block: store elevator state in request

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Add an rq private RQF_ELV flag, which tells the block layer that this
request was initialized on a queue that has an IO scheduler attached.
This allows for faster checking in the fast path, rather than having to
deference rq->q later on.

Elevator switching does full quiesce of the queue before detaching an
IO scheduler, so it's safe to cache this in the request itself.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

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This commit is contained in:

Jens Axboe 2021-10-15 09:44:38 -06:00

parent 90b8faa0e8

commit 2ff0682da6

3 changed files with 29 additions and 20 deletions

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27

block/blk-mq-sched.h

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20

block/blk-mq.c

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2

include/linux/blk-mq.h

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