On 2019/07/12 3:09, Jens Axboe wrote:
> On 7/11/19 5:17 AM, Christoph Hellwig wrote:
>> Make the zoned device write path the special case and just fall
>> though to the defaul case to make the code easier to read. Also
>> update the top of function comment to use the proper kdoc format
>> and remove the extra in-function comments that just duplicate it.
>>
>> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
>> ---
>> block/blk-mq.h | 14 ++++----------
>> 1 file changed, 4 insertions(+), 10 deletions(-)
>>
>> diff --git a/block/blk-mq.h b/block/blk-mq.h
>> index 32c62c64e6c2..ab80fd2b3803 100644
>> --- a/block/blk-mq.h
>> +++ b/block/blk-mq.h
>> @@ -233,7 +233,7 @@ static inline void blk_mq_clear_mq_map(struct blk_mq_queue_map *qmap)
>> qmap->mq_map[cpu] = 0;
>> }
>>
>> -/*
>> +/**
>> * blk_mq_plug() - Get caller context plug
>> * @q: request queue
>> * @bio : the bio being submitted by the caller context
>> @@ -254,15 +254,9 @@ static inline void blk_mq_clear_mq_map(struct blk_mq_queue_map *qmap)
>> static inline struct blk_plug *blk_mq_plug(struct request_queue *q,
>> struct bio *bio)
>> {
>> - /*
>> - * For regular block devices or read operations, use the context plug
>> - * which may be NULL if blk_start_plug() was not executed.
>> - */
>> - if (!blk_queue_is_zoned(q) || !op_is_write(bio_op(bio)))
>> - return current->plug;
>> -
>> - /* Zoned block device write operation case: do not plug the BIO */
>> - return NULL;
>> + if (blk_queue_is_zoned(q) && op_is_write(bio_op(bio)))
>> + return NULL;
>> + return current->plug;
>> }
>>
>> #endif
>
> I agree it's more readable, but probably also means that the path that we
> care the least about (zoned+write) is now the inline one.
What about an additional inline function ?
So something like this is very readable I think and blk_mq_plug() can also be
optimized with #ifdef for the !CONFIG_BLK_DEV_ZONED case.
#ifndef CONFIG_BLK_DEV_ZONED
static inline struct blk_plug *blk_mq_plug(struct request_queue *q,
struct bio *bio)
{
return current->plug;
}
#else
static inline struct blk_plug *blk_zoned_get_plug(struct request_queue *q,
struct bio *bio)
{
if (op_is_write(bio_op(bio)))
return NULL;
return current->plug;
}
static inline struct blk_plug *blk_mq_plug(struct request_queue *q,
struct bio *bio)
{
if (!blk_queue_is_zoned(q))
return current->plug;
return blk_zoned_get_plug(q, bio);
}
#endif
--
Damien Le Moal
Western Digital Research
