From: Mike Snitzer <snitzer@redhat.com>
Date: Sun, 10 Dec 2017 15:37:21 -0500
Subject: [PATCH] dm mpath: optimize NVMe bio-based support
Git-commit: 848b8aefd44df99b3e38a872acb8d54d3530bebf
Patch-mainline: v4.16-rc1
References: bsc#1104967,FATE#325924
All code that deals with pg_init is not used with bio-based NVMe mode.
This includes skipping initialization of pg_init related variables.
Also, pg_init related members on 'struct multipath' have been grouped
together.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: Hannes Reinecke <hare@suse.com>
---
drivers/md/dm-mpath.c | 171 +++++++++++++++++++++++++++-----------------------
1 file changed, 95 insertions(+), 76 deletions(-)
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -64,36 +64,30 @@ struct priority_group {
/* Multipath context */
struct multipath {
- struct list_head list;
- struct dm_target *ti;
-
- const char *hw_handler_name;
- char *hw_handler_params;
+ unsigned long flags; /* Multipath state flags */
spinlock_t lock;
-
- unsigned nr_priority_groups;
- struct list_head priority_groups;
-
- wait_queue_head_t pg_init_wait; /* Wait for pg_init completion */
+ enum dm_queue_mode queue_mode;
struct pgpath *current_pgpath;
struct priority_group *current_pg;
struct priority_group *next_pg; /* Switch to this PG if set */
- unsigned long flags; /* Multipath state flags */
+ atomic_t nr_valid_paths; /* Total number of usable paths */
+ unsigned nr_priority_groups;
+ struct list_head priority_groups;
+ const char *hw_handler_name;
+ char *hw_handler_params;
+ wait_queue_head_t pg_init_wait; /* Wait for pg_init completion */
unsigned pg_init_retries; /* Number of times to retry pg_init */
unsigned pg_init_delay_msecs; /* Number of msecs before pg_init retry */
-
- atomic_t nr_valid_paths; /* Total number of usable paths */
atomic_t pg_init_in_progress; /* Only one pg_init allowed at once */
atomic_t pg_init_count; /* Number of times pg_init called */
- enum dm_queue_mode queue_mode;
-
struct mutex work_mutex;
struct work_struct trigger_event;
+ struct dm_target *ti;
struct work_struct process_queued_bios;
struct bio_list queued_bios;
@@ -135,10 +129,10 @@ static struct pgpath *alloc_pgpath(void)
{
struct pgpath *pgpath = kzalloc(sizeof(*pgpath), GFP_KERNEL);
- if (pgpath) {
- pgpath->is_active = true;
- INIT_DELAYED_WORK(&pgpath->activate_path, activate_path_work);
- }
+ if (!pgpath)
+ return NULL;
+
+ pgpath->is_active = true;
return pgpath;
}
@@ -193,13 +187,8 @@ static struct multipath *alloc_multipath
if (m) {
INIT_LIST_HEAD(&m->priority_groups);
spin_lock_init(&m->lock);
- set_bit(MPATHF_QUEUE_IO, &m->flags);
atomic_set(&m->nr_valid_paths, 0);
- 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_WORK(&m->trigger_event, trigger_event);
- init_waitqueue_head(&m->pg_init_wait);
mutex_init(&m->work_mutex);
m->queue_mode = DM_TYPE_NONE;
@@ -235,6 +224,14 @@ static int alloc_multipath_stage2(struct
}
}
+ 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);
return 0;
@@ -339,6 +336,9 @@ static void __switch_pg(struct multipath
{
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);
@@ -384,7 +384,8 @@ static struct pgpath *choose_pgpath(stru
unsigned bypassed = 1;
if (!atomic_read(&m->nr_valid_paths)) {
- clear_bit(MPATHF_QUEUE_IO, &m->flags);
+ if (m->queue_mode != DM_TYPE_NVME_BIO_BASED)
+ clear_bit(MPATHF_QUEUE_IO, &m->flags);
goto failed;
}
@@ -528,8 +529,7 @@ static int multipath_clone_and_map(struc
clone = blk_get_request(q, rq->cmd_flags | REQ_NOMERGE, GFP_ATOMIC);
if (IS_ERR(clone)) {
/* EBUSY, ENODEV or EWOULDBLOCK: requeue */
- bool queue_dying = blk_queue_dying(q);
- if (queue_dying) {
+ if (blk_queue_dying(q)) {
atomic_inc(&m->pg_init_in_progress);
activate_or_offline_path(pgpath);
}
@@ -563,21 +563,28 @@ static int __multipath_map_bio(struct mu
/* Do we need to select a new 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);
if (!pgpath || !queue_io)
pgpath = choose_pgpath(m, mpio->nr_bytes);
- if ((pgpath && queue_io) ||
- (!pgpath && test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))) {
+ if ((!pgpath && test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) ||
+ (pgpath && queue_io)) {
/* 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);
- /* PG_INIT_REQUIRED cannot be set without QUEUE_IO */
- if (queue_io || test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
- pg_init_all_paths(m);
- else if (!queue_io)
+
+ 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 */
+ if (queue_io || test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
+ pg_init_all_paths(m);
+ else if (!queue_io)
+ queue_work(kmultipathd, &m->process_queued_bios);
+ }
+
return DM_MAPIO_SUBMITTED;
}
@@ -750,34 +757,11 @@ static int parse_path_selector(struct dm
return 0;
}
-static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps,
- struct dm_target *ti)
+static int setup_scsi_dh(struct block_device *bdev, struct multipath *m, char **error)
{
- int r;
- struct pgpath *p;
- struct multipath *m = ti->private;
- struct request_queue *q = NULL;
+ struct request_queue *q = bdev_get_queue(bdev);
const char *attached_handler_name;
-
- /* we need at least a path arg */
- if (as->argc < 1) {
- ti->error = "no device given";
- return ERR_PTR(-EINVAL);
- }
-
- p = alloc_pgpath();
- if (!p)
- return ERR_PTR(-ENOMEM);
-
- r = dm_get_device(ti, dm_shift_arg(as), dm_table_get_mode(ti->table),
- &p->path.dev);
- if (r) {
- ti->error = "error getting device";
- goto bad;
- }
-
- if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags) || m->hw_handler_name)
- q = bdev_get_queue(p->path.dev->bdev);
+ int r;
if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags)) {
retain:
@@ -809,26 +793,59 @@ retain:
char b[BDEVNAME_SIZE];
printk(KERN_INFO "dm-mpath: retaining handler on device %s\n",
- bdevname(p->path.dev->bdev, b));
+ bdevname(bdev, b));
goto retain;
}
if (r < 0) {
- ti->error = "error attaching hardware handler";
- dm_put_device(ti, p->path.dev);
- goto bad;
+ *error = "error attaching hardware handler";
+ return r;
}
if (m->hw_handler_params) {
r = scsi_dh_set_params(q, m->hw_handler_params);
if (r < 0) {
- ti->error = "unable to set hardware "
- "handler parameters";
- dm_put_device(ti, p->path.dev);
- goto bad;
+ *error = "unable to set hardware handler parameters";
+ return r;
}
}
}
+ return 0;
+}
+
+static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps,
+ struct dm_target *ti)
+{
+ int r;
+ struct pgpath *p;
+ struct multipath *m = ti->private;
+
+ /* we need at least a path arg */
+ if (as->argc < 1) {
+ ti->error = "no device given";
+ return ERR_PTR(-EINVAL);
+ }
+
+ p = alloc_pgpath();
+ if (!p)
+ return ERR_PTR(-ENOMEM);
+
+ r = dm_get_device(ti, dm_shift_arg(as), dm_table_get_mode(ti->table),
+ &p->path.dev);
+ if (r) {
+ ti->error = "error getting device";
+ goto bad;
+ }
+
+ if (m->queue_mode != DM_TYPE_NVME_BIO_BASED) {
+ INIT_DELAYED_WORK(&p->activate_path, activate_path_work);
+ r = setup_scsi_dh(p->path.dev->bdev, m, &ti->error);
+ if (r) {
+ dm_put_device(ti, p->path.dev);
+ goto bad;
+ }
+ }
+
r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error);
if (r) {
dm_put_device(ti, p->path.dev);
@@ -836,7 +853,6 @@ retain:
}
return p;
-
bad:
free_pgpath(p);
return ERR_PTR(r);
@@ -1152,16 +1168,19 @@ static void multipath_wait_for_pg_init_c
static void flush_multipath_work(struct multipath *m)
{
- set_bit(MPATHF_PG_INIT_DISABLED, &m->flags);
- smp_mb__after_atomic();
+ if (m->hw_handler_name) {
+ set_bit(MPATHF_PG_INIT_DISABLED, &m->flags);
+ smp_mb__after_atomic();
+
+ flush_workqueue(kmpath_handlerd);
+ multipath_wait_for_pg_init_completion(m);
+
+ clear_bit(MPATHF_PG_INIT_DISABLED, &m->flags);
+ smp_mb__after_atomic();
+ }
- flush_workqueue(kmpath_handlerd);
- multipath_wait_for_pg_init_completion(m);
flush_workqueue(kmultipathd);
flush_work(&m->trigger_event);
-
- clear_bit(MPATHF_PG_INIT_DISABLED, &m->flags);
- smp_mb__after_atomic();
}
static void multipath_dtr(struct dm_target *ti)
@@ -1522,7 +1541,7 @@ static int multipath_end_io(struct dm_ta
}
static int multipath_end_io_bio(struct dm_target *ti, struct bio *clone,
- blk_status_t *error)
+ blk_status_t *error)
{
struct multipath *m = ti->private;
struct dm_mpath_io *mpio = get_mpio_from_bio(clone);