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Re: [Qemu-block] [Qemu-devel] [PATCH for-2.8 v3] xen_disk: split discard
From: |
Eric Blake |
Subject: |
Re: [Qemu-block] [Qemu-devel] [PATCH for-2.8 v3] xen_disk: split discard input to match internal representation |
Date: |
Wed, 23 Nov 2016 05:40:00 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 |
On 11/23/2016 04:39 AM, Olaf Hering wrote:
> The guest sends discard requests as u64 sector/count pairs, but the
> block layer operates internally with s64/s32 pairs. The conversion
> leads to IO errors in the guest, the discard request is not processed.
>
> domU.cfg:
> 'vdev=xvda, format=qcow2, backendtype=qdisk, target=/x.qcow2'
> domU:
> mkfs.ext4 -F /dev/xvda
> Discarding device blocks: failed - Input/output error
>
> Fix this by splitting the request into chunks of BDRV_REQUEST_MAX_SECTORS.
> Add input range checking to avoid overflow.
>
> Fixes f313520 ("xen_disk: add discard support")
>
> Signed-off-by: Olaf Hering <address@hidden>
> ---
Qualifies as a bug fix, so requesting 2.8 inclusion.
Reviewed-by: Eric Blake <address@hidden>
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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