--- /dev/null
+#ifndef _LINUX_ELEVATOR_H
+#define _LINUX_ELEVATOR_H
+
+#include <linux/percpu.h>
+#include <linux/hashtable.h>
+
+#ifdef CONFIG_BLOCK
+
+struct io_cq;
+struct elevator_type;
+
+typedef int (elevator_merge_fn) (struct request_queue *, struct request **,
+ struct bio *);
+
+typedef void (elevator_merge_req_fn) (struct request_queue *, struct request *, struct request *);
+
+typedef void (elevator_merged_fn) (struct request_queue *, struct request *, int);
+
+typedef int (elevator_allow_merge_fn) (struct request_queue *, struct request *, struct bio *);
+
+typedef void (elevator_bio_merged_fn) (struct request_queue *,
+ struct request *, struct bio *);
+
+typedef int (elevator_dispatch_fn) (struct request_queue *, int);
+
+typedef void (elevator_add_req_fn) (struct request_queue *, struct request *);
+typedef struct request *(elevator_request_list_fn) (struct request_queue *, struct request *);
+typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *);
+typedef int (elevator_may_queue_fn) (struct request_queue *, int);
+
+typedef void (elevator_init_icq_fn) (struct io_cq *);
+typedef void (elevator_exit_icq_fn) (struct io_cq *);
+typedef int (elevator_set_req_fn) (struct request_queue *, struct request *,
+ struct bio *, gfp_t);
+typedef void (elevator_put_req_fn) (struct request *);
+typedef void (elevator_activate_req_fn) (struct request_queue *, struct request *);
+typedef void (elevator_deactivate_req_fn) (struct request_queue *, struct request *);
+
+typedef int (elevator_init_fn) (struct request_queue *,
+ struct elevator_type *e);
+typedef void (elevator_exit_fn) (struct elevator_queue *);
+
+struct elevator_ops
+{
+ elevator_merge_fn *elevator_merge_fn;
+ elevator_merged_fn *elevator_merged_fn;
+ elevator_merge_req_fn *elevator_merge_req_fn;
+ elevator_allow_merge_fn *elevator_allow_merge_fn;
+ elevator_bio_merged_fn *elevator_bio_merged_fn;
+
+ elevator_dispatch_fn *elevator_dispatch_fn;
+ elevator_add_req_fn *elevator_add_req_fn;
+ elevator_activate_req_fn *elevator_activate_req_fn;
+ elevator_deactivate_req_fn *elevator_deactivate_req_fn;
+
+ elevator_completed_req_fn *elevator_completed_req_fn;
+
+ elevator_request_list_fn *elevator_former_req_fn;
+ elevator_request_list_fn *elevator_latter_req_fn;
+
+ elevator_init_icq_fn *elevator_init_icq_fn; /* see iocontext.h */
+ elevator_exit_icq_fn *elevator_exit_icq_fn; /* ditto */
+
+ elevator_set_req_fn *elevator_set_req_fn;
+ elevator_put_req_fn *elevator_put_req_fn;
+
+ elevator_may_queue_fn *elevator_may_queue_fn;
+
+ elevator_init_fn *elevator_init_fn;
+ elevator_exit_fn *elevator_exit_fn;
+};
+
+#define ELV_NAME_MAX (16)
+
+struct elv_fs_entry {
+ struct attribute attr;
+ ssize_t (*show)(struct elevator_queue *, char *);
+ ssize_t (*store)(struct elevator_queue *, const char *, size_t);
+};
+
+/*
+ * identifies an elevator type, such as AS or deadline
+ */
+struct elevator_type
+{
+ /* managed by elevator core */
+ struct kmem_cache *icq_cache;
+
+ /* fields provided by elevator implementation */
+ struct elevator_ops ops;
+ size_t icq_size; /* see iocontext.h */
+ size_t icq_align; /* ditto */
+ struct elv_fs_entry *elevator_attrs;
+ char elevator_name[ELV_NAME_MAX];
+ struct module *elevator_owner;
+
+ /* managed by elevator core */
+ char icq_cache_name[ELV_NAME_MAX + 5]; /* elvname + "_io_cq" */
+ struct list_head list;
+};
+
+#define ELV_HASH_BITS 6
+
+/*
+ * each queue has an elevator_queue associated with it
+ */
+struct elevator_queue
+{
+ struct elevator_type *type;
+ void *elevator_data;
+ struct kobject kobj;
+ struct mutex sysfs_lock;
+ unsigned int registered:1;
+ DECLARE_HASHTABLE(hash, ELV_HASH_BITS);
+};
+
+/*
+ * block elevator interface
+ */
+extern void elv_dispatch_sort(struct request_queue *, struct request *);
+extern void elv_dispatch_add_tail(struct request_queue *, struct request *);
+extern void elv_add_request(struct request_queue *, struct request *, int);
+extern void __elv_add_request(struct request_queue *, struct request *, int);
+extern int elv_merge(struct request_queue *, struct request **, struct bio *);
+extern void elv_merge_requests(struct request_queue *, struct request *,
+ struct request *);
+extern void elv_merged_request(struct request_queue *, struct request *, int);
+extern void elv_bio_merged(struct request_queue *q, struct request *,
+ struct bio *);
+extern void elv_requeue_request(struct request_queue *, struct request *);
+extern struct request *elv_former_request(struct request_queue *, struct request *);
+extern struct request *elv_latter_request(struct request_queue *, struct request *);
+extern int elv_register_queue(struct request_queue *q);
+extern void elv_unregister_queue(struct request_queue *q);
+extern int elv_may_queue(struct request_queue *, int);
+extern void elv_completed_request(struct request_queue *, struct request *);
+extern int elv_set_request(struct request_queue *q, struct request *rq,
+ struct bio *bio, gfp_t gfp_mask);
+extern void elv_put_request(struct request_queue *, struct request *);
+extern void elv_drain_elevator(struct request_queue *);
+
+/*
+ * io scheduler registration
+ */
+extern void __init load_default_elevator_module(void);
+extern int elv_register(struct elevator_type *);
+extern void elv_unregister(struct elevator_type *);
+
+/*
+ * io scheduler sysfs switching
+ */
+extern ssize_t elv_iosched_show(struct request_queue *, char *);
+extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
+
+extern int elevator_init(struct request_queue *, char *);
+extern void elevator_exit(struct elevator_queue *);
+extern int elevator_change(struct request_queue *, const char *);
+extern bool elv_rq_merge_ok(struct request *, struct bio *);
+extern struct elevator_queue *elevator_alloc(struct request_queue *,
+ struct elevator_type *);
+
+/*
+ * Helper functions.
+ */
+extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
+extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);
+
+/*
+ * rb support functions.
+ */
+extern void elv_rb_add(struct rb_root *, struct request *);
+extern void elv_rb_del(struct rb_root *, struct request *);
+extern struct request *elv_rb_find(struct rb_root *, sector_t);
+
+/*
+ * Return values from elevator merger
+ */
+#define ELEVATOR_NO_MERGE 0
+#define ELEVATOR_FRONT_MERGE 1
+#define ELEVATOR_BACK_MERGE 2
+
+/*
+ * Insertion selection
+ */
+#define ELEVATOR_INSERT_FRONT 1
+#define ELEVATOR_INSERT_BACK 2
+#define ELEVATOR_INSERT_SORT 3
+#define ELEVATOR_INSERT_REQUEUE 4
+#define ELEVATOR_INSERT_FLUSH 5
+#define ELEVATOR_INSERT_SORT_MERGE 6
+
+/*
+ * return values from elevator_may_queue_fn
+ */
+enum {
+ ELV_MQUEUE_MAY,
+ ELV_MQUEUE_NO,
+ ELV_MQUEUE_MUST,
+};
+
+#define rq_end_sector(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq))
+#define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
+
+#define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
+#define rq_fifo_clear(rq) list_del_init(&(rq)->queuelist)
+
+#else /* CONFIG_BLOCK */
+
+static inline void load_default_elevator_module(void) { }
+
+#endif /* CONFIG_BLOCK */
+#endif
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