block/blk.h

   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_list *rl);
  63 void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
  64                         struct bio *bio);
  65 void blk_queue_bypass_start(struct request_queue *q);
  66 void blk_queue_bypass_end(struct request_queue *q);
  67 void blk_dequeue_request(struct request *rq);
  68 void __blk_queue_free_tags(struct request_queue *q);
  69 void blk_freeze_queue(struct request_queue *q);
  70
  71 static inline void blk_queue_enter_live(struct request_queue *q)
  72 {
  73         /*
  74          * Given that running in generic_make_request() context
  75          * guarantees that a live reference against q_usage_counter has
  76          * been established, further references under that same context
  77          * need not check that the queue has been frozen (marked dead).
  78          */
  79         percpu_ref_get(&q->q_usage_counter);
  80 }
  81
  82 #ifdef CONFIG_BLK_DEV_INTEGRITY
  83 void blk_flush_integrity(void);
  84 #else
  85 static inline void blk_flush_integrity(void)
  86 {
  87 }
  88 #endif
  89
  90 void blk_timeout_work(struct work_struct *work);
  91 unsigned long blk_rq_timeout(unsigned long timeout);
  92 void blk_add_timer(struct request *req);
  93 void blk_delete_timer(struct request *);
  94
  95
  96 bool bio_attempt_front_merge(struct request_queue *q, struct request *req,
  97                              struct bio *bio);
  98 bool bio_attempt_back_merge(struct request_queue *q, struct request *req,
  99                             struct bio *bio);
 100 bool bio_attempt_discard_merge(struct request_queue *q, struct request *req,
 101                 struct bio *bio);
 102 bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
 103                             unsigned int *request_count,
 104                             struct request **same_queue_rq);
 105 unsigned int blk_plug_queued_count(struct request_queue *q);
 106
 107 void blk_account_io_start(struct request *req, bool new_io);
 108 void blk_account_io_completion(struct request *req, unsigned int bytes);
 109 void blk_account_io_done(struct request *req);
 110
 111 /*
 112  * Internal atomic flags for request handling
 113  */
 114 enum rq_atomic_flags {
 115         REQ_ATOM_COMPLETE = 0,
 116         REQ_ATOM_STARTED,
 117         REQ_ATOM_POLL_SLEPT,
 118 };
 119
 120 /*
 121  * EH timer and IO completion will both attempt to 'grab' the request, make
 122  * sure that only one of them succeeds
 123  */
 124 static inline int blk_mark_rq_complete(struct request *rq)
 125 {
 126         return test_and_set_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
 127 }
 128
 129 static inline void blk_clear_rq_complete(struct request *rq)
 130 {
 131         clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
 132 }
 133
 134 /*
 135  * Internal elevator interface
 136  */
 137 #define ELV_ON_HASH(rq) ((rq)->rq_flags & RQF_HASHED)
 138
 139 void blk_insert_flush(struct request *rq);
 140
 141 static inline struct request *__elv_next_request(struct request_queue *q)
 142 {
 143         struct request *rq;
 144         struct blk_flush_queue *fq = blk_get_flush_queue(q, NULL);
 145
 146         while (1) {
 147                 if (!list_empty(&q->queue_head)) {
 148                         rq = list_entry_rq(q->queue_head.next);
 149                         return rq;
 150                 }
 151
 152                 /*
 153                  * Flush request is running and flush request isn't queueable
 154                  * in the drive, we can hold the queue till flush request is
 155                  * finished. Even we don't do this, driver can't dispatch next
 156                  * requests and will requeue them. And this can improve
 157                  * throughput too. For example, we have request flush1, write1,
 158                  * flush 2. flush1 is dispatched, then queue is hold, write1
 159                  * isn't inserted to queue. After flush1 is finished, flush2
 160                  * will be dispatched. Since disk cache is already clean,
 161                  * flush2 will be finished very soon, so looks like flush2 is
 162                  * folded to flush1.
 163                  * Since the queue is hold, a flag is set to indicate the queue
 164                  * should be restarted later. Please see flush_end_io() for
 165                  * details.
 166                  */
 167                 if (fq->flush_pending_idx != fq->flush_running_idx &&
 168                                 !queue_flush_queueable(q)) {
 169                         fq->flush_queue_delayed = 1;
 170                         return NULL;
 171                 }
 172                 if (unlikely(blk_queue_bypass(q)) ||
 173                     !q->elevator->type->ops.sq.elevator_dispatch_fn(q, 0))
 174                         return NULL;
 175         }
 176 }
 177
 178 static inline void elv_activate_rq(struct request_queue *q, struct request *rq)
 179 {
 180         struct elevator_queue *e = q->elevator;
 181
 182         if (e->type->ops.sq.elevator_activate_req_fn)
 183                 e->type->ops.sq.elevator_activate_req_fn(q, rq);
 184 }
 185
 186 static inline void elv_deactivate_rq(struct request_queue *q, struct request *rq)
 187 {
 188         struct elevator_queue *e = q->elevator;
 189
 190         if (e->type->ops.sq.elevator_deactivate_req_fn)
 191                 e->type->ops.sq.elevator_deactivate_req_fn(q, rq);
 192 }
 193
 194 #ifdef CONFIG_FAIL_IO_TIMEOUT
 195 int blk_should_fake_timeout(struct request_queue *);
 196 ssize_t part_timeout_show(struct device *, struct device_attribute *, char *);
 197 ssize_t part_timeout_store(struct device *, struct device_attribute *,
 198                                 const char *, size_t);
 199 #else
 200 static inline int blk_should_fake_timeout(struct request_queue *q)
 201 {
 202         return 0;
 203 }
 204 #endif
 205
 206 int ll_back_merge_fn(struct request_queue *q, struct request *req,
 207                      struct bio *bio);
 208 int ll_front_merge_fn(struct request_queue *q, struct request *req,
 209                       struct bio *bio);
 210 struct request *attempt_back_merge(struct request_queue *q, struct request *rq);
 211 struct request *attempt_front_merge(struct request_queue *q, struct request *rq);
 212 int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
 213                                 struct request *next);
 214 void blk_recalc_rq_segments(struct request *rq);
 215 void blk_rq_set_mixed_merge(struct request *rq);
 216 bool blk_rq_merge_ok(struct request *rq, struct bio *bio);
 217 enum elv_merge blk_try_merge(struct request *rq, struct bio *bio);
 218
 219 void blk_queue_congestion_threshold(struct request_queue *q);
 220
 221 int blk_dev_init(void);
 222
 223
 224 /*
 225  * Return the threshold (number of used requests) at which the queue is
 226  * considered to be congested.  It include a little hysteresis to keep the
 227  * context switch rate down.
 228  */
 229 static inline int queue_congestion_on_threshold(struct request_queue *q)
 230 {
 231         return q->nr_congestion_on;
 232 }
 233
 234 /*
 235  * The threshold at which a queue is considered to be uncongested
 236  */
 237 static inline int queue_congestion_off_threshold(struct request_queue *q)
 238 {
 239         return q->nr_congestion_off;
 240 }
 241
 242 extern int blk_update_nr_requests(struct request_queue *, unsigned int);
 243
 244 /*
 245  * Contribute to IO statistics IFF:
 246  *
 247  *      a) it's attached to a gendisk, and
 248  *      b) the queue had IO stats enabled when this request was started, and
 249  *      c) it's a file system request
 250  */
 251 static inline int blk_do_io_stat(struct request *rq)
 252 {
 253         return rq->rq_disk &&
 254                (rq->rq_flags & RQF_IO_STAT) &&
 255                 !blk_rq_is_passthrough(rq);
 256 }
 257
 258 static inline void req_set_nomerge(struct request_queue *q, struct request *req)
 259 {
 260         req->cmd_flags |= REQ_NOMERGE;
 261         if (req == q->last_merge)
 262                 q->last_merge = NULL;
 263 }
 264
 265 /*
 266  * Internal io_context interface
 267  */
 268 void get_io_context(struct io_context *ioc);
 269 struct io_cq *ioc_lookup_icq(struct io_context *ioc, struct request_queue *q);
 270 struct io_cq *ioc_create_icq(struct io_context *ioc, struct request_queue *q,
 271                              gfp_t gfp_mask);
 272 void ioc_clear_queue(struct request_queue *q);
 273
 274 int create_task_io_context(struct task_struct *task, gfp_t gfp_mask, int node);
 275
 276 /**
 277  * rq_ioc - determine io_context for request allocation
 278  * @bio: request being allocated is for this bio (can be %NULL)
 279  *
 280  * Determine io_context to use for request allocation for @bio.  May return
 281  * %NULL if %current->io_context doesn't exist.
 282  */
 283 static inline struct io_context *rq_ioc(struct bio *bio)
 284 {
 285 #ifdef CONFIG_BLK_CGROUP
 286         if (bio && bio->bi_ioc)
 287                 return bio->bi_ioc;
 288 #endif
 289         return current->io_context;
 290 }
 291
 292 /**
 293  * create_io_context - try to create task->io_context
 294  * @gfp_mask: allocation mask
 295  * @node: allocation node
 296  *
 297  * If %current->io_context is %NULL, allocate a new io_context and install
 298  * it.  Returns the current %current->io_context which may be %NULL if
 299  * allocation failed.
 300  *
 301  * Note that this function can't be called with IRQ disabled because
 302  * task_lock which protects %current->io_context is IRQ-unsafe.
 303  */
 304 static inline struct io_context *create_io_context(gfp_t gfp_mask, int node)
 305 {
 306         WARN_ON_ONCE(irqs_disabled());
 307         if (unlikely(!current->io_context))
 308                 create_task_io_context(current, gfp_mask, node);
 309         return current->io_context;
 310 }
 311
 312 /*
 313  * Internal throttling interface
 314  */
 315 #ifdef CONFIG_BLK_DEV_THROTTLING
 316 extern void blk_throtl_drain(struct request_queue *q);
 317 extern int blk_throtl_init(struct request_queue *q);
 318 extern void blk_throtl_exit(struct request_queue *q);
 319 extern void blk_throtl_register_queue(struct request_queue *q);
 320 #else /* CONFIG_BLK_DEV_THROTTLING */
 321 static inline void blk_throtl_drain(struct request_queue *q) { }
 322 static inline int blk_throtl_init(struct request_queue *q) { return 0; }
 323 static inline void blk_throtl_exit(struct request_queue *q) { }
 324 static inline void blk_throtl_register_queue(struct request_queue *q) { }
 325 #endif /* CONFIG_BLK_DEV_THROTTLING */
 326 #ifdef CONFIG_BLK_DEV_THROTTLING_LOW
 327 extern ssize_t blk_throtl_sample_time_show(struct request_queue *q, char *page);
 328 extern ssize_t blk_throtl_sample_time_store(struct request_queue *q,
 329         const char *page, size_t count);
 330 extern void blk_throtl_bio_endio(struct bio *bio);
 331 extern void blk_throtl_stat_add(struct request *rq, u64 time);
 332 #else
 333 static inline void blk_throtl_bio_endio(struct bio *bio) { }
 334 static inline void blk_throtl_stat_add(struct request *rq, u64 time) { }
 335 #endif
 336
 337 #endif /* BLK_INTERNAL_H */