blk-mq.h

   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef BLK_MQ_H
   3#define BLK_MQ_H
   4
   5#include <linux/blkdev.h>
   6#include <linux/sbitmap.h>
   7#include <linux/lockdep.h>
   8#include <linux/scatterlist.h>
   9#include <linux/prefetch.h>
  10#include <linux/srcu.h>
  11#include <linux/rw_hint.h>
  12#include <linux/rwsem.h>
  13
  14struct blk_mq_tags;
  15struct blk_flush_queue;
  16
  17#define BLKDEV_MIN_RQ	4
  18#define BLKDEV_DEFAULT_RQ	128
  19
  20enum rq_end_io_ret {
  21	RQ_END_IO_NONE,
  22	RQ_END_IO_FREE,
  23};
  24
  25typedef enum rq_end_io_ret (rq_end_io_fn)(struct request *, blk_status_t);
  26
  27/*
  28 * request flags */
  29typedef __u32 __bitwise req_flags_t;
  30
  31/* Keep rqf_name[] in sync with the definitions below */
  32enum rqf_flags {
  33	/* drive already may have started this one */
  34	__RQF_STARTED,
  35	/* request for flush sequence */
  36	__RQF_FLUSH_SEQ,
  37	/* merge of different types, fail separately */
  38	__RQF_MIXED_MERGE,
  39	/* don't call prep for this one */
  40	__RQF_DONTPREP,
  41	/* use hctx->sched_tags */
  42	__RQF_SCHED_TAGS,
  43	/* use an I/O scheduler for this request */
  44	__RQF_USE_SCHED,
  45	/* vaguely specified driver internal error.  Ignored by block layer */
  46	__RQF_FAILED,
  47	/* don't warn about errors */
  48	__RQF_QUIET,
  49	/* account into disk and partition IO statistics */
  50	__RQF_IO_STAT,
  51	/* runtime pm request */
  52	__RQF_PM,
  53	/* on IO scheduler merge hash */
  54	__RQF_HASHED,
  55	/* track IO completion time */
  56	__RQF_STATS,
  57	/* Look at ->special_vec for the actual data payload instead of the
  58	   bio chain. */
  59	__RQF_SPECIAL_PAYLOAD,
  60	/* request completion needs to be signaled to zone write plugging. */
  61	__RQF_ZONE_WRITE_PLUGGING,
  62	/* ->timeout has been called, don't expire again */
  63	__RQF_TIMED_OUT,
  64	__RQF_RESV,
  65	__RQF_BITS
  66};
  67
  68#define RQF_STARTED		((__force req_flags_t)(1 << __RQF_STARTED))
  69#define RQF_FLUSH_SEQ		((__force req_flags_t)(1 << __RQF_FLUSH_SEQ))
  70#define RQF_MIXED_MERGE		((__force req_flags_t)(1 << __RQF_MIXED_MERGE))
  71#define RQF_DONTPREP		((__force req_flags_t)(1 << __RQF_DONTPREP))
  72#define RQF_SCHED_TAGS		((__force req_flags_t)(1 << __RQF_SCHED_TAGS))
  73#define RQF_USE_SCHED		((__force req_flags_t)(1 << __RQF_USE_SCHED))
  74#define RQF_FAILED		((__force req_flags_t)(1 << __RQF_FAILED))
  75#define RQF_QUIET		((__force req_flags_t)(1 << __RQF_QUIET))
  76#define RQF_IO_STAT		((__force req_flags_t)(1 << __RQF_IO_STAT))
  77#define RQF_PM			((__force req_flags_t)(1 << __RQF_PM))
  78#define RQF_HASHED		((__force req_flags_t)(1 << __RQF_HASHED))
  79#define RQF_STATS		((__force req_flags_t)(1 << __RQF_STATS))
  80#define RQF_SPECIAL_PAYLOAD	\
  81			((__force req_flags_t)(1 << __RQF_SPECIAL_PAYLOAD))
  82#define RQF_ZONE_WRITE_PLUGGING	\
  83			((__force req_flags_t)(1 << __RQF_ZONE_WRITE_PLUGGING))
  84#define RQF_TIMED_OUT		((__force req_flags_t)(1 << __RQF_TIMED_OUT))
  85#define RQF_RESV		((__force req_flags_t)(1 << __RQF_RESV))
  86
  87/* flags that prevent us from merging requests: */
  88#define RQF_NOMERGE_FLAGS \
  89	(RQF_STARTED | RQF_FLUSH_SEQ | RQF_SPECIAL_PAYLOAD)
  90
  91enum mq_rq_state {
  92	MQ_RQ_IDLE		= 0,
  93	MQ_RQ_IN_FLIGHT		= 1,
  94	MQ_RQ_COMPLETE		= 2,
  95};
  96
  97/*
  98 * Try to put the fields that are referenced together in the same cacheline.
  99 *
 100 * If you modify this structure, make sure to update blk_rq_init() and
 101 * especially blk_mq_rq_ctx_init() to take care of the added fields.
 102 */
 103struct request {
 104	struct request_queue *q;
 105	struct blk_mq_ctx *mq_ctx;
 106	struct blk_mq_hw_ctx *mq_hctx;
 107
 108	blk_opf_t cmd_flags;		/* op and common flags */
 109	req_flags_t rq_flags;
 110
 111	int tag;
 112	int internal_tag;
 113
 114	unsigned int timeout;
 115
 116	/* the following two fields are internal, NEVER access directly */
 117	unsigned int __data_len;	/* total data len */
 118	sector_t __sector;		/* sector cursor */
 119
 120	struct bio *bio;
 121	struct bio *biotail;
 122
 123	union {
 124		struct list_head queuelist;
 125		struct request *rq_next;
 126	};
 127
 128	struct block_device *part;
 129#ifdef CONFIG_BLK_RQ_ALLOC_TIME
 130	/* Time that the first bio started allocating this request. */
 131	u64 alloc_time_ns;
 132#endif
 133	/* Time that this request was allocated for this IO. */
 134	u64 start_time_ns;
 135	/* Time that I/O was submitted to the device. */
 136	u64 io_start_time_ns;
 137
 138#ifdef CONFIG_BLK_WBT
 139	unsigned short wbt_flags;
 140#endif
 141	/*
 142	 * rq sectors used for blk stats. It has the same value
 143	 * with blk_rq_sectors(rq), except that it never be zeroed
 144	 * by completion.
 145	 */
 146	unsigned short stats_sectors;
 147
 148	/*
 149	 * Number of scatter-gather DMA addr+len pairs after
 150	 * physical address coalescing is performed.
 151	 */
 152	unsigned short nr_phys_segments;
 153	unsigned short nr_integrity_segments;
 154
 155	/*
 156	 * The lowest set bit for address gaps between physical segments. This
 157	 * provides information necessary for dma optimization opprotunities,
 158	 * like for testing if the segments can be coalesced against the
 159	 * device's iommu granule.
 160	 */
 161	unsigned char phys_gap_bit;
 162
 163#ifdef CONFIG_BLK_INLINE_ENCRYPTION
 164	struct bio_crypt_ctx *crypt_ctx;
 165	struct blk_crypto_keyslot *crypt_keyslot;
 166#endif
 167
 168	enum mq_rq_state state;
 169	atomic_t ref;
 170
 171	unsigned long deadline;
 172
 173	/*
 174	 * The hash is used inside the scheduler, and killed once the
 175	 * request reaches the dispatch list. The ipi_list is only used
 176	 * to queue the request for softirq completion, which is long
 177	 * after the request has been unhashed (and even removed from
 178	 * the dispatch list).
 179	 */
 180	union {
 181		struct hlist_node hash;	/* merge hash */
 182		struct llist_node ipi_list;
 183	};
 184
 185	/*
 186	 * The rb_node is only used inside the io scheduler, requests
 187	 * are pruned when moved to the dispatch queue. special_vec must
 188	 * only be used if RQF_SPECIAL_PAYLOAD is set, and those cannot be
 189	 * insert into an IO scheduler.
 190	 */
 191	union {
 192		struct rb_node rb_node;	/* sort/lookup */
 193		struct bio_vec special_vec;
 194	};
 195
 196	/*
 197	 * Three pointers are available for the IO schedulers, if they need
 198	 * more they have to dynamically allocate it.
 199	 */
 200	struct {
 201		struct io_cq		*icq;
 202		void			*priv[2];
 203	} elv;
 204
 205	struct {
 206		unsigned int		seq;
 207		rq_end_io_fn		*saved_end_io;
 208	} flush;
 209
 210	u64 fifo_time;
 211
 212	/*
 213	 * completion callback.
 214	 */
 215	rq_end_io_fn *end_io;
 216	void *end_io_data;
 217};
 218
 219/*
 220 * Returns a mask with all bits starting at req->phys_gap_bit set to 1.
 221 */
 222static inline unsigned long req_phys_gap_mask(const struct request *req)
 223{
 224	return ~(((1 << req->phys_gap_bit) >> 1) - 1);
 225}
 226
 227static inline enum req_op req_op(const struct request *req)
 228{
 229	return req->cmd_flags & REQ_OP_MASK;
 230}
 231
 232static inline bool blk_rq_is_passthrough(struct request *rq)
 233{
 234	return blk_op_is_passthrough(rq->cmd_flags);
 235}
 236
 237static inline unsigned short req_get_ioprio(struct request *req)
 238{
 239	if (req->bio)
 240		return req->bio->bi_ioprio;
 241	return 0;
 242}
 243
 244#define rq_data_dir(rq)		(op_is_write(req_op(rq)) ? WRITE : READ)
 245
 246#define rq_dma_dir(rq) \
 247	(op_is_write(req_op(rq)) ? DMA_TO_DEVICE : DMA_FROM_DEVICE)
 248
 249static inline int rq_list_empty(const struct rq_list *rl)
 250{
 251	return rl->head == NULL;
 252}
 253
 254static inline void rq_list_init(struct rq_list *rl)
 255{
 256	rl->head = NULL;
 257	rl->tail = NULL;
 258}
 259
 260static inline void rq_list_add_tail(struct rq_list *rl, struct request *rq)
 261{
 262	rq->rq_next = NULL;
 263	if (rl->tail)
 264		rl->tail->rq_next = rq;
 265	else
 266		rl->head = rq;
 267	rl->tail = rq;
 268}
 269
 270static inline void rq_list_add_head(struct rq_list *rl, struct request *rq)
 271{
 272	rq->rq_next = rl->head;
 273	rl->head = rq;
 274	if (!rl->tail)
 275		rl->tail = rq;
 276}
 277
 278static inline struct request *rq_list_pop(struct rq_list *rl)
 279{
 280	struct request *rq = rl->head;
 281
 282	if (rq) {
 283		rl->head = rl->head->rq_next;
 284		if (!rl->head)
 285			rl->tail = NULL;
 286		rq->rq_next = NULL;
 287	}
 288
 289	return rq;
 290}
 291
 292static inline struct request *rq_list_peek(struct rq_list *rl)
 293{
 294	return rl->head;
 295}
 296
 297#define rq_list_for_each(rl, pos)					\
 298	for (pos = rq_list_peek((rl)); (pos); pos = pos->rq_next)
 299
 300#define rq_list_for_each_safe(rl, pos, nxt)				\
 301	for (pos = rq_list_peek((rl)), nxt = pos->rq_next;		\
 302		pos; pos = nxt, nxt = pos ? pos->rq_next : NULL)
 303
 304/**
 305 * enum blk_eh_timer_return - How the timeout handler should proceed
 306 * @BLK_EH_DONE: The block driver completed the command or will complete it at
 307 *	a later time.
 308 * @BLK_EH_RESET_TIMER: Reset the request timer and continue waiting for the
 309 *	request to complete.
 310 */
 311enum blk_eh_timer_return {
 312	BLK_EH_DONE,
 313	BLK_EH_RESET_TIMER,
 314};
 315
 316/**
 317 * struct blk_mq_hw_ctx - State for a hardware queue facing the hardware
 318 * block device
 319 */
 320struct blk_mq_hw_ctx {
 321	struct {
 322		/** @lock: Protects the dispatch list. */
 323		spinlock_t		lock;
 324		/**
 325		 * @dispatch: Used for requests that are ready to be
 326		 * dispatched to the hardware but for some reason (e.g. lack of
 327		 * resources) could not be sent to the hardware. As soon as the
 328		 * driver can send new requests, requests at this list will
 329		 * be sent first for a fairer dispatch.
 330		 */
 331		struct list_head	dispatch;
 332		 /**
 333		  * @state: BLK_MQ_S_* flags. Defines the state of the hw
 334		  * queue (active, scheduled to restart, stopped).
 335		  */
 336		unsigned long		state;
 337	} ____cacheline_aligned_in_smp;
 338
 339	/**
 340	 * @run_work: Used for scheduling a hardware queue run at a later time.
 341	 */
 342	struct delayed_work	run_work;
 343	/** @cpumask: Map of available CPUs where this hctx can run. */
 344	cpumask_var_t		cpumask;
 345	/**
 346	 * @next_cpu: Used by blk_mq_hctx_next_cpu() for round-robin CPU
 347	 * selection from @cpumask.
 348	 */
 349	int			next_cpu;
 350	/**
 351	 * @next_cpu_batch: Counter of how many works left in the batch before
 352	 * changing to the next CPU.
 353	 */
 354	int			next_cpu_batch;
 355
 356	/** @flags: BLK_MQ_F_* flags. Defines the behaviour of the queue. */
 357	unsigned long		flags;
 358
 359	/**
 360	 * @sched_data: Pointer owned by the IO scheduler attached to a request
 361	 * queue. It's up to the IO scheduler how to use this pointer.
 362	 */
 363	void			*sched_data;
 364	/**
 365	 * @queue: Pointer to the request queue that owns this hardware context.
 366	 */
 367	struct request_queue	*queue;
 368	/** @fq: Queue of requests that need to perform a flush operation. */
 369	struct blk_flush_queue	*fq;
 370
 371	/**
 372	 * @driver_data: Pointer to data owned by the block driver that created
 373	 * this hctx
 374	 */
 375	void			*driver_data;
 376
 377	/**
 378	 * @ctx_map: Bitmap for each software queue. If bit is on, there is a
 379	 * pending request in that software queue.
 380	 */
 381	struct sbitmap		ctx_map;
 382
 383	/**
 384	 * @dispatch_from: Software queue to be used when no scheduler was
 385	 * selected.
 386	 */
 387	struct blk_mq_ctx	*dispatch_from;
 388	/**
 389	 * @dispatch_busy: Number used by blk_mq_update_dispatch_busy() to
 390	 * decide if the hw_queue is busy using Exponential Weighted Moving
 391	 * Average algorithm.
 392	 */
 393	unsigned int		dispatch_busy;
 394
 395	/** @type: HCTX_TYPE_* flags. Type of hardware queue. */
 396	unsigned short		type;
 397	/** @nr_ctx: Number of software queues. */
 398	unsigned short		nr_ctx;
 399	/** @ctxs: Array of software queues. */
 400	struct blk_mq_ctx	**ctxs;
 401
 402	/** @dispatch_wait_lock: Lock for dispatch_wait queue. */
 403	spinlock_t		dispatch_wait_lock;
 404	/**
 405	 * @dispatch_wait: Waitqueue to put requests when there is no tag
 406	 * available at the moment, to wait for another try in the future.
 407	 */
 408	wait_queue_entry_t	dispatch_wait;
 409
 410	/**
 411	 * @wait_index: Index of next available dispatch_wait queue to insert
 412	 * requests.
 413	 */
 414	atomic_t		wait_index;
 415
 416	/**
 417	 * @tags: Tags owned by the block driver. A tag at this set is only
 418	 * assigned when a request is dispatched from a hardware queue.
 419	 */
 420	struct blk_mq_tags	*tags;
 421	/**
 422	 * @sched_tags: Tags owned by I/O scheduler. If there is an I/O
 423	 * scheduler associated with a request queue, a tag is assigned when
 424	 * that request is allocated. Else, this member is not used.
 425	 */
 426	struct blk_mq_tags	*sched_tags;
 427
 428	/** @numa_node: NUMA node the storage adapter has been connected to. */
 429	unsigned int		numa_node;
 430	/** @queue_num: Index of this hardware queue. */
 431	unsigned int		queue_num;
 432
 433	/**
 434	 * @nr_active: Number of active requests. Only used when a tag set is
 435	 * shared across request queues.
 436	 */
 437	atomic_t		nr_active;
 438
 439	/** @cpuhp_online: List to store request if CPU is going to die */
 440	struct hlist_node	cpuhp_online;
 441	/** @cpuhp_dead: List to store request if some CPU die. */
 442	struct hlist_node	cpuhp_dead;
 443	/** @kobj: Kernel object for sysfs. */
 444	struct kobject		kobj;
 445
 446#ifdef CONFIG_BLK_DEBUG_FS
 447	/**
 448	 * @debugfs_dir: debugfs directory for this hardware queue. Named
 449	 * as cpu<cpu_number>.
 450	 */
 451	struct dentry		*debugfs_dir;
 452	/** @sched_debugfs_dir:	debugfs directory for the scheduler. */
 453	struct dentry		*sched_debugfs_dir;
 454#endif
 455
 456	/**
 457	 * @hctx_list: if this hctx is not in use, this is an entry in
 458	 * q->unused_hctx_list.
 459	 */
 460	struct list_head	hctx_list;
 461};
 462
 463/**
 464 * struct blk_mq_queue_map - Map software queues to hardware queues
 465 * @mq_map:       CPU ID to hardware queue index map. This is an array
 466 *	with nr_cpu_ids elements. Each element has a value in the range
 467 *	[@queue_offset, @queue_offset + @nr_queues).
 468 * @nr_queues:    Number of hardware queues to map CPU IDs onto.
 469 * @queue_offset: First hardware queue to map onto. Used by the PCIe NVMe
 470 *	driver to map each hardware queue type (enum hctx_type) onto a distinct
 471 *	set of hardware queues.
 472 */
 473struct blk_mq_queue_map {
 474	unsigned int *mq_map;
 475	unsigned int nr_queues;
 476	unsigned int queue_offset;
 477};
 478
 479/**
 480 * enum hctx_type - Type of hardware queue
 481 * @HCTX_TYPE_DEFAULT:	All I/O not otherwise accounted for.
 482 * @HCTX_TYPE_READ:	Just for READ I/O.
 483 * @HCTX_TYPE_POLL:	Polled I/O of any kind.
 484 * @HCTX_MAX_TYPES:	Number of types of hctx.
 485 */
 486enum hctx_type {
 487	HCTX_TYPE_DEFAULT,
 488	HCTX_TYPE_READ,
 489	HCTX_TYPE_POLL,
 490
 491	HCTX_MAX_TYPES,
 492};
 493
 494/**
 495 * struct blk_mq_tag_set - tag set that can be shared between request queues
 496 * @ops:	   Pointers to functions that implement block driver behavior.
 497 * @map:	   One or more ctx -> hctx mappings. One map exists for each
 498 *		   hardware queue type (enum hctx_type) that the driver wishes
 499 *		   to support. There are no restrictions on maps being of the
 500 *		   same size, and it's perfectly legal to share maps between
 501 *		   types.
 502 * @nr_maps:	   Number of elements in the @map array. A number in the range
 503 *		   [1, HCTX_MAX_TYPES].
 504 * @nr_hw_queues:  Number of hardware queues supported by the block driver that
 505 *		   owns this data structure.
 506 * @queue_depth:   Number of tags per hardware queue, reserved tags included.
 507 * @reserved_tags: Number of tags to set aside for BLK_MQ_REQ_RESERVED tag
 508 *		   allocations.
 509 * @cmd_size:	   Number of additional bytes to allocate per request. The block
 510 *		   driver owns these additional bytes.
 511 * @numa_node:	   NUMA node the storage adapter has been connected to.
 512 * @timeout:	   Request processing timeout in jiffies.
 513 * @flags:	   Zero or more BLK_MQ_F_* flags.
 514 * @driver_data:   Pointer to data owned by the block driver that created this
 515 *		   tag set.
 516 * @tags:	   Tag sets. One tag set per hardware queue. Has @nr_hw_queues
 517 *		   elements.
 518 * @shared_tags:
 519 *		   Shared set of tags. Has @nr_hw_queues elements. If set,
 520 *		   shared by all @tags.
 521 * @tag_list_lock: Serializes tag_list accesses.
 522 * @tag_list:	   List of the request queues that use this tag set. See also
 523 *		   request_queue.tag_set_list.
 524 * @srcu:	   Use as lock when type of the request queue is blocking
 525 *		   (BLK_MQ_F_BLOCKING).
 526 * @tags_srcu:	   SRCU used to defer freeing of tags page_list to prevent
 527 *		   use-after-free when iterating tags.
 528 * @update_nr_hwq_lock:
 529 * 		   Synchronize updating nr_hw_queues with add/del disk &
 530 * 		   switching elevator.
 531 */
 532struct blk_mq_tag_set {
 533	const struct blk_mq_ops	*ops;
 534	struct blk_mq_queue_map	map[HCTX_MAX_TYPES];
 535	unsigned int		nr_maps;
 536	unsigned int		nr_hw_queues;
 537	unsigned int		queue_depth;
 538	unsigned int		reserved_tags;
 539	unsigned int		cmd_size;
 540	int			numa_node;
 541	unsigned int		timeout;
 542	unsigned int		flags;
 543	void			*driver_data;
 544
 545	struct blk_mq_tags	**tags;
 546
 547	struct blk_mq_tags	*shared_tags;
 548
 549	struct mutex		tag_list_lock;
 550	struct list_head	tag_list;
 551	struct srcu_struct	*srcu;
 552	struct srcu_struct	tags_srcu;
 553
 554	struct rw_semaphore	update_nr_hwq_lock;
 555};
 556
 557/**
 558 * struct blk_mq_queue_data - Data about a request inserted in a queue
 559 *
 560 * @rq:   Request pointer.
 561 * @last: If it is the last request in the queue.
 562 */
 563struct blk_mq_queue_data {
 564	struct request *rq;
 565	bool last;
 566};
 567
 568typedef bool (busy_tag_iter_fn)(struct request *, void *);
 569
 570/**
 571 * struct blk_mq_ops - Callback functions that implements block driver
 572 * behaviour.
 573 */
 574struct blk_mq_ops {
 575	/**
 576	 * @queue_rq: Queue a new request from block IO.
 577	 */
 578	blk_status_t (*queue_rq)(struct blk_mq_hw_ctx *,
 579				 const struct blk_mq_queue_data *);
 580
 581	/**
 582	 * @commit_rqs: If a driver uses bd->last to judge when to submit
 583	 * requests to hardware, it must define this function. In case of errors
 584	 * that make us stop issuing further requests, this hook serves the
 585	 * purpose of kicking the hardware (which the last request otherwise
 586	 * would have done).
 587	 */
 588	void (*commit_rqs)(struct blk_mq_hw_ctx *);
 589
 590	/**
 591	 * @queue_rqs: Queue a list of new requests. Driver is guaranteed
 592	 * that each request belongs to the same queue. If the driver doesn't
 593	 * empty the @rqlist completely, then the rest will be queued
 594	 * individually by the block layer upon return.
 595	 */
 596	void (*queue_rqs)(struct rq_list *rqlist);
 597
 598	/**
 599	 * @get_budget: Reserve budget before queue request, once .queue_rq is
 600	 * run, it is driver's responsibility to release the
 601	 * reserved budget. Also we have to handle failure case
 602	 * of .get_budget for avoiding I/O deadlock.
 603	 */
 604	int (*get_budget)(struct request_queue *);
 605
 606	/**
 607	 * @put_budget: Release the reserved budget.
 608	 */
 609	void (*put_budget)(struct request_queue *, int);
 610
 611	/**
 612	 * @set_rq_budget_token: store rq's budget token
 613	 */
 614	void (*set_rq_budget_token)(struct request *, int);
 615	/**
 616	 * @get_rq_budget_token: retrieve rq's budget token
 617	 */
 618	int (*get_rq_budget_token)(struct request *);
 619
 620	/**
 621	 * @timeout: Called on request timeout.
 622	 */
 623	enum blk_eh_timer_return (*timeout)(struct request *);
 624
 625	/**
 626	 * @poll: Called to poll for completion of a specific tag.
 627	 */
 628	int (*poll)(struct blk_mq_hw_ctx *, struct io_comp_batch *);
 629
 630	/**
 631	 * @complete: Mark the request as complete.
 632	 */
 633	void (*complete)(struct request *);
 634
 635	/**
 636	 * @init_hctx: Called when the block layer side of a hardware queue has
 637	 * been set up, allowing the driver to allocate/init matching
 638	 * structures.
 639	 */
 640	int (*init_hctx)(struct blk_mq_hw_ctx *, void *, unsigned int);
 641	/**
 642	 * @exit_hctx: Ditto for exit/teardown.
 643	 */
 644	void (*exit_hctx)(struct blk_mq_hw_ctx *, unsigned int);
 645
 646	/**
 647	 * @init_request: Called for every command allocated by the block layer
 648	 * to allow the driver to set up driver specific data.
 649	 *
 650	 * Tag greater than or equal to queue_depth is for setting up
 651	 * flush request.
 652	 */
 653	int (*init_request)(struct blk_mq_tag_set *set, struct request *,
 654			    unsigned int, unsigned int);
 655	/**
 656	 * @exit_request: Ditto for exit/teardown.
 657	 */
 658	void (*exit_request)(struct blk_mq_tag_set *set, struct request *,
 659			     unsigned int);
 660
 661	/**
 662	 * @cleanup_rq: Called before freeing one request which isn't completed
 663	 * yet, and usually for freeing the driver private data.
 664	 */
 665	void (*cleanup_rq)(struct request *);
 666
 667	/**
 668	 * @busy: If set, returns whether or not this queue currently is busy.
 669	 */
 670	bool (*busy)(struct request_queue *);
 671
 672	/**
 673	 * @map_queues: This allows drivers specify their own queue mapping by
 674	 * overriding the setup-time function that builds the mq_map.
 675	 */
 676	void (*map_queues)(struct blk_mq_tag_set *set);
 677
 678#ifdef CONFIG_BLK_DEBUG_FS
 679	/**
 680	 * @show_rq: Used by the debugfs implementation to show driver-specific
 681	 * information about a request.
 682	 */
 683	void (*show_rq)(struct seq_file *m, struct request *rq);
 684#endif
 685};
 686
 687/* Keep hctx_flag_name[] in sync with the definitions below */
 688enum {
 689	BLK_MQ_F_TAG_QUEUE_SHARED = 1 << 1,
 690	/*
 691	 * Set when this device requires underlying blk-mq device for
 692	 * completing IO:
 693	 */
 694	BLK_MQ_F_STACKING	= 1 << 2,
 695	BLK_MQ_F_TAG_HCTX_SHARED = 1 << 3,
 696	BLK_MQ_F_BLOCKING	= 1 << 4,
 697
 698	/*
 699	 * Alloc tags on a round-robin base instead of the first available one.
 700	 */
 701	BLK_MQ_F_TAG_RR		= 1 << 5,
 702
 703	/*
 704	 * Select 'none' during queue registration in case of a single hwq
 705	 * or shared hwqs instead of 'mq-deadline'.
 706	 */
 707	BLK_MQ_F_NO_SCHED_BY_DEFAULT	= 1 << 6,
 708
 709	BLK_MQ_F_MAX = 1 << 7,
 710};
 711
 712#define BLK_MQ_MAX_DEPTH	(10240)
 713#define BLK_MQ_NO_HCTX_IDX	(-1U)
 714
 715enum {
 716	/* Keep hctx_state_name[] in sync with the definitions below */
 717	BLK_MQ_S_STOPPED,
 718	BLK_MQ_S_TAG_ACTIVE,
 719	BLK_MQ_S_SCHED_RESTART,
 720	/* hw queue is inactive after all its CPUs become offline */
 721	BLK_MQ_S_INACTIVE,
 722	BLK_MQ_S_MAX
 723};
 724
 725struct gendisk *__blk_mq_alloc_disk(struct blk_mq_tag_set *set,
 726		struct queue_limits *lim, void *queuedata,
 727		struct lock_class_key *lkclass);
 728#define blk_mq_alloc_disk(set, lim, queuedata)				\
 729({									\
 730	static struct lock_class_key __key;				\
 731									\
 732	__blk_mq_alloc_disk(set, lim, queuedata, &__key);		\
 733})
 734struct gendisk *blk_mq_alloc_disk_for_queue(struct request_queue *q,
 735		struct lock_class_key *lkclass);
 736struct request_queue *blk_mq_alloc_queue(struct blk_mq_tag_set *set,
 737		struct queue_limits *lim, void *queuedata);
 738int blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
 739		struct request_queue *q);
 740void blk_mq_destroy_queue(struct request_queue *);
 741
 742int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set);
 743int blk_mq_alloc_sq_tag_set(struct blk_mq_tag_set *set,
 744		const struct blk_mq_ops *ops, unsigned int queue_depth,
 745		unsigned int set_flags);
 746void blk_mq_free_tag_set(struct blk_mq_tag_set *set);
 747
 748void blk_mq_free_request(struct request *rq);
 749int blk_rq_poll(struct request *rq, struct io_comp_batch *iob,
 750		unsigned int poll_flags);
 751
 752bool blk_mq_queue_inflight(struct request_queue *q);
 753
 754enum {
 755	/* return when out of requests */
 756	BLK_MQ_REQ_NOWAIT	= (__force blk_mq_req_flags_t)(1 << 0),
 757	/* allocate from reserved pool */
 758	BLK_MQ_REQ_RESERVED	= (__force blk_mq_req_flags_t)(1 << 1),
 759	/* set RQF_PM */
 760	BLK_MQ_REQ_PM		= (__force blk_mq_req_flags_t)(1 << 2),
 761};
 762
 763struct request *blk_mq_alloc_request(struct request_queue *q, blk_opf_t opf,
 764		blk_mq_req_flags_t flags);
 765struct request *blk_mq_alloc_request_hctx(struct request_queue *q,
 766		blk_opf_t opf, blk_mq_req_flags_t flags,
 767		unsigned int hctx_idx);
 768
 769/*
 770 * Tag address space map.
 771 */
 772struct blk_mq_tags {
 773	unsigned int nr_tags;
 774	unsigned int nr_reserved_tags;
 775	unsigned int active_queues;
 776
 777	struct sbitmap_queue bitmap_tags;
 778	struct sbitmap_queue breserved_tags;
 779
 780	struct request **rqs;
 781	struct request **static_rqs;
 782	struct list_head page_list;
 783
 784	/*
 785	 * used to clear request reference in rqs[] before freeing one
 786	 * request pool
 787	 */
 788	spinlock_t lock;
 789	struct rcu_head rcu_head;
 790};
 791
 792static inline struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags,
 793					       unsigned int tag)
 794{
 795	if (tag < tags->nr_tags) {
 796		prefetch(tags->rqs[tag]);
 797		return tags->rqs[tag];
 798	}
 799
 800	return NULL;
 801}
 802
 803enum {
 804	BLK_MQ_UNIQUE_TAG_BITS = 16,
 805	BLK_MQ_UNIQUE_TAG_MASK = (1 << BLK_MQ_UNIQUE_TAG_BITS) - 1,
 806};
 807
 808u32 blk_mq_unique_tag(struct request *rq);
 809
 810static inline u16 blk_mq_unique_tag_to_hwq(u32 unique_tag)
 811{
 812	return unique_tag >> BLK_MQ_UNIQUE_TAG_BITS;
 813}
 814
 815static inline u16 blk_mq_unique_tag_to_tag(u32 unique_tag)
 816{
 817	return unique_tag & BLK_MQ_UNIQUE_TAG_MASK;
 818}
 819
 820/**
 821 * blk_mq_rq_state() - read the current MQ_RQ_* state of a request
 822 * @rq: target request.
 823 */
 824static inline enum mq_rq_state blk_mq_rq_state(struct request *rq)
 825{
 826	return READ_ONCE(rq->state);
 827}
 828
 829static inline int blk_mq_request_started(struct request *rq)
 830{
 831	return blk_mq_rq_state(rq) != MQ_RQ_IDLE;
 832}
 833
 834static inline int blk_mq_request_completed(struct request *rq)
 835{
 836	return blk_mq_rq_state(rq) == MQ_RQ_COMPLETE;
 837}
 838
 839/*
 840 * 
 841 * Set the state to complete when completing a request from inside ->queue_rq.
 842 * This is used by drivers that want to ensure special complete actions that
 843 * need access to the request are called on failure, e.g. by nvme for
 844 * multipathing.
 845 */
 846static inline void blk_mq_set_request_complete(struct request *rq)
 847{
 848	WRITE_ONCE(rq->state, MQ_RQ_COMPLETE);
 849}
 850
 851/*
 852 * Complete the request directly instead of deferring it to softirq or
 853 * completing it another CPU. Useful in preemptible instead of an interrupt.
 854 */
 855static inline void blk_mq_complete_request_direct(struct request *rq,
 856		   void (*complete)(struct request *rq))
 857{
 858	WRITE_ONCE(rq->state, MQ_RQ_COMPLETE);
 859	complete(rq);
 860}
 861
 862void blk_mq_start_request(struct request *rq);
 863void blk_mq_end_request(struct request *rq, blk_status_t error);
 864void __blk_mq_end_request(struct request *rq, blk_status_t error);
 865void blk_mq_end_request_batch(struct io_comp_batch *ib);
 866
 867/*
 868 * Only need start/end time stamping if we have iostat or
 869 * blk stats enabled, or using an IO scheduler.
 870 */
 871static inline bool blk_mq_need_time_stamp(struct request *rq)
 872{
 873	return (rq->rq_flags & (RQF_IO_STAT | RQF_STATS | RQF_USE_SCHED));
 874}
 875
 876static inline bool blk_mq_is_reserved_rq(struct request *rq)
 877{
 878	return rq->rq_flags & RQF_RESV;
 879}
 880
 881/**
 882 * blk_mq_add_to_batch() - add a request to the completion batch
 883 * @req: The request to add to batch
 884 * @iob: The batch to add the request
 885 * @is_error: Specify true if the request failed with an error
 886 * @complete: The completaion handler for the request
 887 *
 888 * Batched completions only work when there is no I/O error and no special
 889 * ->end_io handler.
 890 *
 891 * Return: true when the request was added to the batch, otherwise false
 892 */
 893static inline bool blk_mq_add_to_batch(struct request *req,
 894				       struct io_comp_batch *iob, bool is_error,
 895				       void (*complete)(struct io_comp_batch *))
 896{
 897	/*
 898	 * Check various conditions that exclude batch processing:
 899	 * 1) No batch container
 900	 * 2) Has scheduler data attached
 901	 * 3) Not a passthrough request and end_io set
 902	 * 4) Not a passthrough request and failed with an error
 903	 */
 904	if (!iob)
 905		return false;
 906	if (req->rq_flags & RQF_SCHED_TAGS)
 907		return false;
 908	if (!blk_rq_is_passthrough(req)) {
 909		if (req->end_io)
 910			return false;
 911		if (is_error)
 912			return false;
 913	}
 914
 915	if (!iob->complete)
 916		iob->complete = complete;
 917	else if (iob->complete != complete)
 918		return false;
 919	iob->need_ts |= blk_mq_need_time_stamp(req);
 920	rq_list_add_tail(&iob->req_list, req);
 921	return true;
 922}
 923
 924void blk_mq_requeue_request(struct request *rq, bool kick_requeue_list);
 925void blk_mq_kick_requeue_list(struct request_queue *q);
 926void blk_mq_delay_kick_requeue_list(struct request_queue *q, unsigned long msecs);
 927void blk_mq_complete_request(struct request *rq);
 928bool blk_mq_complete_request_remote(struct request *rq);
 929void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx);
 930void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx);
 931void blk_mq_stop_hw_queues(struct request_queue *q);
 932void blk_mq_start_hw_queues(struct request_queue *q);
 933void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx *hctx, bool async);
 934void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async);
 935void blk_mq_quiesce_queue(struct request_queue *q);
 936void blk_mq_wait_quiesce_done(struct blk_mq_tag_set *set);
 937void blk_mq_quiesce_tagset(struct blk_mq_tag_set *set);
 938void blk_mq_unquiesce_tagset(struct blk_mq_tag_set *set);
 939void blk_mq_unquiesce_queue(struct request_queue *q);
 940void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs);
 941void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async);
 942void blk_mq_run_hw_queues(struct request_queue *q, bool async);
 943void blk_mq_delay_run_hw_queues(struct request_queue *q, unsigned long msecs);
 944void blk_mq_tagset_busy_iter(struct blk_mq_tag_set *tagset,
 945		busy_tag_iter_fn *fn, void *priv);
 946void blk_mq_tagset_wait_completed_request(struct blk_mq_tag_set *tagset);
 947void blk_mq_freeze_queue_nomemsave(struct request_queue *q);
 948void blk_mq_unfreeze_queue_nomemrestore(struct request_queue *q);
 949static inline unsigned int __must_check
 950blk_mq_freeze_queue(struct request_queue *q)
 951{
 952	unsigned int memflags = memalloc_noio_save();
 953
 954	blk_mq_freeze_queue_nomemsave(q);
 955	return memflags;
 956}
 957static inline void
 958blk_mq_unfreeze_queue(struct request_queue *q, unsigned int memflags)
 959{
 960	blk_mq_unfreeze_queue_nomemrestore(q);
 961	memalloc_noio_restore(memflags);
 962}
 963void blk_freeze_queue_start(struct request_queue *q);
 964void blk_mq_freeze_queue_wait(struct request_queue *q);
 965int blk_mq_freeze_queue_wait_timeout(struct request_queue *q,
 966				     unsigned long timeout);
 967void blk_mq_unfreeze_queue_non_owner(struct request_queue *q);
 968void blk_freeze_queue_start_non_owner(struct request_queue *q);
 969
 970unsigned int blk_mq_num_possible_queues(unsigned int max_queues);
 971unsigned int blk_mq_num_online_queues(unsigned int max_queues);
 972void blk_mq_map_queues(struct blk_mq_queue_map *qmap);
 973void blk_mq_map_hw_queues(struct blk_mq_queue_map *qmap,
 974			  struct device *dev, unsigned int offset);
 975void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues);
 976
 977void blk_mq_quiesce_queue_nowait(struct request_queue *q);
 978
 979unsigned int blk_mq_rq_cpu(struct request *rq);
 980
 981bool __blk_should_fake_timeout(struct request_queue *q);
 982static inline bool blk_should_fake_timeout(struct request_queue *q)
 983{
 984	if (IS_ENABLED(CONFIG_FAIL_IO_TIMEOUT) &&
 985	    test_bit(QUEUE_FLAG_FAIL_IO, &q->queue_flags))
 986		return __blk_should_fake_timeout(q);
 987	return false;
 988}
 989
 990/**
 991 * blk_mq_rq_from_pdu - cast a PDU to a request
 992 * @pdu: the PDU (Protocol Data Unit) to be casted
 993 *
 994 * Return: request
 995 *
 996 * Driver command data is immediately after the request. So subtract request
 997 * size to get back to the original request.
 998 */
 999static inline struct request *blk_mq_rq_from_pdu(void *pdu)
1000{
1001	return pdu - sizeof(struct request);
1002}
1003
1004/**
1005 * blk_mq_rq_to_pdu - cast a request to a PDU
1006 * @rq: the request to be casted
1007 *
1008 * Return: pointer to the PDU
1009 *
1010 * Driver command data is immediately after the request. So add request to get
1011 * the PDU.
1012 */
1013static inline void *blk_mq_rq_to_pdu(struct request *rq)
1014{
1015	return rq + 1;
1016}
1017
1018static inline struct blk_mq_hw_ctx *queue_hctx(struct request_queue *q, int id)
1019{
1020	struct blk_mq_hw_ctx *hctx;
1021
1022	rcu_read_lock();
1023	hctx = rcu_dereference(q->queue_hw_ctx)[id];
1024	rcu_read_unlock();
1025
1026	return hctx;
1027}
1028
1029#define queue_for_each_hw_ctx(q, hctx, i)				\
1030	for ((i) = 0; (i) < (q)->nr_hw_queues &&			\
1031	     ({ hctx = queue_hctx((q), i); 1; }); (i)++)
1032
1033#define hctx_for_each_ctx(hctx, ctx, i)					\
1034	for ((i) = 0; (i) < (hctx)->nr_ctx &&				\
1035	     ({ ctx = (hctx)->ctxs[(i)]; 1; }); (i)++)
1036
1037static inline void blk_mq_cleanup_rq(struct request *rq)
1038{
1039	if (rq->q->mq_ops->cleanup_rq)
1040		rq->q->mq_ops->cleanup_rq(rq);
1041}
1042
1043void blk_mq_hctx_set_fq_lock_class(struct blk_mq_hw_ctx *hctx,
1044		struct lock_class_key *key);
1045
1046static inline bool rq_is_sync(struct request *rq)
1047{
1048	return op_is_sync(rq->cmd_flags);
1049}
1050
1051void blk_rq_init(struct request_queue *q, struct request *rq);
1052int blk_rq_prep_clone(struct request *rq, struct request *rq_src,
1053		struct bio_set *bs, gfp_t gfp_mask,
1054		int (*bio_ctr)(struct bio *, struct bio *, void *), void *data);
1055void blk_rq_unprep_clone(struct request *rq);
1056blk_status_t blk_insert_cloned_request(struct request *rq);
1057
1058struct rq_map_data {
1059	struct page **pages;
1060	unsigned long offset;
1061	unsigned short page_order;
1062	unsigned short nr_entries;
1063	bool null_mapped;
1064	bool from_user;
1065};
1066
1067int blk_rq_map_user(struct request_queue *, struct request *,
1068		struct rq_map_data *, void __user *, unsigned long, gfp_t);
1069int blk_rq_map_user_io(struct request *, struct rq_map_data *,
1070		void __user *, unsigned long, gfp_t, bool, int, bool, int);
1071int blk_rq_map_user_iov(struct request_queue *, struct request *,
1072		struct rq_map_data *, const struct iov_iter *, gfp_t);
1073int blk_rq_unmap_user(struct bio *);
1074int blk_rq_map_kern(struct request *rq, void *kbuf, unsigned int len,
1075		gfp_t gfp);
1076int blk_rq_append_bio(struct request *rq, struct bio *bio);
1077void blk_execute_rq_nowait(struct request *rq, bool at_head);
1078blk_status_t blk_execute_rq(struct request *rq, bool at_head);
1079bool blk_rq_is_poll(struct request *rq);
1080
1081struct req_iterator {
1082	struct bvec_iter iter;
1083	struct bio *bio;
1084};
1085
1086#define __rq_for_each_bio(_bio, rq)	\
1087	if ((rq->bio))			\
1088		for (_bio = (rq)->bio; _bio; _bio = _bio->bi_next)
1089
1090#define rq_for_each_segment(bvl, _rq, _iter)			\
1091	__rq_for_each_bio(_iter.bio, _rq)			\
1092		bio_for_each_segment(bvl, _iter.bio, _iter.iter)
1093
1094#define rq_for_each_bvec(bvl, _rq, _iter)			\
1095	__rq_for_each_bio(_iter.bio, _rq)			\
1096		bio_for_each_bvec(bvl, _iter.bio, _iter.iter)
1097
1098#define rq_iter_last(bvec, _iter)				\
1099		(_iter.bio->bi_next == NULL &&			\
1100		 bio_iter_last(bvec, _iter.iter))
1101
1102/*
1103 * blk_rq_pos()			: the current sector
1104 * blk_rq_bytes()		: bytes left in the entire request
1105 * blk_rq_cur_bytes()		: bytes left in the current segment
1106 * blk_rq_sectors()		: sectors left in the entire request
1107 * blk_rq_cur_sectors()		: sectors left in the current segment
1108 * blk_rq_stats_sectors()	: sectors of the entire request used for stats
1109 */
1110static inline sector_t blk_rq_pos(const struct request *rq)
1111{
1112	return rq->__sector;
1113}
1114
1115static inline unsigned int blk_rq_bytes(const struct request *rq)
1116{
1117	return rq->__data_len;
1118}
1119
1120static inline int blk_rq_cur_bytes(const struct request *rq)
1121{
1122	if (!rq->bio)
1123		return 0;
1124	if (!bio_has_data(rq->bio))	/* dataless requests such as discard */
1125		return rq->bio->bi_iter.bi_size;
1126	return bio_iovec(rq->bio).bv_len;
1127}
1128
1129static inline unsigned int blk_rq_sectors(const struct request *rq)
1130{
1131	return blk_rq_bytes(rq) >> SECTOR_SHIFT;
1132}
1133
1134static inline unsigned int blk_rq_cur_sectors(const struct request *rq)
1135{
1136	return blk_rq_cur_bytes(rq) >> SECTOR_SHIFT;
1137}
1138
1139static inline unsigned int blk_rq_stats_sectors(const struct request *rq)
1140{
1141	return rq->stats_sectors;
1142}
1143
1144/*
1145 * Some commands like WRITE SAME have a payload or data transfer size which
1146 * is different from the size of the request.  Any driver that supports such
1147 * commands using the RQF_SPECIAL_PAYLOAD flag needs to use this helper to
1148 * calculate the data transfer size.
1149 */
1150static inline unsigned int blk_rq_payload_bytes(struct request *rq)
1151{
1152	if (rq->rq_flags & RQF_SPECIAL_PAYLOAD)
1153		return rq->special_vec.bv_len;
1154	return blk_rq_bytes(rq);
1155}
1156
1157/*
1158 * Return the first full biovec in the request.  The caller needs to check that
1159 * there are any bvecs before calling this helper.
1160 */
1161static inline struct bio_vec req_bvec(struct request *rq)
1162{
1163	if (rq->rq_flags & RQF_SPECIAL_PAYLOAD)
1164		return rq->special_vec;
1165	return mp_bvec_iter_bvec(rq->bio->bi_io_vec, rq->bio->bi_iter);
1166}
1167
1168static inline unsigned int blk_rq_count_bios(struct request *rq)
1169{
1170	unsigned int nr_bios = 0;
1171	struct bio *bio;
1172
1173	__rq_for_each_bio(bio, rq)
1174		nr_bios++;
1175
1176	return nr_bios;
1177}
1178
1179void blk_steal_bios(struct bio_list *list, struct request *rq);
1180
1181/*
1182 * Request completion related functions.
1183 *
1184 * blk_update_request() completes given number of bytes and updates
1185 * the request without completing it.
1186 */
1187bool blk_update_request(struct request *rq, blk_status_t error,
1188			       unsigned int nr_bytes);
1189void blk_abort_request(struct request *);
1190
1191/*
1192 * Number of physical segments as sent to the device.
1193 *
1194 * Normally this is the number of discontiguous data segments sent by the
1195 * submitter.  But for data-less command like discard we might have no
1196 * actual data segments submitted, but the driver might have to add it's
1197 * own special payload.  In that case we still return 1 here so that this
1198 * special payload will be mapped.
1199 */
1200static inline unsigned short blk_rq_nr_phys_segments(struct request *rq)
1201{
1202	if (rq->rq_flags & RQF_SPECIAL_PAYLOAD)
1203		return 1;
1204	return rq->nr_phys_segments;
1205}
1206
1207/*
1208 * Number of discard segments (or ranges) the driver needs to fill in.
1209 * Each discard bio merged into a request is counted as one segment.
1210 */
1211static inline unsigned short blk_rq_nr_discard_segments(struct request *rq)
1212{
1213	return max_t(unsigned short, rq->nr_phys_segments, 1);
1214}
1215
1216/**
1217 * blk_rq_nr_bvec - return number of bvecs in a request
1218 * @rq: request to calculate bvecs for
1219 *
1220 * Returns the number of bvecs.
1221 */
1222static inline unsigned int blk_rq_nr_bvec(struct request *rq)
1223{
1224	struct req_iterator rq_iter;
1225	struct bio_vec bv;
1226	unsigned int nr_bvec = 0;
1227
1228	rq_for_each_bvec(bv, rq, rq_iter)
1229		nr_bvec++;
1230
1231	return nr_bvec;
1232}
1233
1234int __blk_rq_map_sg(struct request *rq, struct scatterlist *sglist,
1235		struct scatterlist **last_sg);
1236static inline int blk_rq_map_sg(struct request *rq, struct scatterlist *sglist)
1237{
1238	struct scatterlist *last_sg = NULL;
1239
1240	return __blk_rq_map_sg(rq, sglist, &last_sg);
1241}
1242void blk_dump_rq_flags(struct request *, char *);
1243
1244#endif /* BLK_MQ_H */