FreeBSD/Linux Kernel Cross Reference
sys/block/blk.h

     #ifndef BLK_INTERNAL_H
     #define BLK_INTERNAL_H
     
     #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)
    {
            kobject_get(&q->kobj);
    }
    
    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 {
            REQ_ATOM_COMPLETE = 0,
    };
    
    /*
     * 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)         (!hlist_unhashed(&(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->queue_head.next);
                            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);
   }
   
   #ifdef CONFIG_FAIL_IO_TIMEOUT
   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);
   #else
   static inline int blk_should_fake_timeout(struct request_queue *q)
   {
           return 0;
   }
   #endif
   
   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)
   {
           WARN_ON_ONCE(irqs_disabled());
           if (unlikely(!current->io_context))
                   create_task_io_context(current, gfp_mask, node);
           return current->io_context;
   }
   
   /*
    * Internal throttling interface
    */
   #ifdef CONFIG_BLK_DEV_THROTTLING
   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);
   #else /* CONFIG_BLK_DEV_THROTTLING */
   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 /* CONFIG_BLK_DEV_THROTTLING */
   
   #endif /* BLK_INTERNAL_H */

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