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Re: [Qemu-devel] [Qemu-block] [PATCH v6 0/8] block: Mirror discarded sec
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [Qemu-block] [PATCH v6 0/8] block: Mirror discarded sectors |
Date: |
Tue, 2 Jun 2015 17:02:52 +0100 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
On Thu, May 28, 2015 at 01:29:42PM +0800, Fam Zheng wrote:
> v6: Fix pnum in bdrv_get_block_status_above. [Paolo]
>
> v5: Rewrite patch 1.
> Address Eric's comments on patch 3.
> Add Eric's rev-by to patches 2 & 4.
> Check BDRV_BLOCK_DATA in patch 3. [Paolo]
>
> This fixes the mirror assert failure reported by wangxiaolong:
>
> https://lists.gnu.org/archive/html/qemu-devel/2015-04/msg04458.html
>
> The direct cause is that hbitmap code couldn't handle unset of bits *after*
> iterator's current position. We could fix that, but the bdrv_reset_dirty()
> call
> is more questionable:
>
> Before, if guest discarded some sectors during migration, it could see
> different data after moving to dest side, depending on block backends of the
> src and the dest. This is IMO worse than mirroring the actual reading as done
> in this series, because we don't know what the guest is doing.
>
> For example if a guest first issues WRITE SAME to wipe out the area then
> issues
> UNMAP to discard it, just to get rid of some sensitive data completely, we may
> miss both operations and leave stale data on dest image.
>
>
> Fam Zheng (8):
> block: Add bdrv_get_block_status_above
> qmp: Add optional bool "unmap" to drive-mirror
> mirror: Do zero write on target if sectors not allocated
> block: Fix dirty bitmap in bdrv_co_discard
> block: Remove bdrv_reset_dirty
> qemu-iotests: Make block job methods common
> qemu-iotests: Add test case for mirror with unmap
> iotests: Use event_wait in wait_ready
>
> block.c | 12 --------
> block/io.c | 60 ++++++++++++++++++++++++++++++---------
> block/mirror.c | 27 +++++++++++++++---
> blockdev.c | 5 ++++
> hmp.c | 2 +-
> include/block/block.h | 4 +++
> include/block/block_int.h | 4 +--
> qapi/block-core.json | 8 +++++-
> qmp-commands.hx | 3 ++
> tests/qemu-iotests/041 | 66
> ++++++++++---------------------------------
> tests/qemu-iotests/132 | 59 ++++++++++++++++++++++++++++++++++++++
> tests/qemu-iotests/132.out | 5 ++++
> tests/qemu-iotests/group | 1 +
> tests/qemu-iotests/iotests.py | 23 +++++++++++++++
> 14 files changed, 195 insertions(+), 84 deletions(-)
> create mode 100644 tests/qemu-iotests/132
> create mode 100644 tests/qemu-iotests/132.out
>
> --
> 2.4.1
>
>
Thanks, applied to my block tree:
https://github.com/stefanha/qemu/commits/block
Stefan
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Stefan Hajnoczi <=