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Commit e6f7f93d authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jens Axboe
Browse files

block: fix elevator init check 



We can't initalize the elevator fields for flushes as flush share space
in struct request with the elevator data.  But currently we can't
communicate that a request is a flush through blk_get_request as we
can only pass READ or WRITE, and the low-level code looks at the
possible NULL bio to check for a flush.

Fix this by allowing to pass any block op and flags, and by checking for
the flush flags in __get_request.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarBart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: default avatarHannes Reinecke <hare@suse.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 309bd96a

block/blk-core.c

+4 −22
Original line number Diff line number Diff line
@@ -1022,25 +1022,6 @@ int blk_update_nr_requests(struct request_queue *q, unsigned int nr) 
	return 0;

}



/*

 * Determine if elevator data should be initialized when allocating the

 * request associated with @bio.

 */

static bool blk_rq_should_init_elevator(struct bio *bio)

{

	if (!bio)

		return true;



	/*

	 * Flush requests do not use the elevator so skip initialization.

	 * This allows a request to share the flush and elevator data.

	 */

	if (op_is_flush(bio->bi_opf))

		return false;



	return true;

}



/**

 * __get_request - get a free request

 * @rl: request list to allocate from
@@ -1119,10 +1100,13 @@ static struct request *__get_request(struct request_list *rl, unsigned int op, 
	 * request is freed.  This guarantees icq's won't be destroyed and

	 * makes creating new ones safe.

	 *

	 * Flush requests do not use the elevator so skip initialization.

	 * This allows a request to share the flush and elevator data.

	 *

	 * Also, lookup icq while holding queue_lock.  If it doesn't exist,

	 * it will be created after releasing queue_lock.

	 */

	if (blk_rq_should_init_elevator(bio) && !blk_queue_bypass(q)) {

	if (!op_is_flush(op) && !blk_queue_bypass(q)) {

		rq_flags |= RQF_ELVPRIV;

		q->nr_rqs_elvpriv++;

		if (et->icq_cache && ioc)
@@ -1276,8 +1260,6 @@ static struct request *blk_old_get_request(struct request_queue *q, int rw, 
{

	struct request *rq;



	BUG_ON(rw != READ && rw != WRITE);



	/* create ioc upfront */

	create_io_context(gfp_mask, q->node);