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Re: [Qemu-devel] [Qemu-block] [PATCH v2 0/6] block: Mirror discarded sec
From: |
Fam Zheng |
Subject: |
Re: [Qemu-devel] [Qemu-block] [PATCH v2 0/6] block: Mirror discarded sectors |
Date: |
Fri, 8 May 2015 10:58:16 +0800 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
On Thu, 05/07 14:20, Stefan Hajnoczi wrote:
> On Wed, May 06, 2015 at 12:52:02PM +0800, Fam Zheng wrote:
> > v2: Fix typo and add Eric's rev-by in patch 3.
> > Add patch 1 to discard target in mirror job. (Paolo)
> > Add patch 6 to improve iotests.wait_ready. (John)
> >
> > 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 (6):
> > mirror: Discard target sectors if not allocated at source side
> > 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 | 4 +--
> > block/mirror.c | 12 ++++++--
> > include/block/block_int.h | 2 --
> > tests/qemu-iotests/041 | 66
> > ++++++++++---------------------------------
> > tests/qemu-iotests/131 | 59 ++++++++++++++++++++++++++++++++++++++
> > tests/qemu-iotests/131.out | 5 ++++
> > tests/qemu-iotests/group | 1 +
> > tests/qemu-iotests/iotests.py | 23 +++++++++++++++
> > 9 files changed, 115 insertions(+), 69 deletions(-)
> > create mode 100644 tests/qemu-iotests/131
> > create mode 100644 tests/qemu-iotests/131.out
>
> CCing Jeff Cody for block jobs
Thanks,
Note that in the discussion of v1 Paolo pointed out that discard on target is
not safe in some cases, I need to fix that in v3.
Fam
- [Qemu-devel] [PATCH v2 0/6] block: Mirror discarded sectors, Fam Zheng, 2015/05/06
- [Qemu-devel] [PATCH v2 1/6] mirror: Discard target sectors if not allocated at source side, Fam Zheng, 2015/05/06
- [Qemu-devel] [PATCH v2 2/6] block: Fix dirty bitmap in bdrv_co_discard, Fam Zheng, 2015/05/06
- [Qemu-devel] [PATCH v2 3/6] block: Remove bdrv_reset_dirty, Fam Zheng, 2015/05/06
- [Qemu-devel] [PATCH v2 4/6] qemu-iotests: Make block job methods common, Fam Zheng, 2015/05/06
- [Qemu-devel] [PATCH v2 5/6] qemu-iotests: Add test case for mirror with unmap, Fam Zheng, 2015/05/06
- [Qemu-devel] [PATCH v2 6/6] iotests: Use event_wait in wait_ready, Fam Zheng, 2015/05/06
- Re: [Qemu-devel] [Qemu-block] [PATCH v2 0/6] block: Mirror discarded sectors, Stefan Hajnoczi, 2015/05/07
- Re: [Qemu-devel] [Qemu-block] [PATCH v2 0/6] block: Mirror discarded sectors,
Fam Zheng <=