[PATCH 7/7] dm: add 'use_blk_mq' module param and expose in per-device ro sysfs attr
From: Mike Snitzer
Date: Wed Mar 11 2015 - 23:57:11 EST
Request-based DM's blk-mq support defaults to off; but a user can easily
change the default using the dm_mod.use_blk_mq module/boot option.
Also, you can check what mode a given request-based DM device is using
with: cat /sys/block/dm-X/dm/use_blk_mq
This change enabled further cleanup and reduced work (e.g. the
md->io_pool and md->rq_pool isn't created if using blk-mq).
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
---
drivers/md/Kconfig | 11 +++++++++++
drivers/md/dm-sysfs.c | 9 +++++++++
drivers/md/dm-table.c | 6 +++---
drivers/md/dm.c | 51 ++++++++++++++++++++++++++++++++++++++++-----------
drivers/md/dm.h | 5 ++++-
5 files changed, 67 insertions(+), 15 deletions(-)
diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
index 63e05e3..109f9dc 100644
--- a/drivers/md/Kconfig
+++ b/drivers/md/Kconfig
@@ -196,6 +196,17 @@ config BLK_DEV_DM
If unsure, say N.
+config DM_MQ_DEFAULT
+ bool "request-based DM: use blk-mq I/O path by default"
+ depends on BLK_DEV_DM
+ ---help---
+ This option enables the blk-mq based I/O path for request-based
+ DM devices by default. With the option the dm_mod.use_blk_mq
+ module/boot option defaults to Y, without it to N, but it can
+ still be overriden either way.
+
+ If unsure say N.
+
config DM_DEBUG
bool "Device mapper debugging support"
depends on BLK_DEV_DM
diff --git a/drivers/md/dm-sysfs.c b/drivers/md/dm-sysfs.c
index f5bb394..7e818f5 100644
--- a/drivers/md/dm-sysfs.c
+++ b/drivers/md/dm-sysfs.c
@@ -89,15 +89,24 @@ static ssize_t dm_attr_suspended_show(struct mapped_device *md, char *buf)
return strlen(buf);
}
+static ssize_t dm_attr_use_blk_mq_show(struct mapped_device *md, char *buf)
+{
+ sprintf(buf, "%d\n", dm_use_blk_mq(md));
+
+ return strlen(buf);
+}
+
static DM_ATTR_RO(name);
static DM_ATTR_RO(uuid);
static DM_ATTR_RO(suspended);
+static DM_ATTR_RO(use_blk_mq);
static DM_ATTR_RW(rq_based_seq_io_merge_deadline);
static struct attribute *dm_attrs[] = {
&dm_attr_name.attr,
&dm_attr_uuid.attr,
&dm_attr_suspended.attr,
+ &dm_attr_use_blk_mq.attr,
&dm_attr_rq_based_seq_io_merge_deadline.attr,
NULL,
};
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 66600ca..8d025f3 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -940,7 +940,7 @@ bool dm_table_mq_request_based(struct dm_table *t)
return dm_table_get_type(t) == DM_TYPE_MQ_REQUEST_BASED;
}
-static int dm_table_alloc_md_mempools(struct dm_table *t)
+static int dm_table_alloc_md_mempools(struct dm_table *t, struct mapped_device *md)
{
unsigned type = dm_table_get_type(t);
unsigned per_bio_data_size = 0;
@@ -958,7 +958,7 @@ static int dm_table_alloc_md_mempools(struct dm_table *t)
per_bio_data_size = max(per_bio_data_size, tgt->per_bio_data_size);
}
- t->mempools = dm_alloc_md_mempools(type, t->integrity_supported, per_bio_data_size);
+ t->mempools = dm_alloc_md_mempools(md, type, t->integrity_supported, per_bio_data_size);
if (!t->mempools)
return -ENOMEM;
@@ -1128,7 +1128,7 @@ int dm_table_complete(struct dm_table *t)
return r;
}
- r = dm_table_alloc_md_mempools(t);
+ r = dm_table_alloc_md_mempools(t, t->md);
if (r)
DMERR("unable to allocate mempools");
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index b0c965a..3165b94 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -228,8 +228,20 @@ struct mapped_device {
/* for blk-mq request-based DM support */
struct blk_mq_tag_set tag_set;
+ bool use_blk_mq;
};
+#ifdef CONFIG_DM_MQ_DEFAULT
+static bool use_blk_mq = true;
+#else
+static bool use_blk_mq = false;
+#endif
+
+bool dm_use_blk_mq(struct mapped_device *md)
+{
+ return md->use_blk_mq;
+}
+
/*
* For mempools pre-allocation at the table loading time.
*/
@@ -2219,6 +2231,7 @@ static void dm_init_md_queue(struct mapped_device *md)
static void dm_init_old_md_queue(struct mapped_device *md)
{
+ md->use_blk_mq = false;
dm_init_md_queue(md);
/*
@@ -2260,6 +2273,7 @@ static struct mapped_device *alloc_dev(int minor)
if (r < 0)
goto bad_io_barrier;
+ md->use_blk_mq = use_blk_mq;
md->type = DM_TYPE_NONE;
mutex_init(&md->suspend_lock);
mutex_init(&md->type_lock);
@@ -2346,7 +2360,6 @@ static void unlock_fs(struct mapped_device *md);
static void free_dev(struct mapped_device *md)
{
int minor = MINOR(disk_devt(md->disk));
- bool using_blk_mq = !!md->queue->mq_ops;
unlock_fs(md);
bdput(md->bdev);
@@ -2372,7 +2385,7 @@ static void free_dev(struct mapped_device *md)
put_disk(md->disk);
blk_cleanup_queue(md->queue);
- if (using_blk_mq)
+ if (md->use_blk_mq)
blk_mq_free_tag_set(&md->tag_set);
dm_stats_cleanup(&md->stats);
module_put(THIS_MODULE);
@@ -2383,7 +2396,7 @@ static void __bind_mempools(struct mapped_device *md, struct dm_table *t)
{
struct dm_md_mempools *p = dm_table_get_md_mempools(t);
- if (md->io_pool && md->bs) {
+ if (md->bs) {
/* The md already has necessary mempools. */
if (dm_table_get_type(t) == DM_TYPE_BIO_BASED) {
/*
@@ -2793,13 +2806,21 @@ out_tag_set:
return err;
}
+static unsigned filter_md_type(unsigned type, struct mapped_device *md)
+{
+ if (type == DM_TYPE_BIO_BASED)
+ return type;
+
+ return !md->use_blk_mq ? DM_TYPE_REQUEST_BASED : DM_TYPE_MQ_REQUEST_BASED;
+}
+
/*
* Setup the DM device's queue based on md's type
*/
int dm_setup_md_queue(struct mapped_device *md)
{
int r;
- unsigned md_type = dm_get_md_type(md);
+ unsigned md_type = filter_md_type(dm_get_md_type(md), md);
switch (md_type) {
case DM_TYPE_REQUEST_BASED:
@@ -3503,16 +3524,19 @@ int dm_noflush_suspending(struct dm_target *ti)
}
EXPORT_SYMBOL_GPL(dm_noflush_suspending);
-struct dm_md_mempools *dm_alloc_md_mempools(unsigned type, unsigned integrity, unsigned per_bio_data_size)
+struct dm_md_mempools *dm_alloc_md_mempools(struct mapped_device *md, unsigned type,
+ unsigned integrity, unsigned per_bio_data_size)
{
struct dm_md_mempools *pools = kzalloc(sizeof(*pools), GFP_KERNEL);
- struct kmem_cache *cachep;
+ struct kmem_cache *cachep = NULL;
unsigned int pool_size = 0;
unsigned int front_pad;
if (!pools)
return NULL;
+ type = filter_md_type(type, md);
+
switch (type) {
case DM_TYPE_BIO_BASED:
cachep = _io_cache;
@@ -3520,13 +3544,13 @@ struct dm_md_mempools *dm_alloc_md_mempools(unsigned type, unsigned integrity, u
front_pad = roundup(per_bio_data_size, __alignof__(struct dm_target_io)) + offsetof(struct dm_target_io, clone);
break;
case DM_TYPE_REQUEST_BASED:
+ cachep = _rq_tio_cache;
pool_size = dm_get_reserved_rq_based_ios();
pools->rq_pool = mempool_create_slab_pool(pool_size, _rq_cache);
if (!pools->rq_pool)
goto out;
/* fall through to setup remaining rq-based pools */
case DM_TYPE_MQ_REQUEST_BASED:
- cachep = _rq_tio_cache;
if (!pool_size)
pool_size = dm_get_reserved_rq_based_ios();
front_pad = offsetof(struct dm_rq_clone_bio_info, clone);
@@ -3534,12 +3558,14 @@ struct dm_md_mempools *dm_alloc_md_mempools(unsigned type, unsigned integrity, u
WARN_ON(per_bio_data_size != 0);
break;
default:
- goto out;
+ BUG();
}
- pools->io_pool = mempool_create_slab_pool(pool_size, cachep);
- if (!pools->io_pool)
- goto out;
+ if (cachep) {
+ pools->io_pool = mempool_create_slab_pool(pool_size, cachep);
+ if (!pools->io_pool)
+ goto out;
+ }
pools->bs = bioset_create_nobvec(pool_size, front_pad);
if (!pools->bs)
@@ -3596,6 +3622,9 @@ MODULE_PARM_DESC(reserved_bio_based_ios, "Reserved IOs in bio-based mempools");
module_param(reserved_rq_based_ios, uint, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(reserved_rq_based_ios, "Reserved IOs in request-based mempools");
+module_param(use_blk_mq, bool, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(use_blk_mq, "Use block multiqueue for request-based DM devices");
+
MODULE_DESCRIPTION(DM_NAME " driver");
MODULE_AUTHOR("Joe Thornber <dm-devel@xxxxxxxxxx>");
MODULE_LICENSE("GPL");
diff --git a/drivers/md/dm.h b/drivers/md/dm.h
index 5522422..6123c2b 100644
--- a/drivers/md/dm.h
+++ b/drivers/md/dm.h
@@ -211,6 +211,8 @@ int dm_kobject_uevent(struct mapped_device *md, enum kobject_action action,
void dm_internal_suspend(struct mapped_device *md);
void dm_internal_resume(struct mapped_device *md);
+bool dm_use_blk_mq(struct mapped_device *md);
+
int dm_io_init(void);
void dm_io_exit(void);
@@ -220,7 +222,8 @@ void dm_kcopyd_exit(void);
/*
* Mempool operations
*/
-struct dm_md_mempools *dm_alloc_md_mempools(unsigned type, unsigned integrity, unsigned per_bio_data_size);
+struct dm_md_mempools *dm_alloc_md_mempools(struct mapped_device *md, unsigned type,
+ unsigned integrity, unsigned per_bio_data_size);
void dm_free_md_mempools(struct dm_md_mempools *pools);
/*
--
1.9.5 (Apple Git-50.3)
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