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block, cfq: move io_cq exit/release to blk-ioc.c

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With kmem_cache managed by blk-ioc, io_cq exit/release can be moved to
blk-ioc too.  The odd ->io_cq->exit/release() callbacks are replaced
with elevator_ops->elevator_exit_icq_fn() with unlinking from both ioc
and q, and freeing automatically handled by blk-ioc.  The elevator
operation only need to perform exit operation specific to the elevator
- in cfq's case, exiting the cfqq's.

Also, clearing of io_cq's on q detach is moved to block core and
automatically performed on elevator switch and q release.

Because the q io_cq points to might be freed before RCU callback for
the io_cq runs, blk-ioc code should remember to which cache the io_cq
needs to be freed when the io_cq is released.  New field
io_cq->__rcu_icq_cache is added for this purpose.  As both the new
field and rcu_head are used only after io_cq is released and the
q/ioc_node fields aren't, they are put into unions.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Tejun Heo 2011-12-14 00:33:42 +01:00 • committed by Jens Axboe
parent 3d3c2379fe
commit 7e5a879449
7 changed files with 97 additions and 61 deletions
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5
include/linux/elevator.h
View file

@ -5,6 +5,8 @@
#ifdef CONFIG_BLOCK
struct io_cq;
typedef int (elevator_merge_fn) (struct request_queue *, struct request **,
struct bio *);
@ -24,6 +26,7 @@ typedef struct request *(elevator_request_list_fn) (struct request_queue *, stru
typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *);
typedef int (elevator_may_queue_fn) (struct request_queue *, int);
typedef void (elevator_exit_icq_fn) (struct io_cq *);
typedef int (elevator_set_req_fn) (struct request_queue *, struct request *, gfp_t);
typedef void (elevator_put_req_fn) (struct request *);
typedef void (elevator_activate_req_fn) (struct request_queue *, struct request *);
@ -56,6 +59,8 @@ struct elevator_ops
elevator_request_list_fn *elevator_former_req_fn;
elevator_request_list_fn *elevator_latter_req_fn;
elevator_exit_icq_fn *elevator_exit_icq_fn;
elevator_set_req_fn *elevator_set_req_fn;
elevator_put_req_fn *elevator_put_req_fn;