > again and report back? (this time it should apply cleanly)
> >
> > Thanks, Roger.
>
>
>
> --
> Arthur Borsboom

-- 
Arthur Borsboom