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

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