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

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