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Linux/block/blk.h

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

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