On 7.06.19 г. 9:02 ч., Hannes Reinecke wrote:
> On 6/6/19 12:29 PM, Christoph Hellwig wrote:
>> We only need the number of segments in the blk-mq submission path.
>> Remove the field from struct bio, and return it from a variant of
>> blk_queue_split instead of that it can passed as an argument to
>> those functions that need the value.
>>
>> This also means we stop recounting segments except for cloning
>> and partial segments.
>>
>> To keep the number of arguments in this how path down remove
>> pointless struct request_queue arguments from any of the functions
>> that had it and grew a nr_segs argument.
>>
>> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
>> ---
>> Documentation/block/biodoc.txt | 1 -
>> block/bfq-iosched.c | 5 ++-
>> block/bio.c | 15 +------
>> block/blk-core.c | 32 +++++++--------
>> block/blk-map.c | 10 ++++-
>> block/blk-merge.c | 75 ++++++++++++----------------------
>> block/blk-mq-sched.c | 26 +++++++-----
>> block/blk-mq-sched.h | 10 +++--
>> block/blk-mq.c | 23 ++++++-----
>> block/blk.h | 23 ++++++-----
>> block/kyber-iosched.c | 5 ++-
>> block/mq-deadline.c | 5 ++-
>> drivers/md/raid5.c | 1 -
>> include/linux/bio.h | 1 -
>> include/linux/blk-mq.h | 2 +-
>> include/linux/blk_types.h | 6 ---
>> include/linux/blkdev.h | 1 -
>> include/linux/elevator.h | 2 +-
>> 18 files changed, 106 insertions(+), 137 deletions(-)
>>
> In general a very good idea, but:
>
>> @@ -304,6 +301,13 @@ void blk_queue_split(struct request_queue *q, struct bio **bio)
>> *bio = split;
>> }
>> }
>> +
>> +void blk_queue_split(struct request_queue *q, struct bio **bio)
>> +{
>> + unsigned int nr_segs;
>> +
>> + __blk_queue_split(q, bio, &nr_segs);
>> +}
>> EXPORT_SYMBOL(blk_queue_split);
>>
> That looks a bit weird, and I guess some or other compiler might
> complain here about nr_segs being unused.
> Can't we modify __blk_queue_split() to accept a NULL argument here?
How about __maybe_unused so the compiler doesn't complain?
>
> Cheers,
>
> Hannes
>
