On 07.02.2016 13:46, Fam Zheng wrote:
> On Sat, 02/06 14:24, Max Reitz wrote:
>> On 05.02.2016 03:00, Fam Zheng wrote:
>>> The "pnum < nb_sectors" condition in deciding whether to actually copy
>>> data is unnecessarily strict, and the qiov initialization is
>>> unnecessarily for bdrv_aio_write_zeroes and bdrv_aio_discard.
>>>
>>> Rewrite mirror_iteration to fix both flaws.
>>>
>>> The output of iotests 109 is updated because we now report the offset
>>> and len slightly differently in mirroring progress.
>>>
>>> Signed-off-by: Fam Zheng <f...@redhat.com>
>>> ---
>>> block/mirror.c | 335
>>> +++++++++++++++++++++++++++------------------
>>> tests/qemu-iotests/109.out | 80 +++++------
>>> trace-events | 1 -
>>> 3 files changed, 243 insertions(+), 173 deletions(-)
>>>
>>> diff --git a/block/mirror.c b/block/mirror.c
>>> index 2c0edfa..48cd0b3 100644
>>> --- a/block/mirror.c
>>> +++ b/block/mirror.c
>>
>> [...]
>>
>>> @@ -449,16 +520,16 @@ static void coroutine_fn mirror_run(void *opaque)
>>> */
>>> bdrv_get_backing_filename(s->target, backing_filename,
>>> sizeof(backing_filename));
>>> - if (backing_filename[0] && !s->target->backing) {
>>> - ret = bdrv_get_info(s->target, &bdi);
>>> - if (ret < 0) {
>>> - goto immediate_exit;
>>> - }
>>> - if (s->granularity < bdi.cluster_size) {
>>> - s->buf_size = MAX(s->buf_size, bdi.cluster_size);
>>> - s->cow_bitmap = bitmap_new(length);
>>> - }
>>> + if (!bdrv_get_info(s->target, &bdi) && bdi.cluster_size) {
>>
>> This should be bdi.has_cluster_size...
>
> has_cluster_size is a member of ImageInfo not BlockDriverInfo, and is derived
> from (bdi.cluster_size != 0).
You're right, my bad.
>>> + target_cluster_size = bdi.cluster_size;
>>
>> ...and maybe we want an explicit minimum of BDRV_SECTOR_SIZE here; but I
>> guess this is already assumed all over the block layer, so it may be
>> fine without.
>
> Okay, it doesn't hurt to add an assert here.
I'd be happy to take the patch without, too (although I wouldn't decline
a follow-up adding an assertion).
Reviewed-by: Max Reitz <mre...@redhat.com>
>>> }
>>> + if (backing_filename[0] && !s->target->backing
>>> + && s->granularity < target_cluster_size) {
>>> + s->buf_size = MAX(s->buf_size, target_cluster_size);
>>> + s->cow_bitmap = bitmap_new(length);
>>> + }
>>> + s->target_cluster_sectors = target_cluster_size >> BDRV_SECTOR_BITS;
>>
>> (this shouldn't be 0, so target_cluster_size needs to be at least
>> BDRV_SECTOR_SIZE)
>>
>> Max
>>
>
>
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