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