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