Re: [Qemu-devel] [PATCH] block-backend: allow flush on devices with open tray

[John Snow <jsnow@redhat.com>]

On 06/10/2016 06:42 PM, Eric Blake wrote:
> On 06/10/2016 03:59 PM, John Snow wrote:
>> If a device still has an attached BDS because the medium has not yet
>> been removed, we will be unable to migrate to a new host because
>> blk_flush will return an error for that backend.
>>
>> Replace the call to blk_is_available to blk_is_inserted to weaken
>> the check and allow flushes from the backend to work, while still
>> disallowing flushes from the frontend/device model to work.
>>
>> This fixes a regression present in 2.6.0 caused by the following commit:
>> fe1a9cbc339bb54d20f1ca4c1e8788d16944d5cf
>> block: Move some bdrv_*_all() functions to BB
>>
>> Signed-off-by: John Snow <jsnow@redhat.com>
>> ---
>>  block/block-backend.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> Worth testsuite coverage to prevent future regressions?
> 

I'll look into it.

(Ugh, migration tests. wah. etc.)

--js

> At any rate,
> Reviewed-by: Eric Blake <eblake@redhat.com>
> 
>>
>> diff --git a/block/block-backend.c b/block/block-backend.c
>> index 34500e6..d1e875e 100644
>> --- a/block/block-backend.c
>> +++ b/block/block-backend.c
>> @@ -1122,7 +1122,7 @@ int blk_co_flush(BlockBackend *blk)
>>  
>>  int blk_flush(BlockBackend *blk)
>>  {
>> -    if (!blk_is_available(blk)) {
>> +    if (!blk_is_inserted(blk)) {
>>          return -ENOMEDIUM;
>>      }
>>  
>>
>