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/srcu.h>
  8
  9struct blk_mq_tags;
 10struct blk_flush_queue;
 11
 12/**
 13 * struct blk_mq_hw_ctx - State for a hardware queue facing the hardware
 14 * block device
 15 */
 16struct blk_mq_hw_ctx {
 17	struct {
 18		/** @lock: Protects the dispatch list. */
 19		spinlock_t		lock;
 20		/**
 21		 * @dispatch: Used for requests that are ready to be
 22		 * dispatched to the hardware but for some reason (e.g. lack of
 23		 * resources) could not be sent to the hardware. As soon as the
 24		 * driver can send new requests, requests at this list will
 25		 * be sent first for a fairer dispatch.
 26		 */
 27		struct list_head	dispatch;
 28		 /**
 29		  * @state: BLK_MQ_S_* flags. Defines the state of the hw
 30		  * queue (active, scheduled to restart, stopped).
 31		  */
 32		unsigned long		state;
 33	} ____cacheline_aligned_in_smp;
 34
 35	/**
 36	 * @run_work: Used for scheduling a hardware queue run at a later time.
 37	 */
 38	struct delayed_work	run_work;
 39	/** @cpumask: Map of available CPUs where this hctx can run. */
 40	cpumask_var_t		cpumask;
 41	/**
 42	 * @next_cpu: Used by blk_mq_hctx_next_cpu() for round-robin CPU
 43	 * selection from @cpumask.
 44	 */
 45	int			next_cpu;
 46	/**
 47	 * @next_cpu_batch: Counter of how many works left in the batch before
 48	 * changing to the next CPU.
 49	 */
 50	int			next_cpu_batch;
 51
 52	/** @flags: BLK_MQ_F_* flags. Defines the behaviour of the queue. */
 53	unsigned long		flags;
 54
 55	/**
 56	 * @sched_data: Pointer owned by the IO scheduler attached to a request
 57	 * queue. It's up to the IO scheduler how to use this pointer.
 58	 */
 59	void			*sched_data;
 60	/**
 61	 * @queue: Pointer to the request queue that owns this hardware context.
 62	 */
 63	struct request_queue	*queue;
 64	/** @fq: Queue of requests that need to perform a flush operation. */
 65	struct blk_flush_queue	*fq;
 66
 67	/**
 68	 * @driver_data: Pointer to data owned by the block driver that created
 69	 * this hctx
 70	 */
 71	void			*driver_data;
 72
 73	/**
 74	 * @ctx_map: Bitmap for each software queue. If bit is on, there is a
 75	 * pending request in that software queue.
 76	 */
 77	struct sbitmap		ctx_map;
 78
 79	/**
 80	 * @dispatch_from: Software queue to be used when no scheduler was
 81	 * selected.
 82	 */
 83	struct blk_mq_ctx	*dispatch_from;
 84	/**
 85	 * @dispatch_busy: Number used by blk_mq_update_dispatch_busy() to
 86	 * decide if the hw_queue is busy using Exponential Weighted Moving
 87	 * Average algorithm.
 88	 */
 89	unsigned int		dispatch_busy;
 90
 91	/** @type: HCTX_TYPE_* flags. Type of hardware queue. */
 92	unsigned short		type;
 93	/** @nr_ctx: Number of software queues. */
 94	unsigned short		nr_ctx;
 95	/** @ctxs: Array of software queues. */
 96	struct blk_mq_ctx	**ctxs;
 97
 98	/** @dispatch_wait_lock: Lock for dispatch_wait queue. */
 99	spinlock_t		dispatch_wait_lock;
100	/**
101	 * @dispatch_wait: Waitqueue to put requests when there is no tag
102	 * available at the moment, to wait for another try in the future.
103	 */
104	wait_queue_entry_t	dispatch_wait;
105
106	/**
107	 * @wait_index: Index of next available dispatch_wait queue to insert
108	 * requests.
109	 */
110	atomic_t		wait_index;
111
112	/**
113	 * @tags: Tags owned by the block driver. A tag at this set is only
114	 * assigned when a request is dispatched from a hardware queue.
115	 */
116	struct blk_mq_tags	*tags;
117	/**
118	 * @sched_tags: Tags owned by I/O scheduler. If there is an I/O
119	 * scheduler associated with a request queue, a tag is assigned when
120	 * that request is allocated. Else, this member is not used.
121	 */
122	struct blk_mq_tags	*sched_tags;
123
124	/** @queued: Number of queued requests. */
125	unsigned long		queued;
126	/** @run: Number of dispatched requests. */
127	unsigned long		run;
128#define BLK_MQ_MAX_DISPATCH_ORDER	7
129	/** @dispatched: Number of dispatch requests by queue. */
130	unsigned long		dispatched[BLK_MQ_MAX_DISPATCH_ORDER];
131
132	/** @numa_node: NUMA node the storage adapter has been connected to. */
133	unsigned int		numa_node;
134	/** @queue_num: Index of this hardware queue. */
135	unsigned int		queue_num;
136
137	/**
138	 * @nr_active: Number of active requests. Only used when a tag set is
139	 * shared across request queues.
140	 */
141	atomic_t		nr_active;
142
143	/** @cpuhp_online: List to store request if CPU is going to die */
144	struct hlist_node	cpuhp_online;
145	/** @cpuhp_dead: List to store request if some CPU die. */
146	struct hlist_node	cpuhp_dead;
147	/** @kobj: Kernel object for sysfs. */
148	struct kobject		kobj;
149
150	/** @poll_considered: Count times blk_poll() was called. */
151	unsigned long		poll_considered;
152	/** @poll_invoked: Count how many requests blk_poll() polled. */
153	unsigned long		poll_invoked;
154	/** @poll_success: Count how many polled requests were completed. */
155	unsigned long		poll_success;
156
157#ifdef CONFIG_BLK_DEBUG_FS
158	/**
159	 * @debugfs_dir: debugfs directory for this hardware queue. Named
160	 * as cpu<cpu_number>.
161	 */
162	struct dentry		*debugfs_dir;
163	/** @sched_debugfs_dir:	debugfs directory for the scheduler. */
164	struct dentry		*sched_debugfs_dir;
165#endif
166
167	/**
168	 * @hctx_list: if this hctx is not in use, this is an entry in
169	 * q->unused_hctx_list.
170	 */
171	struct list_head	hctx_list;
172
173	/**
174	 * @srcu: Sleepable RCU. Use as lock when type of the hardware queue is
175	 * blocking (BLK_MQ_F_BLOCKING). Must be the last member - see also
176	 * blk_mq_hw_ctx_size().
177	 */
178	struct srcu_struct	srcu[];
179};
180
181/**
182 * struct blk_mq_queue_map - Map software queues to hardware queues
183 * @mq_map:       CPU ID to hardware queue index map. This is an array
184 *	with nr_cpu_ids elements. Each element has a value in the range
185 *	[@queue_offset, @queue_offset + @nr_queues).
186 * @nr_queues:    Number of hardware queues to map CPU IDs onto.
187 * @queue_offset: First hardware queue to map onto. Used by the PCIe NVMe
188 *	driver to map each hardware queue type (enum hctx_type) onto a distinct
189 *	set of hardware queues.
190 */
191struct blk_mq_queue_map {
192	unsigned int *mq_map;
193	unsigned int nr_queues;
194	unsigned int queue_offset;
195};
196
197/**
198 * enum hctx_type - Type of hardware queue
199 * @HCTX_TYPE_DEFAULT:	All I/O not otherwise accounted for.
200 * @HCTX_TYPE_READ:	Just for READ I/O.
201 * @HCTX_TYPE_POLL:	Polled I/O of any kind.
202 * @HCTX_MAX_TYPES:	Number of types of hctx.
203 */
204enum hctx_type {
205	HCTX_TYPE_DEFAULT,
206	HCTX_TYPE_READ,
207	HCTX_TYPE_POLL,
208
209	HCTX_MAX_TYPES,
210};
211
212/**
213 * struct blk_mq_tag_set - tag set that can be shared between request queues
214 * @map:	   One or more ctx -> hctx mappings. One map exists for each
215 *		   hardware queue type (enum hctx_type) that the driver wishes
216 *		   to support. There are no restrictions on maps being of the
217 *		   same size, and it's perfectly legal to share maps between
218 *		   types.
219 * @nr_maps:	   Number of elements in the @map array. A number in the range
220 *		   [1, HCTX_MAX_TYPES].
221 * @ops:	   Pointers to functions that implement block driver behavior.
222 * @nr_hw_queues:  Number of hardware queues supported by the block driver that
223 *		   owns this data structure.
224 * @queue_depth:   Number of tags per hardware queue, reserved tags included.
225 * @reserved_tags: Number of tags to set aside for BLK_MQ_REQ_RESERVED tag
226 *		   allocations.
227 * @cmd_size:	   Number of additional bytes to allocate per request. The block
228 *		   driver owns these additional bytes.
229 * @numa_node:	   NUMA node the storage adapter has been connected to.
230 * @timeout:	   Request processing timeout in jiffies.
231 * @flags:	   Zero or more BLK_MQ_F_* flags.
232 * @driver_data:   Pointer to data owned by the block driver that created this
233 *		   tag set.
234 * @tags:	   Tag sets. One tag set per hardware queue. Has @nr_hw_queues
235 *		   elements.
236 * @tag_list_lock: Serializes tag_list accesses.
237 * @tag_list:	   List of the request queues that use this tag set. See also
238 *		   request_queue.tag_set_list.
239 */
240struct blk_mq_tag_set {
241	struct blk_mq_queue_map	map[HCTX_MAX_TYPES];
242	unsigned int		nr_maps;
243	const struct blk_mq_ops	*ops;
244	unsigned int		nr_hw_queues;
245	unsigned int		queue_depth;
246	unsigned int		reserved_tags;
247	unsigned int		cmd_size;
248	int			numa_node;
249	unsigned int		timeout;
250	unsigned int		flags;
251	void			*driver_data;
252
253	struct blk_mq_tags	**tags;
254
255	struct mutex		tag_list_lock;
256	struct list_head	tag_list;
257};
258
259/**
260 * struct blk_mq_queue_data - Data about a request inserted in a queue
261 *
262 * @rq:   Request pointer.
263 * @last: If it is the last request in the queue.
264 */
265struct blk_mq_queue_data {
266	struct request *rq;
267	bool last;
268};
269
270typedef bool (busy_iter_fn)(struct blk_mq_hw_ctx *, struct request *, void *,
271		bool);
272typedef bool (busy_tag_iter_fn)(struct request *, void *, bool);
273
274/**
275 * struct blk_mq_ops - Callback functions that implements block driver
276 * behaviour.
277 */
278struct blk_mq_ops {
279	/**
280	 * @queue_rq: Queue a new request from block IO.
281	 */
282	blk_status_t (*queue_rq)(struct blk_mq_hw_ctx *,
283				 const struct blk_mq_queue_data *);
284
285	/**
286	 * @commit_rqs: If a driver uses bd->last to judge when to submit
287	 * requests to hardware, it must define this function. In case of errors
288	 * that make us stop issuing further requests, this hook serves the
289	 * purpose of kicking the hardware (which the last request otherwise
290	 * would have done).
291	 */
292	void (*commit_rqs)(struct blk_mq_hw_ctx *);
293
294	/**
295	 * @get_budget: Reserve budget before queue request, once .queue_rq is
296	 * run, it is driver's responsibility to release the
297	 * reserved budget. Also we have to handle failure case
298	 * of .get_budget for avoiding I/O deadlock.
299	 */
300	bool (*get_budget)(struct request_queue *);
301
302	/**
303	 * @put_budget: Release the reserved budget.
304	 */
305	void (*put_budget)(struct request_queue *);
306
307	/**
308	 * @timeout: Called on request timeout.
309	 */
310	enum blk_eh_timer_return (*timeout)(struct request *, bool);
311
312	/**
313	 * @poll: Called to poll for completion of a specific tag.
314	 */
315	int (*poll)(struct blk_mq_hw_ctx *);
316
317	/**
318	 * @complete: Mark the request as complete.
319	 */
320	void (*complete)(struct request *);
321
322	/**
323	 * @init_hctx: Called when the block layer side of a hardware queue has
324	 * been set up, allowing the driver to allocate/init matching
325	 * structures.
326	 */
327	int (*init_hctx)(struct blk_mq_hw_ctx *, void *, unsigned int);
328	/**
329	 * @exit_hctx: Ditto for exit/teardown.
330	 */
331	void (*exit_hctx)(struct blk_mq_hw_ctx *, unsigned int);
332
333	/**
334	 * @init_request: Called for every command allocated by the block layer
335	 * to allow the driver to set up driver specific data.
336	 *
337	 * Tag greater than or equal to queue_depth is for setting up
338	 * flush request.
339	 */
340	int (*init_request)(struct blk_mq_tag_set *set, struct request *,
341			    unsigned int, unsigned int);
342	/**
343	 * @exit_request: Ditto for exit/teardown.
344	 */
345	void (*exit_request)(struct blk_mq_tag_set *set, struct request *,
346			     unsigned int);
347
348	/**
349	 * @initialize_rq_fn: Called from inside blk_get_request().
350	 */
351	void (*initialize_rq_fn)(struct request *rq);
352
353	/**
354	 * @cleanup_rq: Called before freeing one request which isn't completed
355	 * yet, and usually for freeing the driver private data.
356	 */
357	void (*cleanup_rq)(struct request *);
358
359	/**
360	 * @busy: If set, returns whether or not this queue currently is busy.
361	 */
362	bool (*busy)(struct request_queue *);
363
364	/**
365	 * @map_queues: This allows drivers specify their own queue mapping by
366	 * overriding the setup-time function that builds the mq_map.
367	 */
368	int (*map_queues)(struct blk_mq_tag_set *set);
369
370#ifdef CONFIG_BLK_DEBUG_FS
371	/**
372	 * @show_rq: Used by the debugfs implementation to show driver-specific
373	 * information about a request.
374	 */
375	void (*show_rq)(struct seq_file *m, struct request *rq);
376#endif
377};
378
379enum {
380	BLK_MQ_F_SHOULD_MERGE	= 1 << 0,
381	BLK_MQ_F_TAG_SHARED	= 1 << 1,
382	/*
383	 * Set when this device requires underlying blk-mq device for
384	 * completing IO:
385	 */
386	BLK_MQ_F_STACKING	= 1 << 2,
387	BLK_MQ_F_BLOCKING	= 1 << 5,
388	BLK_MQ_F_NO_SCHED	= 1 << 6,
389	BLK_MQ_F_ALLOC_POLICY_START_BIT = 8,
390	BLK_MQ_F_ALLOC_POLICY_BITS = 1,
391
392	BLK_MQ_S_STOPPED	= 0,
393	BLK_MQ_S_TAG_ACTIVE	= 1,
394	BLK_MQ_S_SCHED_RESTART	= 2,
395
396	/* hw queue is inactive after all its CPUs become offline */
397	BLK_MQ_S_INACTIVE	= 3,
398
399	BLK_MQ_MAX_DEPTH	= 10240,
400
401	BLK_MQ_CPU_WORK_BATCH	= 8,
402};
403#define BLK_MQ_FLAG_TO_ALLOC_POLICY(flags) \
404	((flags >> BLK_MQ_F_ALLOC_POLICY_START_BIT) & \
405		((1 << BLK_MQ_F_ALLOC_POLICY_BITS) - 1))
406#define BLK_ALLOC_POLICY_TO_MQ_FLAG(policy) \
407	((policy & ((1 << BLK_MQ_F_ALLOC_POLICY_BITS) - 1)) \
408		<< BLK_MQ_F_ALLOC_POLICY_START_BIT)
409
410struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *);
411struct request_queue *blk_mq_init_queue_data(struct blk_mq_tag_set *set,
412		void *queuedata);
413struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
414						  struct request_queue *q,
415						  bool elevator_init);
416struct request_queue *blk_mq_init_sq_queue(struct blk_mq_tag_set *set,
417						const struct blk_mq_ops *ops,
418						unsigned int queue_depth,
419						unsigned int set_flags);
420void blk_mq_unregister_dev(struct device *, struct request_queue *);
421
422int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set);
423void blk_mq_free_tag_set(struct blk_mq_tag_set *set);
424
425void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule);
426
427void blk_mq_free_request(struct request *rq);
428
429bool blk_mq_queue_inflight(struct request_queue *q);
430
431enum {
432	/* return when out of requests */
433	BLK_MQ_REQ_NOWAIT	= (__force blk_mq_req_flags_t)(1 << 0),
434	/* allocate from reserved pool */
435	BLK_MQ_REQ_RESERVED	= (__force blk_mq_req_flags_t)(1 << 1),
436	/* set RQF_PREEMPT */
437	BLK_MQ_REQ_PREEMPT	= (__force blk_mq_req_flags_t)(1 << 3),
438};
439
440struct request *blk_mq_alloc_request(struct request_queue *q, unsigned int op,
441		blk_mq_req_flags_t flags);
442struct request *blk_mq_alloc_request_hctx(struct request_queue *q,
443		unsigned int op, blk_mq_req_flags_t flags,
444		unsigned int hctx_idx);
445struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag);
446
447enum {
448	BLK_MQ_UNIQUE_TAG_BITS = 16,
449	BLK_MQ_UNIQUE_TAG_MASK = (1 << BLK_MQ_UNIQUE_TAG_BITS) - 1,
450};
451
452u32 blk_mq_unique_tag(struct request *rq);
453
454static inline u16 blk_mq_unique_tag_to_hwq(u32 unique_tag)
455{
456	return unique_tag >> BLK_MQ_UNIQUE_TAG_BITS;
457}
458
459static inline u16 blk_mq_unique_tag_to_tag(u32 unique_tag)
460{
461	return unique_tag & BLK_MQ_UNIQUE_TAG_MASK;
462}
463
464/**
465 * blk_mq_rq_state() - read the current MQ_RQ_* state of a request
466 * @rq: target request.
467 */
468static inline enum mq_rq_state blk_mq_rq_state(struct request *rq)
469{
470	return READ_ONCE(rq->state);
471}
472
473static inline int blk_mq_request_started(struct request *rq)
474{
475	return blk_mq_rq_state(rq) != MQ_RQ_IDLE;
476}
477
478static inline int blk_mq_request_completed(struct request *rq)
479{
480	return blk_mq_rq_state(rq) == MQ_RQ_COMPLETE;
481}
482
483void blk_mq_start_request(struct request *rq);
484void blk_mq_end_request(struct request *rq, blk_status_t error);
485void __blk_mq_end_request(struct request *rq, blk_status_t error);
486
487void blk_mq_requeue_request(struct request *rq, bool kick_requeue_list);
488void blk_mq_kick_requeue_list(struct request_queue *q);
489void blk_mq_delay_kick_requeue_list(struct request_queue *q, unsigned long msecs);
490void blk_mq_complete_request(struct request *rq);
491bool blk_mq_complete_request_remote(struct request *rq);
492bool blk_mq_bio_list_merge(struct request_queue *q, struct list_head *list,
493			   struct bio *bio, unsigned int nr_segs);
494bool blk_mq_queue_stopped(struct request_queue *q);
495void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx);
496void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx);
497void blk_mq_stop_hw_queues(struct request_queue *q);
498void blk_mq_start_hw_queues(struct request_queue *q);
499void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx *hctx, bool async);
500void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async);
501void blk_mq_quiesce_queue(struct request_queue *q);
502void blk_mq_unquiesce_queue(struct request_queue *q);
503void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs);
504void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async);
505void blk_mq_run_hw_queues(struct request_queue *q, bool async);
506void blk_mq_delay_run_hw_queues(struct request_queue *q, unsigned long msecs);
507void blk_mq_tagset_busy_iter(struct blk_mq_tag_set *tagset,
508		busy_tag_iter_fn *fn, void *priv);
509void blk_mq_tagset_wait_completed_request(struct blk_mq_tag_set *tagset);
510void blk_mq_freeze_queue(struct request_queue *q);
511void blk_mq_unfreeze_queue(struct request_queue *q);
512void blk_freeze_queue_start(struct request_queue *q);
513void blk_mq_freeze_queue_wait(struct request_queue *q);
514int blk_mq_freeze_queue_wait_timeout(struct request_queue *q,
515				     unsigned long timeout);
516
517int blk_mq_map_queues(struct blk_mq_queue_map *qmap);
518void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues);
519
520void blk_mq_quiesce_queue_nowait(struct request_queue *q);
521
522unsigned int blk_mq_rq_cpu(struct request *rq);
523
524bool __blk_should_fake_timeout(struct request_queue *q);
525static inline bool blk_should_fake_timeout(struct request_queue *q)
526{
527	if (IS_ENABLED(CONFIG_FAIL_IO_TIMEOUT) &&
528	    test_bit(QUEUE_FLAG_FAIL_IO, &q->queue_flags))
529		return __blk_should_fake_timeout(q);
530	return false;
531}
532
533/**
534 * blk_mq_rq_from_pdu - cast a PDU to a request
535 * @pdu: the PDU (Protocol Data Unit) to be casted
536 *
537 * Return: request
538 *
539 * Driver command data is immediately after the request. So subtract request
540 * size to get back to the original request.
541 */
542static inline struct request *blk_mq_rq_from_pdu(void *pdu)
543{
544	return pdu - sizeof(struct request);
545}
546
547/**
548 * blk_mq_rq_to_pdu - cast a request to a PDU
549 * @rq: the request to be casted
550 *
551 * Return: pointer to the PDU
552 *
553 * Driver command data is immediately after the request. So add request to get
554 * the PDU.
555 */
556static inline void *blk_mq_rq_to_pdu(struct request *rq)
557{
558	return rq + 1;
559}
560
561#define queue_for_each_hw_ctx(q, hctx, i)				\
562	for ((i) = 0; (i) < (q)->nr_hw_queues &&			\
563	     ({ hctx = (q)->queue_hw_ctx[i]; 1; }); (i)++)
564
565#define hctx_for_each_ctx(hctx, ctx, i)					\
566	for ((i) = 0; (i) < (hctx)->nr_ctx &&				\
567	     ({ ctx = (hctx)->ctxs[(i)]; 1; }); (i)++)
568
569static inline blk_qc_t request_to_qc_t(struct blk_mq_hw_ctx *hctx,
570		struct request *rq)
571{
572	if (rq->tag != -1)
573		return rq->tag | (hctx->queue_num << BLK_QC_T_SHIFT);
574
575	return rq->internal_tag | (hctx->queue_num << BLK_QC_T_SHIFT) |
576			BLK_QC_T_INTERNAL;
577}
578
579static inline void blk_mq_cleanup_rq(struct request *rq)
580{
581	if (rq->q->mq_ops->cleanup_rq)
582		rq->q->mq_ops->cleanup_rq(rq);
583}
584
585blk_qc_t blk_mq_submit_bio(struct bio *bio);
586
587#endif