/*
* 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 && hctx->sched_data)
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)) {
rq->rq_flags |= RQF_ELVPRIV;
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;
const bool is_flush = op & (REQ_PREFLUSH | REQ_FUA);
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;
/*
* Flush requests are special and go directly to the
* dispatch list.
*/
if (!is_flush && e->type->ops.mq.get_request) {
rq = e->type->ops.mq.get_request(q, op, data);
if (rq)
rq->rq_flags |= RQF_QUEUED;
} else
rq = __blk_mq_alloc_request(data, op);
} else {
rq = __blk_mq_alloc_request(data, op);
data->hctx->tags->rqs[rq->tag] = rq;
}
if (rq) {
if (!is_flush) {
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 ((rq->rq_flags & RQF_QUEUED) && 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
blk_mq_sched_mark_restart(hctx);
blk_mq_dispatch_rq_list(hctx, &rq_list);
}
void blk_mq_sched_move_to_dispatch(struct blk_mq_hw_ctx *hctx,
struct list_head *rq_list,
struct request *(*get_rq)(struct blk_mq_hw_ctx *))
{
do {
struct request *rq;
rq = get_rq(hctx);
if (!rq)
break;
list_add_tail(&rq->queuelist, rq_list);
} while (1);
}
EXPORT_SYMBOL_GPL(blk_mq_sched_move_to_dispatch);
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 (!blk_mq_sched_allow_merge(q, rq, bio))
return false;
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 (!blk_mq_sched_allow_merge(q, rq, bio))
return false;
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);
bool blk_mq_sched_bypass_insert(struct blk_mq_hw_ctx *hctx, struct request *rq)
{
if (rq->tag == -1) {
rq->rq_flags |= RQF_SORTED;
return false;
}
/*
* If we already have a real request tag, send directly to
* the dispatch list.
*/
spin_lock(&hctx->lock);
list_add(&rq->queuelist, &hctx->dispatch);
spin_unlock(&hctx->lock);
return true;
}
EXPORT_SYMBOL_GPL(blk_mq_sched_bypass_insert);
static void blk_mq_sched_free_tags(struct blk_mq_tag_set *set,
struct blk_mq_hw_ctx *hctx,
unsigned int hctx_idx)
{
if (hctx->sched_tags) {
blk_mq_free_rqs(set, hctx->sched_tags, hctx_idx);
blk_mq_free_rq_map(hctx->sched_tags);
hctx->sched_tags = NULL;
}
}
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_sched_free_tags(set, hctx, i);
}
return ret;
}
return 0;
}
void 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;
queue_for_each_hw_ctx(q, hctx, i)
blk_mq_sched_free_tags(set, hctx, i);
}
