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Re: [Qemu-devel] [PATCH 2/8] qcow2: add dirty-bitmaps feature
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [PATCH 2/8] qcow2: add dirty-bitmaps feature |
Date: |
Mon, 15 Jun 2015 15:42:37 +0100 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
On Fri, Jun 12, 2015 at 03:02:33PM -0400, John Snow wrote:
>
>
> On 06/10/2015 10:30 AM, Stefan Hajnoczi wrote:
> > On Mon, Jun 08, 2015 at 06:21:20PM +0300, Vladimir Sementsov-Ogievskiy
> > wrote:
> >
> > I noticed a corner case, it's probably not a problem in practice:
> >
> > Since the dirty bitmap is stored with the help of a BlockDriverState
> > (and its bs->file), it's possible that writing the bitmap will cause
> > bits in the bitmap to be dirtied!
> >
>
> But since it's metadata and not stored within a disk sector, can this
> actually happen? Do you have an example of a scenario where this might
> come up?
The persistent dirty bitmap for bs->file is storeed in the qcow2 BDS.
This results in recursion.
This is a misconfiguration but I just want to understand what happens
when someone does this by mistake.
Stefan
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Description: PGP signature
- Re: [Qemu-devel] [PATCH 6/8] qcow2: add autoclear bit for dirty bitmaps, (continued)
[Qemu-devel] [PATCH 7/8] qemu: command line option for dirty bitmaps, Vladimir Sementsov-Ogievskiy, 2015/06/08
[Qemu-devel] [PATCH 2/8] qcow2: add dirty-bitmaps feature, Vladimir Sementsov-Ogievskiy, 2015/06/08
Re: [Qemu-devel] [PATCH 2/8] qcow2: add dirty-bitmaps feature, John Snow, 2015/06/11
Re: [Qemu-devel] [PATCH 2/8] qcow2: add dirty-bitmaps feature, John Snow, 2015/06/12
Re: [Qemu-devel] [PATCH v2 RFC 0/8] block: persistent dirty bitmaps, Stefan Hajnoczi, 2015/06/10
Re: [Qemu-devel] [PATCH v2 RFC 0/8] block: persistent dirty bitmaps, Stefan Hajnoczi, 2015/06/11