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