/* SPDX-License-Identifier: GPL-2.0 */
#ifndef BLK_MQ_H
#define BLK_MQ_H

#include <linux/blkdev.h>
#include <linux/sbitmap.h>
#include <linux/srcu.h>
#include <linux/lockdep.h>

struct blk_mq_tags;
struct blk_flush_queue;

/**
 * struct blk_mq_hw_ctx - State for a hardware queue facing the hardware
 * block device
 */
struct blk_mq_hw_ctx {
        struct {
                /** @lock: Protects the dispatch list. */
                spinlock_t              lock;
                /**
                 * @dispatch: Used for requests that are ready to be
                 * dispatched to the hardware but for some reason (e.g. lack of
                 * resources) could not be sent to the hardware. As soon as the
                 * driver can send new requests, requests at this list will
                 * be sent first for a fairer dispatch.
                 */
                struct list_head        dispatch;
                 /**
                  * @state: BLK_MQ_S_* flags. Defines the state of the hw
                  * queue (active, scheduled to restart, stopped).
                  */
                unsigned long           state;
        } ____cacheline_aligned_in_smp;

        /**
         * @run_work: Used for scheduling a hardware queue run at a later time.
         */
        struct delayed_work     run_work;
        /** @cpumask: Map of available CPUs where this hctx can run. */
        cpumask_var_t           cpumask;
        /**
         * @next_cpu: Used by blk_mq_hctx_next_cpu() for round-robin CPU
         * selection from @cpumask.
         */
        int                     next_cpu;
        /**
         * @next_cpu_batch: Counter of how many works left in the batch before
         * changing to the next CPU.
         */
        int                     next_cpu_batch;

        /** @flags: BLK_MQ_F_* flags. Defines the behaviour of the queue. */
        unsigned long           flags;

        /**
         * @sched_data: Pointer owned by the IO scheduler attached to a request
         * queue. It's up to the IO scheduler how to use this pointer.
         */
        void                    *sched_data;
        /**
         * @queue: Pointer to the request queue that owns this hardware context.
         */
        struct request_queue    *queue;
        /** @fq: Queue of requests that need to perform a flush operation. */
        struct blk_flush_queue  *fq;

        /**
         * @driver_data: Pointer to data owned by the block driver that created
         * this hctx
         */
        void                    *driver_data;

        /**
         * @ctx_map: Bitmap for each software queue. If bit is on, there is a
         * pending request in that software queue.
         */
        struct sbitmap          ctx_map;

        /**
         * @dispatch_from: Software queue to be used when no scheduler was
         * selected.
         */
        struct blk_mq_ctx       *dispatch_from;
        /**
         * @dispatch_busy: Number used by blk_mq_update_dispatch_busy() to
         * decide if the hw_queue is busy using Exponential Weighted Moving
         * Average algorithm.
         */
        unsigned int            dispatch_busy;

        /** @type: HCTX_TYPE_* flags. Type of hardware queue. */
        unsigned short          type;
        /** @nr_ctx: Number of software queues. */
        unsigned short          nr_ctx;
        /** @ctxs: Array of software queues. */
        struct blk_mq_ctx       **ctxs;

        /** @dispatch_wait_lock: Lock for dispatch_wait queue. */
        spinlock_t              dispatch_wait_lock;
        /**
         * @dispatch_wait: Waitqueue to put requests when there is no tag
         * available at the moment, to wait for another try in the future.
         */
        wait_queue_entry_t      dispatch_wait;

        /**
         * @wait_index: Index of next available dispatch_wait queue to insert
         * requests.
         */
        atomic_t                wait_index;

        /**
         * @tags: Tags owned by the block driver. A tag at this set is only
         * assigned when a request is dispatched from a hardware queue.
         */
        struct blk_mq_tags      *tags;
        /**
         * @sched_tags: Tags owned by I/O scheduler. If there is an I/O
         * scheduler associated with a request queue, a tag is assigned when
         * that request is allocated. Else, this member is not used.
         */
        struct blk_mq_tags      *sched_tags;

        /** @queued: Number of queued requests. */
        unsigned long           queued;
        /** @run: Number of dispatched requests. */
        unsigned long           run;
#define BLK_MQ_MAX_DISPATCH_ORDER       7
        /** @dispatched: Number of dispatch requests by queue. */
        unsigned long           dispatched[BLK_MQ_MAX_DISPATCH_ORDER];

        /** @numa_node: NUMA node the storage adapter has been connected to. */
        unsigned int            numa_node;
        /** @queue_num: Index of this hardware queue. */
        unsigned int            queue_num;

        /**
         * @nr_active: Number of active requests. Only used when a tag set is
         * shared across request queues.
         */
        atomic_t                nr_active;

        /** @cpuhp_online: List to store request if CPU is going to die */
        struct hlist_node       cpuhp_online;
        /** @cpuhp_dead: List to store request if some CPU die. */
        struct hlist_node       cpuhp_dead;
        /** @kobj: Kernel object for sysfs. */
        struct kobject          kobj;

        /** @poll_considered: Count times blk_poll() was called. */
        unsigned long           poll_considered;
        /** @poll_invoked: Count how many requests blk_poll() polled. */
        unsigned long           poll_invoked;
        /** @poll_success: Count how many polled requests were completed. */
        unsigned long           poll_success;

#ifdef CONFIG_BLK_DEBUG_FS
        /**
         * @debugfs_dir: debugfs directory for this hardware queue. Named
         * as cpu<cpu_number>.
         */
        struct dentry           *debugfs_dir;
        /** @sched_debugfs_dir: debugfs directory for the scheduler. */
        struct dentry           *sched_debugfs_dir;
#endif

        /**
         * @hctx_list: if this hctx is not in use, this is an entry in
         * q->unused_hctx_list.
         */
        struct list_head        hctx_list;

        /**
         * @srcu: Sleepable RCU. Use as lock when type of the hardware queue is
         * blocking (BLK_MQ_F_BLOCKING). Must be the last member - see also
         * blk_mq_hw_ctx_size().
         */
        struct srcu_struct      srcu[];
};

/**
 * struct blk_mq_queue_map - Map software queues to hardware queues
 * @mq_map:       CPU ID to hardware queue index map. This is an array
 *      with nr_cpu_ids elements. Each element has a value in the range
 *      [@queue_offset, @queue_offset + @nr_queues).
 * @nr_queues:    Number of hardware queues to map CPU IDs onto.
 * @queue_offset: First hardware queue to map onto. Used by the PCIe NVMe
 *      driver to map each hardware queue type (enum hctx_type) onto a distinct
 *      set of hardware queues.
 */
struct blk_mq_queue_map {
        unsigned int *mq_map;
        unsigned int nr_queues;
        unsigned int queue_offset;
};

/**
 * enum hctx_type - Type of hardware queue
 * @HCTX_TYPE_DEFAULT:  All I/O not otherwise accounted for.
 * @HCTX_TYPE_READ:     Just for READ I/O.
 * @HCTX_TYPE_POLL:     Polled I/O of any kind.
 * @HCTX_MAX_TYPES:     Number of types of hctx.
 */
enum hctx_type {
        HCTX_TYPE_DEFAULT,
        HCTX_TYPE_READ,
        HCTX_TYPE_POLL,

        HCTX_MAX_TYPES,
};

/**
 * struct blk_mq_tag_set - tag set that can be shared between request queues
 * @map:           One or more ctx -> hctx mappings. One map exists for each
 *                 hardware queue type (enum hctx_type) that the driver wishes
 *                 to support. There are no restrictions on maps being of the
 *                 same size, and it's perfectly legal to share maps between
 *                 types.
 * @nr_maps:       Number of elements in the @map array. A number in the range
 *                 [1, HCTX_MAX_TYPES].
 * @ops:           Pointers to functions that implement block driver behavior.
 * @nr_hw_queues:  Number of hardware queues supported by the block driver that
 *                 owns this data structure.
 * @queue_depth:   Number of tags per hardware queue, reserved tags included.
 * @reserved_tags: Number of tags to set aside for BLK_MQ_REQ_RESERVED tag
 *                 allocations.
 * @cmd_size:      Number of additional bytes to allocate per request. The block
 *                 driver owns these additional bytes.
 * @numa_node:     NUMA node the storage adapter has been connected to.
 * @timeout:       Request processing timeout in jiffies.
 * @flags:         Zero or more BLK_MQ_F_* flags.
 * @driver_data:   Pointer to data owned by the block driver that created this
 *                 tag set.
 * @active_queues_shared_sbitmap:
 *                 number of active request queues per tag set.
 * @__bitmap_tags: A shared tags sbitmap, used over all hctx's
 * @__breserved_tags:
 *                 A shared reserved tags sbitmap, used over all hctx's
 * @tags:          Tag sets. One tag set per hardware queue. Has @nr_hw_queues
 *                 elements.
 * @tag_list_lock: Serializes tag_list accesses.
 * @tag_list:      List of the request queues that use this tag set. See also
 *                 request_queue.tag_set_list.
 */
struct blk_mq_tag_set {
        struct blk_mq_queue_map map[HCTX_MAX_TYPES];
        unsigned int            nr_maps;
        const struct blk_mq_ops *ops;
        unsigned int            nr_hw_queues;
        unsigned int            queue_depth;
        unsigned int            reserved_tags;
        unsigned int            cmd_size;
        int                     numa_node;
        unsigned int            timeout;
        unsigned int            flags;
        void                    *driver_data;
        atomic_t                active_queues_shared_sbitmap;

        struct sbitmap_queue    __bitmap_tags;
        struct sbitmap_queue    __breserved_tags;
        struct blk_mq_tags      **tags;

        struct mutex            tag_list_lock;
        struct list_head        tag_list;
};

/**
 * struct blk_mq_queue_data - Data about a request inserted in a queue
 *
 * @rq:   Request pointer.
 * @last: If it is the last request in the queue.
 */
struct blk_mq_queue_data {
        struct request *rq;
        bool last;
};

typedef bool (busy_iter_fn)(struct blk_mq_hw_ctx *, struct request *, void *,
                bool);
typedef bool (busy_tag_iter_fn)(struct request *, void *, bool);

/**
 * struct blk_mq_ops - Callback functions that implements block driver
 * behaviour.
 */
struct blk_mq_ops {
        /**
         * @queue_rq: Queue a new request from block IO.
         */
        blk_status_t (*queue_rq)(struct blk_mq_hw_ctx *,
                                 const struct blk_mq_queue_data *);

        /**
         * @commit_rqs: If a driver uses bd->last to judge when to submit
         * requests to hardware, it must define this function. In case of errors
         * that make us stop issuing further requests, this hook serves the
         * purpose of kicking the hardware (which the last request otherwise
         * would have done).
         */
        void (*commit_rqs)(struct blk_mq_hw_ctx *);

        /**
         * @get_budget: Reserve budget before queue request, once .queue_rq is
         * run, it is driver's responsibility to release the
         * reserved budget. Also we have to handle failure case
         * of .get_budget for avoiding I/O deadlock.
         */
        int (*get_budget)(struct request_queue *);

        /**
         * @put_budget: Release the reserved budget.
         */
        void (*put_budget)(struct request_queue *, int);

        /**
         * @set_rq_budget_token: store rq's budget token
         */
        void (*set_rq_budget_token)(struct request *, int);
        /**
         * @get_rq_budget_token: retrieve rq's budget token
         */
        int (*get_rq_budget_token)(struct request *);

        /**
         * @timeout: Called on request timeout.
         */
        enum blk_eh_timer_return (*timeout)(struct request *, bool);

        /**
         * @poll: Called to poll for completion of a specific tag.
         */
        int (*poll)(struct blk_mq_hw_ctx *);

        /**
         * @complete: Mark the request as complete.
         */
        void (*complete)(struct request *);

        /**
         * @init_hctx: Called when the block layer side of a hardware queue has
         * been set up, allowing the driver to allocate/init matching
         * structures.
         */
        int (*init_hctx)(struct blk_mq_hw_ctx *, void *, unsigned int);
        /**
         * @exit_hctx: Ditto for exit/teardown.
         */
        void (*exit_hctx)(struct blk_mq_hw_ctx *, unsigned int);

        /**
         * @init_request: Called for every command allocated by the block layer
         * to allow the driver to set up driver specific data.
         *
         * Tag greater than or equal to queue_depth is for setting up
         * flush request.
         */
        int (*init_request)(struct blk_mq_tag_set *set, struct request *,
                            unsigned int, unsigned int);
        /**
         * @exit_request: Ditto for exit/teardown.
         */
        void (*exit_request)(struct blk_mq_tag_set *set, struct request *,
                             unsigned int);

        /**
         * @initialize_rq_fn: Called from inside blk_get_request().
         */
        void (*initialize_rq_fn)(struct request *rq);

        /**
         * @cleanup_rq: Called before freeing one request which isn't completed
         * yet, and usually for freeing the driver private data.
         */
        void (*cleanup_rq)(struct request *);

        /**
         * @busy: If set, returns whether or not this queue currently is busy.
         */
        bool (*busy)(struct request_queue *);

        /**
         * @map_queues: This allows drivers specify their own queue mapping by
         * overriding the setup-time function that builds the mq_map.
         */
        int (*map_queues)(struct blk_mq_tag_set *set);

#ifdef CONFIG_BLK_DEBUG_FS
        /**
         * @show_rq: Used by the debugfs implementation to show driver-specific
         * information about a request.
         */
        void (*show_rq)(struct seq_file *m, struct request *rq);
#endif
};

enum {
        BLK_MQ_F_SHOULD_MERGE   = 1 << 0,
        BLK_MQ_F_TAG_QUEUE_SHARED = 1 << 1,
        /*
         * Set when this device requires underlying blk-mq device for
         * completing IO:
         */
        BLK_MQ_F_STACKING       = 1 << 2,
        BLK_MQ_F_TAG_HCTX_SHARED = 1 << 3,
        BLK_MQ_F_BLOCKING       = 1 << 5,
        BLK_MQ_F_NO_SCHED       = 1 << 6,
        BLK_MQ_F_ALLOC_POLICY_START_BIT = 8,
        BLK_MQ_F_ALLOC_POLICY_BITS = 1,

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

        /* hw queue is inactive after all its CPUs become offline */
        BLK_MQ_S_INACTIVE       = 3,

        BLK_MQ_MAX_DEPTH        = 10240,

        BLK_MQ_CPU_WORK_BATCH   = 8,
};
#define BLK_MQ_FLAG_TO_ALLOC_POLICY(flags) \
        ((flags >> BLK_MQ_F_ALLOC_POLICY_START_BIT) & \
                ((1 << BLK_MQ_F_ALLOC_POLICY_BITS) - 1))
#define BLK_ALLOC_POLICY_TO_MQ_FLAG(policy) \
        ((policy & ((1 << BLK_MQ_F_ALLOC_POLICY_BITS) - 1)) \
                << BLK_MQ_F_ALLOC_POLICY_START_BIT)

#define blk_mq_alloc_disk(set, queuedata)                               \
({                                                                      \
        static struct lock_class_key __key;                             \
        struct gendisk *__disk = __blk_mq_alloc_disk(set, queuedata);   \
                                                                        \
        if (!IS_ERR(__disk))                                            \
                lockdep_init_map(&__disk->lockdep_map,                  \
                        "(bio completion)", &__key, 0);                 \
        __disk;                                                         \
})
struct gendisk *__blk_mq_alloc_disk(struct blk_mq_tag_set *set,
                void *queuedata);
struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *);
int blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
                struct request_queue *q);
void blk_mq_unregister_dev(struct device *, struct request_queue *);

int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set);
int blk_mq_alloc_sq_tag_set(struct blk_mq_tag_set *set,
                const struct blk_mq_ops *ops, unsigned int queue_depth,
                unsigned int set_flags);
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_free_request(struct request *rq);

bool blk_mq_queue_inflight(struct request_queue *q);

enum {
        /* return when out of requests */
        BLK_MQ_REQ_NOWAIT       = (__force blk_mq_req_flags_t)(1 << 0),
        /* allocate from reserved pool */
        BLK_MQ_REQ_RESERVED     = (__force blk_mq_req_flags_t)(1 << 1),
        /* set RQF_PM */
        BLK_MQ_REQ_PM           = (__force blk_mq_req_flags_t)(1 << 2),
};

struct request *blk_mq_alloc_request(struct request_queue *q, unsigned int op,
                blk_mq_req_flags_t flags);
struct request *blk_mq_alloc_request_hctx(struct request_queue *q,
                unsigned int op, blk_mq_req_flags_t flags,
                unsigned int hctx_idx);
struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag);

enum {
        BLK_MQ_UNIQUE_TAG_BITS = 16,
        BLK_MQ_UNIQUE_TAG_MASK = (1 << BLK_MQ_UNIQUE_TAG_BITS) - 1,
};

u32 blk_mq_unique_tag(struct request *rq);

static inline u16 blk_mq_unique_tag_to_hwq(u32 unique_tag)
{
        return unique_tag >> BLK_MQ_UNIQUE_TAG_BITS;
}

static inline u16 blk_mq_unique_tag_to_tag(u32 unique_tag)
{
        return unique_tag & BLK_MQ_UNIQUE_TAG_MASK;
}

/**
 * blk_mq_rq_state() - read the current MQ_RQ_* state of a request
 * @rq: target request.
 */
static inline enum mq_rq_state blk_mq_rq_state(struct request *rq)
{
        return READ_ONCE(rq->state);
}

static inline int blk_mq_request_started(struct request *rq)
{
        return blk_mq_rq_state(rq) != MQ_RQ_IDLE;
}

static inline int blk_mq_request_completed(struct request *rq)
{
        return blk_mq_rq_state(rq) == MQ_RQ_COMPLETE;
}

/*
 * 
 * Set the state to complete when completing a request from inside ->queue_rq.
 * This is used by drivers that want to ensure special complete actions that
 * need access to the request are called on failure, e.g. by nvme for
 * multipathing.
 */
static inline void blk_mq_set_request_complete(struct request *rq)
{
        WRITE_ONCE(rq->state, MQ_RQ_COMPLETE);
}

void blk_mq_start_request(struct request *rq);
void blk_mq_end_request(struct request *rq, blk_status_t error);
void __blk_mq_end_request(struct request *rq, blk_status_t error);

void blk_mq_requeue_request(struct request *rq, bool kick_requeue_list);
void blk_mq_kick_requeue_list(struct request_queue *q);
void blk_mq_delay_kick_requeue_list(struct request_queue *q, unsigned long msecs);
void blk_mq_complete_request(struct request *rq);
bool blk_mq_complete_request_remote(struct request *rq);
bool blk_mq_queue_stopped(struct request_queue *q);
void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx);
void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx);
void blk_mq_stop_hw_queues(struct request_queue *q);
void blk_mq_start_hw_queues(struct request_queue *q);
void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx *hctx, bool async);
void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async);
void blk_mq_quiesce_queue(struct request_queue *q);
void blk_mq_unquiesce_queue(struct request_queue *q);
void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs);
void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async);
void blk_mq_run_hw_queues(struct request_queue *q, bool async);
void blk_mq_delay_run_hw_queues(struct request_queue *q, unsigned long msecs);
void blk_mq_tagset_busy_iter(struct blk_mq_tag_set *tagset,
                busy_tag_iter_fn *fn, void *priv);
void blk_mq_tagset_wait_completed_request(struct blk_mq_tag_set *tagset);
void blk_mq_freeze_queue(struct request_queue *q);
void blk_mq_unfreeze_queue(struct request_queue *q);
void blk_freeze_queue_start(struct request_queue *q);
void blk_mq_freeze_queue_wait(struct request_queue *q);
int blk_mq_freeze_queue_wait_timeout(struct request_queue *q,
                                     unsigned long timeout);

int blk_mq_map_queues(struct blk_mq_queue_map *qmap);
void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues);

void blk_mq_quiesce_queue_nowait(struct request_queue *q);

unsigned int blk_mq_rq_cpu(struct request *rq);

bool __blk_should_fake_timeout(struct request_queue *q);
static inline bool blk_should_fake_timeout(struct request_queue *q)
{
        if (IS_ENABLED(CONFIG_FAIL_IO_TIMEOUT) &&
            test_bit(QUEUE_FLAG_FAIL_IO, &q->queue_flags))
                return __blk_should_fake_timeout(q);
        return false;
}

/**
 * blk_mq_rq_from_pdu - cast a PDU to a request
 * @pdu: the PDU (Protocol Data Unit) to be casted
 *
 * Return: request
 *
 * Driver command data is immediately after the request. So subtract request
 * size to get back to the original request.
 */
static inline struct request *blk_mq_rq_from_pdu(void *pdu)
{
        return pdu - sizeof(struct request);
}

/**
 * blk_mq_rq_to_pdu - cast a request to a PDU
 * @rq: the request to be casted
 *
 * Return: pointer to the PDU
 *
 * Driver command data is immediately after the request. So add request to get
 * the PDU.
 */
static inline void *blk_mq_rq_to_pdu(struct request *rq)
{
        return rq + 1;
}

#define queue_for_each_hw_ctx(q, hctx, i)                               \
        for ((i) = 0; (i) < (q)->nr_hw_queues &&                        \
             ({ hctx = (q)->queue_hw_ctx[i]; 1; }); (i)++)

#define hctx_for_each_ctx(hctx, ctx, i)                                 \
        for ((i) = 0; (i) < (hctx)->nr_ctx &&                           \
             ({ ctx = (hctx)->ctxs[(i)]; 1; }); (i)++)

static inline blk_qc_t request_to_qc_t(struct blk_mq_hw_ctx *hctx,
                struct request *rq)
{
        if (rq->tag != -1)
                return rq->tag | (hctx->queue_num << BLK_QC_T_SHIFT);

        return rq->internal_tag | (hctx->queue_num << BLK_QC_T_SHIFT) |
                        BLK_QC_T_INTERNAL;
}

static inline void blk_mq_cleanup_rq(struct request *rq)
{
        if (rq->q->mq_ops->cleanup_rq)
                rq->q->mq_ops->cleanup_rq(rq);
}

static inline void blk_rq_bio_prep(struct request *rq, struct bio *bio,
                unsigned int nr_segs)
{
        rq->nr_phys_segments = nr_segs;
        rq->__data_len = bio->bi_iter.bi_size;
        rq->bio = rq->biotail = bio;
        rq->ioprio = bio_prio(bio);

        if (bio->bi_bdev)
                rq->rq_disk = bio->bi_bdev->bd_disk;
}

blk_qc_t blk_mq_submit_bio(struct bio *bio);
void blk_mq_hctx_set_fq_lock_class(struct blk_mq_hw_ctx *hctx,
                struct lock_class_key *key);

#endif