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SCSI uses a global atomic variable to track queue depth for each LUN/request queue. This doesn't scale well when there are lots of CPU cores and the disk is very fast. It has been observed that IOPS is affected a lot by tracking queue depth via sdev->device_busy in the I/O path. Return budget token from .get_budget callback. The budget token can be passed to driver so that we can replace the atomic variable with sbitmap_queue and alleviate the scaling problems that way. Link: https://lore.kernel.org/r/20210122023317.687987-9-ming.lei@redhat.com Cc: Omar Sandoval <osandov@fb.com> Cc: Kashyap Desai <kashyap.desai@broadcom.com> Cc: Sumanesh Samanta <sumanesh.samanta@broadcom.com> Cc: Ewan D. Milne <emilne@redhat.com> Tested-by: Sumanesh Samanta <sumanesh.samanta@broadcom.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
345 lines
9.8 KiB
C
345 lines
9.8 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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struct blk_mq_ctxs {
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struct kobject kobj;
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struct blk_mq_ctx __percpu *queue_ctx;
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};
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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_lists[HCTX_MAX_TYPES];
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} ____cacheline_aligned_in_smp;
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unsigned int cpu;
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unsigned short index_hw[HCTX_MAX_TYPES];
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struct blk_mq_hw_ctx *hctxs[HCTX_MAX_TYPES];
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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 blk_mq_ctxs *ctxs;
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struct kobject kobj;
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} ____cacheline_aligned_in_smp;
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void blk_mq_exit_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 blk_mq_hw_ctx *hctx, struct list_head *,
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unsigned int);
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void blk_mq_add_to_requeue_list(struct request *rq, bool at_head,
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bool kick_requeue_list);
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void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list);
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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, unsigned int flags);
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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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unsigned int flags);
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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 at_head,
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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, bool last);
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void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx *hctx,
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struct list_head *list);
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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(struct blk_mq_queue_map *qmap, unsigned int);
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/*
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* blk_mq_map_queue_type() - map (hctx_type,cpu) to hardware queue
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* @q: request queue
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* @type: the hctx type index
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* @cpu: CPU
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*/
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static inline struct blk_mq_hw_ctx *blk_mq_map_queue_type(struct request_queue *q,
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enum hctx_type type,
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unsigned int cpu)
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{
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return q->queue_hw_ctx[q->tag_set->map[type].mq_map[cpu]];
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}
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/*
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* blk_mq_map_queue() - map (cmd_flags,type) to hardware queue
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* @q: request queue
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* @flags: request command flags
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* @ctx: software queue cpu ctx
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*/
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static inline struct blk_mq_hw_ctx *blk_mq_map_queue(struct request_queue *q,
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unsigned int flags,
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struct blk_mq_ctx *ctx)
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{
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enum hctx_type type = HCTX_TYPE_DEFAULT;
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/*
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* The caller ensure that if REQ_HIPRI, poll must be enabled.
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*/
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if (flags & REQ_HIPRI)
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type = HCTX_TYPE_POLL;
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else if ((flags & REQ_OP_MASK) == REQ_OP_READ)
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type = HCTX_TYPE_READ;
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return ctx->hctxs[type];
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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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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, raw_smp_processor_id());
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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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unsigned int cmd_flags;
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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 bool blk_mq_is_sbitmap_shared(unsigned int flags)
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{
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return flags & BLK_MQ_F_TAG_HCTX_SHARED;
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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->q->elevator)
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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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unsigned int blk_mq_in_flight(struct request_queue *q,
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struct block_device *part);
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void blk_mq_in_flight_rw(struct request_queue *q, struct block_device *part,
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unsigned int inflight[2]);
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static inline void blk_mq_put_dispatch_budget(struct request_queue *q,
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int budget_token)
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{
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if (q->mq_ops->put_budget)
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q->mq_ops->put_budget(q, budget_token);
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}
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static inline int blk_mq_get_dispatch_budget(struct request_queue *q)
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{
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if (q->mq_ops->get_budget)
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return q->mq_ops->get_budget(q);
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return 0;
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}
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static inline void blk_mq_set_rq_budget_token(struct request *rq, int token)
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{
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if (token < 0)
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return;
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if (rq->q->mq_ops->set_rq_budget_token)
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rq->q->mq_ops->set_rq_budget_token(rq, token);
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}
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static inline int blk_mq_get_rq_budget_token(struct request *rq)
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{
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if (rq->q->mq_ops->get_rq_budget_token)
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return rq->q->mq_ops->get_rq_budget_token(rq);
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return -1;
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}
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static inline void __blk_mq_inc_active_requests(struct blk_mq_hw_ctx *hctx)
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{
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if (blk_mq_is_sbitmap_shared(hctx->flags))
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atomic_inc(&hctx->queue->nr_active_requests_shared_sbitmap);
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else
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atomic_inc(&hctx->nr_active);
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}
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static inline void __blk_mq_dec_active_requests(struct blk_mq_hw_ctx *hctx)
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{
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if (blk_mq_is_sbitmap_shared(hctx->flags))
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atomic_dec(&hctx->queue->nr_active_requests_shared_sbitmap);
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else
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atomic_dec(&hctx->nr_active);
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}
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static inline int __blk_mq_active_requests(struct blk_mq_hw_ctx *hctx)
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{
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if (blk_mq_is_sbitmap_shared(hctx->flags))
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return atomic_read(&hctx->queue->nr_active_requests_shared_sbitmap);
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return atomic_read(&hctx->nr_active);
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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->tags, rq->mq_ctx, rq->tag);
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rq->tag = BLK_MQ_NO_TAG;
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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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__blk_mq_dec_active_requests(hctx);
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}
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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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if (rq->tag == BLK_MQ_NO_TAG || rq->internal_tag == BLK_MQ_NO_TAG)
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return;
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__blk_mq_put_driver_tag(rq->mq_hctx, rq);
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}
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static inline void blk_mq_clear_mq_map(struct blk_mq_queue_map *qmap)
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{
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int cpu;
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for_each_possible_cpu(cpu)
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qmap->mq_map[cpu] = 0;
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}
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/*
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* blk_mq_plug() - Get caller context plug
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* @q: request queue
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* @bio : the bio being submitted by the caller context
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*
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* Plugging, by design, may delay the insertion of BIOs into the elevator in
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* order to increase BIO merging opportunities. This however can cause BIO
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* insertion order to change from the order in which submit_bio() is being
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* executed in the case of multiple contexts concurrently issuing BIOs to a
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* device, even if these context are synchronized to tightly control BIO issuing
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* order. While this is not a problem with regular block devices, this ordering
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* change can cause write BIO failures with zoned block devices as these
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* require sequential write patterns to zones. Prevent this from happening by
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* ignoring the plug state of a BIO issuing context if the target request queue
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* is for a zoned block device and the BIO to plug is a write operation.
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*
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* Return current->plug if the bio can be plugged and NULL otherwise
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*/
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static inline struct blk_plug *blk_mq_plug(struct request_queue *q,
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struct bio *bio)
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{
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/*
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* For regular block devices or read operations, use the context plug
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* which may be NULL if blk_start_plug() was not executed.
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*/
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if (!blk_queue_is_zoned(q) || !op_is_write(bio_op(bio)))
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return current->plug;
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/* Zoned block device write operation case: do not plug the BIO */
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return NULL;
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}
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/*
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* For shared tag users, we track the number of currently active users
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* and attempt to provide a fair share of the tag depth for each of them.
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*/
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static inline bool hctx_may_queue(struct blk_mq_hw_ctx *hctx,
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struct sbitmap_queue *bt)
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{
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unsigned int depth, users;
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if (!hctx || !(hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED))
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return true;
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/*
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* Don't try dividing an ant
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*/
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if (bt->sb.depth == 1)
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return true;
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if (blk_mq_is_sbitmap_shared(hctx->flags)) {
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struct request_queue *q = hctx->queue;
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struct blk_mq_tag_set *set = q->tag_set;
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if (!test_bit(QUEUE_FLAG_HCTX_ACTIVE, &q->queue_flags))
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return true;
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users = atomic_read(&set->active_queues_shared_sbitmap);
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} else {
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if (!test_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state))
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return true;
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users = atomic_read(&hctx->tags->active_queues);
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}
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if (!users)
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return true;
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/*
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* Allow at least some tags
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*/
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depth = max((bt->sb.depth + users - 1) / users, 4U);
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return __blk_mq_active_requests(hctx) < depth;
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}
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#endif
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