From 17e149b8f73ba116e71e25930dd6f2eb3828792d Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Wed, 11 Mar 2015 15:01:09 -0400 Subject: [PATCH] dm: add 'use_blk_mq' module param and expose in per-device ro sysfs attr 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 --- Documentation/ABI/testing/sysfs-block-dm | 8 ++++ drivers/md/Kconfig | 11 +++++ drivers/md/dm-sysfs.c | 9 ++++ drivers/md/dm-table.c | 6 +-- drivers/md/dm.c | 53 ++++++++++++++++++------ drivers/md/dm.h | 5 ++- 6 files changed, 76 insertions(+), 16 deletions(-) diff --git a/Documentation/ABI/testing/sysfs-block-dm b/Documentation/ABI/testing/sysfs-block-dm index ac4b6fe245d9..f9f2339b9a0a 100644 --- a/Documentation/ABI/testing/sysfs-block-dm +++ b/Documentation/ABI/testing/sysfs-block-dm @@ -37,3 +37,11 @@ Description: Allow control over how long a request that is a accounting. This attribute is not applicable to bio-based DM devices so it will only ever report 0 for them. + +What: /sys/block/dm-/dm/use_blk_mq +Date: March 2015 +KernelVersion: 4.1 +Contact: dm-devel@redhat.com +Description: Request-based Device-mapper blk-mq I/O path mode. + Contains the value 1 if the device is using blk-mq. + Otherwise it contains 0. Read-only attribute. diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig index 63e05e32b462..109f9dcc9cab 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 f5bb3944f75e..7e818f5f1dc4 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 66600cab9fa5..8d025f33de92 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 55cadb1a2735..944cdb322708 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. */ @@ -2034,7 +2046,7 @@ ssize_t dm_attr_rq_based_seq_io_merge_deadline_store(struct mapped_device *md, { unsigned deadline; - if (!dm_request_based(md)) + if (!dm_request_based(md) || md->use_blk_mq) return count; if (kstrtouint(buf, 10, &deadline)) @@ -2222,6 +2234,7 @@ 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); /* @@ -2263,6 +2276,7 @@ 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); @@ -2349,7 +2363,6 @@ 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); destroy_workqueue(md->wq); @@ -2375,7 +2388,7 @@ static void free_dev(struct mapped_device *md) del_gendisk(md->disk); 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); bdput(md->bdev); free_minor(minor); @@ -2388,7 +2401,7 @@ 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) { /* @@ -2798,13 +2811,21 @@ 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: @@ -3509,16 +3530,19 @@ 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; @@ -3526,13 +3550,13 @@ 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); @@ -3540,12 +3564,14 @@ 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) @@ -3602,6 +3628,9 @@ 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 "); MODULE_LICENSE("GPL"); diff --git a/drivers/md/dm.h b/drivers/md/dm.h index 5522422cc6c4..6123c2bf9150 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); /* -- 2.34.1