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Commit 0001ec56 authored by Mike Snitzer's avatar Mike Snitzer
Browse files

dm mpath: factor out SCSI vs NVMe path selection 



Trying to do both SCSI and NVMe bio-based handling with branching in the
same common code has proven too tedious on a code maintenance level.  In
addition it slightly hurts IO performance.

Fix this by factoring out __map_bio() and __map_bio_nvme().

Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent 848b8aef

drivers/md/dm-mpath.c

+55 −13
Original line number Original line Diff line number Diff line
@@ -555,7 +555,8 @@ static void multipath_release_clone(struct request *clone) 
/*

/*

 * Map cloned bios (bio-based multipath)

 * Map cloned bios (bio-based multipath)

 */

 */

static int __multipath_map_bio(struct multipath *m, struct bio *bio, struct dm_mpath_io *mpio)



static struct pgpath *__map_bio(struct multipath *m, struct bio *bio)

{

{

	struct pgpath *pgpath;

	struct pgpath *pgpath;

	unsigned long flags;

	unsigned long flags;
@@ -563,31 +564,72 @@ static int __multipath_map_bio(struct multipath *m, struct bio *bio, struct dm_m 




	/* Do we need to select a new pgpath? */

	/* Do we need to select a new pgpath? */

	pgpath = READ_ONCE(m->current_pgpath);

	pgpath = READ_ONCE(m->current_pgpath);

	/* MPATHF_QUEUE_IO will never be set for NVMe */

	queue_io = test_bit(MPATHF_QUEUE_IO, &m->flags);

	queue_io = test_bit(MPATHF_QUEUE_IO, &m->flags);

	if (!pgpath || !queue_io)

	if (!pgpath || !queue_io)

		pgpath = choose_pgpath(m, mpio->nr_bytes);

		pgpath = choose_pgpath(m, bio->bi_iter.bi_size);





	if ((!pgpath && test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) ||

	if ((pgpath && queue_io) ||

	    (pgpath && queue_io)) {

	    (!pgpath && test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))) {

		/* Queue for the daemon to resubmit */

		/* Queue for the daemon to resubmit */

		spin_lock_irqsave(&m->lock, flags);

		spin_lock_irqsave(&m->lock, flags);

		bio_list_add(&m->queued_bios, bio);

		bio_list_add(&m->queued_bios, bio);

		spin_unlock_irqrestore(&m->lock, flags);

		spin_unlock_irqrestore(&m->lock, flags);





		if (m->queue_mode == DM_TYPE_NVME_BIO_BASED) {

			queue_work(kmultipathd, &m->process_queued_bios);

		} else {

		/* PG_INIT_REQUIRED cannot be set without QUEUE_IO */

		/* PG_INIT_REQUIRED cannot be set without QUEUE_IO */

		if (queue_io || test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))

		if (queue_io || test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))

			pg_init_all_paths(m);

			pg_init_all_paths(m);

		else if (!queue_io)

		else if (!queue_io)

			queue_work(kmultipathd, &m->process_queued_bios);

			queue_work(kmultipathd, &m->process_queued_bios);



		return ERR_PTR(-EAGAIN);

	}

	}





		return DM_MAPIO_SUBMITTED;

	return pgpath;

}



static struct pgpath *__map_bio_nvme(struct multipath *m, struct bio *bio)

{

	struct pgpath *pgpath;

	unsigned long flags;



	/* Do we need to select a new pgpath? */

	/*

	 * FIXME: currently only switching path if no path (due to failure, etc)

	 * - which negates the point of using a path selector

	 */

	pgpath = READ_ONCE(m->current_pgpath);

	if (!pgpath)

		pgpath = choose_pgpath(m, bio->bi_iter.bi_size);



	if (!pgpath) {

		if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {

			/* Queue for the daemon to resubmit */

			spin_lock_irqsave(&m->lock, flags);

			bio_list_add(&m->queued_bios, bio);

			spin_unlock_irqrestore(&m->lock, flags);

			queue_work(kmultipathd, &m->process_queued_bios);



			return ERR_PTR(-EAGAIN);

		}

		return NULL;

	}

	}





	return pgpath;

}



static int __multipath_map_bio(struct multipath *m, struct bio *bio,

			       struct dm_mpath_io *mpio)

{

	struct pgpath *pgpath;



	if (m->queue_mode == DM_TYPE_NVME_BIO_BASED)

		pgpath = __map_bio_nvme(m, bio);

	else

		pgpath = __map_bio(m, bio);



	if (IS_ERR(pgpath))

		return DM_MAPIO_SUBMITTED;



	if (!pgpath) {

	if (!pgpath) {

		if (must_push_back_bio(m))

		if (must_push_back_bio(m))

			return DM_MAPIO_REQUEUE;

			return DM_MAPIO_REQUEUE;