tree 2d1f9dc740b6d47257404c02292493568c8ee656
parent 600271d9000027c013c01be87cbb90a5a18c5c3f
author Jens Axboe <axboe@fb.com> 1459354868 -0600
committer Jens Axboe <axboe@fb.com> 1478387393 -0600

block: add code to track actual device queue depth

For blk-mq, ->nr_requests does track queue depth, at least at init
time. But for the older queue paths, it's simply a soft setting.
On top of that, it's generally larger than the hardware setting
on purpose, to allow backup of requests for merging.

Fill a hole in struct request with a 'queue_depth' member, that
drivers can call to more closely inform the block layer of the
real queue depth.

Signed-off-by: Jens Axboe <axboe@fb.com>
Reviewed-by: Jan Kara <jack@suse.cz>