We have various block drivers that need to execute long term blocking
operations during I/O submission like file system or network I/O.
Currently these drivers just queue up work to an internal workqueue
from their request_fn. With blk-mq we can make sure they always get
called on their own workqueue directly for I/O submission by:
1) adding a flag to prevent inline submission of I/O, and
2) allowing the driver to pass in a workqueue in the tag_set that
will be used instead of kblockd.
Signed-off-by: Christoph Hellwig <[email protected]>
---
block/blk-core.c | 2 +-
block/blk-mq.c | 12 +++++++++---
block/blk.h | 1 +
include/linux/blk-mq.h | 4 ++++
4 files changed, 15 insertions(+), 4 deletions(-)
diff --git a/block/blk-core.c b/block/blk-core.c
index 0421b53..7f7249f 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -61,7 +61,7 @@ struct kmem_cache *blk_requestq_cachep;
/*
* Controlling structure to kblockd
*/
-static struct workqueue_struct *kblockd_workqueue;
+struct workqueue_struct *kblockd_workqueue;
void blk_queue_congestion_threshold(struct request_queue *q)
{
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 22e50a5..3d27d22 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -804,12 +804,13 @@ void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool
async)
if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->state)))
return;
- if (!async && cpumask_test_cpu(smp_processor_id(), hctx->cpumask)) {
+ if (!async && !(hctx->flags & BLK_MQ_F_WORKQUEUE) &&
+ cpumask_test_cpu(smp_processor_id(), hctx->cpumask)) {
__blk_mq_run_hw_queue(hctx);
return;
}
- kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx),
+ queue_delayed_work_on(blk_mq_hctx_next_cpu(hctx), hctx->wq,
&hctx->run_work, 0);
}
@@ -908,7 +909,7 @@ static void blk_mq_delay_work_fn(struct work_struct *work)
void blk_mq_delay_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
{
- kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx),
+ queue_delayed_work_on(blk_mq_hctx_next_cpu(hctx), hctx->wq,
&hctx->delay_work, msecs_to_jiffies(msecs));
}
EXPORT_SYMBOL(blk_mq_delay_queue);
@@ -1581,6 +1582,11 @@ static int blk_mq_init_hctx(struct request_queue *q,
hctx->flags = set->flags;
hctx->cmd_size = set->cmd_size;
+ if (set->wq)
+ hctx->wq = set->wq;
+ else
+ hctx->wq = kblockd_workqueue;
+
blk_mq_init_cpu_notifier(&hctx->cpu_notifier,
blk_mq_hctx_notify, hctx);
blk_mq_register_cpu_notifier(&hctx->cpu_notifier);
diff --git a/block/blk.h b/block/blk.h
index 43b0361..fb46ad0 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -25,6 +25,7 @@ struct blk_flush_queue {
spinlock_t mq_flush_lock;
};
+extern struct workqueue_struct *kblockd_workqueue;
extern struct kmem_cache *blk_requestq_cachep;
extern struct kmem_cache *request_cachep;
extern struct kobj_type blk_queue_ktype;
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 5a901d0..ebe4699 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -37,6 +37,8 @@ struct blk_mq_hw_ctx {
unsigned int queue_num;
struct blk_flush_queue *fq;
+ struct workqueue_struct *wq;
+
void *driver_data;
struct blk_mq_ctxmap ctx_map;
@@ -64,6 +66,7 @@ struct blk_mq_hw_ctx {
struct blk_mq_tag_set {
struct blk_mq_ops *ops;
+ struct workqueue_struct *wq;
unsigned int nr_hw_queues;
unsigned int queue_depth; /* max hw supported */
unsigned int reserved_tags;
@@ -156,6 +159,7 @@ enum {
BLK_MQ_F_SG_MERGE = 1 << 2,
BLK_MQ_F_SYSFS_UP = 1 << 3,
BLK_MQ_F_DEFER_ISSUE = 1 << 4,
+ BLK_MQ_F_WORKQUEUE = 1 << 5,
BLK_MQ_S_STOPPED = 0,
BLK_MQ_S_TAG_ACTIVE = 1,
--
1.9.1
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