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Re: [Qemu-devel] [PATCH v6 01/14] qcow2: Allow "full" discard
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH v6 01/14] qcow2: Allow "full" discard |
Date: |
Tue, 29 Apr 2014 10:57:30 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.4.0 |
On 04/29/2014 09:07 AM, Max Reitz wrote:
> Normally, discarded sectors should read back as zero. However, there are
> cases in which a sector (or rather cluster) should be discarded as if
> they were never written in the first place, that is, reading them should
> fall through to the backing file again.
>
> Signed-off-by: Max Reitz <address@hidden>
> ---
> block/qcow2-cluster.c | 27 +++++++++++++++++----------
> block/qcow2-snapshot.c | 2 +-
> block/qcow2.c | 2 +-
> block/qcow2.h | 2 +-
> 4 files changed, 20 insertions(+), 13 deletions(-)
> + *
> + * In case of full_discard being true, the sector should not be read
> + * back as zeroes, but rather fall through to the backing file.
Maybe less awkward as:
If full_discard is true, the sector should not read back as zeroes, but
rather fall through to the backing file.
But minor enough that I'm okay with:
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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- [Qemu-devel] [PATCH v6 00/14] qemu-img: Implement commit like QMP, Max Reitz, 2014/04/29
- [Qemu-devel] [PATCH v6 01/14] qcow2: Allow "full" discard, Max Reitz, 2014/04/29
- Re: [Qemu-devel] [PATCH v6 01/14] qcow2: Allow "full" discard,
Eric Blake <=
- [Qemu-devel] [PATCH v6 02/14] qcow2: Implement bdrv_make_empty(), Max Reitz, 2014/04/29
- [Qemu-devel] [PATCH v6 03/14] qcow2: Optimize bdrv_make_empty(), Max Reitz, 2014/04/29
- [Qemu-devel] [PATCH v6 04/14] blockjob: Introduce block_job_complete_sync(), Max Reitz, 2014/04/29
- [Qemu-devel] [PATCH v6 05/14] blockjob: Add "ready" field, Max Reitz, 2014/04/29
- [Qemu-devel] [PATCH v6 06/14] block/mirror: Improve progress report, Max Reitz, 2014/04/29