Re: [Qemu-devel] [PATCH v4 1/1] blockdev: acquire aio_context for bitmap add/remove

[John Snow]

On 2/18/19 4:55 PM, Eric Blake wrote:
> On 2/18/19 3:42 PM, John Snow wrote:
>> When bitmaps are persistent, they may incur a disk read or write when bitmaps
>> are added or removed. For configurations like virtio-dataplane, failing to
>> acquire this lock will abort QEMU when disk IO occurs.
>>
>> We used to acquire aio_context as part of the bitmap lookup, so re-introduce
>> the lock for just the cases that have an IO penalty. Commit 2119882c removed
>> these locks, and I failed to notice this when we committed fd5ae4cc, so this
>> has been broken since persistent bitmaps were introduced.
>>
>> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1672010
>> Reported-By: Aihua Liang <address@hidden>
>> Signed-off-by: John Snow <address@hidden>
>> Reviewed-by: Eric Blake <address@hidden>
>> ---
>>  blockdev.c | 26 ++++++++++++++++++++------
>>  1 file changed, 20 insertions(+), 6 deletions(-)
>>
> 
>>      bitmap = bdrv_create_dirty_bitmap(bs, granularity, name, errp);
>>      if (bitmap == NULL) {
>> -        return;
>> +        goto out
>>      }
>>  
> 
> Your scripts are still going haywire. :(
> 

Sigh. I ran the full suite of build tests but that doesn't do one bit of
good if I don't run `stg refresh` before sending it out.

I'm really not having a good run of it it here.

NACK,

--js