diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index a29f09240c0faa6cae5aa37a229959a6c801089f..32dd3e4b041d75ff4abec2a50c81c2b74d2bce22 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -102,7 +102,7 @@ struct throtl_data
/* Work for dispatching throttled bios */
struct delayed_work throtl_work;
- atomic_t limits_changed;
+ bool limits_changed;
};
enum tg_state_flags {
@@ -201,6 +201,7 @@ static struct throtl_grp * throtl_find_alloc_tg(struct throtl_data *td,
RB_CLEAR_NODE(&tg->rb_node);
bio_list_init(&tg->bio_lists[0]);
bio_list_init(&tg->bio_lists[1]);
+ td->limits_changed = false;
/*
* Take the initial reference that will be released on destroy
@@ -737,34 +738,27 @@ static void throtl_process_limit_change(struct throtl_data *td)
struct throtl_grp *tg;
struct hlist_node *pos, *n;
- if (!atomic_read(&td->limits_changed))
+ if (!td->limits_changed)
return;
- throtl_log(td, "limit changed =%d", atomic_read(&td->limits_changed));
+ xchg(&td->limits_changed, false);
- /*
- * Make sure updates from throtl_update_blkio_group_read_bps() group
- * of functions to tg->limits_changed are visible. We do not
- * want update td->limits_changed to be visible but update to
- * tg->limits_changed not being visible yet on this cpu. Hence
- * the read barrier.
- */
- smp_rmb();
+ throtl_log(td, "limits changed");
hlist_for_each_entry_safe(tg, pos, n, &td->tg_list, tg_node) {
- if (throtl_tg_on_rr(tg) && tg->limits_changed) {
- throtl_log_tg(td, tg, "limit change rbps=%llu wbps=%llu"
- " riops=%u wiops=%u", tg->bps[READ],
- tg->bps[WRITE], tg->iops[READ],
- tg->iops[WRITE]);
+ if (!tg->limits_changed)
+ continue;
+
+ if (!xchg(&tg->limits_changed, false))
+ continue;
+
+ throtl_log_tg(td, tg, "limit change rbps=%llu wbps=%llu"
+ " riops=%u wiops=%u", tg->bps[READ], tg->bps[WRITE],
+ tg->iops[READ], tg->iops[WRITE]);
+
+ if (throtl_tg_on_rr(tg))
tg_update_disptime(td, tg);
- tg->limits_changed = false;
- }
}
-
- smp_mb__before_atomic_dec();
- atomic_dec(&td->limits_changed);
- smp_mb__after_atomic_dec();
}
/* Dispatch throttled bios. Should be called without queue lock held. */
@@ -898,6 +892,15 @@ void throtl_unlink_blkio_group(void *key, struct blkio_group *blkg)
spin_unlock_irqrestore(td->queue->queue_lock, flags);
}
+static void throtl_update_blkio_group_common(struct throtl_data *td,
+ struct throtl_grp *tg)
+{
+ xchg(&tg->limits_changed, true);
+ xchg(&td->limits_changed, true);
+ /* Schedule a work now to process the limit change */
+ throtl_schedule_delayed_work(td, 0);
+}
+
/*
* For all update functions, key should be a valid pointer because these
* update functions are called under blkcg_lock, that means, blkg is
@@ -911,61 +914,40 @@ static void throtl_update_blkio_group_read_bps(void *key,
struct blkio_group *blkg, u64 read_bps)
{
struct throtl_data *td = key;
+ struct throtl_grp *tg = tg_of_blkg(blkg);
- tg_of_blkg(blkg)->bps[READ] = read_bps;
- /* Make sure read_bps is updated before setting limits_changed */
- smp_wmb();
- tg_of_blkg(blkg)->limits_changed = true;
-
- /* Make sure tg->limits_changed is updated before td->limits_changed */
- smp_mb__before_atomic_inc();
- atomic_inc(&td->limits_changed);
- smp_mb__after_atomic_inc();
-
- /* Schedule a work now to process the limit change */
- throtl_schedule_delayed_work(td, 0);
+ tg->bps[READ] = read_bps;
+ throtl_update_blkio_group_common(td, tg);
}
static void throtl_update_blkio_group_write_bps(void *key,
struct blkio_group *blkg, u64 write_bps)
{
struct throtl_data *td = key;
+ struct throtl_grp *tg = tg_of_blkg(blkg);
- tg_of_blkg(blkg)->bps[WRITE] = write_bps;
- smp_wmb();
- tg_of_blkg(blkg)->limits_changed = true;
- smp_mb__before_atomic_inc();
- atomic_inc(&td->limits_changed);
- smp_mb__after_atomic_inc();
- throtl_schedule_delayed_work(td, 0);
+ tg->bps[WRITE] = write_bps;
+ throtl_update_blkio_group_common(td, tg);
}
static void throtl_update_blkio_group_read_iops(void *key,
struct blkio_group *blkg, unsigned int read_iops)
{
struct throtl_data *td = key;
+ struct throtl_grp *tg = tg_of_blkg(blkg);
- tg_of_blkg(blkg)->iops[READ] = read_iops;
- smp_wmb();
- tg_of_blkg(blkg)->limits_changed = true;
- smp_mb__before_atomic_inc();
- atomic_inc(&td->limits_changed);
- smp_mb__after_atomic_inc();
- throtl_schedule_delayed_work(td, 0);
+ tg->iops[READ] = read_iops;
+ throtl_update_blkio_group_common(td, tg);
}
static void throtl_update_blkio_group_write_iops(void *key,
struct blkio_group *blkg, unsigned int write_iops)
{
struct throtl_data *td = key;
+ struct throtl_grp *tg = tg_of_blkg(blkg);
- tg_of_blkg(blkg)->iops[WRITE] = write_iops;
- smp_wmb();
- tg_of_blkg(blkg)->limits_changed = true;
- smp_mb__before_atomic_inc();
- atomic_inc(&td->limits_changed);
- smp_mb__after_atomic_inc();
- throtl_schedule_delayed_work(td, 0);
+ tg->iops[WRITE] = write_iops;
+ throtl_update_blkio_group_common(td, tg);
}
static void throtl_shutdown_wq(struct request_queue *q)
@@ -1012,6 +994,7 @@ int blk_throtl_bio(struct request_queue *q, struct bio **biop)
*/
update_disptime = false;
goto queue_bio;
+
}
/* Bio is with-in rate limit of group */
@@ -1052,7 +1035,7 @@ int blk_throtl_init(struct request_queue *q)
INIT_HLIST_HEAD(&td->tg_list);
td->tg_service_tree = THROTL_RB_ROOT;
- atomic_set(&td->limits_changed, 0);
+ td->limits_changed = false;
/* Init root group */
tg = &td->root_tg;
@@ -1064,6 +1047,7 @@ int blk_throtl_init(struct request_queue *q)
/* Practically unlimited BW */
tg->bps[0] = tg->bps[1] = -1;
tg->iops[0] = tg->iops[1] = -1;
+ td->limits_changed = false;
/*
* Set root group reference to 2. One reference will be dropped when