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

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