Eric Blake <ebl...@redhat.com> writes:
> 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 <f...@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).
Yes. See commit 0fb6395. Another instance in PATCH 14.
>> + 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) {
Actually, unconditional error_free(bs->backing_blocker) is fine.
