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         if (q->mq_ops)
  43                 return blk_mq_map_queue(q, ctx->cpu)->fq;
  44         return q->fq;
  45 }
  46
  47 static inline void __blk_get_queue(struct request_queue *q)
  48 {
  49         kobject_get(&q->kobj);
  50 }
  51
  52 struct blk_flush_queue *blk_alloc_flush_queue(struct request_queue *q,
  53                 int node, int cmd_size);
  54 void blk_free_flush_queue(struct blk_flush_queue *q);
  55
  56 int blk_init_rl(struct request_list *rl, struct request_queue *q,
  57                 gfp_t gfp_mask);
  58 void blk_exit_rl(struct request_list *rl);
  59 void init_request_from_bio(struct request *req, struct bio *bio);
  60 void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
  61                         struct bio *bio);
  62 void blk_queue_bypass_start(struct request_queue *q);
  63 void blk_queue_bypass_end(struct request_queue *q);
  64 void blk_dequeue_request(struct request *rq);
  65 void __blk_queue_free_tags(struct request_queue *q);
  66 bool __blk_end_bidi_request(struct request *rq, int error,
  67                             unsigned int nr_bytes, unsigned int bidi_bytes);
  68 void blk_freeze_queue(struct request_queue *q);
  69
  70 static inline void blk_queue_enter_live(struct request_queue *q)
  71 {
  72         /*
  73          * Given that running in generic_make_request() context
  74          * guarantees that a live reference against q_usage_counter has
  75          * been established, further references under that same context
  76          * need not check that the queue has been frozen (marked dead).
  77          */
  78         percpu_ref_get(&q->q_usage_counter);
  79 }
  80
  81 #ifdef CONFIG_BLK_DEV_INTEGRITY
  82 void blk_flush_integrity(void);
  83 #else
  84 static inline void blk_flush_integrity(void)
  85 {
  86 }
  87 #endif
  88
  89 void blk_timeout_work(struct work_struct *work);
  90 unsigned long blk_rq_timeout(unsigned long timeout);
  91 void blk_add_timer(struct request *req);
  92 void blk_delete_timer(struct request *);
  93
  94
  95 bool bio_attempt_front_merge(struct request_queue *q, struct request *req,
  96                              struct bio *bio);
  97 bool bio_attempt_back_merge(struct request_queue *q, struct request *req,
  98                             struct bio *bio);
  99 bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
 100                             unsigned int *request_count,
 101                             struct request **same_queue_rq);
 102 unsigned int blk_plug_queued_count(struct request_queue *q);
 103
 104 void blk_account_io_start(struct request *req, bool new_io);
 105 void blk_account_io_completion(struct request *req, unsigned int bytes);
 106 void blk_account_io_done(struct request *req);
 107
 108 /*
 109  * Internal atomic flags for request handling
 110  */
 111 enum rq_atomic_flags {
 112         REQ_ATOM_COMPLETE = 0,
 113         REQ_ATOM_STARTED,
 114 };
 115
 116 /*
 117  * EH timer and IO completion will both attempt to 'grab' the request, make
 118  * sure that only one of them succeeds
 119  */
 120 static inline int blk_mark_rq_complete(struct request *rq)
 121 {
 122         return test_and_set_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
 123 }
 124
 125 static inline void blk_clear_rq_complete(struct request *rq)
 126 {
 127         clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
 128 }
 129
 130 /*
 131  * Internal elevator interface
 132  */
 133 #define ELV_ON_HASH(rq) ((rq)->cmd_flags & REQ_HASHED)
 134
 135 void blk_insert_flush(struct request *rq);
 136
 137 static inline struct request *__elv_next_request(struct request_queue *q)
 138 {
 139         struct request *rq;
 140         struct blk_flush_queue *fq = blk_get_flush_queue(q, NULL);
 141
 142         while (1) {
 143                 if (!list_empty(&q->queue_head)) {
 144                         rq = list_entry_rq(q->queue_head.next);
 145                         return rq;
 146                 }
 147
 148                 /*
 149                  * Flush request is running and flush request isn't queueable
 150                  * in the drive, we can hold the queue till flush request is
 151                  * finished. Even we don't do this, driver can't dispatch next
 152                  * requests and will requeue them. And this can improve
 153                  * throughput too. For example, we have request flush1, write1,
 154                  * flush 2. flush1 is dispatched, then queue is hold, write1
 155                  * isn't inserted to queue. After flush1 is finished, flush2
 156                  * will be dispatched. Since disk cache is already clean,
 157                  * flush2 will be finished very soon, so looks like flush2 is
 158                  * folded to flush1.
 159                  * Since the queue is hold, a flag is set to indicate the queue
 160                  * should be restarted later. Please see flush_end_io() for
 161                  * details.
 162                  */
 163                 if (fq->flush_pending_idx != fq->flush_running_idx &&
 164                                 !queue_flush_queueable(q)) {
 165                         fq->flush_queue_delayed = 1;
 166                         return NULL;
 167                 }
 168                 if (unlikely(blk_queue_bypass(q)) ||
 169                     !q->elevator->type->ops.elevator_dispatch_fn(q, 0))
 170                         return NULL;
 171         }
 172 }
 173
 174 static inline void elv_activate_rq(struct request_queue *q, struct request *rq)
 175 {
 176         struct elevator_queue *e = q->elevator;
 177
 178         if (e->type->ops.elevator_activate_req_fn)
 179                 e->type->ops.elevator_activate_req_fn(q, rq);
 180 }
 181
 182 static inline void elv_deactivate_rq(struct request_queue *q, struct request *rq)
 183 {
 184         struct elevator_queue *e = q->elevator;
 185
 186         if (e->type->ops.elevator_deactivate_req_fn)
 187                 e->type->ops.elevator_deactivate_req_fn(q, rq);
 188 }
 189
 190 #ifdef CONFIG_FAIL_IO_TIMEOUT
 191 int blk_should_fake_timeout(struct request_queue *);
 192 ssize_t part_timeout_show(struct device *, struct device_attribute *, char *);
 193 ssize_t part_timeout_store(struct device *, struct device_attribute *,
 194                                 const char *, size_t);
 195 #else
 196 static inline int blk_should_fake_timeout(struct request_queue *q)
 197 {
 198         return 0;
 199 }
 200 #endif
 201
 202 int ll_back_merge_fn(struct request_queue *q, struct request *req,
 203                      struct bio *bio);
 204 int ll_front_merge_fn(struct request_queue *q, struct request *req,
 205                       struct bio *bio);
 206 int attempt_back_merge(struct request_queue *q, struct request *rq);
 207 int attempt_front_merge(struct request_queue *q, struct request *rq);
 208 int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
 209                                 struct request *next);
 210 void blk_recalc_rq_segments(struct request *rq);
 211 void blk_rq_set_mixed_merge(struct request *rq);
 212 bool blk_rq_merge_ok(struct request *rq, struct bio *bio);
 213 int blk_try_merge(struct request *rq, struct bio *bio);
 214
 215 void blk_queue_congestion_threshold(struct request_queue *q);
 216
 217 int blk_dev_init(void);
 218
 219
 220 /*
 221  * Return the threshold (number of used requests) at which the queue is
 222  * considered to be congested.  It include a little hysteresis to keep the
 223  * context switch rate down.
 224  */
 225 static inline int queue_congestion_on_threshold(struct request_queue *q)
 226 {
 227         return q->nr_congestion_on;
 228 }
 229
 230 /*
 231  * The threshold at which a queue is considered to be uncongested
 232  */
 233 static inline int queue_congestion_off_threshold(struct request_queue *q)
 234 {
 235         return q->nr_congestion_off;
 236 }
 237
 238 extern int blk_update_nr_requests(struct request_queue *, unsigned int);
 239
 240 /*
 241  * Contribute to IO statistics IFF:
 242  *
 243  *      a) it's attached to a gendisk, and
 244  *      b) the queue had IO stats enabled when this request was started, and
 245  *      c) it's a file system request
 246  */
 247 static inline int blk_do_io_stat(struct request *rq)
 248 {
 249         return rq->rq_disk &&
 250                (rq->cmd_flags & REQ_IO_STAT) &&
 251                 (rq->cmd_type == REQ_TYPE_FS);
 252 }
 253
 254 /*
 255  * Internal io_context interface
 256  */
 257 void get_io_context(struct io_context *ioc);
 258 struct io_cq *ioc_lookup_icq(struct io_context *ioc, struct request_queue *q);
 259 struct io_cq *ioc_create_icq(struct io_context *ioc, struct request_queue *q,
 260                              gfp_t gfp_mask);
 261 void ioc_clear_queue(struct request_queue *q);
 262
 263 int create_task_io_context(struct task_struct *task, gfp_t gfp_mask, int node);
 264
 265 /**
 266  * create_io_context - try to create task->io_context
 267  * @gfp_mask: allocation mask
 268  * @node: allocation node
 269  *
 270  * If %current->io_context is %NULL, allocate a new io_context and install
 271  * it.  Returns the current %current->io_context which may be %NULL if
 272  * allocation failed.
 273  *
 274  * Note that this function can't be called with IRQ disabled because
 275  * task_lock which protects %current->io_context is IRQ-unsafe.
 276  */
 277 static inline struct io_context *create_io_context(gfp_t gfp_mask, int node)
 278 {
 279         WARN_ON_ONCE(irqs_disabled());
 280         if (unlikely(!current->io_context))
 281                 create_task_io_context(current, gfp_mask, node);
 282         return current->io_context;
 283 }
 284
 285 /*
 286  * Internal throttling interface
 287  */
 288 #ifdef CONFIG_BLK_DEV_THROTTLING
 289 extern void blk_throtl_drain(struct request_queue *q);
 290 extern int blk_throtl_init(struct request_queue *q);
 291 extern void blk_throtl_exit(struct request_queue *q);
 292 #else /* CONFIG_BLK_DEV_THROTTLING */
 293 static inline void blk_throtl_drain(struct request_queue *q) { }
 294 static inline int blk_throtl_init(struct request_queue *q) { return 0; }
 295 static inline void blk_throtl_exit(struct request_queue *q) { }
 296 #endif /* CONFIG_BLK_DEV_THROTTLING */
 297
 298 #endif /* BLK_INTERNAL_H */