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