12f5b93145
This patch simplifies the timeout handling by relying on the request reference counting to ensure the iterator is operating on an inflight and truly timed out request. Since the reference counting prevents the tag from being reallocated, the block layer no longer needs to prevent drivers from completing their requests while the timeout handler is operating on it: a driver completing a request is allowed to proceed to the next state without additional syncronization with the block layer. This also removes any need for generation sequence numbers since the request lifetime is prevented from being reallocated as a new sequence while timeout handling is operating on it. To enables this a refcount is added to struct request so that request users can be sure they're operating on the same request without it changing while they're processing it. The request's tag won't be released for reuse until both the timeout handler and the completion are done with it. Signed-off-by: Keith Busch <keith.busch@intel.com> [hch: slight cleanups, added back submission side hctx lock, use cmpxchg for completions] Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
207 lines
5.6 KiB
C
207 lines
5.6 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef INT_BLK_MQ_H
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#define INT_BLK_MQ_H
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#include "blk-stat.h"
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#include "blk-mq-tag.h"
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struct blk_mq_tag_set;
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/**
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* struct blk_mq_ctx - State for a software queue facing the submitting CPUs
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*/
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struct blk_mq_ctx {
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struct {
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spinlock_t lock;
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struct list_head rq_list;
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} ____cacheline_aligned_in_smp;
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unsigned int cpu;
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unsigned int index_hw;
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/* incremented at dispatch time */
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unsigned long rq_dispatched[2];
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unsigned long rq_merged;
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/* incremented at completion time */
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unsigned long ____cacheline_aligned_in_smp rq_completed[2];
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struct request_queue *queue;
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struct kobject kobj;
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} ____cacheline_aligned_in_smp;
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void blk_mq_freeze_queue(struct request_queue *q);
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void blk_mq_free_queue(struct request_queue *q);
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int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr);
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void blk_mq_wake_waiters(struct request_queue *q);
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bool blk_mq_dispatch_rq_list(struct request_queue *, struct list_head *, bool);
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void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list);
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bool blk_mq_get_driver_tag(struct request *rq, struct blk_mq_hw_ctx **hctx,
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bool wait);
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struct request *blk_mq_dequeue_from_ctx(struct blk_mq_hw_ctx *hctx,
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struct blk_mq_ctx *start);
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/*
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* Internal helpers for allocating/freeing the request map
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*/
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void blk_mq_free_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
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unsigned int hctx_idx);
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void blk_mq_free_rq_map(struct blk_mq_tags *tags);
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struct blk_mq_tags *blk_mq_alloc_rq_map(struct blk_mq_tag_set *set,
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unsigned int hctx_idx,
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unsigned int nr_tags,
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unsigned int reserved_tags);
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int blk_mq_alloc_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
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unsigned int hctx_idx, unsigned int depth);
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/*
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* Internal helpers for request insertion into sw queues
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*/
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void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
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bool at_head);
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void blk_mq_request_bypass_insert(struct request *rq, bool run_queue);
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void blk_mq_insert_requests(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
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struct list_head *list);
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/* Used by blk_insert_cloned_request() to issue request directly */
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blk_status_t blk_mq_request_issue_directly(struct request *rq);
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/*
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* CPU -> queue mappings
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*/
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extern int blk_mq_hw_queue_to_node(unsigned int *map, unsigned int);
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static inline struct blk_mq_hw_ctx *blk_mq_map_queue(struct request_queue *q,
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int cpu)
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{
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return q->queue_hw_ctx[q->mq_map[cpu]];
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}
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/*
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* sysfs helpers
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*/
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extern void blk_mq_sysfs_init(struct request_queue *q);
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extern void blk_mq_sysfs_deinit(struct request_queue *q);
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extern int __blk_mq_register_dev(struct device *dev, struct request_queue *q);
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extern int blk_mq_sysfs_register(struct request_queue *q);
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extern void blk_mq_sysfs_unregister(struct request_queue *q);
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extern void blk_mq_hctx_kobj_init(struct blk_mq_hw_ctx *hctx);
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void blk_mq_release(struct request_queue *q);
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/**
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* blk_mq_rq_state() - read the current MQ_RQ_* state of a request
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* @rq: target request.
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*/
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static inline enum mq_rq_state blk_mq_rq_state(struct request *rq)
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{
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return READ_ONCE(rq->state);
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}
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static inline struct blk_mq_ctx *__blk_mq_get_ctx(struct request_queue *q,
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unsigned int cpu)
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{
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return per_cpu_ptr(q->queue_ctx, cpu);
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}
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/*
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* This assumes per-cpu software queueing queues. They could be per-node
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* as well, for instance. For now this is hardcoded as-is. Note that we don't
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* care about preemption, since we know the ctx's are persistent. This does
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* mean that we can't rely on ctx always matching the currently running CPU.
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*/
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static inline struct blk_mq_ctx *blk_mq_get_ctx(struct request_queue *q)
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{
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return __blk_mq_get_ctx(q, get_cpu());
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}
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static inline void blk_mq_put_ctx(struct blk_mq_ctx *ctx)
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{
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put_cpu();
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}
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struct blk_mq_alloc_data {
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/* input parameter */
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struct request_queue *q;
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blk_mq_req_flags_t flags;
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unsigned int shallow_depth;
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/* input & output parameter */
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struct blk_mq_ctx *ctx;
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struct blk_mq_hw_ctx *hctx;
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};
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static inline struct blk_mq_tags *blk_mq_tags_from_data(struct blk_mq_alloc_data *data)
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{
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if (data->flags & BLK_MQ_REQ_INTERNAL)
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return data->hctx->sched_tags;
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return data->hctx->tags;
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}
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static inline bool blk_mq_hctx_stopped(struct blk_mq_hw_ctx *hctx)
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{
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return test_bit(BLK_MQ_S_STOPPED, &hctx->state);
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}
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static inline bool blk_mq_hw_queue_mapped(struct blk_mq_hw_ctx *hctx)
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{
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return hctx->nr_ctx && hctx->tags;
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}
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void blk_mq_in_flight(struct request_queue *q, struct hd_struct *part,
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unsigned int inflight[2]);
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void blk_mq_in_flight_rw(struct request_queue *q, struct hd_struct *part,
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unsigned int inflight[2]);
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static inline void blk_mq_put_dispatch_budget(struct blk_mq_hw_ctx *hctx)
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{
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struct request_queue *q = hctx->queue;
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if (q->mq_ops->put_budget)
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q->mq_ops->put_budget(hctx);
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}
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static inline bool blk_mq_get_dispatch_budget(struct blk_mq_hw_ctx *hctx)
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{
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struct request_queue *q = hctx->queue;
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if (q->mq_ops->get_budget)
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return q->mq_ops->get_budget(hctx);
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return true;
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}
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static inline void __blk_mq_put_driver_tag(struct blk_mq_hw_ctx *hctx,
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struct request *rq)
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{
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blk_mq_put_tag(hctx, hctx->tags, rq->mq_ctx, rq->tag);
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rq->tag = -1;
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if (rq->rq_flags & RQF_MQ_INFLIGHT) {
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rq->rq_flags &= ~RQF_MQ_INFLIGHT;
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atomic_dec(&hctx->nr_active);
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}
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}
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static inline void blk_mq_put_driver_tag_hctx(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 || rq->internal_tag == -1)
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return;
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__blk_mq_put_driver_tag(hctx, rq);
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}
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static inline void blk_mq_put_driver_tag(struct request *rq)
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{
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struct blk_mq_hw_ctx *hctx;
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if (rq->tag == -1 || rq->internal_tag == -1)
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return;
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hctx = blk_mq_map_queue(rq->q, rq->mq_ctx->cpu);
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__blk_mq_put_driver_tag(hctx, rq);
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}
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#endif
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