xref: /linux/block/blk.h (revision 905e46acd3272d04566fec49afbd7ad9e2ed9ae3)
1 #ifndef BLK_INTERNAL_H
2 #define BLK_INTERNAL_H
3 
4 #include <linux/idr.h>
5 #include <linux/blk-mq.h>
6 #include "blk-mq.h"
7 
8 /* Amount of time in which a process may batch requests */
9 #define BLK_BATCH_TIME	(HZ/50UL)
10 
11 /* Number of requests a "batching" process may submit */
12 #define BLK_BATCH_REQ	32
13 
14 /* Max future timer expiry for timeouts */
15 #define BLK_MAX_TIMEOUT		(5 * HZ)
16 
17 #ifdef CONFIG_DEBUG_FS
18 extern struct dentry *blk_debugfs_root;
19 #endif
20 
21 struct blk_flush_queue {
22 	unsigned int		flush_queue_delayed:1;
23 	unsigned int		flush_pending_idx:1;
24 	unsigned int		flush_running_idx:1;
25 	unsigned long		flush_pending_since;
26 	struct list_head	flush_queue[2];
27 	struct list_head	flush_data_in_flight;
28 	struct request		*flush_rq;
29 
30 	/*
31 	 * flush_rq shares tag with this rq, both can't be active
32 	 * at the same time
33 	 */
34 	struct request		*orig_rq;
35 	spinlock_t		mq_flush_lock;
36 };
37 
38 extern struct kmem_cache *blk_requestq_cachep;
39 extern struct kmem_cache *request_cachep;
40 extern struct kobj_type blk_queue_ktype;
41 extern struct ida blk_queue_ida;
42 
43 static inline struct blk_flush_queue *blk_get_flush_queue(
44 		struct request_queue *q, struct blk_mq_ctx *ctx)
45 {
46 	if (q->mq_ops)
47 		return blk_mq_map_queue(q, ctx->cpu)->fq;
48 	return q->fq;
49 }
50 
51 static inline void __blk_get_queue(struct request_queue *q)
52 {
53 	kobject_get(&q->kobj);
54 }
55 
56 struct blk_flush_queue *blk_alloc_flush_queue(struct request_queue *q,
57 		int node, int cmd_size);
58 void blk_free_flush_queue(struct blk_flush_queue *q);
59 
60 int blk_init_rl(struct request_list *rl, struct request_queue *q,
61 		gfp_t gfp_mask);
62 void blk_exit_rl(struct request_list *rl);
63 void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
64 			struct bio *bio);
65 void blk_queue_bypass_start(struct request_queue *q);
66 void blk_queue_bypass_end(struct request_queue *q);
67 void blk_dequeue_request(struct request *rq);
68 void __blk_queue_free_tags(struct request_queue *q);
69 void blk_freeze_queue(struct request_queue *q);
70 
71 static inline void blk_queue_enter_live(struct request_queue *q)
72 {
73 	/*
74 	 * Given that running in generic_make_request() context
75 	 * guarantees that a live reference against q_usage_counter has
76 	 * been established, further references under that same context
77 	 * need not check that the queue has been frozen (marked dead).
78 	 */
79 	percpu_ref_get(&q->q_usage_counter);
80 }
81 
82 #ifdef CONFIG_BLK_DEV_INTEGRITY
83 void blk_flush_integrity(void);
84 #else
85 static inline void blk_flush_integrity(void)
86 {
87 }
88 #endif
89 
90 void blk_timeout_work(struct work_struct *work);
91 unsigned long blk_rq_timeout(unsigned long timeout);
92 void blk_add_timer(struct request *req);
93 void blk_delete_timer(struct request *);
94 
95 
96 bool bio_attempt_front_merge(struct request_queue *q, struct request *req,
97 			     struct bio *bio);
98 bool bio_attempt_back_merge(struct request_queue *q, struct request *req,
99 			    struct bio *bio);
100 bool bio_attempt_discard_merge(struct request_queue *q, struct request *req,
101 		struct bio *bio);
102 bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
103 			    unsigned int *request_count,
104 			    struct request **same_queue_rq);
105 unsigned int blk_plug_queued_count(struct request_queue *q);
106 
107 void blk_account_io_start(struct request *req, bool new_io);
108 void blk_account_io_completion(struct request *req, unsigned int bytes);
109 void blk_account_io_done(struct request *req);
110 
111 /*
112  * Internal atomic flags for request handling
113  */
114 enum rq_atomic_flags {
115 	REQ_ATOM_COMPLETE = 0,
116 	REQ_ATOM_STARTED,
117 	REQ_ATOM_POLL_SLEPT,
118 };
119 
120 /*
121  * EH timer and IO completion will both attempt to 'grab' the request, make
122  * sure that only one of them succeeds
123  */
124 static inline int blk_mark_rq_complete(struct request *rq)
125 {
126 	return test_and_set_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
127 }
128 
129 static inline void blk_clear_rq_complete(struct request *rq)
130 {
131 	clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
132 }
133 
134 /*
135  * Internal elevator interface
136  */
137 #define ELV_ON_HASH(rq) ((rq)->rq_flags & RQF_HASHED)
138 
139 void blk_insert_flush(struct request *rq);
140 
141 static inline struct request *__elv_next_request(struct request_queue *q)
142 {
143 	struct request *rq;
144 	struct blk_flush_queue *fq = blk_get_flush_queue(q, NULL);
145 
146 	while (1) {
147 		if (!list_empty(&q->queue_head)) {
148 			rq = list_entry_rq(q->queue_head.next);
149 			return rq;
150 		}
151 
152 		/*
153 		 * Flush request is running and flush request isn't queueable
154 		 * in the drive, we can hold the queue till flush request is
155 		 * finished. Even we don't do this, driver can't dispatch next
156 		 * requests and will requeue them. And this can improve
157 		 * throughput too. For example, we have request flush1, write1,
158 		 * flush 2. flush1 is dispatched, then queue is hold, write1
159 		 * isn't inserted to queue. After flush1 is finished, flush2
160 		 * will be dispatched. Since disk cache is already clean,
161 		 * flush2 will be finished very soon, so looks like flush2 is
162 		 * folded to flush1.
163 		 * Since the queue is hold, a flag is set to indicate the queue
164 		 * should be restarted later. Please see flush_end_io() for
165 		 * details.
166 		 */
167 		if (fq->flush_pending_idx != fq->flush_running_idx &&
168 				!queue_flush_queueable(q)) {
169 			fq->flush_queue_delayed = 1;
170 			return NULL;
171 		}
172 		if (unlikely(blk_queue_bypass(q)) ||
173 		    !q->elevator->type->ops.sq.elevator_dispatch_fn(q, 0))
174 			return NULL;
175 	}
176 }
177 
178 static inline void elv_activate_rq(struct request_queue *q, struct request *rq)
179 {
180 	struct elevator_queue *e = q->elevator;
181 
182 	if (e->type->ops.sq.elevator_activate_req_fn)
183 		e->type->ops.sq.elevator_activate_req_fn(q, rq);
184 }
185 
186 static inline void elv_deactivate_rq(struct request_queue *q, struct request *rq)
187 {
188 	struct elevator_queue *e = q->elevator;
189 
190 	if (e->type->ops.sq.elevator_deactivate_req_fn)
191 		e->type->ops.sq.elevator_deactivate_req_fn(q, rq);
192 }
193 
194 #ifdef CONFIG_FAIL_IO_TIMEOUT
195 int blk_should_fake_timeout(struct request_queue *);
196 ssize_t part_timeout_show(struct device *, struct device_attribute *, char *);
197 ssize_t part_timeout_store(struct device *, struct device_attribute *,
198 				const char *, size_t);
199 #else
200 static inline int blk_should_fake_timeout(struct request_queue *q)
201 {
202 	return 0;
203 }
204 #endif
205 
206 int ll_back_merge_fn(struct request_queue *q, struct request *req,
207 		     struct bio *bio);
208 int ll_front_merge_fn(struct request_queue *q, struct request *req,
209 		      struct bio *bio);
210 struct request *attempt_back_merge(struct request_queue *q, struct request *rq);
211 struct request *attempt_front_merge(struct request_queue *q, struct request *rq);
212 int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
213 				struct request *next);
214 void blk_recalc_rq_segments(struct request *rq);
215 void blk_rq_set_mixed_merge(struct request *rq);
216 bool blk_rq_merge_ok(struct request *rq, struct bio *bio);
217 enum elv_merge blk_try_merge(struct request *rq, struct bio *bio);
218 
219 void blk_queue_congestion_threshold(struct request_queue *q);
220 
221 int blk_dev_init(void);
222 
223 
224 /*
225  * Return the threshold (number of used requests) at which the queue is
226  * considered to be congested.  It include a little hysteresis to keep the
227  * context switch rate down.
228  */
229 static inline int queue_congestion_on_threshold(struct request_queue *q)
230 {
231 	return q->nr_congestion_on;
232 }
233 
234 /*
235  * The threshold at which a queue is considered to be uncongested
236  */
237 static inline int queue_congestion_off_threshold(struct request_queue *q)
238 {
239 	return q->nr_congestion_off;
240 }
241 
242 extern int blk_update_nr_requests(struct request_queue *, unsigned int);
243 
244 /*
245  * Contribute to IO statistics IFF:
246  *
247  *	a) it's attached to a gendisk, and
248  *	b) the queue had IO stats enabled when this request was started, and
249  *	c) it's a file system request
250  */
251 static inline int blk_do_io_stat(struct request *rq)
252 {
253 	return rq->rq_disk &&
254 	       (rq->rq_flags & RQF_IO_STAT) &&
255 		!blk_rq_is_passthrough(rq);
256 }
257 
258 static inline void req_set_nomerge(struct request_queue *q, struct request *req)
259 {
260 	req->cmd_flags |= REQ_NOMERGE;
261 	if (req == q->last_merge)
262 		q->last_merge = NULL;
263 }
264 
265 /*
266  * Internal io_context interface
267  */
268 void get_io_context(struct io_context *ioc);
269 struct io_cq *ioc_lookup_icq(struct io_context *ioc, struct request_queue *q);
270 struct io_cq *ioc_create_icq(struct io_context *ioc, struct request_queue *q,
271 			     gfp_t gfp_mask);
272 void ioc_clear_queue(struct request_queue *q);
273 
274 int create_task_io_context(struct task_struct *task, gfp_t gfp_mask, int node);
275 
276 /**
277  * rq_ioc - determine io_context for request allocation
278  * @bio: request being allocated is for this bio (can be %NULL)
279  *
280  * Determine io_context to use for request allocation for @bio.  May return
281  * %NULL if %current->io_context doesn't exist.
282  */
283 static inline struct io_context *rq_ioc(struct bio *bio)
284 {
285 #ifdef CONFIG_BLK_CGROUP
286 	if (bio && bio->bi_ioc)
287 		return bio->bi_ioc;
288 #endif
289 	return current->io_context;
290 }
291 
292 /**
293  * create_io_context - try to create task->io_context
294  * @gfp_mask: allocation mask
295  * @node: allocation node
296  *
297  * If %current->io_context is %NULL, allocate a new io_context and install
298  * it.  Returns the current %current->io_context which may be %NULL if
299  * allocation failed.
300  *
301  * Note that this function can't be called with IRQ disabled because
302  * task_lock which protects %current->io_context is IRQ-unsafe.
303  */
304 static inline struct io_context *create_io_context(gfp_t gfp_mask, int node)
305 {
306 	WARN_ON_ONCE(irqs_disabled());
307 	if (unlikely(!current->io_context))
308 		create_task_io_context(current, gfp_mask, node);
309 	return current->io_context;
310 }
311 
312 /*
313  * Internal throttling interface
314  */
315 #ifdef CONFIG_BLK_DEV_THROTTLING
316 extern void blk_throtl_drain(struct request_queue *q);
317 extern int blk_throtl_init(struct request_queue *q);
318 extern void blk_throtl_exit(struct request_queue *q);
319 extern void blk_throtl_register_queue(struct request_queue *q);
320 #else /* CONFIG_BLK_DEV_THROTTLING */
321 static inline void blk_throtl_drain(struct request_queue *q) { }
322 static inline int blk_throtl_init(struct request_queue *q) { return 0; }
323 static inline void blk_throtl_exit(struct request_queue *q) { }
324 static inline void blk_throtl_register_queue(struct request_queue *q) { }
325 #endif /* CONFIG_BLK_DEV_THROTTLING */
326 #ifdef CONFIG_BLK_DEV_THROTTLING_LOW
327 extern ssize_t blk_throtl_sample_time_show(struct request_queue *q, char *page);
328 extern ssize_t blk_throtl_sample_time_store(struct request_queue *q,
329 	const char *page, size_t count);
330 extern void blk_throtl_bio_endio(struct bio *bio);
331 extern void blk_throtl_stat_add(struct request *rq, u64 time);
332 #else
333 static inline void blk_throtl_bio_endio(struct bio *bio) { }
334 static inline void blk_throtl_stat_add(struct request *rq, u64 time) { }
335 #endif
336 
337 #endif /* BLK_INTERNAL_H */
338