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Commit 8d47e659 authored by Mike Snitzer's avatar Mike Snitzer
Browse files

dm mpath: remove unnecessary NVMe branching in favor of scsi_dh checks 



This eliminates the "queue_mode" configuration's "nvme" mode.  There
wasn't anything NVMe-specific about that mode.  It was named "nvme"
because it was a short name for the mode.  But the entire point of the
mode was to optimize the multipath target for underlying devices that
are _not_ SCSI-based.  Devices that aren't SCSI have no need for the
various SCSI device handler (scsi_dh) specific code in DM multipath.

But rather than narrowly define this scsi_dh vs not branching in terms
of "nvme": invert the logic so that we're just checking whether a
multipath device is layered on SCSI devices with scsi_dh attached.

This allows any future storage technology to avoid scsi_dh specific code
in the multipath target too.

Fixes: 848b8aef ("dm mpath: optimize NVMe bio-based support")
Suggested-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent 99243b92

drivers/md/dm-mpath.c

+29 −37
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ 
#include <linux/time.h>

#include <linux/workqueue.h>

#include <linux/delay.h>

#include <scsi/scsi_device.h>

#include <scsi/scsi_dh.h>

#include <linux/atomic.h>

#include <linux/blk-mq.h>
@@ -211,26 +212,14 @@ static int alloc_multipath_stage2(struct dm_target *ti, struct multipath *m) 
		else

			m->queue_mode = DM_TYPE_REQUEST_BASED;



	} else if (m->queue_mode == DM_TYPE_BIO_BASED ||

		   m->queue_mode == DM_TYPE_NVME_BIO_BASED) {

	} else if (m->queue_mode == DM_TYPE_BIO_BASED) {

		INIT_WORK(&m->process_queued_bios, process_queued_bios);



		if (m->queue_mode == DM_TYPE_BIO_BASED) {

		/*

		 * bio-based doesn't support any direct scsi_dh management;

		 * it just discovers if a scsi_dh is attached.

		 */

		set_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags);

	}

	}



	if (m->queue_mode != DM_TYPE_NVME_BIO_BASED) {

		set_bit(MPATHF_QUEUE_IO, &m->flags);

		atomic_set(&m->pg_init_in_progress, 0);

		atomic_set(&m->pg_init_count, 0);

		m->pg_init_delay_msecs = DM_PG_INIT_DELAY_DEFAULT;

		init_waitqueue_head(&m->pg_init_wait);

	}



	dm_table_set_type(ti->table, m->queue_mode);
@@ -337,14 +326,12 @@ static void __switch_pg(struct multipath *m, struct priority_group *pg) 
{

	m->current_pg = pg;



	if (m->queue_mode == DM_TYPE_NVME_BIO_BASED)

		return;



	/* Must we initialise the PG first, and queue I/O till it's ready? */

	if (m->hw_handler_name) {

		set_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);

		set_bit(MPATHF_QUEUE_IO, &m->flags);

	} else {

		/* FIXME: not needed if no scsi_dh is attached */

		clear_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);

		clear_bit(MPATHF_QUEUE_IO, &m->flags);

	}
@@ -385,7 +372,6 @@ static struct pgpath *choose_pgpath(struct multipath *m, size_t nr_bytes) 
	unsigned bypassed = 1;



	if (!atomic_read(&m->nr_valid_paths)) {

		if (m->queue_mode != DM_TYPE_NVME_BIO_BASED)

		clear_bit(MPATHF_QUEUE_IO, &m->flags);

		goto failed;

	}
@@ -599,7 +585,7 @@ static struct pgpath *__map_bio(struct multipath *m, struct bio *bio) 
	return pgpath;

}



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

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

{

	struct pgpath *pgpath;

	unsigned long flags;
@@ -634,8 +620,8 @@ static int __multipath_map_bio(struct multipath *m, struct bio *bio, 
{

	struct pgpath *pgpath;



	if (m->queue_mode == DM_TYPE_NVME_BIO_BASED)

		pgpath = __map_bio_nvme(m, bio);

	if (!m->hw_handler_name)

		pgpath = __map_bio_fast(m, bio);

	else

		pgpath = __map_bio(m, bio);
@@ -675,8 +661,7 @@ static void process_queued_io_list(struct multipath *m) 
{

	if (m->queue_mode == DM_TYPE_MQ_REQUEST_BASED)

		dm_mq_kick_requeue_list(dm_table_get_md(m->ti->table));

	else if (m->queue_mode == DM_TYPE_BIO_BASED ||

		 m->queue_mode == DM_TYPE_NVME_BIO_BASED)

	else if (m->queue_mode == DM_TYPE_BIO_BASED)

		queue_work(kmultipathd, &m->process_queued_bios);

}
@@ -838,6 +823,16 @@ static int setup_scsi_dh(struct block_device *bdev, struct multipath *m, char ** 
			 */

			kfree(m->hw_handler_name);

			m->hw_handler_name = attached_handler_name;



			/*

			 * Init fields that are only used when a scsi_dh is attached

			 */

			if (!test_and_set_bit(MPATHF_QUEUE_IO, &m->flags)) {

				atomic_set(&m->pg_init_in_progress, 0);

				atomic_set(&m->pg_init_count, 0);

				m->pg_init_delay_msecs = DM_PG_INIT_DELAY_DEFAULT;

				init_waitqueue_head(&m->pg_init_wait);

			}

		}

	}
@@ -873,6 +868,7 @@ static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps 
	int r;

	struct pgpath *p;

	struct multipath *m = ti->private;

	struct scsi_device *sdev;



	/* we need at least a path arg */

	if (as->argc < 1) {
@@ -891,7 +887,9 @@ static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps 
		goto bad;

	}



	if (m->queue_mode != DM_TYPE_NVME_BIO_BASED) {

	sdev = scsi_device_from_queue(bdev_get_queue(p->path.dev->bdev));

	if (sdev) {

		put_device(&sdev->sdev_gendev);

		INIT_DELAYED_WORK(&p->activate_path, activate_path_work);

		r = setup_scsi_dh(p->path.dev->bdev, m, &ti->error);

		if (r) {
@@ -1001,8 +999,7 @@ static int parse_hw_handler(struct dm_arg_set *as, struct multipath *m) 
	if (!hw_argc)

		return 0;



	if (m->queue_mode == DM_TYPE_BIO_BASED ||

	    m->queue_mode == DM_TYPE_NVME_BIO_BASED) {

	if (m->queue_mode == DM_TYPE_BIO_BASED) {

		dm_consume_args(as, hw_argc);

		DMERR("bio-based multipath doesn't allow hardware handler args");

		return 0;
@@ -1091,8 +1088,6 @@ static int parse_features(struct dm_arg_set *as, struct multipath *m) 


			if (!strcasecmp(queue_mode_name, "bio"))

				m->queue_mode = DM_TYPE_BIO_BASED;

			else if (!strcasecmp(queue_mode_name, "nvme"))

				m->queue_mode = DM_TYPE_NVME_BIO_BASED;

			else if (!strcasecmp(queue_mode_name, "rq"))

				m->queue_mode = DM_TYPE_REQUEST_BASED;

			else if (!strcasecmp(queue_mode_name, "mq"))
@@ -1193,7 +1188,7 @@ static int multipath_ctr(struct dm_target *ti, unsigned argc, char **argv) 
	ti->num_discard_bios = 1;

	ti->num_write_same_bios = 1;

	ti->num_write_zeroes_bios = 1;

	if (m->queue_mode == DM_TYPE_BIO_BASED || m->queue_mode == DM_TYPE_NVME_BIO_BASED)

	if (m->queue_mode == DM_TYPE_BIO_BASED)

		ti->per_io_data_size = multipath_per_bio_data_size();

	else

		ti->per_io_data_size = sizeof(struct dm_mpath_io);
@@ -1730,9 +1725,6 @@ static void multipath_status(struct dm_target *ti, status_type_t type, 
			case DM_TYPE_BIO_BASED:

				DMEMIT("queue_mode bio ");

				break;

			case DM_TYPE_NVME_BIO_BASED:

				DMEMIT("queue_mode nvme ");

				break;

			case DM_TYPE_MQ_REQUEST_BASED:

				DMEMIT("queue_mode mq ");

				break;