Re: [PATCH 01/16] block: make blkdev_nr_zones and blk_queue_zone_no generic for npo2 zsze

Damien Le Moal
2022-05-03T16:43:29Z

On 2022/05/04 1:37, Bart Van Assche wrote:
> On 4/27/22 09:02, Pankaj Raghav wrote:
>> Adapt blkdev_nr_zones and blk_queue_zone_no function so that it can
>> also work for non-power-of-2 zone sizes.
>>
>> As the existing deployments of zoned devices had power-of-2
>> assumption, power-of-2 optimized calculation is kept for those devices.
>>
>> There are no direct hot paths modified and the changes just
>> introduce one new branch per call.
>>
>> Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
>> Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
>> ---
>> block/blk-zoned.c | 8 +++++++-
>> include/linux/blkdev.h | 8 +++++++-
>> 2 files changed, 14 insertions(+), 2 deletions(-)
>>
>> diff --git a/block/blk-zoned.c b/block/blk-zoned.c
>> index 38cd840d8838..1dff4a8bd51d 100644
>> --- a/block/blk-zoned.c
>> +++ b/block/blk-zoned.c
>> @@ -117,10 +117,16 @@ EXPORT_SYMBOL_GPL(__blk_req_zone_write_unlock);
>> unsigned int blkdev_nr_zones(struct gendisk *disk)
>> {
>> sector_t zone_sectors = blk_queue_zone_sectors(disk->queue);
>> + sector_t capacity = get_capacity(disk);
>>
>> if (!blk_queue_is_zoned(disk->queue))
>> return 0;
>> - return (get_capacity(disk) + zone_sectors - 1) >> ilog2(zone_sectors);
>> +
>> + if (is_power_of_2(zone_sectors))
>> + return (capacity + zone_sectors - 1) >>
>> + ilog2(zone_sectors);
>> +
>> + return div64_u64(capacity + zone_sectors - 1, zone_sectors);
>> }
>> EXPORT_SYMBOL_GPL(blkdev_nr_zones);
>
> Does anyone need support for more than 4 billion sectors per zone? If
> not, do_div() should be sufficient.
>
>> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
>> index 60d016138997..c4e4c7071b7b 100644
>> --- a/include/linux/blkdev.h
>> +++ b/include/linux/blkdev.h
>> @@ -665,9 +665,15 @@ static inline unsigned int blk_queue_nr_zones(struct request_queue *q)
>> static inline unsigned int blk_queue_zone_no(struct request_queue *q,
>> sector_t sector)
>> {
>> + sector_t zone_sectors = blk_queue_zone_sectors(q);
>> +
>> if (!blk_queue_is_zoned(q))
>> return 0;
>> - return sector >> ilog2(q->limits.chunk_sectors);
>> +
>> + if (is_power_of_2(zone_sectors))
>> + return sector >> ilog2(zone_sectors);
>> +
>> + return div64_u64(sector, zone_sectors);
>> }
>
> Same comment here.

sector_t is 64-bits even on 32-bits arch, no ?
so div64_u64 is needed here I think, which will be a simple regular division for
64-bit arch.

>
> Thanks,
>
> Bart.

--
Damien Le Moal
Western Digital Research