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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 struct blk_flush_queue {
 18         unsigned int            flush_queue_delayed:1;
 19         unsigned int            flush_pending_idx:1;
 20         unsigned int            flush_running_idx:1;
 21         unsigned long           flush_pending_since;
 22         struct list_head        flush_queue[2];
 23         struct list_head        flush_data_in_flight;
 24         struct request          *flush_rq;
 25 
 26         /*
 27          * flush_rq shares tag with this rq, both can't be active
 28          * at the same time
 29          */
 30         struct request          *orig_rq;
 31         spinlock_t              mq_flush_lock;
 32 };
 33 
 34 extern struct kmem_cache *blk_requestq_cachep;
 35 extern struct kmem_cache *request_cachep;
 36 extern struct kobj_type blk_queue_ktype;
 37 extern struct ida blk_queue_ida;
 38 
 39 static inline struct blk_flush_queue *blk_get_flush_queue(
 40                 struct request_queue *q, struct blk_mq_ctx *ctx)
 41 {
 42         struct blk_mq_hw_ctx *hctx;
 43 
 44         if (!q->mq_ops)
 45                 return q->fq;
 46 
 47         hctx = q->mq_ops->map_queue(q, ctx->cpu);
 48 
 49         return hctx->fq;
 50 }
 51 
 52 static inline void __blk_get_queue(struct request_queue *q)
 53 {
 54         kobject_get(&q->kobj);
 55 }
 56 
 57 struct blk_flush_queue *blk_alloc_flush_queue(struct request_queue *q,
 58                 int node, int cmd_size);
 59 void blk_free_flush_queue(struct blk_flush_queue *q);
 60 
 61 int blk_init_rl(struct request_list *rl, struct request_queue *q,
 62                 gfp_t gfp_mask);
 63 void blk_exit_rl(struct request_list *rl);
 64 void init_request_from_bio(struct request *req, struct bio *bio);
 65 void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
 66                         struct bio *bio);
 67 int blk_rq_append_bio(struct request_queue *q, struct request *rq,
 68                       struct bio *bio);
 69 void blk_queue_bypass_start(struct request_queue *q);
 70 void blk_queue_bypass_end(struct request_queue *q);
 71 void blk_dequeue_request(struct request *rq);
 72 void __blk_queue_free_tags(struct request_queue *q);
 73 bool __blk_end_bidi_request(struct request *rq, int error,
 74                             unsigned int nr_bytes, unsigned int bidi_bytes);
 75 
 76 void blk_rq_timed_out_timer(unsigned long data);
 77 unsigned long blk_rq_timeout(unsigned long timeout);
 78 void blk_add_timer(struct request *req);
 79 void blk_delete_timer(struct request *);
 80 
 81 
 82 bool bio_attempt_front_merge(struct request_queue *q, struct request *req,
 83                              struct bio *bio);
 84 bool bio_attempt_back_merge(struct request_queue *q, struct request *req,
 85                             struct bio *bio);
 86 bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
 87                             unsigned int *request_count,
 88                             struct request **same_queue_rq);
 89 
 90 void blk_account_io_start(struct request *req, bool new_io);
 91 void blk_account_io_completion(struct request *req, unsigned int bytes);
 92 void blk_account_io_done(struct request *req);
 93 
 94 /*
 95  * Internal atomic flags for request handling
 96  */
 97 enum rq_atomic_flags {
 98         REQ_ATOM_COMPLETE = 0,
 99         REQ_ATOM_STARTED,
100 };
101 
102 /*
103  * EH timer and IO completion will both attempt to 'grab' the request, make
104  * sure that only one of them succeeds
105  */
106 static inline int blk_mark_rq_complete(struct request *rq)
107 {
108         return test_and_set_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
109 }
110 
111 static inline void blk_clear_rq_complete(struct request *rq)
112 {
113         clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
114 }
115 
116 /*
117  * Internal elevator interface
118  */
119 #define ELV_ON_HASH(rq) ((rq)->cmd_flags & REQ_HASHED)
120 
121 void blk_insert_flush(struct request *rq);
122 
123 static inline struct request *__elv_next_request(struct request_queue *q)
124 {
125         struct request *rq;
126         struct blk_flush_queue *fq = blk_get_flush_queue(q, NULL);
127 
128         while (1) {
129                 if (!list_empty(&q->queue_head)) {
130                         rq = list_entry_rq(q->queue_head.next);
131                         return rq;
132                 }
133 
134                 /*
135                  * Flush request is running and flush request isn't queueable
136                  * in the drive, we can hold the queue till flush request is
137                  * finished. Even we don't do this, driver can't dispatch next
138                  * requests and will requeue them. And this can improve
139                  * throughput too. For example, we have request flush1, write1,
140                  * flush 2. flush1 is dispatched, then queue is hold, write1
141                  * isn't inserted to queue. After flush1 is finished, flush2
142                  * will be dispatched. Since disk cache is already clean,
143                  * flush2 will be finished very soon, so looks like flush2 is
144                  * folded to flush1.
145                  * Since the queue is hold, a flag is set to indicate the queue
146                  * should be restarted later. Please see flush_end_io() for
147                  * details.
148                  */
149                 if (fq->flush_pending_idx != fq->flush_running_idx &&
150                                 !queue_flush_queueable(q)) {
151                         fq->flush_queue_delayed = 1;
152                         return NULL;
153                 }
154                 if (unlikely(blk_queue_bypass(q)) ||
155                     !q->elevator->type->ops.elevator_dispatch_fn(q, 0))
156                         return NULL;
157         }
158 }
159 
160 static inline void elv_activate_rq(struct request_queue *q, struct request *rq)
161 {
162         struct elevator_queue *e = q->elevator;
163 
164         if (e->type->ops.elevator_activate_req_fn)
165                 e->type->ops.elevator_activate_req_fn(q, rq);
166 }
167 
168 static inline void elv_deactivate_rq(struct request_queue *q, struct request *rq)
169 {
170         struct elevator_queue *e = q->elevator;
171 
172         if (e->type->ops.elevator_deactivate_req_fn)
173                 e->type->ops.elevator_deactivate_req_fn(q, rq);
174 }
175 
176 #ifdef CONFIG_FAIL_IO_TIMEOUT
177 int blk_should_fake_timeout(struct request_queue *);
178 ssize_t part_timeout_show(struct device *, struct device_attribute *, char *);
179 ssize_t part_timeout_store(struct device *, struct device_attribute *,
180                                 const char *, size_t);
181 #else
182 static inline int blk_should_fake_timeout(struct request_queue *q)
183 {
184         return 0;
185 }
186 #endif
187 
188 int ll_back_merge_fn(struct request_queue *q, struct request *req,
189                      struct bio *bio);
190 int ll_front_merge_fn(struct request_queue *q, struct request *req, 
191                       struct bio *bio);
192 int attempt_back_merge(struct request_queue *q, struct request *rq);
193 int attempt_front_merge(struct request_queue *q, struct request *rq);
194 int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
195                                 struct request *next);
196 void blk_recalc_rq_segments(struct request *rq);
197 void blk_rq_set_mixed_merge(struct request *rq);
198 bool blk_rq_merge_ok(struct request *rq, struct bio *bio);
199 int blk_try_merge(struct request *rq, struct bio *bio);
200 
201 void blk_queue_congestion_threshold(struct request_queue *q);
202 
203 int blk_dev_init(void);
204 
205 
206 /*
207  * Return the threshold (number of used requests) at which the queue is
208  * considered to be congested.  It include a little hysteresis to keep the
209  * context switch rate down.
210  */
211 static inline int queue_congestion_on_threshold(struct request_queue *q)
212 {
213         return q->nr_congestion_on;
214 }
215 
216 /*
217  * The threshold at which a queue is considered to be uncongested
218  */
219 static inline int queue_congestion_off_threshold(struct request_queue *q)
220 {
221         return q->nr_congestion_off;
222 }
223 
224 extern int blk_update_nr_requests(struct request_queue *, unsigned int);
225 
226 /*
227  * Contribute to IO statistics IFF:
228  *
229  *      a) it's attached to a gendisk, and
230  *      b) the queue had IO stats enabled when this request was started, and
231  *      c) it's a file system request
232  */
233 static inline int blk_do_io_stat(struct request *rq)
234 {
235         return rq->rq_disk &&
236                (rq->cmd_flags & REQ_IO_STAT) &&
237                 (rq->cmd_type == REQ_TYPE_FS);
238 }
239 
240 /*
241  * Internal io_context interface
242  */
243 void get_io_context(struct io_context *ioc);
244 struct io_cq *ioc_lookup_icq(struct io_context *ioc, struct request_queue *q);
245 struct io_cq *ioc_create_icq(struct io_context *ioc, struct request_queue *q,
246                              gfp_t gfp_mask);
247 void ioc_clear_queue(struct request_queue *q);
248 
249 int create_task_io_context(struct task_struct *task, gfp_t gfp_mask, int node);
250 
251 /**
252  * create_io_context - try to create task->io_context
253  * @gfp_mask: allocation mask
254  * @node: allocation node
255  *
256  * If %current->io_context is %NULL, allocate a new io_context and install
257  * it.  Returns the current %current->io_context which may be %NULL if
258  * allocation failed.
259  *
260  * Note that this function can't be called with IRQ disabled because
261  * task_lock which protects %current->io_context is IRQ-unsafe.
262  */
263 static inline struct io_context *create_io_context(gfp_t gfp_mask, int node)
264 {
265         WARN_ON_ONCE(irqs_disabled());
266         if (unlikely(!current->io_context))
267                 create_task_io_context(current, gfp_mask, node);
268         return current->io_context;
269 }
270 
271 /*
272  * Internal throttling interface
273  */
274 #ifdef CONFIG_BLK_DEV_THROTTLING
275 extern bool blk_throtl_bio(struct request_queue *q, struct bio *bio);
276 extern void blk_throtl_drain(struct request_queue *q);
277 extern int blk_throtl_init(struct request_queue *q);
278 extern void blk_throtl_exit(struct request_queue *q);
279 #else /* CONFIG_BLK_DEV_THROTTLING */
280 static inline bool blk_throtl_bio(struct request_queue *q, struct bio *bio)
281 {
282         return false;
283 }
284 static inline void blk_throtl_drain(struct request_queue *q) { }
285 static inline int blk_throtl_init(struct request_queue *q) { return 0; }
286 static inline void blk_throtl_exit(struct request_queue *q) { }
287 #endif /* CONFIG_BLK_DEV_THROTTLING */
288 
289 #endif /* BLK_INTERNAL_H */
290 

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