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Re: [Qemu-block] [PATCH v2 06/16] backup: Request BLK_PERM_AIO_CONTEXT_C
Re: [Qemu-block] [PATCH v2 06/16] backup: Request BLK_PERM_AIO_CONTEXT_CHANGE on target
Wed, 31 May 2017 10:39:21 +0100
On Wed, May 24, 2017 at 10:18:44AM +0800, Fam Zheng wrote:
> On Thu, 05/11 15:41, Stefan Hajnoczi wrote:
> > On Wed, Apr 19, 2017 at 05:43:46PM +0800, Fam Zheng wrote:
> > > What's done in the source's context change notifier is moving the
> > > target's context to follow the new one, so we request this permission
> > > here.
> > It's true that the backup block job must be able to set target's
> > AioContext, but does this change also allow other users to set target's
> > AioContext while the backup job is running? If yes, then we need to
> > handle that.
> If through job->target, yes, but I don't think there is any user of
> Otherwise, it's not allowed, because the second parameter of blk_new doesn't
> have BLK_PERM_AIO_CONTEXT_CHANGE.
> So it's okay.
What about blockdev-backup? It allows the user to specify 'target'.
Therefore the user can also run other monitor commands on target. Some
of them could change the AioContext and the backup job wouldn't know!
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