[PATCH 09/13] blk-rq-qos: refactor out common elements of blk-wbt

From: Josef Bacik
Date: Tue Jun 05 2018 - 09:31:51 EST

From: Josef Bacik <jbacik@xxxxxx>

blkcg-qos is going to do essentially what wbt does, only on a cgroup
basis. Break out the common code that will be shared between blkcg-qos
and wbt into blk-rq-qos.* so they can both utilize the same
infrastructure.

Signed-off-by: Josef Bacik <jbacik@xxxxxx>
---
block/Makefile | 2 +-
block/blk-core.c | 12 +-
block/blk-mq.c | 12 +-
block/blk-rq-qos.c | 178 +++++++++++++++++++++++++++
block/blk-rq-qos.h | 91 ++++++++++++++
block/blk-settings.c | 4 +-
block/blk-sysfs.c | 22 ++--
block/blk-wbt.c | 326 ++++++++++++++++++++++---------------------------
block/blk-wbt.h | 63 ++++------
include/linux/blkdev.h | 4 +-
10 files changed, 463 insertions(+), 251 deletions(-)
create mode 100644 block/blk-rq-qos.c
create mode 100644 block/blk-rq-qos.h

diff --git a/block/Makefile b/block/Makefile
index 6a56303b9925..981605042cad 100644
--- a/block/Makefile
+++ b/block/Makefile
@@ -9,7 +9,7 @@ obj-$(CONFIG_BLOCK) := bio.o elevator.o blk-core.o blk-tag.o blk-sysfs.o \
blk-lib.o blk-mq.o blk-mq-tag.o blk-stat.o \
blk-mq-sysfs.o blk-mq-cpumap.o blk-mq-sched.o ioctl.o \
genhd.o partition-generic.o ioprio.o \
- badblocks.o partitions/
+ badblocks.o partitions/ blk-rq-qos.o

obj-$(CONFIG_BOUNCE) += bounce.o
obj-$(CONFIG_BLK_SCSI_REQUEST) += scsi_ioctl.o
diff --git a/block/blk-core.c b/block/blk-core.c
index 43370faee935..07594fb34c0f 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1653,7 +1653,7 @@ void blk_requeue_request(struct request_queue *q, struct request *rq)
blk_delete_timer(rq);
blk_clear_rq_complete(rq);
trace_block_rq_requeue(q, rq);
- wbt_requeue(q->rq_wb, rq);
+ rq_qos_requeue(q, rq);

if (rq->rq_flags & RQF_QUEUED)
blk_queue_end_tag(q, rq);
@@ -1760,7 +1760,7 @@ void __blk_put_request(struct request_queue *q, struct request *req)
/* this is a bio leak */
WARN_ON(req->bio != NULL);

- wbt_done(q->rq_wb, req);
+ rq_qos_done(q, req);

/*
* Request may not have originated from ll_rw_blk. if not,
@@ -2052,7 +2052,7 @@ static blk_qc_t blk_queue_bio(struct request_queue *q, struct bio *bio)
}

get_rq:
- wb_acct = wbt_wait(q->rq_wb, bio, q->queue_lock);
+ wb_acct = rq_qos_throttle(q, bio, q->queue_lock);

/*
* Grab a free request. This is might sleep but can not fail.
@@ -2062,7 +2062,7 @@ static blk_qc_t blk_queue_bio(struct request_queue *q, struct bio *bio)
req = get_request(q, bio->bi_opf, bio, 0, GFP_NOIO);
if (IS_ERR(req)) {
blk_queue_exit(q);
- __wbt_done(q->rq_wb, wb_acct);
+ rq_qos_cleanup(q, wb_acct);
if (PTR_ERR(req) == -ENOMEM)
bio->bi_status = BLK_STS_RESOURCE;
else
@@ -2989,7 +2989,7 @@ void blk_start_request(struct request *req)
req->throtl_size = blk_rq_sectors(req);
#endif
req->rq_flags |= RQF_STATS;
- wbt_issue(req->q->rq_wb, req);
+ rq_qos_issue(req->q, req);
}

BUG_ON(blk_rq_is_complete(req));
@@ -3211,7 +3211,7 @@ void blk_finish_request(struct request *req, blk_status_t error)
blk_account_io_done(req, now);

if (req->end_io) {
- wbt_done(req->q->rq_wb, req);
+ rq_qos_done(q, req);
req->end_io(req, error);
} else {
if (blk_bidi_rq(req))
diff --git a/block/blk-mq.c b/block/blk-mq.c
index df928200b17e..5308396ee22a 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -489,7 +489,7 @@ void blk_mq_free_request(struct request *rq)
if (unlikely(laptop_mode && !blk_rq_is_passthrough(rq)))
laptop_io_completion(q->backing_dev_info);

- wbt_done(q->rq_wb, rq);
+ rq_qos_done(q, rq);

if (blk_rq_rl(rq))
blk_put_rl(blk_rq_rl(rq));
@@ -516,7 +516,7 @@ inline void __blk_mq_end_request(struct request *rq, blk_status_t error)
blk_account_io_done(rq, now);

if (rq->end_io) {
- wbt_done(rq->q->rq_wb, rq);
+ rq_qos_done(rq->q, rq);
rq->end_io(rq, error);
} else {
if (unlikely(blk_bidi_rq(rq)))
@@ -678,7 +678,7 @@ void blk_mq_start_request(struct request *rq)
rq->throtl_size = blk_rq_sectors(rq);
#endif
rq->rq_flags |= RQF_STATS;
- wbt_issue(q->rq_wb, rq);
+ rq_qos_issue(q, rq);
}

WARN_ON_ONCE(blk_mq_rq_state(rq) != MQ_RQ_IDLE);
@@ -726,7 +726,7 @@ static void __blk_mq_requeue_request(struct request *rq)
blk_mq_put_driver_tag(rq);

trace_block_rq_requeue(q, rq);
- wbt_requeue(q->rq_wb, rq);
+ rq_qos_requeue(q, rq);

if (blk_mq_rq_state(rq) != MQ_RQ_IDLE) {
blk_mq_rq_update_state(rq, MQ_RQ_IDLE);
@@ -1868,13 +1868,13 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
if (blk_mq_sched_bio_merge(q, bio))
return BLK_QC_T_NONE;

- wb_acct = wbt_wait(q->rq_wb, bio, NULL);
+ wb_acct = rq_qos_throttle(q, bio, NULL);

trace_block_getrq(q, bio, bio->bi_opf);

rq = blk_mq_get_request(q, bio, bio->bi_opf, &data);
if (unlikely(!rq)) {
- __wbt_done(q->rq_wb, wb_acct);
+ rq_qos_cleanup(q, wb_acct);
if (bio->bi_opf & REQ_NOWAIT)
bio_wouldblock_error(bio);
return BLK_QC_T_NONE;
diff --git a/block/blk-rq-qos.c b/block/blk-rq-qos.c
new file mode 100644
index 000000000000..d2f2af8aa10c
--- /dev/null
+++ b/block/blk-rq-qos.c
@@ -0,0 +1,178 @@
+#include "blk-rq-qos.h"
+
+#include "blk-wbt.h"
+
+/*
+ * Increment 'v', if 'v' is below 'below'. Returns true if we succeeded,
+ * false if 'v' + 1 would be bigger than 'below'.
+ */
+static bool atomic_inc_below(atomic_t *v, int below)
+{
+ int cur = atomic_read(v);
+
+ for (;;) {
+ int old;
+
+ if (cur >= below)
+ return false;
+ old = atomic_cmpxchg(v, cur, cur + 1);
+ if (old == cur)
+ break;
+ cur = old;
+ }
+
+ return true;
+}
+
+bool rq_wait_inc_below(struct rq_wait *rq_wait, int limit)
+{
+ return atomic_inc_below(&rq_wait->inflight, limit);
+}
+
+void rq_qos_cleanup(struct request_queue *q, enum wbt_flags wb_acct)
+{
+ struct rq_qos *rqos;
+
+ for (rqos = q->rq_qos; rqos; rqos = rqos->next) {
+ if (rqos->ops->cleanup)
+ rqos->ops->cleanup(rqos, wb_acct);
+ }
+}
+
+void rq_qos_done(struct request_queue *q, struct request *rq)
+{
+ struct rq_qos *rqos;
+
+ for (rqos = q->rq_qos; rqos; rqos = rqos->next) {
+ if (rqos->ops->done)
+ rqos->ops->done(rqos, rq);
+ }
+}
+
+void rq_qos_issue(struct request_queue *q, struct request *rq)
+{
+ struct rq_qos *rqos;
+
+ for(rqos = q->rq_qos; rqos; rqos = rqos->next) {
+ if (rqos->ops->issue)
+ rqos->ops->issue(rqos, rq);
+ }
+}
+
+void rq_qos_requeue(struct request_queue *q, struct request *rq)
+{
+ struct rq_qos *rqos;
+
+ for(rqos = q->rq_qos; rqos; rqos = rqos->next) {
+ if (rqos->ops->requeue)
+ rqos->ops->requeue(rqos, rq);
+ }
+}
+
+enum wbt_flags rq_qos_throttle(struct request_queue *q, struct bio *bio,
+ spinlock_t *lock)
+{
+ struct rq_qos *rqos;
+ enum wbt_flags flags = 0;
+
+ for(rqos = q->rq_qos; rqos; rqos = rqos->next) {
+ if (rqos->ops->throttle)
+ flags |= rqos->ops->throttle(rqos, bio, lock);
+ }
+ return flags;
+}
+
+/*
+ * Return true, if we can't increase the depth further by scaling
+ */
+bool rq_depth_calc_max_depth(struct rq_depth *rqd)
+{
+ unsigned int depth;
+ bool ret = false;
+
+ /*
+ * For QD=1 devices, this is a special case. It's important for those
+ * to have one request ready when one completes, so force a depth of
+ * 2 for those devices. On the backend, it'll be a depth of 1 anyway,
+ * since the device can't have more than that in flight. If we're
+ * scaling down, then keep a setting of 1/1/1.
+ */
+ if (rqd->queue_depth == 1) {
+ if (rqd->scale_step > 0)
+ rqd->max_depth = 1;
+ else {
+ rqd->max_depth = 2;
+ ret = true;
+ }
+ } else {
+ /*
+ * scale_step == 0 is our default state. If we have suffered
+ * latency spikes, step will be > 0, and we shrink the
+ * allowed write depths. If step is < 0, we're only doing
+ * writes, and we allow a temporarily higher depth to
+ * increase performance.
+ */
+ depth = min_t(unsigned int, rqd->default_depth,
+ rqd->queue_depth);
+ if (rqd->scale_step > 0)
+ depth = 1 + ((depth - 1) >> min(31, rqd->scale_step));
+ else if (rqd->scale_step < 0) {
+ unsigned int maxd = 3 * rqd->queue_depth / 4;
+
+ depth = 1 + ((depth - 1) << -rqd->scale_step);
+ if (depth > maxd) {
+ depth = maxd;
+ ret = true;
+ }
+ }
+
+ rqd->max_depth = depth;
+ }
+
+ return ret;
+}
+
+void rq_depth_scale_up(struct rq_depth *rqd)
+{
+ /*
+ * Hit max in previous round, stop here
+ */
+ if (rqd->scaled_max)
+ return;
+
+ rqd->scale_step--;
+
+ rqd->scaled_max = rq_depth_calc_max_depth(rqd);
+}
+
+/*
+ * Scale rwb down. If 'hard_throttle' is set, do it quicker, since we
+ * had a latency violation.
+ */
+void rq_depth_scale_down(struct rq_depth *rqd, bool hard_throttle)
+{
+ /*
+ * Stop scaling down when we've hit the limit. This also prevents
+ * ->scale_step from going to crazy values, if the device can't
+ * keep up.
+ */
+ if (rqd->max_depth == 1)
+ return;
+
+ if (rqd->scale_step < 0 && hard_throttle)
+ rqd->scale_step = 0;
+ else
+ rqd->scale_step++;
+
+ rqd->scaled_max = false;
+ rq_depth_calc_max_depth(rqd);
+}
+
+void rq_qos_exit(struct request_queue *q)
+{
+ while (q->rq_qos) {
+ struct rq_qos *rqos = q->rq_qos;
+ q->rq_qos = rqos->next;
+ rqos->ops->exit(rqos);
+ }
+}
diff --git a/block/blk-rq-qos.h b/block/blk-rq-qos.h
new file mode 100644
index 000000000000..a321e9e2ba70
--- /dev/null
+++ b/block/blk-rq-qos.h
@@ -0,0 +1,91 @@
+#ifndef RQ_QOS_H
+#define RQ_QOS_H
+
+#include <linux/kernel.h>
+#include <linux/blkdev.h>
+#include <linux/blk_types.h>
+#include <linux/atomic.h>
+#include <linux/wait.h>
+
+enum rq_qos_id {
+ RQ_QOS_WBT,
+ RQ_QOS_CGROUP,
+};
+
+struct rq_wait {
+ wait_queue_head_t wait;
+ atomic_t inflight;
+};
+
+struct rq_qos {
+ struct rq_qos_ops *ops;
+ struct request_queue *q;
+ enum rq_qos_id id;
+ struct rq_qos *next;
+};
+
+struct rq_qos_ops {
+ enum wbt_flags (*throttle)(struct rq_qos *, struct bio *,
+ spinlock_t *);
+ void (*issue)(struct rq_qos *, struct request *);
+ void (*requeue)(struct rq_qos *, struct request *);
+ void (*done)(struct rq_qos *, struct request *);
+ void (*cleanup)(struct rq_qos *, enum wbt_flags);
+ void (*exit)(struct rq_qos *);
+};
+
+struct rq_depth {
+ unsigned int max_depth;
+
+ int scale_step;
+ bool scaled_max;
+
+ unsigned int queue_depth;
+ unsigned int default_depth;
+};
+
+static inline struct rq_qos *rq_qos_id(struct request_queue *q,
+ enum rq_qos_id id)
+{
+ struct rq_qos *rqos;
+ for (rqos = q->rq_qos; rqos; rqos = rqos->next) {
+ if (rqos->id == id)
+ break;
+ }
+ return rqos;
+}
+
+static inline struct rq_qos *wbt_rq_qos(struct request_queue *q)
+{
+ return rq_qos_id(q, RQ_QOS_WBT);
+}
+
+static inline struct rq_qos *blkcg_rq_qos(struct request_queue *q)
+{
+ return rq_qos_id(q, RQ_QOS_CGROUP);
+}
+
+static inline void rq_wait_init(struct rq_wait *rq_wait)
+{
+ atomic_set(&rq_wait->inflight, 0);
+ init_waitqueue_head(&rq_wait->wait);
+}
+
+static inline void rq_qos_add(struct request_queue *q, struct rq_qos *rqos)
+{
+ rqos->next = q->rq_qos;
+ q->rq_qos = rqos;
+}
+
+bool rq_wait_inc_below(struct rq_wait *rq_wait, int limit);
+void rq_depth_scale_up(struct rq_depth *rqd);
+void rq_depth_scale_down(struct rq_depth *rqd, bool hard_throttle);
+bool rq_depth_calc_max_depth(struct rq_depth *rqd);
+
+void rq_qos_cleanup(struct request_queue *, enum wbt_flags);
+void rq_qos_done(struct request_queue *, struct request *);
+void rq_qos_issue(struct request_queue *, struct request *);
+void rq_qos_requeue(struct request_queue *, struct request *);
+enum wbt_flags rq_qos_throttle(struct request_queue *, struct bio *, spinlock_t *);
+void rq_qos_exit(struct request_queue *);
+#endif
diff --git a/block/blk-settings.c b/block/blk-settings.c
index d1de71124656..053de87d1fda 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -875,7 +875,7 @@ EXPORT_SYMBOL_GPL(blk_queue_flush_queueable);
void blk_set_queue_depth(struct request_queue *q, unsigned int depth)
{
q->queue_depth = depth;
- wbt_set_queue_depth(q->rq_wb, depth);
+ wbt_set_queue_depth(q, depth);
}
EXPORT_SYMBOL(blk_set_queue_depth);

@@ -900,7 +900,7 @@ void blk_queue_write_cache(struct request_queue *q, bool wc, bool fua)
queue_flag_clear(QUEUE_FLAG_FUA, q);
spin_unlock_irq(q->queue_lock);

- wbt_set_write_cache(q->rq_wb, test_bit(QUEUE_FLAG_WC, &q->queue_flags));
+ wbt_set_write_cache(q, test_bit(QUEUE_FLAG_WC, &q->queue_flags));
}
EXPORT_SYMBOL_GPL(blk_queue_write_cache);

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index cae525b7aae6..6c23404c01db 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -422,16 +422,16 @@ static ssize_t queue_poll_store(struct request_queue *q, const char *page,

static ssize_t queue_wb_lat_show(struct request_queue *q, char *page)
{
- if (!q->rq_wb)
+ if (!wbt_rq_qos(q))
return -EINVAL;

- return sprintf(page, "%llu\n", div_u64(q->rq_wb->min_lat_nsec, 1000));
+ return sprintf(page, "%llu\n", div_u64(wbt_get_min_lat(q), 1000));
}

static ssize_t queue_wb_lat_store(struct request_queue *q, const char *page,
size_t count)
{
- struct rq_wb *rwb;
+ struct rq_qos *rqos;
ssize_t ret;
s64 val;

@@ -441,23 +441,21 @@ static ssize_t queue_wb_lat_store(struct request_queue *q, const char *page,
if (val < -1)
return -EINVAL;

- rwb = q->rq_wb;
- if (!rwb) {
+ rqos = wbt_rq_qos(q);
+ if (!rqos) {
ret = wbt_init(q);
if (ret)
return ret;
}

- rwb = q->rq_wb;
if (val == -1)
- rwb->min_lat_nsec = wbt_default_latency_nsec(q);
+ val = wbt_default_latency_nsec(q);
else if (val >= 0)
- rwb->min_lat_nsec = val * 1000ULL;
+ val *= 1000ULL;

- if (rwb->enable_state == WBT_STATE_ON_DEFAULT)
- rwb->enable_state = WBT_STATE_ON_MANUAL;
+ wbt_set_min_lat(q, val);

- wbt_update_limits(rwb);
+ wbt_update_limits(q);
return count;
}

@@ -965,7 +963,7 @@ void blk_unregister_queue(struct gendisk *disk)
kobject_del(&q->kobj);
blk_trace_remove_sysfs(disk_to_dev(disk));

- wbt_exit(q);
+ rq_qos_exit(q);

mutex_lock(&q->sysfs_lock);
if (q->request_fn || (q->mq_ops && q->elevator))
diff --git a/block/blk-wbt.c b/block/blk-wbt.c
index 4f89b28fa652..6fe20fb823e4 100644
--- a/block/blk-wbt.c
+++ b/block/blk-wbt.c
@@ -25,6 +25,7 @@
#include <linux/swap.h>

#include "blk-wbt.h"
+#include "blk-rq-qos.h"

#define CREATE_TRACE_POINTS
#include <trace/events/wbt.h>
@@ -78,28 +79,6 @@ static inline bool rwb_enabled(struct rq_wb *rwb)
return rwb && rwb->wb_normal != 0;
}

-/*
- * Increment 'v', if 'v' is below 'below'. Returns true if we succeeded,
- * false if 'v' + 1 would be bigger than 'below'.
- */
-static bool atomic_inc_below(atomic_t *v, int below)
-{
- int cur = atomic_read(v);
-
- for (;;) {
- int old;
-
- if (cur >= below)
- return false;
- old = atomic_cmpxchg(v, cur, cur + 1);
- if (old == cur)
- break;
- cur = old;
- }
-
- return true;
-}
-
static void wb_timestamp(struct rq_wb *rwb, unsigned long *var)
{
if (rwb_enabled(rwb)) {
@@ -116,7 +95,7 @@ static void wb_timestamp(struct rq_wb *rwb, unsigned long *var)
*/
static bool wb_recent_wait(struct rq_wb *rwb)
{
- struct bdi_writeback *wb = &rwb->queue->backing_dev_info->wb;
+ struct bdi_writeback *wb = &rwb->rqos.q->backing_dev_info->wb;

return time_before(jiffies, wb->dirty_sleep + HZ);
}
@@ -144,8 +123,9 @@ static void rwb_wake_all(struct rq_wb *rwb)
}
}

-void __wbt_done(struct rq_wb *rwb, enum wbt_flags wb_acct)
+static void __wbt_done(struct rq_qos *rqos, enum wbt_flags wb_acct)
{
+ struct rq_wb *rwb = RQWB(rqos);
struct rq_wait *rqw;
int inflight, limit;

@@ -194,10 +174,9 @@ void __wbt_done(struct rq_wb *rwb, enum wbt_flags wb_acct)
* Called on completion of a request. Note that it's also called when
* a request is merged, when the request gets freed.
*/
-void wbt_done(struct rq_wb *rwb, struct request *rq)
+static void wbt_done(struct rq_qos *rqos, struct request *rq)
{
- if (!rwb)
- return;
+ struct rq_wb *rwb = RQWB(rqos);

if (!wbt_is_tracked(rq)) {
if (rwb->sync_cookie == rq) {
@@ -209,72 +188,11 @@ void wbt_done(struct rq_wb *rwb, struct request *rq)
wb_timestamp(rwb, &rwb->last_comp);
} else {
WARN_ON_ONCE(rq == rwb->sync_cookie);
- __wbt_done(rwb, wbt_flags(rq));
+ __wbt_done(rqos, wbt_flags(rq));
}
wbt_clear_state(rq);
}

-/*
- * Return true, if we can't increase the depth further by scaling
- */
-static bool calc_wb_limits(struct rq_wb *rwb)
-{
- unsigned int depth;
- bool ret = false;
-
- if (!rwb->min_lat_nsec) {
- rwb->wb_max = rwb->wb_normal = rwb->wb_background = 0;
- return false;
- }
-
- /*
- * For QD=1 devices, this is a special case. It's important for those
- * to have one request ready when one completes, so force a depth of
- * 2 for those devices. On the backend, it'll be a depth of 1 anyway,
- * since the device can't have more than that in flight. If we're
- * scaling down, then keep a setting of 1/1/1.
- */
- if (rwb->queue_depth == 1) {
- if (rwb->scale_step > 0)
- rwb->wb_max = rwb->wb_normal = 1;
- else {
- rwb->wb_max = rwb->wb_normal = 2;
- ret = true;
- }
- rwb->wb_background = 1;
- } else {
- /*
- * scale_step == 0 is our default state. If we have suffered
- * latency spikes, step will be > 0, and we shrink the
- * allowed write depths. If step is < 0, we're only doing
- * writes, and we allow a temporarily higher depth to
- * increase performance.
- */
- depth = min_t(unsigned int, RWB_DEF_DEPTH, rwb->queue_depth);
- if (rwb->scale_step > 0)
- depth = 1 + ((depth - 1) >> min(31, rwb->scale_step));
- else if (rwb->scale_step < 0) {
- unsigned int maxd = 3 * rwb->queue_depth / 4;
-
- depth = 1 + ((depth - 1) << -rwb->scale_step);
- if (depth > maxd) {
- depth = maxd;
- ret = true;
- }
- }
-
- /*
- * Set our max/normal/bg queue depths based on how far
- * we have scaled down (->scale_step).
- */
- rwb->wb_max = depth;
- rwb->wb_normal = (rwb->wb_max + 1) / 2;
- rwb->wb_background = (rwb->wb_max + 3) / 4;
- }
-
- return ret;
-}
-
static inline bool stat_sample_valid(struct blk_rq_stat *stat)
{
/*
@@ -307,7 +225,8 @@ enum {

static int latency_exceeded(struct rq_wb *rwb, struct blk_rq_stat *stat)
{
- struct backing_dev_info *bdi = rwb->queue->backing_dev_info;
+ struct backing_dev_info *bdi = rwb->rqos.q->backing_dev_info;
+ struct rq_depth *rqd = &rwb->rq_depth;
u64 thislat;

/*
@@ -351,7 +270,7 @@ static int latency_exceeded(struct rq_wb *rwb, struct blk_rq_stat *stat)
return LAT_EXCEEDED;
}

- if (rwb->scale_step)
+ if (rqd->scale_step)
trace_wbt_stat(bdi, stat);

return LAT_OK;
@@ -359,58 +278,48 @@ static int latency_exceeded(struct rq_wb *rwb, struct blk_rq_stat *stat)

static void rwb_trace_step(struct rq_wb *rwb, const char *msg)
{
- struct backing_dev_info *bdi = rwb->queue->backing_dev_info;
+ struct backing_dev_info *bdi = rwb->rqos.q->backing_dev_info;
+ struct rq_depth *rqd = &rwb->rq_depth;

- trace_wbt_step(bdi, msg, rwb->scale_step, rwb->cur_win_nsec,
- rwb->wb_background, rwb->wb_normal, rwb->wb_max);
+ trace_wbt_step(bdi, msg, rqd->scale_step, rwb->cur_win_nsec,
+ rwb->wb_background, rwb->wb_normal, rqd->max_depth);
}

-static void scale_up(struct rq_wb *rwb)
+static void calc_wb_limits(struct rq_wb *rwb)
{
- /*
- * Hit max in previous round, stop here
- */
- if (rwb->scaled_max)
- return;
+ if (rwb->min_lat_nsec == 0) {
+ rwb->wb_normal = rwb->wb_background = 0;
+ } else if (rwb->rq_depth.max_depth <= 2) {
+ rwb->wb_normal = rwb->rq_depth.max_depth;
+ rwb->wb_background = 1;
+ } else {
+ rwb->wb_normal = (rwb->rq_depth.max_depth + 1) / 2;
+ rwb->wb_background = (rwb->rq_depth.max_depth + 3) / 4;
+ }
+}

- rwb->scale_step--;
+static void scale_up(struct rq_wb *rwb)
+{
+ rq_depth_scale_up(&rwb->rq_depth);
+ calc_wb_limits(rwb);
rwb->unknown_cnt = 0;
-
- rwb->scaled_max = calc_wb_limits(rwb);
-
- rwb_wake_all(rwb);
-
- rwb_trace_step(rwb, "step up");
+ rwb_trace_step(rwb, "scale up");
}

-/*
- * Scale rwb down. If 'hard_throttle' is set, do it quicker, since we
- * had a latency violation.
- */
static void scale_down(struct rq_wb *rwb, bool hard_throttle)
{
- /*
- * Stop scaling down when we've hit the limit. This also prevents
- * ->scale_step from going to crazy values, if the device can't
- * keep up.
- */
- if (rwb->wb_max == 1)
- return;
-
- if (rwb->scale_step < 0 && hard_throttle)
- rwb->scale_step = 0;
- else
- rwb->scale_step++;
-
- rwb->scaled_max = false;
- rwb->unknown_cnt = 0;
+ rq_depth_scale_down(&rwb->rq_depth, hard_throttle);
calc_wb_limits(rwb);
- rwb_trace_step(rwb, "step down");
+ rwb->unknown_cnt = 0;
+ rwb_wake_all(rwb);
+ rwb_trace_step(rwb, "scale down");
}

static void rwb_arm_timer(struct rq_wb *rwb)
{
- if (rwb->scale_step > 0) {
+ struct rq_depth *rqd = &rwb->rq_depth;
+
+ if (rqd->scale_step > 0) {
/*
* We should speed this up, using some variant of a fast
* integer inverse square root calculation. Since we only do
@@ -418,7 +327,7 @@ static void rwb_arm_timer(struct rq_wb *rwb)
* though.
*/
rwb->cur_win_nsec = div_u64(rwb->win_nsec << 4,
- int_sqrt((rwb->scale_step + 1) << 8));
+ int_sqrt((rqd->scale_step + 1) << 8));
} else {
/*
* For step < 0, we don't want to increase/decrease the
@@ -433,12 +342,13 @@ static void rwb_arm_timer(struct rq_wb *rwb)
static void wb_timer_fn(struct blk_stat_callback *cb)
{
struct rq_wb *rwb = cb->data;
+ struct rq_depth *rqd = &rwb->rq_depth;
unsigned int inflight = wbt_inflight(rwb);
int status;

status = latency_exceeded(rwb, cb->stat);

- trace_wbt_timer(rwb->queue->backing_dev_info, status, rwb->scale_step,
+ trace_wbt_timer(rwb->rqos.q->backing_dev_info, status, rqd->scale_step,
inflight);

/*
@@ -469,9 +379,9 @@ static void wb_timer_fn(struct blk_stat_callback *cb)
* currently don't have a valid read/write sample. For that
* case, slowly return to center state (step == 0).
*/
- if (rwb->scale_step > 0)
+ if (rqd->scale_step > 0)
scale_up(rwb);
- else if (rwb->scale_step < 0)
+ else if (rqd->scale_step < 0)
scale_down(rwb, false);
break;
default:
@@ -481,19 +391,50 @@ static void wb_timer_fn(struct blk_stat_callback *cb)
/*
* Re-arm timer, if we have IO in flight
*/
- if (rwb->scale_step || inflight)
+ if (rqd->scale_step || inflight)
rwb_arm_timer(rwb);
}

-void wbt_update_limits(struct rq_wb *rwb)
+static void __wbt_update_limits(struct rq_wb *rwb)
{
- rwb->scale_step = 0;
- rwb->scaled_max = false;
+ struct rq_depth *rqd = &rwb->rq_depth;
+
+ rqd->scale_step = 0;
+ rqd->scaled_max = false;
+
+ rq_depth_calc_max_depth(rqd);
calc_wb_limits(rwb);

rwb_wake_all(rwb);
}

+void wbt_update_limits(struct request_queue *q)
+{
+ struct rq_qos *rqos = wbt_rq_qos(q);
+ if (!rqos)
+ return;
+ __wbt_update_limits(RQWB(rqos));
+}
+
+u64 wbt_get_min_lat(struct request_queue *q)
+{
+ struct rq_qos *rqos = wbt_rq_qos(q);
+ if (!rqos)
+ return 0;
+ return RQWB(rqos)->min_lat_nsec;
+}
+
+void wbt_set_min_lat(struct request_queue *q, u64 val)
+{
+ struct rq_qos *rqos = wbt_rq_qos(q);
+ if (!rqos)
+ return;
+ RQWB(rqos)->min_lat_nsec = val;
+ RQWB(rqos)->enable_state = WBT_STATE_ON_MANUAL;
+ __wbt_update_limits(RQWB(rqos));
+}
+
+
static bool close_io(struct rq_wb *rwb)
{
const unsigned long now = jiffies;
@@ -520,7 +461,7 @@ static inline unsigned int get_limit(struct rq_wb *rwb, unsigned long rw)
* IO for a bit.
*/
if ((rw & REQ_HIPRIO) || wb_recent_wait(rwb) || current_is_kswapd())
- limit = rwb->wb_max;
+ limit = rwb->rq_depth.max_depth;
else if ((rw & REQ_BACKGROUND) || close_io(rwb)) {
/*
* If less than 100ms since we completed unrelated IO,
@@ -554,7 +495,7 @@ static inline bool may_queue(struct rq_wb *rwb, struct rq_wait *rqw,
rqw->wait.head.next != &wait->entry)
return false;

- return atomic_inc_below(&rqw->inflight, get_limit(rwb, rw));
+ return rq_wait_inc_below(rqw, get_limit(rwb, rw));
}

/*
@@ -614,8 +555,10 @@ static inline bool wbt_should_throttle(struct rq_wb *rwb, struct bio *bio)
* in an irq held spinlock, if it holds one when calling this function.
* If we do sleep, we'll release and re-grab it.
*/
-enum wbt_flags wbt_wait(struct rq_wb *rwb, struct bio *bio, spinlock_t *lock)
+static enum wbt_flags wbt_wait(struct rq_qos *rqos, struct bio *bio,
+ spinlock_t *lock)
{
+ struct rq_wb *rwb = RQWB(rqos);
enum wbt_flags ret = 0;

if (!rwb_enabled(rwb))
@@ -643,8 +586,10 @@ enum wbt_flags wbt_wait(struct rq_wb *rwb, struct bio *bio, spinlock_t *lock)
return ret | WBT_TRACKED;
}

-void wbt_issue(struct rq_wb *rwb, struct request *rq)
+void wbt_issue(struct rq_qos *rqos, struct request *rq)
{
+ struct rq_wb *rwb = RQWB(rqos);
+
if (!rwb_enabled(rwb))
return;

@@ -661,8 +606,9 @@ void wbt_issue(struct rq_wb *rwb, struct request *rq)
}
}

-void wbt_requeue(struct rq_wb *rwb, struct request *rq)
+void wbt_requeue(struct rq_qos *rqos, struct request *rq)
{
+ struct rq_wb *rwb = RQWB(rqos);
if (!rwb_enabled(rwb))
return;
if (rq == rwb->sync_cookie) {
@@ -671,39 +617,30 @@ void wbt_requeue(struct rq_wb *rwb, struct request *rq)
}
}

-void wbt_set_queue_depth(struct rq_wb *rwb, unsigned int depth)
+void wbt_set_queue_depth(struct request_queue *q, unsigned int depth)
{
- if (rwb) {
- rwb->queue_depth = depth;
- wbt_update_limits(rwb);
+ struct rq_qos *rqos = wbt_rq_qos(q);
+ if (rqos) {
+ RQWB(rqos)->rq_depth.queue_depth = depth;
+ __wbt_update_limits(RQWB(rqos));
}
}

-void wbt_set_write_cache(struct rq_wb *rwb, bool write_cache_on)
-{
- if (rwb)
- rwb->wc = write_cache_on;
-}
-
-/*
- * Disable wbt, if enabled by default.
- */
-void wbt_disable_default(struct request_queue *q)
+void wbt_set_write_cache(struct request_queue *q, bool write_cache_on)
{
- struct rq_wb *rwb = q->rq_wb;
-
- if (rwb && rwb->enable_state == WBT_STATE_ON_DEFAULT)
- wbt_exit(q);
+ struct rq_qos *rqos = wbt_rq_qos(q);
+ if (rqos)
+ RQWB(rqos)->wc = write_cache_on;
}
-EXPORT_SYMBOL_GPL(wbt_disable_default);

/*
* Enable wbt if defaults are configured that way
*/
void wbt_enable_default(struct request_queue *q)
{
+ struct rq_qos *rqos = wbt_rq_qos(q);
/* Throttling already enabled? */
- if (q->rq_wb)
+ if (rqos)
return;

/* Queue not registered? Maybe shutting down... */
@@ -741,6 +678,41 @@ static int wbt_data_dir(const struct request *rq)
return -1;
}

+static void wbt_exit(struct rq_qos *rqos)
+{
+ struct rq_wb *rwb = RQWB(rqos);
+ struct request_queue *q = rqos->q;
+
+ blk_stat_remove_callback(q, rwb->cb);
+ blk_stat_free_callback(rwb->cb);
+ kfree(rwb);
+}
+
+/*
+ * Disable wbt, if enabled by default.
+ */
+void wbt_disable_default(struct request_queue *q)
+{
+ struct rq_qos *rqos = wbt_rq_qos(q);
+ struct rq_wb *rwb;
+ if (!rqos)
+ return;
+ rwb = RQWB(rqos);
+ if (rwb->enable_state == WBT_STATE_ON_DEFAULT)
+ rwb->wb_normal = 0;
+}
+EXPORT_SYMBOL_GPL(wbt_disable_default);
+
+
+static struct rq_qos_ops wbt_rqos_ops = {
+ .throttle = wbt_wait,
+ .issue = wbt_issue,
+ .requeue = wbt_requeue,
+ .done = wbt_done,
+ .cleanup = __wbt_done,
+ .exit = wbt_exit,
+};
+
int wbt_init(struct request_queue *q)
{
struct rq_wb *rwb;
@@ -756,39 +728,29 @@ int wbt_init(struct request_queue *q)
return -ENOMEM;
}

- for (i = 0; i < WBT_NUM_RWQ; i++) {
- atomic_set(&rwb->rq_wait[i].inflight, 0);
- init_waitqueue_head(&rwb->rq_wait[i].wait);
- }
+ for (i = 0; i < WBT_NUM_RWQ; i++)
+ rq_wait_init(&rwb->rq_wait[i]);

+ rwb->rqos.id = RQ_QOS_WBT;
+ rwb->rqos.ops = &wbt_rqos_ops;
+ rwb->rqos.q = q;
rwb->last_comp = rwb->last_issue = jiffies;
- rwb->queue = q;
rwb->win_nsec = RWB_WINDOW_NSEC;
rwb->enable_state = WBT_STATE_ON_DEFAULT;
- wbt_update_limits(rwb);
+ rwb->wc = 1;
+ rwb->rq_depth.default_depth = RWB_DEF_DEPTH;
+ __wbt_update_limits(rwb);

/*
* Assign rwb and add the stats callback.
*/
- q->rq_wb = rwb;
+ rq_qos_add(q, &rwb->rqos);
blk_stat_add_callback(q, rwb->cb);

rwb->min_lat_nsec = wbt_default_latency_nsec(q);

- wbt_set_queue_depth(rwb, blk_queue_depth(q));
- wbt_set_write_cache(rwb, test_bit(QUEUE_FLAG_WC, &q->queue_flags));
+ wbt_set_queue_depth(q, blk_queue_depth(q));
+ wbt_set_write_cache(q, test_bit(QUEUE_FLAG_WC, &q->queue_flags));

return 0;
}
-
-void wbt_exit(struct request_queue *q)
-{
- struct rq_wb *rwb = q->rq_wb;
-
- if (rwb) {
- blk_stat_remove_callback(q, rwb->cb);
- blk_stat_free_callback(rwb->cb);
- q->rq_wb = NULL;
- kfree(rwb);
- }
-}
diff --git a/block/blk-wbt.h b/block/blk-wbt.h
index 300df531d0a6..53b20a58c0a2 100644
--- a/block/blk-wbt.h
+++ b/block/blk-wbt.h
@@ -9,6 +9,7 @@
#include <linux/ktime.h>

#include "blk-stat.h"
+#include "blk-rq-qos.h"

enum wbt_flags {
WBT_TRACKED = 1, /* write, tracked for throttling */
@@ -35,20 +36,12 @@ enum {
WBT_STATE_ON_MANUAL = 2,
};

-struct rq_wait {
- wait_queue_head_t wait;
- atomic_t inflight;
-};
-
struct rq_wb {
/*
* Settings that govern how we throttle
*/
unsigned int wb_background; /* background writeback */
unsigned int wb_normal; /* normal writeback */
- unsigned int wb_max; /* max throughput writeback */
- int scale_step;
- bool scaled_max;

short enable_state; /* WBT_STATE_* */

@@ -67,15 +60,20 @@ struct rq_wb {
void *sync_cookie;

unsigned int wc;
- unsigned int queue_depth;

unsigned long last_issue; /* last non-throttled issue */
unsigned long last_comp; /* last non-throttled comp */
unsigned long min_lat_nsec;
- struct request_queue *queue;
+ struct rq_qos rqos;
struct rq_wait rq_wait[WBT_NUM_RWQ];
+ struct rq_depth rq_depth;
};

+static inline struct rq_wb *RQWB(struct rq_qos *rqos)
+{
+ return container_of(rqos, struct rq_wb, rqos);
+}
+
static inline unsigned int wbt_inflight(struct rq_wb *rwb)
{
unsigned int i, ret = 0;
@@ -86,6 +84,7 @@ static inline unsigned int wbt_inflight(struct rq_wb *rwb)
return ret;
}

+
#ifdef CONFIG_BLK_WBT

static inline void wbt_track(struct request *rq, enum wbt_flags flags)
@@ -93,19 +92,16 @@ static inline void wbt_track(struct request *rq, enum wbt_flags flags)
rq->wbt_flags |= flags;
}

-void __wbt_done(struct rq_wb *, enum wbt_flags);
-void wbt_done(struct rq_wb *, struct request *);
-enum wbt_flags wbt_wait(struct rq_wb *, struct bio *, spinlock_t *);
int wbt_init(struct request_queue *);
-void wbt_exit(struct request_queue *);
-void wbt_update_limits(struct rq_wb *);
-void wbt_requeue(struct rq_wb *, struct request *);
-void wbt_issue(struct rq_wb *, struct request *);
+void wbt_update_limits(struct request_queue *);
void wbt_disable_default(struct request_queue *);
void wbt_enable_default(struct request_queue *);

-void wbt_set_queue_depth(struct rq_wb *, unsigned int);
-void wbt_set_write_cache(struct rq_wb *, bool);
+u64 wbt_get_min_lat(struct request_queue *q);
+void wbt_set_min_lat(struct request_queue *q, u64 val);
+
+void wbt_set_queue_depth(struct request_queue *, unsigned int);
+void wbt_set_write_cache(struct request_queue *, bool);

u64 wbt_default_latency_nsec(struct request_queue *);

@@ -114,43 +110,30 @@ u64 wbt_default_latency_nsec(struct request_queue *);
static inline void wbt_track(struct request *rq, enum wbt_flags flags)
{
}
-static inline void __wbt_done(struct rq_wb *rwb, enum wbt_flags flags)
-{
-}
-static inline void wbt_done(struct rq_wb *rwb, struct request *rq)
-{
-}
-static inline enum wbt_flags wbt_wait(struct rq_wb *rwb, struct bio *bio,
- spinlock_t *lock)
-{
- return 0;
-}
static inline int wbt_init(struct request_queue *q)
{
return -EINVAL;
}
-static inline void wbt_exit(struct request_queue *q)
-{
-}
-static inline void wbt_update_limits(struct rq_wb *rwb)
+static inline void wbt_update_limits(struct request_queue *q)
{
}
-static inline void wbt_requeue(struct rq_wb *rwb, struct request *rq)
+static inline void wbt_disable_default(struct request_queue *q)
{
}
-static inline void wbt_issue(struct rq_wb *rwb, struct request *rq)
+static inline void wbt_enable_default(struct request_queue *q)
{
}
-static inline void wbt_disable_default(struct request_queue *q)
+static inline void wbt_set_queue_depth(struct request_queue *q, unsigned int depth)
{
}
-static inline void wbt_enable_default(struct request_queue *q)
+static inline void wbt_set_write_cache(struct request_queue *q, bool wc)
{
}
-static inline void wbt_set_queue_depth(struct rq_wb *rwb, unsigned int depth)
+static inline u64 wbt_get_min_lat(struct request_queue *q)
{
+ return 0;
}
-static inline void wbt_set_write_cache(struct rq_wb *rwb, bool wc)
+static inline void wbt_set_min_lat(struct request_queue *q, u64 val)
{
}
static inline u64 wbt_default_latency_nsec(struct request_queue *q)
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index f3999719f828..30c60d049167 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -42,7 +42,7 @@ struct bsg_job;
struct blkcg_gq;
struct blk_flush_queue;
struct pr_ops;
-struct rq_wb;
+struct rq_qos;
struct blk_queue_stats;
struct blk_stat_callback;

@@ -455,7 +455,7 @@ struct request_queue {
atomic_t shared_hctx_restart;

struct blk_queue_stats *stats;
- struct rq_wb *rq_wb;
+ struct rq_qos *rq_qos;

/*
* If blkcg is not used, @q->root_rl serves all requests. If blkcg
--
2.14.3