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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 
  6 /* Amount of time in which a process may batch requests */
  7 #define BLK_BATCH_TIME  (HZ/50UL)
  8 
  9 /* Number of requests a "batching" process may submit */
 10 #define BLK_BATCH_REQ   32
 11 
 12 /* Max future timer expiry for timeouts */
 13 #define BLK_MAX_TIMEOUT         (5 * HZ)
 14 
 15 extern struct kmem_cache *blk_requestq_cachep;
 16 extern struct kmem_cache *request_cachep;
 17 extern struct kobj_type blk_queue_ktype;
 18 extern struct ida blk_queue_ida;
 19 
 20 static inline void __blk_get_queue(struct request_queue *q)
 21 {
 22         kobject_get(&q->kobj);
 23 }
 24 
 25 int blk_init_rl(struct request_list *rl, struct request_queue *q,
 26                 gfp_t gfp_mask);
 27 void blk_exit_rl(struct request_list *rl);
 28 void init_request_from_bio(struct request *req, struct bio *bio);
 29 void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
 30                         struct bio *bio);
 31 int blk_rq_append_bio(struct request_queue *q, struct request *rq,
 32                       struct bio *bio);
 33 void blk_queue_bypass_start(struct request_queue *q);
 34 void blk_queue_bypass_end(struct request_queue *q);
 35 void blk_dequeue_request(struct request *rq);
 36 void __blk_queue_free_tags(struct request_queue *q);
 37 bool __blk_end_bidi_request(struct request *rq, int error,
 38                             unsigned int nr_bytes, unsigned int bidi_bytes);
 39 
 40 void blk_rq_timed_out_timer(unsigned long data);
 41 void blk_rq_check_expired(struct request *rq, unsigned long *next_timeout,
 42                           unsigned int *next_set);
 43 unsigned long blk_rq_timeout(unsigned long timeout);
 44 void blk_add_timer(struct request *req);
 45 void blk_delete_timer(struct request *);
 46 
 47 
 48 bool bio_attempt_front_merge(struct request_queue *q, struct request *req,
 49                              struct bio *bio);
 50 bool bio_attempt_back_merge(struct request_queue *q, struct request *req,
 51                             struct bio *bio);
 52 bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
 53                             unsigned int *request_count);
 54 
 55 void blk_account_io_start(struct request *req, bool new_io);
 56 void blk_account_io_completion(struct request *req, unsigned int bytes);
 57 void blk_account_io_done(struct request *req);
 58 
 59 /*
 60  * Internal atomic flags for request handling
 61  */
 62 enum rq_atomic_flags {
 63         REQ_ATOM_COMPLETE = 0,
 64         REQ_ATOM_STARTED,
 65 };
 66 
 67 /*
 68  * EH timer and IO completion will both attempt to 'grab' the request, make
 69  * sure that only one of them succeeds
 70  */
 71 static inline int blk_mark_rq_complete(struct request *rq)
 72 {
 73         return test_and_set_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
 74 }
 75 
 76 static inline void blk_clear_rq_complete(struct request *rq)
 77 {
 78         clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
 79 }
 80 
 81 /*
 82  * Internal elevator interface
 83  */
 84 #define ELV_ON_HASH(rq) ((rq)->cmd_flags & REQ_HASHED)
 85 
 86 void blk_insert_flush(struct request *rq);
 87 
 88 static inline struct request *__elv_next_request(struct request_queue *q)
 89 {
 90         struct request *rq;
 91 
 92         while (1) {
 93                 if (!list_empty(&q->queue_head)) {
 94                         rq = list_entry_rq(q->queue_head.next);
 95                         return rq;
 96                 }
 97 
 98                 /*
 99                  * Flush request is running and flush request isn't queueable
100                  * in the drive, we can hold the queue till flush request is
101                  * finished. Even we don't do this, driver can't dispatch next
102                  * requests and will requeue them. And this can improve
103                  * throughput too. For example, we have request flush1, write1,
104                  * flush 2. flush1 is dispatched, then queue is hold, write1
105                  * isn't inserted to queue. After flush1 is finished, flush2
106                  * will be dispatched. Since disk cache is already clean,
107                  * flush2 will be finished very soon, so looks like flush2 is
108                  * folded to flush1.
109                  * Since the queue is hold, a flag is set to indicate the queue
110                  * should be restarted later. Please see flush_end_io() for
111                  * details.
112                  */
113                 if (q->flush_pending_idx != q->flush_running_idx &&
114                                 !queue_flush_queueable(q)) {
115                         q->flush_queue_delayed = 1;
116                         return NULL;
117                 }
118                 if (unlikely(blk_queue_bypass(q)) ||
119                     !q->elevator->type->ops.elevator_dispatch_fn(q, 0))
120                         return NULL;
121         }
122 }
123 
124 static inline void elv_activate_rq(struct request_queue *q, struct request *rq)
125 {
126         struct elevator_queue *e = q->elevator;
127 
128         if (e->type->ops.elevator_activate_req_fn)
129                 e->type->ops.elevator_activate_req_fn(q, rq);
130 }
131 
132 static inline void elv_deactivate_rq(struct request_queue *q, struct request *rq)
133 {
134         struct elevator_queue *e = q->elevator;
135 
136         if (e->type->ops.elevator_deactivate_req_fn)
137                 e->type->ops.elevator_deactivate_req_fn(q, rq);
138 }
139 
140 #ifdef CONFIG_FAIL_IO_TIMEOUT
141 int blk_should_fake_timeout(struct request_queue *);
142 ssize_t part_timeout_show(struct device *, struct device_attribute *, char *);
143 ssize_t part_timeout_store(struct device *, struct device_attribute *,
144                                 const char *, size_t);
145 #else
146 static inline int blk_should_fake_timeout(struct request_queue *q)
147 {
148         return 0;
149 }
150 #endif
151 
152 int ll_back_merge_fn(struct request_queue *q, struct request *req,
153                      struct bio *bio);
154 int ll_front_merge_fn(struct request_queue *q, struct request *req, 
155                       struct bio *bio);
156 int attempt_back_merge(struct request_queue *q, struct request *rq);
157 int attempt_front_merge(struct request_queue *q, struct request *rq);
158 int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
159                                 struct request *next);
160 void blk_recalc_rq_segments(struct request *rq);
161 void blk_rq_set_mixed_merge(struct request *rq);
162 bool blk_rq_merge_ok(struct request *rq, struct bio *bio);
163 int blk_try_merge(struct request *rq, struct bio *bio);
164 
165 void blk_queue_congestion_threshold(struct request_queue *q);
166 
167 void __blk_run_queue_uncond(struct request_queue *q);
168 
169 int blk_dev_init(void);
170 
171 
172 /*
173  * Return the threshold (number of used requests) at which the queue is
174  * considered to be congested.  It include a little hysteresis to keep the
175  * context switch rate down.
176  */
177 static inline int queue_congestion_on_threshold(struct request_queue *q)
178 {
179         return q->nr_congestion_on;
180 }
181 
182 /*
183  * The threshold at which a queue is considered to be uncongested
184  */
185 static inline int queue_congestion_off_threshold(struct request_queue *q)
186 {
187         return q->nr_congestion_off;
188 }
189 
190 extern int blk_update_nr_requests(struct request_queue *, unsigned int);
191 
192 /*
193  * Contribute to IO statistics IFF:
194  *
195  *      a) it's attached to a gendisk, and
196  *      b) the queue had IO stats enabled when this request was started, and
197  *      c) it's a file system request
198  */
199 static inline int blk_do_io_stat(struct request *rq)
200 {
201         return rq->rq_disk &&
202                (rq->cmd_flags & REQ_IO_STAT) &&
203                 (rq->cmd_type == REQ_TYPE_FS);
204 }
205 
206 /*
207  * Internal io_context interface
208  */
209 void get_io_context(struct io_context *ioc);
210 struct io_cq *ioc_lookup_icq(struct io_context *ioc, struct request_queue *q);
211 struct io_cq *ioc_create_icq(struct io_context *ioc, struct request_queue *q,
212                              gfp_t gfp_mask);
213 void ioc_clear_queue(struct request_queue *q);
214 
215 int create_task_io_context(struct task_struct *task, gfp_t gfp_mask, int node);
216 
217 /**
218  * create_io_context - try to create task->io_context
219  * @gfp_mask: allocation mask
220  * @node: allocation node
221  *
222  * If %current->io_context is %NULL, allocate a new io_context and install
223  * it.  Returns the current %current->io_context which may be %NULL if
224  * allocation failed.
225  *
226  * Note that this function can't be called with IRQ disabled because
227  * task_lock which protects %current->io_context is IRQ-unsafe.
228  */
229 static inline struct io_context *create_io_context(gfp_t gfp_mask, int node)
230 {
231         WARN_ON_ONCE(irqs_disabled());
232         if (unlikely(!current->io_context))
233                 create_task_io_context(current, gfp_mask, node);
234         return current->io_context;
235 }
236 
237 /*
238  * Internal throttling interface
239  */
240 #ifdef CONFIG_BLK_DEV_THROTTLING
241 extern bool blk_throtl_bio(struct request_queue *q, struct bio *bio);
242 extern void blk_throtl_drain(struct request_queue *q);
243 extern int blk_throtl_init(struct request_queue *q);
244 extern void blk_throtl_exit(struct request_queue *q);
245 #else /* CONFIG_BLK_DEV_THROTTLING */
246 static inline bool blk_throtl_bio(struct request_queue *q, struct bio *bio)
247 {
248         return false;
249 }
250 static inline void blk_throtl_drain(struct request_queue *q) { }
251 static inline int blk_throtl_init(struct request_queue *q) { return 0; }
252 static inline void blk_throtl_exit(struct request_queue *q) { }
253 #endif /* CONFIG_BLK_DEV_THROTTLING */
254 
255 #endif /* BLK_INTERNAL_H */
256 

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