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TOMOYO Linux Cross Reference
Linux/block/blk.h

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  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_queue *q, 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 bool __bio_integrity_endio(struct bio *);
 85 static inline bool bio_integrity_endio(struct bio *bio)
 86 {
 87         if (bio_integrity(bio))
 88                 return __bio_integrity_endio(bio);
 89         return true;
 90 }
 91 #else
 92 static inline void blk_flush_integrity(void)
 93 {
 94 }
 95 static inline bool bio_integrity_endio(struct bio *bio)
 96 {
 97         return true;
 98 }
 99 #endif
100 
101 void blk_timeout_work(struct work_struct *work);
102 unsigned long blk_rq_timeout(unsigned long timeout);
103 void blk_add_timer(struct request *req);
104 void blk_delete_timer(struct request *);
105 
106 
107 bool bio_attempt_front_merge(struct request_queue *q, struct request *req,
108                              struct bio *bio);
109 bool bio_attempt_back_merge(struct request_queue *q, struct request *req,
110                             struct bio *bio);
111 bool bio_attempt_discard_merge(struct request_queue *q, struct request *req,
112                 struct bio *bio);
113 bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
114                             unsigned int *request_count,
115                             struct request **same_queue_rq);
116 unsigned int blk_plug_queued_count(struct request_queue *q);
117 
118 void blk_account_io_start(struct request *req, bool new_io);
119 void blk_account_io_completion(struct request *req, unsigned int bytes);
120 void blk_account_io_done(struct request *req);
121 
122 /*
123  * Internal atomic flags for request handling
124  */
125 enum rq_atomic_flags {
126         REQ_ATOM_COMPLETE = 0,
127         REQ_ATOM_STARTED,
128         REQ_ATOM_POLL_SLEPT,
129 };
130 
131 /*
132  * EH timer and IO completion will both attempt to 'grab' the request, make
133  * sure that only one of them succeeds
134  */
135 static inline int blk_mark_rq_complete(struct request *rq)
136 {
137         return test_and_set_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
138 }
139 
140 static inline void blk_clear_rq_complete(struct request *rq)
141 {
142         clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
143 }
144 
145 /*
146  * Internal elevator interface
147  */
148 #define ELV_ON_HASH(rq) ((rq)->rq_flags & RQF_HASHED)
149 
150 void blk_insert_flush(struct request *rq);
151 
152 static inline struct request *__elv_next_request(struct request_queue *q)
153 {
154         struct request *rq;
155         struct blk_flush_queue *fq = blk_get_flush_queue(q, NULL);
156 
157         WARN_ON_ONCE(q->mq_ops);
158 
159         while (1) {
160                 if (!list_empty(&q->queue_head)) {
161                         rq = list_entry_rq(q->queue_head.next);
162                         return rq;
163                 }
164 
165                 /*
166                  * Flush request is running and flush request isn't queueable
167                  * in the drive, we can hold the queue till flush request is
168                  * finished. Even we don't do this, driver can't dispatch next
169                  * requests and will requeue them. And this can improve
170                  * throughput too. For example, we have request flush1, write1,
171                  * flush 2. flush1 is dispatched, then queue is hold, write1
172                  * isn't inserted to queue. After flush1 is finished, flush2
173                  * will be dispatched. Since disk cache is already clean,
174                  * flush2 will be finished very soon, so looks like flush2 is
175                  * folded to flush1.
176                  * Since the queue is hold, a flag is set to indicate the queue
177                  * should be restarted later. Please see flush_end_io() for
178                  * details.
179                  */
180                 if (fq->flush_pending_idx != fq->flush_running_idx &&
181                                 !queue_flush_queueable(q)) {
182                         fq->flush_queue_delayed = 1;
183                         return NULL;
184                 }
185                 if (unlikely(blk_queue_bypass(q)) ||
186                     !q->elevator->type->ops.sq.elevator_dispatch_fn(q, 0))
187                         return NULL;
188         }
189 }
190 
191 static inline void elv_activate_rq(struct request_queue *q, struct request *rq)
192 {
193         struct elevator_queue *e = q->elevator;
194 
195         if (e->type->ops.sq.elevator_activate_req_fn)
196                 e->type->ops.sq.elevator_activate_req_fn(q, rq);
197 }
198 
199 static inline void elv_deactivate_rq(struct request_queue *q, struct request *rq)
200 {
201         struct elevator_queue *e = q->elevator;
202 
203         if (e->type->ops.sq.elevator_deactivate_req_fn)
204                 e->type->ops.sq.elevator_deactivate_req_fn(q, rq);
205 }
206 
207 #ifdef CONFIG_FAIL_IO_TIMEOUT
208 int blk_should_fake_timeout(struct request_queue *);
209 ssize_t part_timeout_show(struct device *, struct device_attribute *, char *);
210 ssize_t part_timeout_store(struct device *, struct device_attribute *,
211                                 const char *, size_t);
212 #else
213 static inline int blk_should_fake_timeout(struct request_queue *q)
214 {
215         return 0;
216 }
217 #endif
218 
219 int ll_back_merge_fn(struct request_queue *q, struct request *req,
220                      struct bio *bio);
221 int ll_front_merge_fn(struct request_queue *q, struct request *req, 
222                       struct bio *bio);
223 struct request *attempt_back_merge(struct request_queue *q, struct request *rq);
224 struct request *attempt_front_merge(struct request_queue *q, struct request *rq);
225 int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
226                                 struct request *next);
227 void blk_recalc_rq_segments(struct request *rq);
228 void blk_rq_set_mixed_merge(struct request *rq);
229 bool blk_rq_merge_ok(struct request *rq, struct bio *bio);
230 enum elv_merge blk_try_merge(struct request *rq, struct bio *bio);
231 
232 void blk_queue_congestion_threshold(struct request_queue *q);
233 
234 int blk_dev_init(void);
235 
236 
237 /*
238  * Return the threshold (number of used requests) at which the queue is
239  * considered to be congested.  It include a little hysteresis to keep the
240  * context switch rate down.
241  */
242 static inline int queue_congestion_on_threshold(struct request_queue *q)
243 {
244         return q->nr_congestion_on;
245 }
246 
247 /*
248  * The threshold at which a queue is considered to be uncongested
249  */
250 static inline int queue_congestion_off_threshold(struct request_queue *q)
251 {
252         return q->nr_congestion_off;
253 }
254 
255 extern int blk_update_nr_requests(struct request_queue *, unsigned int);
256 
257 /*
258  * Contribute to IO statistics IFF:
259  *
260  *      a) it's attached to a gendisk, and
261  *      b) the queue had IO stats enabled when this request was started, and
262  *      c) it's a file system request
263  */
264 static inline int blk_do_io_stat(struct request *rq)
265 {
266         return rq->rq_disk &&
267                (rq->rq_flags & RQF_IO_STAT) &&
268                 !blk_rq_is_passthrough(rq);
269 }
270 
271 static inline void req_set_nomerge(struct request_queue *q, struct request *req)
272 {
273         req->cmd_flags |= REQ_NOMERGE;
274         if (req == q->last_merge)
275                 q->last_merge = NULL;
276 }
277 
278 /*
279  * Internal io_context interface
280  */
281 void get_io_context(struct io_context *ioc);
282 struct io_cq *ioc_lookup_icq(struct io_context *ioc, struct request_queue *q);
283 struct io_cq *ioc_create_icq(struct io_context *ioc, struct request_queue *q,
284                              gfp_t gfp_mask);
285 void ioc_clear_queue(struct request_queue *q);
286 
287 int create_task_io_context(struct task_struct *task, gfp_t gfp_mask, int node);
288 
289 /**
290  * rq_ioc - determine io_context for request allocation
291  * @bio: request being allocated is for this bio (can be %NULL)
292  *
293  * Determine io_context to use for request allocation for @bio.  May return
294  * %NULL if %current->io_context doesn't exist.
295  */
296 static inline struct io_context *rq_ioc(struct bio *bio)
297 {
298 #ifdef CONFIG_BLK_CGROUP
299         if (bio && bio->bi_ioc)
300                 return bio->bi_ioc;
301 #endif
302         return current->io_context;
303 }
304 
305 /**
306  * create_io_context - try to create task->io_context
307  * @gfp_mask: allocation mask
308  * @node: allocation node
309  *
310  * If %current->io_context is %NULL, allocate a new io_context and install
311  * it.  Returns the current %current->io_context which may be %NULL if
312  * allocation failed.
313  *
314  * Note that this function can't be called with IRQ disabled because
315  * task_lock which protects %current->io_context is IRQ-unsafe.
316  */
317 static inline struct io_context *create_io_context(gfp_t gfp_mask, int node)
318 {
319         WARN_ON_ONCE(irqs_disabled());
320         if (unlikely(!current->io_context))
321                 create_task_io_context(current, gfp_mask, node);
322         return current->io_context;
323 }
324 
325 /*
326  * Internal throttling interface
327  */
328 #ifdef CONFIG_BLK_DEV_THROTTLING
329 extern void blk_throtl_drain(struct request_queue *q);
330 extern int blk_throtl_init(struct request_queue *q);
331 extern void blk_throtl_exit(struct request_queue *q);
332 extern void blk_throtl_register_queue(struct request_queue *q);
333 #else /* CONFIG_BLK_DEV_THROTTLING */
334 static inline void blk_throtl_drain(struct request_queue *q) { }
335 static inline int blk_throtl_init(struct request_queue *q) { return 0; }
336 static inline void blk_throtl_exit(struct request_queue *q) { }
337 static inline void blk_throtl_register_queue(struct request_queue *q) { }
338 #endif /* CONFIG_BLK_DEV_THROTTLING */
339 #ifdef CONFIG_BLK_DEV_THROTTLING_LOW
340 extern ssize_t blk_throtl_sample_time_show(struct request_queue *q, char *page);
341 extern ssize_t blk_throtl_sample_time_store(struct request_queue *q,
342         const char *page, size_t count);
343 extern void blk_throtl_bio_endio(struct bio *bio);
344 extern void blk_throtl_stat_add(struct request *rq, u64 time);
345 #else
346 static inline void blk_throtl_bio_endio(struct bio *bio) { }
347 static inline void blk_throtl_stat_add(struct request *rq, u64 time) { }
348 #endif
349 
350 #ifdef CONFIG_BOUNCE
351 extern int init_emergency_isa_pool(void);
352 extern void blk_queue_bounce(struct request_queue *q, struct bio **bio);
353 #else
354 static inline int init_emergency_isa_pool(void)
355 {
356         return 0;
357 }
358 static inline void blk_queue_bounce(struct request_queue *q, struct bio **bio)
359 {
360 }
361 #endif /* CONFIG_BOUNCE */
362 
363 #endif /* BLK_INTERNAL_H */
364 

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