503 lines
12 KiB
C
503 lines
12 KiB
C
/*
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* blk-mq scheduling framework
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*
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* Copyright (C) 2016 Jens Axboe
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/blk-mq.h>
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#include <trace/events/block.h>
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#include "blk.h"
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#include "blk-mq.h"
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#include "blk-mq-sched.h"
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#include "blk-mq-tag.h"
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#include "blk-wbt.h"
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void blk_mq_sched_free_hctx_data(struct request_queue *q,
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void (*exit)(struct blk_mq_hw_ctx *))
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{
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struct blk_mq_hw_ctx *hctx;
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int i;
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queue_for_each_hw_ctx(q, hctx, i) {
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if (exit && hctx->sched_data)
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exit(hctx);
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kfree(hctx->sched_data);
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hctx->sched_data = NULL;
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}
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}
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EXPORT_SYMBOL_GPL(blk_mq_sched_free_hctx_data);
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int blk_mq_sched_init_hctx_data(struct request_queue *q, size_t size,
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int (*init)(struct blk_mq_hw_ctx *),
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void (*exit)(struct blk_mq_hw_ctx *))
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{
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struct blk_mq_hw_ctx *hctx;
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int ret;
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int i;
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queue_for_each_hw_ctx(q, hctx, i) {
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hctx->sched_data = kmalloc_node(size, GFP_KERNEL, hctx->numa_node);
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if (!hctx->sched_data) {
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ret = -ENOMEM;
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goto error;
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}
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if (init) {
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ret = init(hctx);
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if (ret) {
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/*
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* We don't want to give exit() a partially
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* initialized sched_data. init() must clean up
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* if it fails.
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*/
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kfree(hctx->sched_data);
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hctx->sched_data = NULL;
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goto error;
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}
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}
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}
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return 0;
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error:
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blk_mq_sched_free_hctx_data(q, exit);
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return ret;
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}
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EXPORT_SYMBOL_GPL(blk_mq_sched_init_hctx_data);
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static void __blk_mq_sched_assign_ioc(struct request_queue *q,
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struct request *rq,
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struct bio *bio,
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struct io_context *ioc)
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{
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struct io_cq *icq;
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spin_lock_irq(q->queue_lock);
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icq = ioc_lookup_icq(ioc, q);
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spin_unlock_irq(q->queue_lock);
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if (!icq) {
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icq = ioc_create_icq(ioc, q, GFP_ATOMIC);
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if (!icq)
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return;
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}
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rq->elv.icq = icq;
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if (!blk_mq_sched_get_rq_priv(q, rq, bio)) {
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rq->rq_flags |= RQF_ELVPRIV;
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get_io_context(icq->ioc);
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return;
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}
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rq->elv.icq = NULL;
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}
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static void blk_mq_sched_assign_ioc(struct request_queue *q,
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struct request *rq, struct bio *bio)
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{
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struct io_context *ioc;
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ioc = rq_ioc(bio);
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if (ioc)
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__blk_mq_sched_assign_ioc(q, rq, bio, ioc);
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}
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struct request *blk_mq_sched_get_request(struct request_queue *q,
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struct bio *bio,
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unsigned int op,
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struct blk_mq_alloc_data *data)
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{
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struct elevator_queue *e = q->elevator;
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struct blk_mq_hw_ctx *hctx;
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struct blk_mq_ctx *ctx;
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struct request *rq;
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blk_queue_enter_live(q);
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ctx = blk_mq_get_ctx(q);
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hctx = blk_mq_map_queue(q, ctx->cpu);
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blk_mq_set_alloc_data(data, q, data->flags, ctx, hctx);
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if (e) {
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data->flags |= BLK_MQ_REQ_INTERNAL;
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/*
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* Flush requests are special and go directly to the
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* dispatch list.
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*/
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if (!op_is_flush(op) && e->type->ops.mq.get_request) {
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rq = e->type->ops.mq.get_request(q, op, data);
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if (rq)
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rq->rq_flags |= RQF_QUEUED;
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} else
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rq = __blk_mq_alloc_request(data, op);
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} else {
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rq = __blk_mq_alloc_request(data, op);
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if (rq)
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data->hctx->tags->rqs[rq->tag] = rq;
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}
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if (rq) {
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if (!op_is_flush(op)) {
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rq->elv.icq = NULL;
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if (e && e->type->icq_cache)
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blk_mq_sched_assign_ioc(q, rq, bio);
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}
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data->hctx->queued++;
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return rq;
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}
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blk_queue_exit(q);
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return NULL;
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}
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void blk_mq_sched_put_request(struct request *rq)
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{
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struct request_queue *q = rq->q;
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struct elevator_queue *e = q->elevator;
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if (rq->rq_flags & RQF_ELVPRIV) {
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blk_mq_sched_put_rq_priv(rq->q, rq);
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if (rq->elv.icq) {
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put_io_context(rq->elv.icq->ioc);
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rq->elv.icq = NULL;
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}
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}
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if ((rq->rq_flags & RQF_QUEUED) && e && e->type->ops.mq.put_request)
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e->type->ops.mq.put_request(rq);
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else
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blk_mq_finish_request(rq);
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}
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void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
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{
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struct elevator_queue *e = hctx->queue->elevator;
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const bool has_sched_dispatch = e && e->type->ops.mq.dispatch_request;
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bool did_work = false;
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LIST_HEAD(rq_list);
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if (unlikely(blk_mq_hctx_stopped(hctx)))
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return;
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hctx->run++;
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/*
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* If we have previous entries on our dispatch list, grab them first for
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* more fair dispatch.
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*/
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if (!list_empty_careful(&hctx->dispatch)) {
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spin_lock(&hctx->lock);
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if (!list_empty(&hctx->dispatch))
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list_splice_init(&hctx->dispatch, &rq_list);
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spin_unlock(&hctx->lock);
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}
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/*
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* Only ask the scheduler for requests, if we didn't have residual
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* requests from the dispatch list. This is to avoid the case where
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* we only ever dispatch a fraction of the requests available because
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* of low device queue depth. Once we pull requests out of the IO
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* scheduler, we can no longer merge or sort them. So it's best to
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* leave them there for as long as we can. Mark the hw queue as
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* needing a restart in that case.
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*/
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if (!list_empty(&rq_list)) {
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blk_mq_sched_mark_restart_hctx(hctx);
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did_work = blk_mq_dispatch_rq_list(hctx, &rq_list);
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} else if (!has_sched_dispatch) {
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blk_mq_flush_busy_ctxs(hctx, &rq_list);
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blk_mq_dispatch_rq_list(hctx, &rq_list);
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}
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/*
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* We want to dispatch from the scheduler if we had no work left
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* on the dispatch list, OR if we did have work but weren't able
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* to make progress.
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*/
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if (!did_work && has_sched_dispatch) {
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do {
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struct request *rq;
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rq = e->type->ops.mq.dispatch_request(hctx);
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if (!rq)
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break;
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list_add(&rq->queuelist, &rq_list);
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} while (blk_mq_dispatch_rq_list(hctx, &rq_list));
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}
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}
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void blk_mq_sched_move_to_dispatch(struct blk_mq_hw_ctx *hctx,
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struct list_head *rq_list,
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struct request *(*get_rq)(struct blk_mq_hw_ctx *))
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{
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do {
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struct request *rq;
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rq = get_rq(hctx);
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if (!rq)
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break;
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list_add_tail(&rq->queuelist, rq_list);
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} while (1);
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}
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EXPORT_SYMBOL_GPL(blk_mq_sched_move_to_dispatch);
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bool blk_mq_sched_try_merge(struct request_queue *q, struct bio *bio,
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struct request **merged_request)
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{
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struct request *rq;
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switch (elv_merge(q, &rq, bio)) {
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case ELEVATOR_BACK_MERGE:
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if (!blk_mq_sched_allow_merge(q, rq, bio))
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return false;
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if (!bio_attempt_back_merge(q, rq, bio))
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return false;
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*merged_request = attempt_back_merge(q, rq);
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if (!*merged_request)
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elv_merged_request(q, rq, ELEVATOR_BACK_MERGE);
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return true;
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case ELEVATOR_FRONT_MERGE:
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if (!blk_mq_sched_allow_merge(q, rq, bio))
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return false;
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if (!bio_attempt_front_merge(q, rq, bio))
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return false;
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*merged_request = attempt_front_merge(q, rq);
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if (!*merged_request)
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elv_merged_request(q, rq, ELEVATOR_FRONT_MERGE);
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return true;
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default:
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return false;
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}
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}
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EXPORT_SYMBOL_GPL(blk_mq_sched_try_merge);
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bool __blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio)
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{
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struct elevator_queue *e = q->elevator;
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if (e->type->ops.mq.bio_merge) {
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struct blk_mq_ctx *ctx = blk_mq_get_ctx(q);
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struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
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blk_mq_put_ctx(ctx);
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return e->type->ops.mq.bio_merge(hctx, bio);
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}
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return false;
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}
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bool blk_mq_sched_try_insert_merge(struct request_queue *q, struct request *rq)
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{
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return rq_mergeable(rq) && elv_attempt_insert_merge(q, rq);
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}
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EXPORT_SYMBOL_GPL(blk_mq_sched_try_insert_merge);
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void blk_mq_sched_request_inserted(struct request *rq)
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{
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trace_block_rq_insert(rq->q, rq);
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}
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EXPORT_SYMBOL_GPL(blk_mq_sched_request_inserted);
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static bool blk_mq_sched_bypass_insert(struct blk_mq_hw_ctx *hctx,
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struct request *rq)
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{
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if (rq->tag == -1) {
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rq->rq_flags |= RQF_SORTED;
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return false;
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}
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/*
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* If we already have a real request tag, send directly to
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* the dispatch list.
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*/
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spin_lock(&hctx->lock);
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list_add(&rq->queuelist, &hctx->dispatch);
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spin_unlock(&hctx->lock);
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return true;
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}
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static void blk_mq_sched_restart_hctx(struct blk_mq_hw_ctx *hctx)
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{
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if (test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state)) {
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clear_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state);
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if (blk_mq_hctx_has_pending(hctx))
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blk_mq_run_hw_queue(hctx, true);
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}
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}
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void blk_mq_sched_restart_queues(struct blk_mq_hw_ctx *hctx)
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{
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struct request_queue *q = hctx->queue;
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unsigned int i;
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if (test_bit(QUEUE_FLAG_RESTART, &q->queue_flags)) {
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if (test_and_clear_bit(QUEUE_FLAG_RESTART, &q->queue_flags)) {
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queue_for_each_hw_ctx(q, hctx, i)
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blk_mq_sched_restart_hctx(hctx);
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}
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} else {
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blk_mq_sched_restart_hctx(hctx);
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}
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}
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/*
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* Add flush/fua to the queue. If we fail getting a driver tag, then
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* punt to the requeue list. Requeue will re-invoke us from a context
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* that's safe to block from.
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*/
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static void blk_mq_sched_insert_flush(struct blk_mq_hw_ctx *hctx,
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struct request *rq, bool can_block)
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{
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if (blk_mq_get_driver_tag(rq, &hctx, can_block)) {
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blk_insert_flush(rq);
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blk_mq_run_hw_queue(hctx, true);
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} else
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blk_mq_add_to_requeue_list(rq, false, true);
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}
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void blk_mq_sched_insert_request(struct request *rq, bool at_head,
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bool run_queue, bool async, bool can_block)
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{
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struct request_queue *q = rq->q;
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struct elevator_queue *e = q->elevator;
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struct blk_mq_ctx *ctx = rq->mq_ctx;
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struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
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if (rq->tag == -1 && op_is_flush(rq->cmd_flags)) {
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blk_mq_sched_insert_flush(hctx, rq, can_block);
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return;
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}
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if (e && blk_mq_sched_bypass_insert(hctx, rq))
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goto run;
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if (e && e->type->ops.mq.insert_requests) {
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LIST_HEAD(list);
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list_add(&rq->queuelist, &list);
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e->type->ops.mq.insert_requests(hctx, &list, at_head);
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} else {
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spin_lock(&ctx->lock);
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__blk_mq_insert_request(hctx, rq, at_head);
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spin_unlock(&ctx->lock);
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}
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run:
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if (run_queue)
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blk_mq_run_hw_queue(hctx, async);
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}
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void blk_mq_sched_insert_requests(struct request_queue *q,
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struct blk_mq_ctx *ctx,
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struct list_head *list, bool run_queue_async)
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{
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struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
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struct elevator_queue *e = hctx->queue->elevator;
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if (e) {
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struct request *rq, *next;
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/*
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* We bypass requests that already have a driver tag assigned,
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* which should only be flushes. Flushes are only ever inserted
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* as single requests, so we shouldn't ever hit the
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* WARN_ON_ONCE() below (but let's handle it just in case).
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*/
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list_for_each_entry_safe(rq, next, list, queuelist) {
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if (WARN_ON_ONCE(rq->tag != -1)) {
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list_del_init(&rq->queuelist);
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blk_mq_sched_bypass_insert(hctx, rq);
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}
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}
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}
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if (e && e->type->ops.mq.insert_requests)
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e->type->ops.mq.insert_requests(hctx, list, false);
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else
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blk_mq_insert_requests(hctx, ctx, list);
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blk_mq_run_hw_queue(hctx, run_queue_async);
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}
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static void blk_mq_sched_free_tags(struct blk_mq_tag_set *set,
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struct blk_mq_hw_ctx *hctx,
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unsigned int hctx_idx)
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{
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if (hctx->sched_tags) {
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blk_mq_free_rqs(set, hctx->sched_tags, hctx_idx);
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blk_mq_free_rq_map(hctx->sched_tags);
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hctx->sched_tags = NULL;
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}
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}
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int blk_mq_sched_setup(struct request_queue *q)
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{
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struct blk_mq_tag_set *set = q->tag_set;
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struct blk_mq_hw_ctx *hctx;
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int ret, i;
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/*
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* Default to 256, since we don't split into sync/async like the
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* old code did. Additionally, this is a per-hw queue depth.
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*/
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q->nr_requests = 2 * BLKDEV_MAX_RQ;
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/*
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* We're switching to using an IO scheduler, so setup the hctx
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* scheduler tags and switch the request map from the regular
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* tags to scheduler tags. First allocate what we need, so we
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* can safely fail and fallback, if needed.
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*/
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ret = 0;
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queue_for_each_hw_ctx(q, hctx, i) {
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hctx->sched_tags = blk_mq_alloc_rq_map(set, i, q->nr_requests, 0);
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if (!hctx->sched_tags) {
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ret = -ENOMEM;
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break;
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}
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ret = blk_mq_alloc_rqs(set, hctx->sched_tags, i, q->nr_requests);
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if (ret)
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break;
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}
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/*
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* If we failed, free what we did allocate
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*/
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if (ret) {
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queue_for_each_hw_ctx(q, hctx, i) {
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if (!hctx->sched_tags)
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continue;
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blk_mq_sched_free_tags(set, hctx, i);
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}
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return ret;
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}
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return 0;
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}
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void blk_mq_sched_teardown(struct request_queue *q)
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{
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struct blk_mq_tag_set *set = q->tag_set;
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struct blk_mq_hw_ctx *hctx;
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int i;
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queue_for_each_hw_ctx(q, hctx, i)
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blk_mq_sched_free_tags(set, hctx, i);
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}
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int blk_mq_sched_init(struct request_queue *q)
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{
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int ret;
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mutex_lock(&q->sysfs_lock);
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ret = elevator_init(q, NULL);
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mutex_unlock(&q->sysfs_lock);
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return ret;
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}
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