block: make queue flags non-atomic
We can save some atomic ops in the IO path, if we clearly define
the rules of how to modify the queue flags.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/block/blk-core.c b/block/blk-core.c
index e447799..d2f23ec 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -198,7 +198,8 @@
if (blk_queue_stopped(q))
return;
- if (!test_and_set_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags)) {
+ if (!test_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags)) {
+ __set_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags);
mod_timer(&q->unplug_timer, jiffies + q->unplug_delay);
blk_add_trace_generic(q, NULL, 0, BLK_TA_PLUG);
}
@@ -213,9 +214,10 @@
{
WARN_ON(!irqs_disabled());
- if (!test_and_clear_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags))
+ if (!test_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags))
return 0;
+ queue_flag_clear(QUEUE_FLAG_PLUGGED, q);
del_timer(&q->unplug_timer);
return 1;
}
@@ -311,15 +313,16 @@
{
WARN_ON(!irqs_disabled());
- clear_bit(QUEUE_FLAG_STOPPED, &q->queue_flags);
+ queue_flag_clear(QUEUE_FLAG_STOPPED, q);
/*
* one level of recursion is ok and is much faster than kicking
* the unplug handling
*/
- if (!test_and_set_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) {
+ if (!test_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) {
+ queue_flag_set(QUEUE_FLAG_REENTER, q);
q->request_fn(q);
- clear_bit(QUEUE_FLAG_REENTER, &q->queue_flags);
+ queue_flag_clear(QUEUE_FLAG_REENTER, q);
} else {
blk_plug_device(q);
kblockd_schedule_work(&q->unplug_work);
@@ -344,7 +347,7 @@
void blk_stop_queue(struct request_queue *q)
{
blk_remove_plug(q);
- set_bit(QUEUE_FLAG_STOPPED, &q->queue_flags);
+ queue_flag_set(QUEUE_FLAG_STOPPED, q);
}
EXPORT_SYMBOL(blk_stop_queue);
@@ -373,11 +376,8 @@
* blk_run_queue - run a single device queue
* @q: The queue to run
*/
-void blk_run_queue(struct request_queue *q)
+void __blk_run_queue(struct request_queue *q)
{
- unsigned long flags;
-
- spin_lock_irqsave(q->queue_lock, flags);
blk_remove_plug(q);
/*
@@ -385,15 +385,28 @@
* handling reinvoke the handler shortly if we already got there.
*/
if (!elv_queue_empty(q)) {
- if (!test_and_set_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) {
+ if (!test_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) {
+ queue_flag_set(QUEUE_FLAG_REENTER, q);
q->request_fn(q);
- clear_bit(QUEUE_FLAG_REENTER, &q->queue_flags);
+ queue_flag_clear(QUEUE_FLAG_REENTER, q);
} else {
blk_plug_device(q);
kblockd_schedule_work(&q->unplug_work);
}
}
+}
+EXPORT_SYMBOL(__blk_run_queue);
+/**
+ * blk_run_queue - run a single device queue
+ * @q: The queue to run
+ */
+void blk_run_queue(struct request_queue *q)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(q->queue_lock, flags);
+ __blk_run_queue(q);
spin_unlock_irqrestore(q->queue_lock, flags);
}
EXPORT_SYMBOL(blk_run_queue);
@@ -406,7 +419,7 @@
void blk_cleanup_queue(struct request_queue *q)
{
mutex_lock(&q->sysfs_lock);
- set_bit(QUEUE_FLAG_DEAD, &q->queue_flags);
+ queue_flag_set_unlocked(QUEUE_FLAG_DEAD, q);
mutex_unlock(&q->sysfs_lock);
if (q->elevator)
diff --git a/block/blk-merge.c b/block/blk-merge.c
index b5c5c4a..73b2356 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -55,7 +55,7 @@
if (!rq->bio)
return;
- cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER);
+ cluster = test_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
hw_seg_size = seg_size = 0;
phys_size = hw_size = nr_phys_segs = nr_hw_segs = 0;
rq_for_each_segment(bv, rq, iter) {
@@ -128,7 +128,7 @@
static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio,
struct bio *nxt)
{
- if (!(q->queue_flags & (1 << QUEUE_FLAG_CLUSTER)))
+ if (!test_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags))
return 0;
if (!BIOVEC_PHYS_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt)))
@@ -175,7 +175,7 @@
int nsegs, cluster;
nsegs = 0;
- cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER);
+ cluster = test_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
/*
* for each bio in rq
diff --git a/block/blk-settings.c b/block/blk-settings.c
index 77b51dc..6089384 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -287,7 +287,7 @@
t->max_segment_size = min(t->max_segment_size, b->max_segment_size);
t->hardsect_size = max(t->hardsect_size, b->hardsect_size);
if (!test_bit(QUEUE_FLAG_CLUSTER, &b->queue_flags))
- clear_bit(QUEUE_FLAG_CLUSTER, &t->queue_flags);
+ queue_flag_clear(QUEUE_FLAG_CLUSTER, t);
}
EXPORT_SYMBOL(blk_queue_stack_limits);
diff --git a/block/blk-tag.c b/block/blk-tag.c
index 4780a46..e176ddb 100644
--- a/block/blk-tag.c
+++ b/block/blk-tag.c
@@ -70,7 +70,7 @@
__blk_free_tags(bqt);
q->queue_tags = NULL;
- q->queue_flags &= ~(1 << QUEUE_FLAG_QUEUED);
+ queue_flag_clear(QUEUE_FLAG_QUEUED, q);
}
/**
@@ -98,7 +98,7 @@
**/
void blk_queue_free_tags(struct request_queue *q)
{
- clear_bit(QUEUE_FLAG_QUEUED, &q->queue_flags);
+ queue_flag_clear(QUEUE_FLAG_QUEUED, q);
}
EXPORT_SYMBOL(blk_queue_free_tags);
@@ -188,7 +188,7 @@
rc = blk_queue_resize_tags(q, depth);
if (rc)
return rc;
- set_bit(QUEUE_FLAG_QUEUED, &q->queue_flags);
+ queue_flag_set(QUEUE_FLAG_QUEUED, q);
return 0;
} else
atomic_inc(&tags->refcnt);
@@ -197,7 +197,7 @@
* assign it, all done
*/
q->queue_tags = tags;
- q->queue_flags |= (1 << QUEUE_FLAG_QUEUED);
+ queue_flag_set(QUEUE_FLAG_QUEUED, q);
INIT_LIST_HEAD(&q->tag_busy_list);
return 0;
fail:
diff --git a/block/elevator.c b/block/elevator.c
index 88318c3..e8a90fe 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -1070,7 +1070,7 @@
*/
spin_lock_irq(q->queue_lock);
- set_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
+ queue_flag_set(QUEUE_FLAG_ELVSWITCH, q);
elv_drain_elevator(q);
@@ -1104,7 +1104,10 @@
* finally exit old elevator and turn off BYPASS.
*/
elevator_exit(old_elevator);
- clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
+ spin_lock_irq(q->queue_lock);
+ queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q);
+ spin_unlock_irq(q->queue_lock);
+
return 1;
fail_register:
@@ -1115,7 +1118,11 @@
elevator_exit(e);
q->elevator = old_elevator;
elv_register_queue(q);
- clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
+
+ spin_lock_irq(q->queue_lock);
+ queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q);
+ spin_unlock_irq(q->queue_lock);
+
return 0;
}