Re: [Qemu-devel] [PATCH] block: drop bs_snapshots global variable

[Eric Blake <eblake@redhat.com>]

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On 03/14/2013 10:04 AM, Stefan Hajnoczi wrote:
> The bs_snapshots global variable points to the BlockDriverState which
> will be used to save vmstate.  This is really a savevm.c concept but was
> moved into block.c:bdrv_snapshots() when it became clear that hotplug
> could result in a dangling pointer.
> 
> While auditing the block layer's global state I came upon bs_snapshots
> and realized that a variable is not necessary here.  Simply find the
> first BlockDriverState capable of internal snapshots each time this is
> needed.
> 
> The behavior of bdrv_snapshots() is preserved across hotplug because new
> drives are always appended to the bdrv_states list.  This means that
> calling the new find_vmstate_bs() function is idempotent - it returns
> the same BlockDriverState unless it was hot-unplugged.
> 
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
>  block.c               | 28 ----------------------------
>  include/block/block.h |  1 -
>  savevm.c              | 19 +++++++++++++++----
>  3 files changed, 15 insertions(+), 33 deletions(-)

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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