From: Mike Snitzer <snitzer@redhat.com>
Date: Mon, 5 Mar 2018 14:10:11 -0500
Subject: [PATCH] dm mpath: remove unnecessary NVMe branching in favor of
scsi_dh checks
Git-commit: 8d47e65948ddea4398892946d9e50778a316b397
Patch-mainline: v4.16-rc5
References: bsc#1104967,FATE#325924
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: 848b8aefd4 ("dm mpath: optimize NVMe bio-based support")
Suggested-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: Hannes Reinecke <hare@suse.com>
---
drivers/md/dm-mpath.c | 66 ++++++++++++++++++++++-----------------------------
1 file changed, 29 insertions(+), 37 deletions(-)
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 7d3e572072f5..3fde9e9faddd 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -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>
@@ -211,25 +212,13 @@ 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);
+ /*
+ * 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);
}
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);
}
@@ -385,8 +372,7 @@ 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);
+ 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;
--
2.16.4