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Date: Thu, 14 Apr 2016 13:46:53 +0800
From: Fam Zheng <famz@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH for-2.7 00/15] block: Lock images when
 opening
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To: "Denis V. Lunev" <den@openvz.org>
Cc: qemu-devel@nongnu.org, Kevin Wolf <kwolf@redhat.com>, Max Reitz <mreitz@redhat.com>, Jeff Cody <jcody@redhat.com>, Markus Armbruster <armbru@redhat.com>, Eric Blake <eblake@redhat.com>, John Snow <jsnow@redhat.com>, qemu-block@nongnu.org, berrange@redhat.com, pbonzini@redhat.com

On Thu, 04/14 08:04, Denis V. Lunev wrote:
> unfortunately no. If the lock will be on the image file,
> we will have get it on the target node on QEMU start
> and re-acquire it in bdrv_invalidate_cache.
> 
> From my POW you should not get the lock if
> BDRV_O_INACTIVE is set.

That is what I meant. :)

At source: Images are unlocked in bdrv_inactivate().

At destinition: Images are not locked if opened with BDRV_O_INACTIVE, and
are locked in bdrv_invalidate_cache() (at the INMIGRATE -> RUNNING switch).

Fam