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Commit 3bc217ff authored by Jens Axboe's avatar Jens Axboe
Browse files

block: kill swap_io_context() 



It blindly copies everything in the io_context, including the lock.
That doesn't work so well for either lock ordering or lockdep.

There seems zero point in swapping io contexts on a request to request
merge, so the best point of action is to just remove it.

Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent 8bdd3f8a

block/as-iosched.c

+0 −14
Original line number Diff line number Diff line
@@ -1268,22 +1268,8 @@ static void as_merged_requests(struct request_queue *q, struct request *req, 
	 */

	if (!list_empty(&req->queuelist) && !list_empty(&next->queuelist)) {

		if (time_before(rq_fifo_time(next), rq_fifo_time(req))) {

			struct io_context *rioc = RQ_IOC(req);

			struct io_context *nioc = RQ_IOC(next);



			list_move(&req->queuelist, &next->queuelist);

			rq_set_fifo_time(req, rq_fifo_time(next));

			/*

			 * Don't copy here but swap, because when anext is

			 * removed below, it must contain the unused context

			 */

			if (rioc != nioc) {

				double_spin_lock(&rioc->lock, &nioc->lock,

								rioc < nioc);

				swap_io_context(&rioc, &nioc);

				double_spin_unlock(&rioc->lock, &nioc->lock,

								rioc < nioc);

			}

		}

	}

block/blk-ioc.c

+0 −9
Original line number Diff line number Diff line
@@ -176,15 +176,6 @@ void copy_io_context(struct io_context **pdst, struct io_context **psrc) 
}

EXPORT_SYMBOL(copy_io_context);



void swap_io_context(struct io_context **ioc1, struct io_context **ioc2)

{

	struct io_context *temp;

	temp = *ioc1;

	*ioc1 = *ioc2;

	*ioc2 = temp;

}

EXPORT_SYMBOL(swap_io_context);



int __init blk_ioc_init(void)

{

	iocontext_cachep = kmem_cache_create("blkdev_ioc",

include/linux/blkdev.h

+0 −1
Original line number Diff line number Diff line
@@ -39,7 +39,6 @@ void exit_io_context(void); 
struct io_context *get_io_context(gfp_t gfp_flags, int node);

struct io_context *alloc_io_context(gfp_t gfp_flags, int node);

void copy_io_context(struct io_context **pdst, struct io_context **psrc);

void swap_io_context(struct io_context **ioc1, struct io_context **ioc2);



struct request;

typedef void (rq_end_io_fn)(struct request *, int);