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Subject[PATCH 08/10] blk-mq-sched: add framework for MQ capable IO schedulers
Date
This adds a set of hooks that intercepts the blk-mq path of
allocating/inserting/issuing/completing requests, allowing
us to develop a scheduler within that framework.

We reuse the existing elevator scheduler API on the registration
side, but augment that with the scheduler flagging support for
the blk-mq interfce, and with a separate set of ops hooks for MQ
devices.

We split driver and scheduler tags, so we can run the scheduling
independent of device queue depth.

Signed-off-by: Jens Axboe <axboe@fb.com>
---
block/Makefile | 2 +-
block/blk-core.c | 3 +-
block/blk-exec.c | 3 +-
block/blk-flush.c | 15 ++-
block/blk-ioc.c | 8 +-
block/blk-merge.c | 2 +-
block/blk-mq-sched.c | 334 +++++++++++++++++++++++++++++++++++++++++++++++
block/blk-mq-sched.h | 155 ++++++++++++++++++++++
block/blk-mq-sysfs.c | 13 ++
block/blk-mq.c | 258 +++++++++++++++++++-----------------
block/blk-mq.h | 8 +-
block/blk-tag.c | 1 +
block/elevator.c | 201 +++++++++++++++++++++-------
include/linux/blk-mq.h | 5 +-
include/linux/blkdev.h | 4 +-
include/linux/elevator.h | 32 +++++
16 files changed, 865 insertions(+), 179 deletions(-)
create mode 100644 block/blk-mq-sched.c
create mode 100644 block/blk-mq-sched.h

diff --git a/block/Makefile b/block/Makefile
index a827f988c4e6..2eee9e1bb6db 100644
--- a/block/Makefile
+++ b/block/Makefile
@@ -6,7 +6,7 @@ obj-$(CONFIG_BLOCK) := bio.o elevator.o blk-core.o blk-tag.o blk-sysfs.o \
blk-flush.o blk-settings.o blk-ioc.o blk-map.o \
blk-exec.o blk-merge.o blk-softirq.o blk-timeout.o \
blk-lib.o blk-mq.o blk-mq-tag.o blk-stat.o \
- blk-mq-sysfs.o blk-mq-cpumap.o ioctl.o \
+ blk-mq-sysfs.o blk-mq-cpumap.o blk-mq-sched.o ioctl.o \
genhd.o scsi_ioctl.o partition-generic.o ioprio.o \
badblocks.o partitions/

diff --git a/block/blk-core.c b/block/blk-core.c
index 92baea07acbc..ee3a6f340cb8 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -39,6 +39,7 @@

#include "blk.h"
#include "blk-mq.h"
+#include "blk-mq-sched.h"
#include "blk-wbt.h"

EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap);
@@ -2127,7 +2128,7 @@ int blk_insert_cloned_request(struct request_queue *q, struct request *rq)
if (q->mq_ops) {
if (blk_queue_io_stat(q))
blk_account_io_start(rq, true);
- blk_mq_insert_request(rq, false, true, false);
+ blk_mq_sched_insert_request(rq, false, true, false);
return 0;
}

diff --git a/block/blk-exec.c b/block/blk-exec.c
index 3ecb00a6cf45..86656fdfa637 100644
--- a/block/blk-exec.c
+++ b/block/blk-exec.c
@@ -9,6 +9,7 @@
#include <linux/sched/sysctl.h>

#include "blk.h"
+#include "blk-mq-sched.h"

/*
* for max sense size
@@ -65,7 +66,7 @@ void blk_execute_rq_nowait(struct request_queue *q, struct gendisk *bd_disk,
* be reused after dying flag is set
*/
if (q->mq_ops) {
- blk_mq_insert_request(rq, at_head, true, false);
+ blk_mq_sched_insert_request(rq, at_head, true, false);
return;
}

diff --git a/block/blk-flush.c b/block/blk-flush.c
index 20b7c7a02f1c..29850d10b30a 100644
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -74,6 +74,7 @@
#include "blk.h"
#include "blk-mq.h"
#include "blk-mq-tag.h"
+#include "blk-mq-sched.h"

/* FLUSH/FUA sequences */
enum {
@@ -169,6 +170,8 @@ static bool blk_flush_complete_seq(struct request *rq,
struct list_head *pending = &fq->flush_queue[fq->flush_pending_idx];
bool queued = false, kicked;

+ BUG_ON(q->mq_ops && rq->tag < 0);
+
BUG_ON(rq->flush.seq & seq);
rq->flush.seq |= seq;

@@ -318,6 +321,8 @@ static bool blk_kick_flush(struct request_queue *q, struct blk_flush_queue *fq)
if (q->mq_ops) {
struct blk_mq_hw_ctx *hctx;

+ BUG_ON(first_rq->tag < 0);
+
flush_rq->mq_ctx = first_rq->mq_ctx;
flush_rq->tag = first_rq->tag;
fq->orig_rq = first_rq;
@@ -451,11 +456,11 @@ void blk_insert_flush(struct request *rq)
* processed directly without going through flush machinery. Queue
* for normal execution.
*/
- if ((policy & REQ_FSEQ_DATA) &&
- !(policy & (REQ_FSEQ_PREFLUSH | REQ_FSEQ_POSTFLUSH))) {
- if (q->mq_ops) {
- blk_mq_insert_request(rq, false, true, false);
- } else
+ if (((policy & REQ_FSEQ_DATA) &&
+ !(policy & (REQ_FSEQ_PREFLUSH | REQ_FSEQ_POSTFLUSH)))) {
+ if (q->mq_ops)
+ blk_mq_sched_insert_request(rq, false, true, false);
+ else
list_add_tail(&rq->queuelist, &q->queue_head);
return;
}
diff --git a/block/blk-ioc.c b/block/blk-ioc.c
index ab372092a57d..fe186a9eade9 100644
--- a/block/blk-ioc.c
+++ b/block/blk-ioc.c
@@ -43,7 +43,9 @@ static void ioc_exit_icq(struct io_cq *icq)
if (icq->flags & ICQ_EXITED)
return;

- if (et->ops.sq.elevator_exit_icq_fn)
+ if (et->uses_mq && et->ops.mq.exit_icq)
+ et->ops.mq.exit_icq(icq);
+ else if (!et->uses_mq && et->ops.sq.elevator_exit_icq_fn)
et->ops.sq.elevator_exit_icq_fn(icq);

icq->flags |= ICQ_EXITED;
@@ -383,7 +385,9 @@ struct io_cq *ioc_create_icq(struct io_context *ioc, struct request_queue *q,
if (likely(!radix_tree_insert(&ioc->icq_tree, q->id, icq))) {
hlist_add_head(&icq->ioc_node, &ioc->icq_list);
list_add(&icq->q_node, &q->icq_list);
- if (et->ops.sq.elevator_init_icq_fn)
+ if (et->uses_mq && et->ops.mq.init_icq)
+ et->ops.mq.init_icq(icq);
+ else if (!et->uses_mq && et->ops.sq.elevator_init_icq_fn)
et->ops.sq.elevator_init_icq_fn(icq);
} else {
kmem_cache_free(et->icq_cache, icq);
diff --git a/block/blk-merge.c b/block/blk-merge.c
index 480570b691dc..6aa43dec5af4 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -763,7 +763,7 @@ int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
{
struct elevator_queue *e = q->elevator;

- if (e->type->ops.sq.elevator_allow_rq_merge_fn)
+ if (!e->uses_mq && e->type->ops.sq.elevator_allow_rq_merge_fn)
if (!e->type->ops.sq.elevator_allow_rq_merge_fn(q, rq, next))
return 0;

diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
new file mode 100644
index 000000000000..44cf30eb1589
--- /dev/null
+++ b/block/blk-mq-sched.c
@@ -0,0 +1,334 @@
+/*
+ * blk-mq scheduling framework
+ *
+ * Copyright (C) 2016 Jens Axboe
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/blk-mq.h>
+
+#include <trace/events/block.h>
+
+#include "blk.h"
+#include "blk-mq.h"
+#include "blk-mq-sched.h"
+#include "blk-mq-tag.h"
+#include "blk-wbt.h"
+
+void blk_mq_sched_free_hctx_data(struct request_queue *q,
+ void (*exit)(struct blk_mq_hw_ctx *))
+{
+ struct blk_mq_hw_ctx *hctx;
+ int i;
+
+ queue_for_each_hw_ctx(q, hctx, i) {
+ if (exit)
+ exit(hctx);
+ kfree(hctx->sched_data);
+ hctx->sched_data = NULL;
+ }
+}
+EXPORT_SYMBOL_GPL(blk_mq_sched_free_hctx_data);
+
+int blk_mq_sched_init_hctx_data(struct request_queue *q, size_t size,
+ int (*init)(struct blk_mq_hw_ctx *),
+ void (*exit)(struct blk_mq_hw_ctx *))
+{
+ struct blk_mq_hw_ctx *hctx;
+ int ret;
+ int i;
+
+ queue_for_each_hw_ctx(q, hctx, i) {
+ hctx->sched_data = kmalloc_node(size, GFP_KERNEL, hctx->numa_node);
+ if (!hctx->sched_data) {
+ ret = -ENOMEM;
+ goto error;
+ }
+
+ if (init) {
+ ret = init(hctx);
+ if (ret) {
+ /*
+ * We don't want to give exit() a partially
+ * initialized sched_data. init() must clean up
+ * if it fails.
+ */
+ kfree(hctx->sched_data);
+ hctx->sched_data = NULL;
+ goto error;
+ }
+ }
+ }
+
+ return 0;
+error:
+ blk_mq_sched_free_hctx_data(q, exit);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(blk_mq_sched_init_hctx_data);
+
+static void __blk_mq_sched_assign_ioc(struct request_queue *q,
+ struct request *rq, struct io_context *ioc)
+{
+ struct io_cq *icq;
+
+ spin_lock_irq(q->queue_lock);
+ icq = ioc_lookup_icq(ioc, q);
+ spin_unlock_irq(q->queue_lock);
+
+ if (!icq) {
+ icq = ioc_create_icq(ioc, q, GFP_ATOMIC);
+ if (!icq)
+ return;
+ }
+
+ rq->elv.icq = icq;
+ if (!blk_mq_sched_get_rq_priv(q, rq)) {
+ get_io_context(icq->ioc);
+ return;
+ }
+
+ rq->elv.icq = NULL;
+}
+
+static void blk_mq_sched_assign_ioc(struct request_queue *q,
+ struct request *rq, struct bio *bio)
+{
+ struct io_context *ioc;
+
+ ioc = rq_ioc(bio);
+ if (ioc)
+ __blk_mq_sched_assign_ioc(q, rq, ioc);
+}
+
+struct request *blk_mq_sched_get_request(struct request_queue *q,
+ struct bio *bio,
+ unsigned int op,
+ struct blk_mq_alloc_data *data)
+{
+ struct elevator_queue *e = q->elevator;
+ struct blk_mq_hw_ctx *hctx;
+ struct blk_mq_ctx *ctx;
+ struct request *rq;
+
+ blk_queue_enter_live(q);
+ ctx = blk_mq_get_ctx(q);
+ hctx = blk_mq_map_queue(q, ctx->cpu);
+
+ blk_mq_set_alloc_data(data, q, 0, ctx, hctx);
+
+ if (e) {
+ data->flags |= BLK_MQ_REQ_INTERNAL;
+ if (e->type->ops.mq.get_request)
+ rq = e->type->ops.mq.get_request(q, op, data);
+ else
+ rq = __blk_mq_alloc_request(data, op);
+ } else {
+ rq = __blk_mq_alloc_request(data, op);
+ if (rq) {
+ rq->tag = rq->internal_tag;
+ rq->internal_tag = -1;
+ }
+ }
+
+ if (rq) {
+ rq->elv.icq = NULL;
+ if (e && e->type->icq_cache)
+ blk_mq_sched_assign_ioc(q, rq, bio);
+ data->hctx->queued++;
+ return rq;
+ }
+
+ blk_queue_exit(q);
+ return NULL;
+}
+
+void blk_mq_sched_put_request(struct request *rq)
+{
+ struct request_queue *q = rq->q;
+ struct elevator_queue *e = q->elevator;
+
+ if (rq->rq_flags & RQF_ELVPRIV) {
+ blk_mq_sched_put_rq_priv(rq->q, rq);
+ if (rq->elv.icq) {
+ put_io_context(rq->elv.icq->ioc);
+ rq->elv.icq = NULL;
+ }
+ }
+
+ if (e && e->type->ops.mq.put_request)
+ e->type->ops.mq.put_request(rq);
+ else
+ blk_mq_finish_request(rq);
+}
+
+void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
+{
+ struct elevator_queue *e = hctx->queue->elevator;
+ LIST_HEAD(rq_list);
+
+ if (unlikely(blk_mq_hctx_stopped(hctx)))
+ return;
+
+ hctx->run++;
+
+ /*
+ * If we have previous entries on our dispatch list, grab them first for
+ * more fair dispatch.
+ */
+ if (!list_empty_careful(&hctx->dispatch)) {
+ spin_lock(&hctx->lock);
+ if (!list_empty(&hctx->dispatch))
+ list_splice_init(&hctx->dispatch, &rq_list);
+ spin_unlock(&hctx->lock);
+ }
+
+ /*
+ * Only ask the scheduler for requests, if we didn't have residual
+ * requests from the dispatch list. This is to avoid the case where
+ * we only ever dispatch a fraction of the requests available because
+ * of low device queue depth. Once we pull requests out of the IO
+ * scheduler, we can no longer merge or sort them. So it's best to
+ * leave them there for as long as we can. Mark the hw queue as
+ * needing a restart in that case.
+ */
+ if (list_empty(&rq_list)) {
+ if (e && e->type->ops.mq.dispatch_requests)
+ e->type->ops.mq.dispatch_requests(hctx, &rq_list);
+ else
+ blk_mq_flush_busy_ctxs(hctx, &rq_list);
+ } else if (!test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state))
+ set_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state);
+
+ blk_mq_dispatch_rq_list(hctx, &rq_list);
+}
+
+bool blk_mq_sched_try_merge(struct request_queue *q, struct bio *bio)
+{
+ struct request *rq;
+ int ret;
+
+ ret = elv_merge(q, &rq, bio);
+ if (ret == ELEVATOR_BACK_MERGE) {
+ if (bio_attempt_back_merge(q, rq, bio)) {
+ if (!attempt_back_merge(q, rq))
+ elv_merged_request(q, rq, ret);
+ return true;
+ }
+ } else if (ret == ELEVATOR_FRONT_MERGE) {
+ if (bio_attempt_front_merge(q, rq, bio)) {
+ if (!attempt_front_merge(q, rq))
+ elv_merged_request(q, rq, ret);
+ return true;
+ }
+ }
+
+ return false;
+}
+EXPORT_SYMBOL_GPL(blk_mq_sched_try_merge);
+
+bool __blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio)
+{
+ struct elevator_queue *e = q->elevator;
+
+ if (e->type->ops.mq.bio_merge) {
+ struct blk_mq_ctx *ctx = blk_mq_get_ctx(q);
+ struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
+
+ blk_mq_put_ctx(ctx);
+ return e->type->ops.mq.bio_merge(hctx, bio);
+ }
+
+ return false;
+}
+
+bool blk_mq_sched_try_insert_merge(struct request_queue *q, struct request *rq)
+{
+ return rq_mergeable(rq) && elv_attempt_insert_merge(q, rq);
+}
+EXPORT_SYMBOL_GPL(blk_mq_sched_try_insert_merge);
+
+void blk_mq_sched_request_inserted(struct request *rq)
+{
+ trace_block_rq_insert(rq->q, rq);
+}
+EXPORT_SYMBOL_GPL(blk_mq_sched_request_inserted);
+
+int blk_mq_sched_setup(struct request_queue *q)
+{
+ struct blk_mq_tag_set *set = q->tag_set;
+ struct blk_mq_hw_ctx *hctx;
+ int ret, i;
+
+ /*
+ * Default to 256, since we don't split into sync/async like the
+ * old code did. Additionally, this is a per-hw queue depth.
+ */
+ q->nr_requests = 2 * BLKDEV_MAX_RQ;
+
+ /*
+ * We're switching to using an IO scheduler, so setup the hctx
+ * scheduler tags and switch the request map from the regular
+ * tags to scheduler tags. First allocate what we need, so we
+ * can safely fail and fallback, if needed.
+ */
+ ret = 0;
+ queue_for_each_hw_ctx(q, hctx, i) {
+ hctx->sched_tags = blk_mq_alloc_rq_map(set, i, q->nr_requests, 0);
+ if (!hctx->sched_tags) {
+ ret = -ENOMEM;
+ break;
+ }
+ ret = blk_mq_alloc_rqs(set, hctx->sched_tags, i, q->nr_requests);
+ if (ret)
+ break;
+ }
+
+ /*
+ * If we failed, free what we did allocate
+ */
+ if (ret) {
+ queue_for_each_hw_ctx(q, hctx, i) {
+ if (!hctx->sched_tags)
+ continue;
+ blk_mq_free_rqs(set, hctx->sched_tags, i);
+ blk_mq_free_rq_map(hctx->sched_tags);
+ hctx->sched_tags = NULL;
+ }
+
+ return ret;
+ }
+
+ queue_for_each_hw_ctx(q, hctx, i)
+ blk_mq_free_rqs(set, hctx->tags, i);
+
+ return 0;
+}
+
+int blk_mq_sched_teardown(struct request_queue *q)
+{
+ struct blk_mq_tag_set *set = q->tag_set;
+ struct blk_mq_hw_ctx *hctx;
+ int i, ret;
+
+ ret = 0;
+ queue_for_each_hw_ctx(q, hctx, i) {
+ ret = blk_mq_alloc_rqs(set, hctx->tags, i, set->queue_depth);
+ if (ret)
+ break;
+ }
+
+ if (ret) {
+ queue_for_each_hw_ctx(q, hctx, i)
+ blk_mq_free_rqs(set, hctx->tags, i);
+ return ret;
+ }
+
+ queue_for_each_hw_ctx(q, hctx, i) {
+ blk_mq_free_rqs(set, hctx->sched_tags, i);
+ blk_mq_free_rq_map(hctx->sched_tags);
+ hctx->sched_tags = NULL;
+ }
+
+ return 0;
+}
diff --git a/block/blk-mq-sched.h b/block/blk-mq-sched.h
new file mode 100644
index 000000000000..68d6a202b827
--- /dev/null
+++ b/block/blk-mq-sched.h
@@ -0,0 +1,155 @@
+#ifndef BLK_MQ_SCHED_H
+#define BLK_MQ_SCHED_H
+
+#include "blk-mq.h"
+#include "blk-mq-tag.h"
+
+int blk_mq_sched_init_hctx_data(struct request_queue *q, size_t size,
+ int (*init)(struct blk_mq_hw_ctx *),
+ void (*exit)(struct blk_mq_hw_ctx *));
+
+void blk_mq_sched_free_hctx_data(struct request_queue *q,
+ void (*exit)(struct blk_mq_hw_ctx *));
+
+struct request *blk_mq_sched_get_request(struct request_queue *q, struct bio *bio, unsigned int op, struct blk_mq_alloc_data *data);
+void blk_mq_sched_put_request(struct request *rq);
+
+void __blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx);
+void blk_mq_sched_request_inserted(struct request *rq);
+bool blk_mq_sched_try_merge(struct request_queue *q, struct bio *bio);
+bool __blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio);
+bool blk_mq_sched_try_insert_merge(struct request_queue *q, struct request *rq);
+
+void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx);
+
+int blk_mq_sched_setup(struct request_queue *q);
+int blk_mq_sched_teardown(struct request_queue *q);
+
+static inline bool
+blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio)
+{
+ struct elevator_queue *e = q->elevator;
+
+ if (!e || blk_queue_nomerges(q) || !bio_mergeable(bio))
+ return false;
+
+ return __blk_mq_sched_bio_merge(q, bio);
+}
+
+static inline int blk_mq_sched_get_rq_priv(struct request_queue *q,
+ struct request *rq)
+{
+ struct elevator_queue *e = q->elevator;
+
+ if (e && e->type->ops.mq.get_rq_priv)
+ return e->type->ops.mq.get_rq_priv(q, rq);
+
+ return 0;
+}
+
+static inline void blk_mq_sched_put_rq_priv(struct request_queue *q,
+ struct request *rq)
+{
+ struct elevator_queue *e = q->elevator;
+
+ if (e && e->type->ops.mq.put_rq_priv)
+ e->type->ops.mq.put_rq_priv(q, rq);
+}
+
+static inline void
+blk_mq_sched_insert_request(struct request *rq, bool at_head, bool run_queue,
+ bool async)
+{
+ struct request_queue *q = rq->q;
+ struct elevator_queue *e = q->elevator;
+ struct blk_mq_ctx *ctx = rq->mq_ctx;
+ struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
+
+ if (e && e->type->ops.mq.insert_requests) {
+ LIST_HEAD(list);
+
+ list_add(&rq->queuelist, &list);
+ e->type->ops.mq.insert_requests(hctx, &list, at_head);
+ } else {
+ spin_lock(&ctx->lock);
+ __blk_mq_insert_request(hctx, rq, at_head);
+ spin_unlock(&ctx->lock);
+ }
+
+ if (run_queue)
+ blk_mq_run_hw_queue(hctx, async);
+}
+
+static inline void
+blk_mq_sched_insert_requests(struct request_queue *q, struct blk_mq_ctx *ctx,
+ struct list_head *list, bool run_queue_async)
+{
+ struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
+ struct elevator_queue *e = hctx->queue->elevator;
+
+ if (e && e->type->ops.mq.insert_requests)
+ e->type->ops.mq.insert_requests(hctx, list, false);
+ else
+ blk_mq_insert_requests(hctx, ctx, list);
+
+ blk_mq_run_hw_queue(hctx, run_queue_async);
+}
+
+static inline bool
+blk_mq_sched_allow_merge(struct request_queue *q, struct request *rq,
+ struct bio *bio)
+{
+ struct elevator_queue *e = q->elevator;
+
+ if (e && e->type->ops.mq.allow_merge)
+ return e->type->ops.mq.allow_merge(q, rq, bio);
+
+ return true;
+}
+
+static inline void
+blk_mq_sched_completed_request(struct blk_mq_hw_ctx *hctx, struct request *rq)
+{
+ struct elevator_queue *e = hctx->queue->elevator;
+
+ if (e && e->type->ops.mq.completed_request)
+ e->type->ops.mq.completed_request(hctx, rq);
+
+ BUG_ON(rq->internal_tag == -1);
+
+ blk_mq_put_tag(hctx, hctx->sched_tags, rq->mq_ctx, rq->internal_tag);
+
+ if (test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state)) {
+ clear_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state);
+ blk_mq_run_hw_queue(hctx, true);
+ }
+}
+
+static inline void blk_mq_sched_started_request(struct request *rq)
+{
+ struct request_queue *q = rq->q;
+ struct elevator_queue *e = q->elevator;
+
+ if (e && e->type->ops.mq.started_request)
+ e->type->ops.mq.started_request(rq);
+}
+
+static inline void blk_mq_sched_requeue_request(struct request *rq)
+{
+ struct request_queue *q = rq->q;
+ struct elevator_queue *e = q->elevator;
+
+ if (e && e->type->ops.mq.requeue_request)
+ e->type->ops.mq.requeue_request(rq);
+}
+
+static inline bool blk_mq_sched_has_work(struct blk_mq_hw_ctx *hctx)
+{
+ struct elevator_queue *e = hctx->queue->elevator;
+
+ if (e && e->type->ops.mq.has_work)
+ return e->type->ops.mq.has_work(hctx);
+
+ return false;
+}
+#endif
diff --git a/block/blk-mq-sysfs.c b/block/blk-mq-sysfs.c
index eacd3af72099..2caecaa98e40 100644
--- a/block/blk-mq-sysfs.c
+++ b/block/blk-mq-sysfs.c
@@ -231,6 +231,14 @@ static ssize_t blk_mq_hw_sysfs_rq_list_show(struct blk_mq_hw_ctx *hctx,
return ret;
}

+static ssize_t blk_mq_hw_sysfs_sched_tags_show(struct blk_mq_hw_ctx *hctx, char *page)
+{
+ if (hctx->sched_tags)
+ return blk_mq_tag_sysfs_show(hctx->sched_tags, page);
+
+ return 0;
+}
+
static ssize_t blk_mq_hw_sysfs_tags_show(struct blk_mq_hw_ctx *hctx, char *page)
{
return blk_mq_tag_sysfs_show(hctx->tags, page);
@@ -345,6 +353,10 @@ static struct blk_mq_hw_ctx_sysfs_entry blk_mq_hw_sysfs_pending = {
.attr = {.name = "pending", .mode = S_IRUGO },
.show = blk_mq_hw_sysfs_rq_list_show,
};
+static struct blk_mq_hw_ctx_sysfs_entry blk_mq_hw_sysfs_sched_tags = {
+ .attr = {.name = "sched_tags", .mode = S_IRUGO },
+ .show = blk_mq_hw_sysfs_sched_tags_show,
+};
static struct blk_mq_hw_ctx_sysfs_entry blk_mq_hw_sysfs_tags = {
.attr = {.name = "tags", .mode = S_IRUGO },
.show = blk_mq_hw_sysfs_tags_show,
@@ -370,6 +382,7 @@ static struct attribute *default_hw_ctx_attrs[] = {
&blk_mq_hw_sysfs_dispatched.attr,
&blk_mq_hw_sysfs_pending.attr,
&blk_mq_hw_sysfs_tags.attr,
+ &blk_mq_hw_sysfs_sched_tags.attr,
&blk_mq_hw_sysfs_cpus.attr,
&blk_mq_hw_sysfs_active.attr,
&blk_mq_hw_sysfs_poll.attr,
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 3b7a087e8bf0..3180b5fac88c 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -32,6 +32,7 @@
#include "blk-mq-tag.h"
#include "blk-stat.h"
#include "blk-wbt.h"
+#include "blk-mq-sched.h"

static DEFINE_MUTEX(all_q_mutex);
static LIST_HEAD(all_q_list);
@@ -41,7 +42,8 @@ static LIST_HEAD(all_q_list);
*/
static bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx *hctx)
{
- return sbitmap_any_bit_set(&hctx->ctx_map);
+ return sbitmap_any_bit_set(&hctx->ctx_map) ||
+ blk_mq_sched_has_work(hctx);
}

/*
@@ -223,14 +225,17 @@ struct request *__blk_mq_alloc_request(struct blk_mq_alloc_data *data,

tag = blk_mq_get_tag(data);
if (tag != BLK_MQ_TAG_FAIL) {
- rq = data->hctx->tags->rqs[tag];
+ struct blk_mq_tags *tags = blk_mq_tags_from_data(data);
+
+ rq = tags->rqs[tag];

if (blk_mq_tag_busy(data->hctx)) {
rq->rq_flags = RQF_MQ_INFLIGHT;
atomic_inc(&data->hctx->nr_active);
}

- rq->tag = tag;
+ rq->tag = -1;
+ rq->internal_tag = tag;
blk_mq_rq_ctx_init(data->q, data->ctx, rq, op);
return rq;
}
@@ -242,26 +247,21 @@ EXPORT_SYMBOL_GPL(__blk_mq_alloc_request);
struct request *blk_mq_alloc_request(struct request_queue *q, int rw,
unsigned int flags)
{
- struct blk_mq_ctx *ctx;
- struct blk_mq_hw_ctx *hctx;
- struct request *rq;
struct blk_mq_alloc_data alloc_data;
+ struct request *rq;
int ret;

ret = blk_queue_enter(q, flags & BLK_MQ_REQ_NOWAIT);
if (ret)
return ERR_PTR(ret);

- ctx = blk_mq_get_ctx(q);
- hctx = blk_mq_map_queue(q, ctx->cpu);
- blk_mq_set_alloc_data(&alloc_data, q, flags, ctx, hctx);
- rq = __blk_mq_alloc_request(&alloc_data, rw);
- blk_mq_put_ctx(ctx);
+ rq = blk_mq_sched_get_request(q, NULL, rw, &alloc_data);

- if (!rq) {
- blk_queue_exit(q);
+ blk_mq_put_ctx(alloc_data.ctx);
+ blk_queue_exit(q);
+
+ if (!rq)
return ERR_PTR(-EWOULDBLOCK);
- }

rq->__data_len = 0;
rq->__sector = (sector_t) -1;
@@ -313,6 +313,9 @@ struct request *blk_mq_alloc_request_hctx(struct request_queue *q, int rw,
goto out_queue_exit;
}

+ rq->tag = rq->internal_tag;
+ rq->internal_tag = -1;
+
return rq;

out_queue_exit:
@@ -321,10 +324,10 @@ struct request *blk_mq_alloc_request_hctx(struct request_queue *q, int rw,
}
EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx);

-void __blk_mq_free_request(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
- struct request *rq)
+void __blk_mq_finish_request(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
+ struct request *rq)
{
- const int tag = rq->tag;
+ const int sched_tag = rq->internal_tag;
struct request_queue *q = rq->q;

if (rq->rq_flags & RQF_MQ_INFLIGHT)
@@ -335,22 +338,32 @@ void __blk_mq_free_request(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,

clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
clear_bit(REQ_ATOM_POLL_SLEPT, &rq->atomic_flags);
- blk_mq_put_tag(hctx, hctx->tags, ctx, tag);
+ if (rq->tag != -1) {
+ WARN_ON_ONCE(hctx->tags->rqs[rq->tag] != rq);
+ blk_mq_put_tag(hctx, hctx->tags, ctx, rq->tag);
+ }
+ if (sched_tag != -1)
+ blk_mq_sched_completed_request(hctx, rq);
blk_queue_exit(q);
}

-static void blk_mq_free_hctx_request(struct blk_mq_hw_ctx *hctx,
+static void blk_mq_finish_hctx_request(struct blk_mq_hw_ctx *hctx,
struct request *rq)
{
struct blk_mq_ctx *ctx = rq->mq_ctx;

ctx->rq_completed[rq_is_sync(rq)]++;
- __blk_mq_free_request(hctx, ctx, rq);
+ __blk_mq_finish_request(hctx, ctx, rq);
+}
+
+void blk_mq_finish_request(struct request *rq)
+{
+ blk_mq_finish_hctx_request(blk_mq_map_queue(rq->q, rq->mq_ctx->cpu), rq);
}

void blk_mq_free_request(struct request *rq)
{
- blk_mq_free_hctx_request(blk_mq_map_queue(rq->q, rq->mq_ctx->cpu), rq);
+ blk_mq_sched_put_request(rq);
}
EXPORT_SYMBOL_GPL(blk_mq_free_request);

@@ -468,6 +481,8 @@ void blk_mq_start_request(struct request *rq)
{
struct request_queue *q = rq->q;

+ blk_mq_sched_started_request(rq);
+
trace_block_rq_issue(q, rq);

rq->resid_len = blk_rq_bytes(rq);
@@ -516,6 +531,7 @@ static void __blk_mq_requeue_request(struct request *rq)

trace_block_rq_requeue(q, rq);
wbt_requeue(q->rq_wb, &rq->issue_stat);
+ blk_mq_sched_requeue_request(rq);

if (test_and_clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags)) {
if (q->dma_drain_size && blk_rq_bytes(rq))
@@ -550,13 +566,13 @@ static void blk_mq_requeue_work(struct work_struct *work)

rq->rq_flags &= ~RQF_SOFTBARRIER;
list_del_init(&rq->queuelist);
- blk_mq_insert_request(rq, true, false, false);
+ blk_mq_sched_insert_request(rq, true, false, false);
}

while (!list_empty(&rq_list)) {
rq = list_entry(rq_list.next, struct request, queuelist);
list_del_init(&rq->queuelist);
- blk_mq_insert_request(rq, false, false, false);
+ blk_mq_sched_insert_request(rq, false, false, false);
}

blk_mq_run_hw_queues(q, false);
@@ -762,8 +778,16 @@ static bool blk_mq_attempt_merge(struct request_queue *q,

if (!blk_rq_merge_ok(rq, bio))
continue;
+ if (!blk_mq_sched_allow_merge(q, rq, bio))
+ break;

el_ret = blk_try_merge(rq, bio);
+ if (el_ret == ELEVATOR_NO_MERGE)
+ continue;
+
+ if (!blk_mq_sched_allow_merge(q, rq, bio))
+ break;
+
if (el_ret == ELEVATOR_BACK_MERGE) {
if (bio_attempt_back_merge(q, rq, bio)) {
ctx->rq_merged++;
@@ -823,6 +847,35 @@ static inline unsigned int queued_to_index(unsigned int queued)
return min(BLK_MQ_MAX_DISPATCH_ORDER - 1, ilog2(queued) + 1);
}

+static bool blk_mq_get_driver_tag(struct request *rq,
+ struct blk_mq_hw_ctx **hctx, bool wait)
+{
+ struct blk_mq_alloc_data data = {
+ .q = rq->q,
+ .ctx = rq->mq_ctx,
+ .hctx = blk_mq_map_queue(rq->q, rq->mq_ctx->cpu),
+ .flags = wait ? 0 : BLK_MQ_REQ_NOWAIT,
+ };
+
+ if (blk_mq_hctx_stopped(data.hctx))
+ return false;
+
+ if (rq->tag != -1) {
+done:
+ if (hctx)
+ *hctx = data.hctx;
+ return true;
+ }
+
+ rq->tag = blk_mq_get_tag(&data);
+ if (rq->tag >= 0) {
+ data.hctx->tags->rqs[rq->tag] = rq;
+ goto done;
+ }
+
+ return false;
+}
+
bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list)
{
struct request_queue *q = hctx->queue;
@@ -845,6 +898,8 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list)
struct blk_mq_queue_data bd;

rq = list_first_entry(list, struct request, queuelist);
+ if (!blk_mq_get_driver_tag(rq, &hctx, false))
+ break;
list_del_init(&rq->queuelist);

bd.rq = rq;
@@ -905,41 +960,6 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list)
return ret != BLK_MQ_RQ_QUEUE_BUSY;
}

-/*
- * Run this hardware queue, pulling any software queues mapped to it in.
- * Note that this function currently has various problems around ordering
- * of IO. In particular, we'd like FIFO behaviour on handling existing
- * items on the hctx->dispatch list. Ignore that for now.
- */
-static void blk_mq_process_rq_list(struct blk_mq_hw_ctx *hctx)
-{
- LIST_HEAD(rq_list);
- LIST_HEAD(driver_list);
-
- if (unlikely(blk_mq_hctx_stopped(hctx)))
- return;
-
- hctx->run++;
-
- /*
- * Touch any software queue that has pending entries.
- */
- blk_mq_flush_busy_ctxs(hctx, &rq_list);
-
- /*
- * If we have previous entries on our dispatch list, grab them
- * and stuff them at the front for more fair dispatch.
- */
- if (!list_empty_careful(&hctx->dispatch)) {
- spin_lock(&hctx->lock);
- if (!list_empty(&hctx->dispatch))
- list_splice_init(&hctx->dispatch, &rq_list);
- spin_unlock(&hctx->lock);
- }
-
- blk_mq_dispatch_rq_list(hctx, &rq_list);
-}
-
static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
{
int srcu_idx;
@@ -949,11 +969,11 @@ static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)

if (!(hctx->flags & BLK_MQ_F_BLOCKING)) {
rcu_read_lock();
- blk_mq_process_rq_list(hctx);
+ blk_mq_sched_dispatch_requests(hctx);
rcu_read_unlock();
} else {
srcu_idx = srcu_read_lock(&hctx->queue_rq_srcu);
- blk_mq_process_rq_list(hctx);
+ blk_mq_sched_dispatch_requests(hctx);
srcu_read_unlock(&hctx->queue_rq_srcu, srcu_idx);
}
}
@@ -1147,32 +1167,10 @@ void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
blk_mq_hctx_mark_pending(hctx, ctx);
}

-void blk_mq_insert_request(struct request *rq, bool at_head, bool run_queue,
- bool async)
-{
- struct blk_mq_ctx *ctx = rq->mq_ctx;
- struct request_queue *q = rq->q;
- struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
-
- spin_lock(&ctx->lock);
- __blk_mq_insert_request(hctx, rq, at_head);
- spin_unlock(&ctx->lock);
-
- if (run_queue)
- blk_mq_run_hw_queue(hctx, async);
-}
-
-static void blk_mq_insert_requests(struct request_queue *q,
- struct blk_mq_ctx *ctx,
- struct list_head *list,
- int depth,
- bool from_schedule)
+void blk_mq_insert_requests(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
+ struct list_head *list)

{
- struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
-
- trace_block_unplug(q, depth, !from_schedule);
-
/*
* preemption doesn't flush plug list, so it's possible ctx->cpu is
* offline now
@@ -1188,8 +1186,6 @@ static void blk_mq_insert_requests(struct request_queue *q,
}
blk_mq_hctx_mark_pending(hctx, ctx);
spin_unlock(&ctx->lock);
-
- blk_mq_run_hw_queue(hctx, from_schedule);
}

static int plug_ctx_cmp(void *priv, struct list_head *a, struct list_head *b)
@@ -1225,9 +1221,10 @@ void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
BUG_ON(!rq->q);
if (rq->mq_ctx != this_ctx) {
if (this_ctx) {
- blk_mq_insert_requests(this_q, this_ctx,
- &ctx_list, depth,
- from_schedule);
+ trace_block_unplug(this_q, depth, from_schedule);
+ blk_mq_sched_insert_requests(this_q, this_ctx,
+ &ctx_list,
+ from_schedule);
}

this_ctx = rq->mq_ctx;
@@ -1244,8 +1241,9 @@ void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
* on 'ctx_list'. Do those.
*/
if (this_ctx) {
- blk_mq_insert_requests(this_q, this_ctx, &ctx_list, depth,
- from_schedule);
+ trace_block_unplug(this_q, depth, from_schedule);
+ blk_mq_sched_insert_requests(this_q, this_ctx, &ctx_list,
+ from_schedule);
}
}

@@ -1283,46 +1281,31 @@ static inline bool blk_mq_merge_queue_io(struct blk_mq_hw_ctx *hctx,
}

spin_unlock(&ctx->lock);
- __blk_mq_free_request(hctx, ctx, rq);
+ __blk_mq_finish_request(hctx, ctx, rq);
return true;
}
}

-static struct request *blk_mq_map_request(struct request_queue *q,
- struct bio *bio,
- struct blk_mq_alloc_data *data)
-{
- struct blk_mq_hw_ctx *hctx;
- struct blk_mq_ctx *ctx;
- struct request *rq;
-
- blk_queue_enter_live(q);
- ctx = blk_mq_get_ctx(q);
- hctx = blk_mq_map_queue(q, ctx->cpu);
-
- trace_block_getrq(q, bio, bio->bi_opf);
- blk_mq_set_alloc_data(data, q, 0, ctx, hctx);
- rq = __blk_mq_alloc_request(data, bio->bi_opf);
-
- data->hctx->queued++;
- return rq;
-}
-
static void blk_mq_try_issue_directly(struct request *rq, blk_qc_t *cookie)
{
- int ret;
struct request_queue *q = rq->q;
- struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, rq->mq_ctx->cpu);
struct blk_mq_queue_data bd = {
.rq = rq,
.list = NULL,
.last = 1
};
- blk_qc_t new_cookie = blk_tag_to_qc_t(rq->tag, hctx->queue_num);
+ struct blk_mq_hw_ctx *hctx;
+ blk_qc_t new_cookie;
+ int ret;

- if (blk_mq_hctx_stopped(hctx))
+ if (q->elevator)
goto insert;

+ if (!blk_mq_get_driver_tag(rq, &hctx, false))
+ goto insert;
+
+ new_cookie = blk_tag_to_qc_t(rq->tag, hctx->queue_num);
+
/*
* For OK queue, we are done. For error, kill it. Any other
* error (busy), just add it to our list as we previously
@@ -1344,7 +1327,7 @@ static void blk_mq_try_issue_directly(struct request *rq, blk_qc_t *cookie)
}

insert:
- blk_mq_insert_request(rq, false, true, true);
+ blk_mq_sched_insert_request(rq, false, true, true);
}

/*
@@ -1377,9 +1360,14 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
blk_attempt_plug_merge(q, bio, &request_count, &same_queue_rq))
return BLK_QC_T_NONE;

+ if (blk_mq_sched_bio_merge(q, bio))
+ return BLK_QC_T_NONE;
+
wb_acct = wbt_wait(q->rq_wb, bio, NULL);

- rq = blk_mq_map_request(q, bio, &data);
+ trace_block_getrq(q, bio, bio->bi_opf);
+
+ rq = blk_mq_sched_get_request(q, bio, bio->bi_opf, &data);
if (unlikely(!rq)) {
__wbt_done(q->rq_wb, wb_acct);
return BLK_QC_T_NONE;
@@ -1391,6 +1379,7 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)

if (unlikely(is_flush_fua)) {
blk_mq_bio_to_request(rq, bio);
+ blk_mq_get_driver_tag(rq, NULL, true);
blk_insert_flush(rq);
goto run_queue;
}
@@ -1441,6 +1430,12 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
goto done;
}

+ if (q->elevator) {
+ blk_mq_put_ctx(data.ctx);
+ blk_mq_bio_to_request(rq, bio);
+ blk_mq_sched_insert_request(rq, false, true, true);
+ goto done;
+ }
if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
/*
* For a SYNC request, send it to the hardware immediately. For
@@ -1486,9 +1481,14 @@ static blk_qc_t blk_sq_make_request(struct request_queue *q, struct bio *bio)
} else
request_count = blk_plug_queued_count(q);

+ if (blk_mq_sched_bio_merge(q, bio))
+ return BLK_QC_T_NONE;
+
wb_acct = wbt_wait(q->rq_wb, bio, NULL);

- rq = blk_mq_map_request(q, bio, &data);
+ trace_block_getrq(q, bio, bio->bi_opf);
+
+ rq = blk_mq_sched_get_request(q, bio, bio->bi_opf, &data);
if (unlikely(!rq)) {
__wbt_done(q->rq_wb, wb_acct);
return BLK_QC_T_NONE;
@@ -1500,6 +1500,7 @@ static blk_qc_t blk_sq_make_request(struct request_queue *q, struct bio *bio)

if (unlikely(is_flush_fua)) {
blk_mq_bio_to_request(rq, bio);
+ blk_mq_get_driver_tag(rq, NULL, true);
blk_insert_flush(rq);
goto run_queue;
}
@@ -1538,6 +1539,12 @@ static blk_qc_t blk_sq_make_request(struct request_queue *q, struct bio *bio)
return cookie;
}

+ if (q->elevator) {
+ blk_mq_put_ctx(data.ctx);
+ blk_mq_bio_to_request(rq, bio);
+ blk_mq_sched_insert_request(rq, false, true, true);
+ goto done;
+ }
if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
/*
* For a SYNC request, send it to the hardware immediately. For
@@ -1550,6 +1557,7 @@ static blk_qc_t blk_sq_make_request(struct request_queue *q, struct bio *bio)
}

blk_mq_put_ctx(data.ctx);
+done:
return cookie;
}

@@ -2483,14 +2491,22 @@ int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
struct blk_mq_hw_ctx *hctx;
int i, ret;

- if (!set || nr > set->queue_depth)
+ if (!set)
return -EINVAL;

ret = 0;
queue_for_each_hw_ctx(q, hctx, i) {
if (!hctx->tags)
continue;
- ret = blk_mq_tag_update_depth(hctx->tags, nr);
+ /*
+ * If we're using an MQ scheduler, just update the scheduler
+ * queue depth. This is similar to what the old code would do.
+ */
+ if (!hctx->sched_tags)
+ ret = blk_mq_tag_update_depth(hctx->tags,
+ min(nr, set->queue_depth));
+ else
+ ret = blk_mq_tag_update_depth(hctx->sched_tags, nr);
if (ret)
break;
}
diff --git a/block/blk-mq.h b/block/blk-mq.h
index 1b279b02d0f6..0c7c034d9ddd 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -52,6 +52,8 @@ int blk_mq_alloc_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
*/
void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
bool at_head);
+void blk_mq_insert_requests(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
+ struct list_head *list);
/*
* CPU hotplug helpers
*/
@@ -124,6 +126,9 @@ static inline void blk_mq_set_alloc_data(struct blk_mq_alloc_data *data,

static inline struct blk_mq_tags *blk_mq_tags_from_data(struct blk_mq_alloc_data *data)
{
+ if (data->flags & BLK_MQ_REQ_INTERNAL)
+ return data->hctx->sched_tags;
+
return data->hctx->tags;
}

@@ -132,8 +137,9 @@ static inline struct blk_mq_tags *blk_mq_tags_from_data(struct blk_mq_alloc_data
*/
void blk_mq_rq_ctx_init(struct request_queue *q, struct blk_mq_ctx *ctx,
struct request *rq, unsigned int op);
-void __blk_mq_free_request(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
+void __blk_mq_finish_request(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
struct request *rq);
+void blk_mq_finish_request(struct request *rq);
struct request *__blk_mq_alloc_request(struct blk_mq_alloc_data *data,
unsigned int op);

diff --git a/block/blk-tag.c b/block/blk-tag.c
index bae1decb6ec3..07cc329fa4b0 100644
--- a/block/blk-tag.c
+++ b/block/blk-tag.c
@@ -272,6 +272,7 @@ void blk_queue_end_tag(struct request_queue *q, struct request *rq)
list_del_init(&rq->queuelist);
rq->rq_flags &= ~RQF_QUEUED;
rq->tag = -1;
+ rq->internal_tag = -1;

if (unlikely(bqt->tag_index[tag] == NULL))
printk(KERN_ERR "%s: tag %d is missing\n",
diff --git a/block/elevator.c b/block/elevator.c
index 022a26830297..79e74da26343 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -40,6 +40,7 @@
#include <trace/events/block.h>

#include "blk.h"
+#include "blk-mq-sched.h"

static DEFINE_SPINLOCK(elv_list_lock);
static LIST_HEAD(elv_list);
@@ -58,7 +59,9 @@ static int elv_iosched_allow_bio_merge(struct request *rq, struct bio *bio)
struct request_queue *q = rq->q;
struct elevator_queue *e = q->elevator;

- if (e->type->ops.sq.elevator_allow_bio_merge_fn)
+ if (e->uses_mq && e->type->ops.mq.allow_merge)
+ return e->type->ops.mq.allow_merge(q, rq, bio);
+ else if (!e->uses_mq && e->type->ops.sq.elevator_allow_bio_merge_fn)
return e->type->ops.sq.elevator_allow_bio_merge_fn(q, rq, bio);

return 1;
@@ -163,6 +166,7 @@ struct elevator_queue *elevator_alloc(struct request_queue *q,
kobject_init(&eq->kobj, &elv_ktype);
mutex_init(&eq->sysfs_lock);
hash_init(eq->hash);
+ eq->uses_mq = e->uses_mq;

return eq;
}
@@ -219,14 +223,26 @@ int elevator_init(struct request_queue *q, char *name)
if (!e) {
printk(KERN_ERR
"Default I/O scheduler not found. " \
- "Using noop.\n");
+ "Using noop/none.\n");
+ if (q->mq_ops) {
+ elevator_put(e);
+ return 0;
+ }
e = elevator_get("noop", false);
}
}

- err = e->ops.sq.elevator_init_fn(q, e);
- if (err)
+ if (e->uses_mq) {
+ err = blk_mq_sched_setup(q);
+ if (!err)
+ err = e->ops.mq.init_sched(q, e);
+ } else
+ err = e->ops.sq.elevator_init_fn(q, e);
+ if (err) {
+ if (e->uses_mq)
+ blk_mq_sched_teardown(q);
elevator_put(e);
+ }
return err;
}
EXPORT_SYMBOL(elevator_init);
@@ -234,7 +250,9 @@ EXPORT_SYMBOL(elevator_init);
void elevator_exit(struct elevator_queue *e)
{
mutex_lock(&e->sysfs_lock);
- if (e->type->ops.sq.elevator_exit_fn)
+ if (e->uses_mq && e->type->ops.mq.exit_sched)
+ e->type->ops.mq.exit_sched(e);
+ else if (!e->uses_mq && e->type->ops.sq.elevator_exit_fn)
e->type->ops.sq.elevator_exit_fn(e);
mutex_unlock(&e->sysfs_lock);

@@ -253,6 +271,7 @@ void elv_rqhash_del(struct request_queue *q, struct request *rq)
if (ELV_ON_HASH(rq))
__elv_rqhash_del(rq);
}
+EXPORT_SYMBOL_GPL(elv_rqhash_del);

void elv_rqhash_add(struct request_queue *q, struct request *rq)
{
@@ -262,6 +281,7 @@ void elv_rqhash_add(struct request_queue *q, struct request *rq)
hash_add(e->hash, &rq->hash, rq_hash_key(rq));
rq->rq_flags |= RQF_HASHED;
}
+EXPORT_SYMBOL_GPL(elv_rqhash_add);

void elv_rqhash_reposition(struct request_queue *q, struct request *rq)
{
@@ -443,7 +463,9 @@ int elv_merge(struct request_queue *q, struct request **req, struct bio *bio)
return ELEVATOR_BACK_MERGE;
}

- if (e->type->ops.sq.elevator_merge_fn)
+ if (e->uses_mq && e->type->ops.mq.request_merge)
+ return e->type->ops.mq.request_merge(q, req, bio);
+ else if (!e->uses_mq && e->type->ops.sq.elevator_merge_fn)
return e->type->ops.sq.elevator_merge_fn(q, req, bio);

return ELEVATOR_NO_MERGE;
@@ -456,8 +478,7 @@ int elv_merge(struct request_queue *q, struct request **req, struct bio *bio)
*
* Returns true if we merged, false otherwise
*/
-static bool elv_attempt_insert_merge(struct request_queue *q,
- struct request *rq)
+bool elv_attempt_insert_merge(struct request_queue *q, struct request *rq)
{
struct request *__rq;
bool ret;
@@ -495,7 +516,9 @@ void elv_merged_request(struct request_queue *q, struct request *rq, int type)
{
struct elevator_queue *e = q->elevator;

- if (e->type->ops.sq.elevator_merged_fn)
+ if (e->uses_mq && e->type->ops.mq.request_merged)
+ e->type->ops.mq.request_merged(q, rq, type);
+ else if (!e->uses_mq && e->type->ops.sq.elevator_merged_fn)
e->type->ops.sq.elevator_merged_fn(q, rq, type);

if (type == ELEVATOR_BACK_MERGE)
@@ -508,10 +531,15 @@ void elv_merge_requests(struct request_queue *q, struct request *rq,
struct request *next)
{
struct elevator_queue *e = q->elevator;
- const int next_sorted = next->rq_flags & RQF_SORTED;
-
- if (next_sorted && e->type->ops.sq.elevator_merge_req_fn)
- e->type->ops.sq.elevator_merge_req_fn(q, rq, next);
+ bool next_sorted = false;
+
+ if (e->uses_mq && e->type->ops.mq.requests_merged)
+ e->type->ops.mq.requests_merged(q, rq, next);
+ else if (e->type->ops.sq.elevator_merge_req_fn) {
+ next_sorted = next->rq_flags & RQF_SORTED;
+ if (next_sorted)
+ e->type->ops.sq.elevator_merge_req_fn(q, rq, next);
+ }

elv_rqhash_reposition(q, rq);

@@ -528,6 +556,9 @@ void elv_bio_merged(struct request_queue *q, struct request *rq,
{
struct elevator_queue *e = q->elevator;

+ if (WARN_ON_ONCE(e->uses_mq))
+ return;
+
if (e->type->ops.sq.elevator_bio_merged_fn)
e->type->ops.sq.elevator_bio_merged_fn(q, rq, bio);
}
@@ -682,8 +713,11 @@ struct request *elv_latter_request(struct request_queue *q, struct request *rq)
{
struct elevator_queue *e = q->elevator;

- if (e->type->ops.sq.elevator_latter_req_fn)
+ if (e->uses_mq && e->type->ops.mq.next_request)
+ return e->type->ops.mq.next_request(q, rq);
+ else if (!e->uses_mq && e->type->ops.sq.elevator_latter_req_fn)
return e->type->ops.sq.elevator_latter_req_fn(q, rq);
+
return NULL;
}

@@ -691,7 +725,9 @@ struct request *elv_former_request(struct request_queue *q, struct request *rq)
{
struct elevator_queue *e = q->elevator;

- if (e->type->ops.sq.elevator_former_req_fn)
+ if (e->uses_mq && e->type->ops.mq.former_request)
+ return e->type->ops.mq.former_request(q, rq);
+ if (!e->uses_mq && e->type->ops.sq.elevator_former_req_fn)
return e->type->ops.sq.elevator_former_req_fn(q, rq);
return NULL;
}
@@ -701,6 +737,9 @@ int elv_set_request(struct request_queue *q, struct request *rq,
{
struct elevator_queue *e = q->elevator;

+ if (WARN_ON_ONCE(e->uses_mq))
+ return 0;
+
if (e->type->ops.sq.elevator_set_req_fn)
return e->type->ops.sq.elevator_set_req_fn(q, rq, bio, gfp_mask);
return 0;
@@ -710,6 +749,9 @@ void elv_put_request(struct request_queue *q, struct request *rq)
{
struct elevator_queue *e = q->elevator;

+ if (WARN_ON_ONCE(e->uses_mq))
+ return;
+
if (e->type->ops.sq.elevator_put_req_fn)
e->type->ops.sq.elevator_put_req_fn(rq);
}
@@ -718,6 +760,9 @@ int elv_may_queue(struct request_queue *q, unsigned int op)
{
struct elevator_queue *e = q->elevator;

+ if (WARN_ON_ONCE(e->uses_mq))
+ return 0;
+
if (e->type->ops.sq.elevator_may_queue_fn)
return e->type->ops.sq.elevator_may_queue_fn(q, op);

@@ -728,6 +773,9 @@ void elv_completed_request(struct request_queue *q, struct request *rq)
{
struct elevator_queue *e = q->elevator;

+ if (WARN_ON_ONCE(e->uses_mq))
+ return;
+
/*
* request is released from the driver, io must be done
*/
@@ -803,7 +851,7 @@ int elv_register_queue(struct request_queue *q)
}
kobject_uevent(&e->kobj, KOBJ_ADD);
e->registered = 1;
- if (e->type->ops.sq.elevator_registered_fn)
+ if (!e->uses_mq && e->type->ops.sq.elevator_registered_fn)
e->type->ops.sq.elevator_registered_fn(q);
}
return error;
@@ -891,9 +939,14 @@ EXPORT_SYMBOL_GPL(elv_unregister);
static int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
{
struct elevator_queue *old = q->elevator;
- bool registered = old->registered;
+ bool old_registered = false;
int err;

+ if (q->mq_ops) {
+ blk_mq_freeze_queue(q);
+ blk_mq_quiesce_queue(q);
+ }
+
/*
* Turn on BYPASS and drain all requests w/ elevator private data.
* Block layer doesn't call into a quiesced elevator - all requests
@@ -901,42 +954,79 @@ static int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
* using INSERT_BACK. All requests have SOFTBARRIER set and no
* merge happens either.
*/
- blk_queue_bypass_start(q);
+ if (old) {
+ old_registered = old->registered;

- /* unregister and clear all auxiliary data of the old elevator */
- if (registered)
- elv_unregister_queue(q);
+ if (old->uses_mq) {
+ err = blk_mq_sched_teardown(q);
+ if (err)
+ goto fail_init;
+ }

- spin_lock_irq(q->queue_lock);
- ioc_clear_queue(q);
- spin_unlock_irq(q->queue_lock);
+ if (!q->mq_ops)
+ blk_queue_bypass_start(q);
+
+ /* unregister and clear all auxiliary data of the old elevator */
+ if (old_registered)
+ elv_unregister_queue(q);
+
+ spin_lock_irq(q->queue_lock);
+ ioc_clear_queue(q);
+ spin_unlock_irq(q->queue_lock);
+ }

/* allocate, init and register new elevator */
- err = new_e->ops.sq.elevator_init_fn(q, new_e);
- if (err)
- goto fail_init;
+ if (new_e) {
+ if (new_e->uses_mq) {
+ err = blk_mq_sched_setup(q);
+ if (!err)
+ err = new_e->ops.mq.init_sched(q, new_e);
+ } else
+ err = new_e->ops.sq.elevator_init_fn(q, new_e);
+ if (err)
+ goto fail_init;

- if (registered) {
err = elv_register_queue(q);
if (err)
goto fail_register;
- }
+ } else
+ q->elevator = NULL;

/* done, kill the old one and finish */
- elevator_exit(old);
- blk_queue_bypass_end(q);
+ if (old) {
+ elevator_exit(old);
+ if (!q->mq_ops)
+ blk_queue_bypass_end(q);
+ }
+
+ if (q->mq_ops) {
+ blk_mq_unfreeze_queue(q);
+ blk_mq_start_stopped_hw_queues(q, true);
+ }

- blk_add_trace_msg(q, "elv switch: %s", new_e->elevator_name);
+ if (new_e)
+ blk_add_trace_msg(q, "elv switch: %s", new_e->elevator_name);
+ else
+ blk_add_trace_msg(q, "elv switch: none");

return 0;

fail_register:
+ if (q->mq_ops)
+ blk_mq_sched_teardown(q);
elevator_exit(q->elevator);
fail_init:
/* switch failed, restore and re-register old elevator */
- q->elevator = old;
- elv_register_queue(q);
- blk_queue_bypass_end(q);
+ if (old) {
+ q->elevator = old;
+ elv_register_queue(q);
+ if (!q->mq_ops)
+ blk_queue_bypass_end(q);
+ }
+ if (q->mq_ops) {
+ blk_mq_unfreeze_queue(q);
+ blk_mq_start_stopped_hw_queues(q, true);
+ }

return err;
}
@@ -949,8 +1039,11 @@ static int __elevator_change(struct request_queue *q, const char *name)
char elevator_name[ELV_NAME_MAX];
struct elevator_type *e;

- if (!q->elevator)
- return -ENXIO;
+ /*
+ * Special case for mq, turn off scheduling
+ */
+ if (q->mq_ops && !strncmp(name, "none", 4))
+ return elevator_switch(q, NULL);

strlcpy(elevator_name, name, sizeof(elevator_name));
e = elevator_get(strstrip(elevator_name), true);
@@ -959,11 +1052,21 @@ static int __elevator_change(struct request_queue *q, const char *name)
return -EINVAL;
}

- if (!strcmp(elevator_name, q->elevator->type->elevator_name)) {
+ if (q->elevator &&
+ !strcmp(elevator_name, q->elevator->type->elevator_name)) {
elevator_put(e);
return 0;
}

+ if (!e->uses_mq && q->mq_ops) {
+ elevator_put(e);
+ return -EINVAL;
+ }
+ if (e->uses_mq && !q->mq_ops) {
+ elevator_put(e);
+ return -EINVAL;
+ }
+
return elevator_switch(q, e);
}

@@ -985,7 +1088,7 @@ ssize_t elv_iosched_store(struct request_queue *q, const char *name,
{
int ret;

- if (!q->elevator)
+ if (!(q->mq_ops || q->request_fn))
return count;

ret = __elevator_change(q, name);
@@ -999,24 +1102,34 @@ ssize_t elv_iosched_store(struct request_queue *q, const char *name,
ssize_t elv_iosched_show(struct request_queue *q, char *name)
{
struct elevator_queue *e = q->elevator;
- struct elevator_type *elv;
+ struct elevator_type *elv = NULL;
struct elevator_type *__e;
int len = 0;

- if (!q->elevator || !blk_queue_stackable(q))
+ if (!blk_queue_stackable(q))
return sprintf(name, "none\n");

- elv = e->type;
+ if (!q->elevator)
+ len += sprintf(name+len, "[none] ");
+ else
+ elv = e->type;

spin_lock(&elv_list_lock);
list_for_each_entry(__e, &elv_list, list) {
- if (!strcmp(elv->elevator_name, __e->elevator_name))
+ if (elv && !strcmp(elv->elevator_name, __e->elevator_name)) {
len += sprintf(name+len, "[%s] ", elv->elevator_name);
- else
+ continue;
+ }
+ if (__e->uses_mq && q->mq_ops)
+ len += sprintf(name+len, "%s ", __e->elevator_name);
+ else if (!__e->uses_mq && !q->mq_ops)
len += sprintf(name+len, "%s ", __e->elevator_name);
}
spin_unlock(&elv_list_lock);

+ if (q->mq_ops && q->elevator)
+ len += sprintf(name+len, "none");
+
len += sprintf(len+name, "\n");
return len;
}
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 2686f9e7302a..63569eb46d15 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -22,6 +22,7 @@ struct blk_mq_hw_ctx {

unsigned long flags; /* BLK_MQ_F_* flags */

+ void *sched_data;
struct request_queue *queue;
struct blk_flush_queue *fq;

@@ -35,6 +36,7 @@ struct blk_mq_hw_ctx {
atomic_t wait_index;

struct blk_mq_tags *tags;
+ struct blk_mq_tags *sched_tags;

struct srcu_struct queue_rq_srcu;

@@ -156,6 +158,7 @@ enum {

BLK_MQ_S_STOPPED = 0,
BLK_MQ_S_TAG_ACTIVE = 1,
+ BLK_MQ_S_SCHED_RESTART = 2,

BLK_MQ_MAX_DEPTH = 10240,

@@ -179,13 +182,13 @@ void blk_mq_free_tag_set(struct blk_mq_tag_set *set);

void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule);

-void blk_mq_insert_request(struct request *, bool, bool, bool);
void blk_mq_free_request(struct request *rq);
bool blk_mq_can_queue(struct blk_mq_hw_ctx *);

enum {
BLK_MQ_REQ_NOWAIT = (1 << 0), /* return when out of requests */
BLK_MQ_REQ_RESERVED = (1 << 1), /* allocate from reserved pool */
+ BLK_MQ_REQ_INTERNAL = (1 << 2), /* allocate internal/sched tag */
};

struct request *blk_mq_alloc_request(struct request_queue *q, int rw,
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index e19fc8e01fb2..1d79837de994 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -154,6 +154,7 @@ struct request {

/* the following two fields are internal, NEVER access directly */
unsigned int __data_len; /* total data len */
+ int tag;
sector_t __sector; /* sector cursor */

struct bio *bio;
@@ -220,9 +221,10 @@ struct request {

unsigned short ioprio;

+ int internal_tag;
+
void *special; /* opaque pointer available for LLD use */

- int tag;
int errors;

/*
diff --git a/include/linux/elevator.h b/include/linux/elevator.h
index 2a9e966eed03..ecb96fd67c6d 100644
--- a/include/linux/elevator.h
+++ b/include/linux/elevator.h
@@ -77,6 +77,34 @@ struct elevator_ops
elevator_registered_fn *elevator_registered_fn;
};

+struct blk_mq_alloc_data;
+struct blk_mq_hw_ctx;
+
+struct elevator_mq_ops {
+ int (*init_sched)(struct request_queue *, struct elevator_type *);
+ void (*exit_sched)(struct elevator_queue *);
+
+ bool (*allow_merge)(struct request_queue *, struct request *, struct bio *);
+ bool (*bio_merge)(struct blk_mq_hw_ctx *, struct bio *);
+ int (*request_merge)(struct request_queue *q, struct request **, struct bio *);
+ void (*request_merged)(struct request_queue *, struct request *, int);
+ void (*requests_merged)(struct request_queue *, struct request *, struct request *);
+ struct request *(*get_request)(struct request_queue *, unsigned int, struct blk_mq_alloc_data *);
+ void (*put_request)(struct request *);
+ void (*insert_requests)(struct blk_mq_hw_ctx *, struct list_head *, bool);
+ void (*dispatch_requests)(struct blk_mq_hw_ctx *, struct list_head *);
+ bool (*has_work)(struct blk_mq_hw_ctx *);
+ void (*completed_request)(struct blk_mq_hw_ctx *, struct request *);
+ void (*started_request)(struct request *);
+ void (*requeue_request)(struct request *);
+ struct request *(*former_request)(struct request_queue *, struct request *);
+ struct request *(*next_request)(struct request_queue *, struct request *);
+ int (*get_rq_priv)(struct request_queue *, struct request *);
+ void (*put_rq_priv)(struct request_queue *, struct request *);
+ void (*init_icq)(struct io_cq *);
+ void (*exit_icq)(struct io_cq *);
+};
+
#define ELV_NAME_MAX (16)

struct elv_fs_entry {
@@ -96,12 +124,14 @@ struct elevator_type
/* fields provided by elevator implementation */
union {
struct elevator_ops sq;
+ struct elevator_mq_ops mq;
} ops;
size_t icq_size; /* see iocontext.h */
size_t icq_align; /* ditto */
struct elv_fs_entry *elevator_attrs;
char elevator_name[ELV_NAME_MAX];
struct module *elevator_owner;
+ bool uses_mq;

/* managed by elevator core */
char icq_cache_name[ELV_NAME_MAX + 5]; /* elvname + "_io_cq" */
@@ -125,6 +155,7 @@ struct elevator_queue
struct kobject kobj;
struct mutex sysfs_lock;
unsigned int registered:1;
+ unsigned int uses_mq:1;
DECLARE_HASHTABLE(hash, ELV_HASH_BITS);
};

@@ -141,6 +172,7 @@ extern void elv_merge_requests(struct request_queue *, struct request *,
extern void elv_merged_request(struct request_queue *, struct request *, int);
extern void elv_bio_merged(struct request_queue *q, struct request *,
struct bio *);
+extern bool elv_attempt_insert_merge(struct request_queue *, struct request *);
extern void elv_requeue_request(struct request_queue *, struct request *);
extern struct request *elv_former_request(struct request_queue *, struct request *);
extern struct request *elv_latter_request(struct request_queue *, struct request *);
--
2.7.4
\
 
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  Last update: 2017-01-11 22:42    [W:0.307 / U:0.744 seconds]
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