Re: [Qemu-devel] [PATCH 05/10] block: Fix blockdev-snapshot error handling

[Eric Blake]

On 03/06/2017 10:21 AM, Kevin Wolf wrote:
> For blockdev-snapshot, external_snapshot_prepare() accepts an arbitrary
> node reference at first and only checks later whether it already has a
> backing file. Between those places, other errors can occur.
> 
> Therefore checking in external_snapshot_abort() whether state->new_bs
> has a backing file is not sufficient to tell whether bdrv_append() was
> already completed or not. Trying to undo the bdrv_append() when it
> wasn't even executed is wrong.
> 
> Introduce a new boolean flag in the state to fix this.
> 
> Signed-off-by: Kevin Wolf <address@hidden>
> ---
>  blockdev.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 

Reviewed-by: Eric Blake <address@hidden>

By the way, how are you finding all these spots? Is it existing qemu-io
tests that are failing? And if so, would mentioning which test exposed
the problem being fixed be worth adding in the commit messages?  If not,
are there some qemu-io tests to be added?

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

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