Re: [PATCH 4/6] block/gluster: Do not force-cap *pnum

[Max Reitz <mreitz@redhat.com>]

On 19.06.21 12:36, Vladimir Sementsov-Ogievskiy wrote:
> 17.06.2021 18:52, Max Reitz wrote:
>> bdrv_co_block_status() does it for us, we do not need to do it here.
>>
>> The advantage of not capping *pnum is that bdrv_co_block_status() can
>> cache larger data regions than requested by its caller.
>>
>> Signed-off-by: Max Reitz <mreitz@redhat.com>
>
>
> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
>
>
>> ---
>>   block/gluster.c | 7 ++++---
>>   1 file changed, 4 insertions(+), 3 deletions(-)
>>
>> diff --git a/block/gluster.c b/block/gluster.c
>> index e8ee14c8e9..8ef7bb18d5 100644
>> --- a/block/gluster.c
>> +++ b/block/gluster.c
>> @@ -1461,7 +1461,8 @@ exit:
>>    * the specified offset) that are known to be in the same
>>    * allocated/unallocated state.
>>    *
>> - * 'bytes' is the max value 'pnum' should be set to.
>> + * 'bytes' is a soft cap for 'pnum'.  If the information is free, 
>> 'pnum' may
>> + * well exceed it.
>>    *
>>    * (Based on raw_co_block_status() from file-posix.c.)
>>    */
>> @@ -1500,12 +1501,12 @@ static int coroutine_fn 
>> qemu_gluster_co_block_status(BlockDriverState *bs,
>>       } else if (data == offset) {
>>           /* On a data extent, compute bytes to the end of the extent,
>>            * possibly including a partial sector at EOF. */
>> -        *pnum = MIN(bytes, hole - offset);
>> +        *pnum = hole - offset;
>>           ret = BDRV_BLOCK_DATA;
>
> Interesting, isn't it a bug that we don't ROUND_UP *pnum to 
> request_alignment here like it is done in file-posix ?

Guess I forgot gluster in 9c3db310ff0 O:)

I don’t think I’ll be able to reproduce it for gluster, but I suppose 
just doing the same thing for gluster should be fine...

Max