Re: [Qemu-devel] [PATCH v19 07/16] block: Add backing_blocker in BlockDriverState

[Eric Blake <eblake@redhat.com>]

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On 05/11/2014 07:35 PM, Fam Zheng wrote:
> This makes use of op_blocker and blocks all the operations except for
> commit target, on each BlockDriverState->backing_hd.
> 
> The asserts for op_blocker in bdrv_swap are removed because with this
> change, the target of block commit has at least the backing blocker of
> its child, so the assertion is not true. Callers should do their check.
> 
> Signed-off-by: Fam Zheng <famz@redhat.com>
> ---
>  block.c                   | 24 ++++++++++++++++++++----
>  block/mirror.c            |  1 +
>  include/block/block_int.h |  3 +++
>  3 files changed, 24 insertions(+), 4 deletions(-)
> 
> diff --git a/block.c b/block.c
> index ec26a2b..8155e68 100644
> --- a/block.c
> +++ b/block.c
> @@ -1097,14 +1097,31 @@ fail:
>  void bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd)
>  {
>  
> +    if (bs->backing_hd) {
> +        assert(error_is_set(&bs->backing_blocker));

error_is_set() is going away.  Please don't use it.
https://lists.gnu.org/archive/html/qemu-devel/2014-05/msg03801.html

This can just be assert(bs->backing_blocker).

> +        bdrv_op_unblock_all(bs->backing_hd, bs->backing_blocker);
> +    } else if (backing_hd) {
> +        error_setg(&bs->backing_blocker,
> +                   "device is used as backing hd of '%s'",
> +                   bs->device_name);
> +    }
> +
>      bs->backing_hd = backing_hd;
>      if (!backing_hd) {
> +        if (error_is_set(&bs->backing_blocker)) {
> +            error_free(bs->backing_blocker);

if (bs->backing_blocker) {

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


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