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#include <linux/idr.h>
/* Amount of time in which a process may batch requests */
#define BLK_BATCH_TIME (HZ/50UL)
/* Number of requests a "batching" process may submit */
#define BLK_BATCH_REQ 32
extern struct kmem_cache *blk_requestq_cachep;
extern struct kobj_type blk_queue_ktype;
extern struct ida blk_queue_ida;
static inline void __blk_get_queue(struct request_queue *q)
int blk_init_rl(struct request_list *rl, struct request_queue *q,
gfp_t gfp_mask);
void blk_exit_rl(struct request_list *rl);
void init_request_from_bio(struct request *req, struct bio *bio);
void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
struct bio *bio);
int blk_rq_append_bio(struct request_queue *q, struct request *rq,
struct bio *bio);
void blk_queue_bypass_start(struct request_queue *q);
void blk_queue_bypass_end(struct request_queue *q);
void blk_dequeue_request(struct request *rq);
void __blk_queue_free_tags(struct request_queue *q);
bool __blk_end_bidi_request(struct request *rq, int error,
unsigned int nr_bytes, unsigned int bidi_bytes);
void blk_rq_timed_out_timer(unsigned long data);
void blk_delete_timer(struct request *);
void blk_add_timer(struct request *);
* Internal atomic flags for request handling
enum rq_atomic_flags {
* EH timer and IO completion will both attempt to 'grab' the request, make
* sure that only one of them succeeds
static inline int blk_mark_rq_complete(struct request *rq)
return test_and_set_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
static inline void blk_clear_rq_complete(struct request *rq)
clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
* Internal elevator interface
#define ELV_ON_HASH(rq) hash_hashed(&(rq)->hash)
void blk_insert_flush(struct request *rq);
void blk_abort_flushes(struct request_queue *q);
static inline struct request *__elv_next_request(struct request_queue *q)
struct request *rq;
while (1) {
if (!list_empty(&q->queue_head)) {
rq = list_entry_rq(q->;
return rq;
* Flush request is running and flush request isn't queueable
* in the drive, we can hold the queue till flush request is
* finished. Even we don't do this, driver can't dispatch next
* requests and will requeue them. And this can improve
* throughput too. For example, we have request flush1, write1,
* flush 2. flush1 is dispatched, then queue is hold, write1
* isn't inserted to queue. After flush1 is finished, flush2
* will be dispatched. Since disk cache is already clean,
* flush2 will be finished very soon, so looks like flush2 is
* folded to flush1.
* Since the queue is hold, a flag is set to indicate the queue
* should be restarted later. Please see flush_end_io() for
* details.
if (q->flush_pending_idx != q->flush_running_idx &&
!queue_flush_queueable(q)) {
q->flush_queue_delayed = 1;
return NULL;
if (unlikely(blk_queue_dying(q)) ||
!q->elevator->type->ops.elevator_dispatch_fn(q, 0))
return NULL;
static inline void elv_activate_rq(struct request_queue *q, struct request *rq)
struct elevator_queue *e = q->elevator;
if (e->type->ops.elevator_activate_req_fn)
e->type->ops.elevator_activate_req_fn(q, rq);
static inline void elv_deactivate_rq(struct request_queue *q, struct request *rq)
struct elevator_queue *e = q->elevator;
if (e->type->ops.elevator_deactivate_req_fn)
e->type->ops.elevator_deactivate_req_fn(q, rq);
int blk_should_fake_timeout(struct request_queue *);
ssize_t part_timeout_show(struct device *, struct device_attribute *, char *);
ssize_t part_timeout_store(struct device *, struct device_attribute *,
const char *, size_t);
static inline int blk_should_fake_timeout(struct request_queue *q)
return 0;
int ll_back_merge_fn(struct request_queue *q, struct request *req,
struct bio *bio);
int ll_front_merge_fn(struct request_queue *q, struct request *req,
struct bio *bio);
int attempt_back_merge(struct request_queue *q, struct request *rq);
int attempt_front_merge(struct request_queue *q, struct request *rq);
int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
struct request *next);
void blk_recalc_rq_segments(struct request *rq);
void blk_rq_set_mixed_merge(struct request *rq);
bool blk_rq_merge_ok(struct request *rq, struct bio *bio);
int blk_try_merge(struct request *rq, struct bio *bio);
void blk_queue_congestion_threshold(struct request_queue *q);
void __blk_run_queue_uncond(struct request_queue *q);
int blk_dev_init(void);
* Return the threshold (number of used requests) at which the queue is
* considered to be congested. It include a little hysteresis to keep the
* context switch rate down.
static inline int queue_congestion_on_threshold(struct request_queue *q)
return q->nr_congestion_on;
* The threshold at which a queue is considered to be uncongested
static inline int queue_congestion_off_threshold(struct request_queue *q)
return q->nr_congestion_off;
* Contribute to IO statistics IFF:
* a) it's attached to a gendisk, and
* b) the queue had IO stats enabled when this request was started, and
* c) it's a file system request
static inline int blk_do_io_stat(struct request *rq)
return rq->rq_disk &&
(rq->cmd_flags & REQ_IO_STAT) &&
(rq->cmd_type == REQ_TYPE_FS);
* Internal io_context interface
void get_io_context(struct io_context *ioc);
struct io_cq *ioc_lookup_icq(struct io_context *ioc, struct request_queue *q);
struct io_cq *ioc_create_icq(struct io_context *ioc, struct request_queue *q,
gfp_t gfp_mask);
void ioc_clear_queue(struct request_queue *q);
int create_task_io_context(struct task_struct *task, gfp_t gfp_mask, int node);
* create_io_context - try to create task->io_context
* @gfp_mask: allocation mask
* @node: allocation node
* If %current->io_context is %NULL, allocate a new io_context and install
* it. Returns the current %current->io_context which may be %NULL if
* allocation failed.
* Note that this function can't be called with IRQ disabled because
* task_lock which protects %current->io_context is IRQ-unsafe.
static inline struct io_context *create_io_context(gfp_t gfp_mask, int node)
if (unlikely(!current->io_context))
create_task_io_context(current, gfp_mask, node);
return current->io_context;
* Internal throttling interface
extern bool blk_throtl_bio(struct request_queue *q, struct bio *bio);
extern void blk_throtl_drain(struct request_queue *q);
extern int blk_throtl_init(struct request_queue *q);
extern void blk_throtl_exit(struct request_queue *q);
static inline bool blk_throtl_bio(struct request_queue *q, struct bio *bio)
return false;
static inline void blk_throtl_drain(struct request_queue *q) { }
static inline int blk_throtl_init(struct request_queue *q) { return 0; }
static inline void blk_throtl_exit(struct request_queue *q) { }
#endif /* BLK_INTERNAL_H */
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