block/elevator.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _ELEVATOR_H
   3 #define _ELEVATOR_H
   4
   5 #include <linux/percpu.h>
   6 #include <linux/hashtable.h>
   7 #include "blk-mq.h"
   8
   9 struct io_cq;
  10 struct elevator_type;
  11 struct blk_mq_debugfs_attr;
  12
  13 /*
  14  * Return values from elevator merger
  15  */
  16 enum elv_merge {
  17         ELEVATOR_NO_MERGE       = 0,
  18         ELEVATOR_FRONT_MERGE    = 1,
  19         ELEVATOR_BACK_MERGE     = 2,
  20         ELEVATOR_DISCARD_MERGE  = 3,
  21 };
  22
  23 struct blk_mq_alloc_data;
  24 struct blk_mq_hw_ctx;
  25
  26 struct elevator_mq_ops {
  27         int (*init_sched)(struct request_queue *, struct elevator_type *);
  28         void (*exit_sched)(struct elevator_queue *);
  29         int (*init_hctx)(struct blk_mq_hw_ctx *, unsigned int);
  30         void (*exit_hctx)(struct blk_mq_hw_ctx *, unsigned int);
  31         void (*depth_updated)(struct blk_mq_hw_ctx *);
  32
  33         bool (*allow_merge)(struct request_queue *, struct request *, struct bio *);
  34         bool (*bio_merge)(struct request_queue *, struct bio *, unsigned int);
  35         int (*request_merge)(struct request_queue *q, struct request **, struct bio *);
  36         void (*request_merged)(struct request_queue *, struct request *, enum elv_merge);
  37         void (*requests_merged)(struct request_queue *, struct request *, struct request *);
  38         void (*limit_depth)(blk_opf_t, struct blk_mq_alloc_data *);
  39         void (*prepare_request)(struct request *);
  40         void (*finish_request)(struct request *);
  41         void (*insert_requests)(struct blk_mq_hw_ctx *hctx, struct list_head *list,
  42                         blk_insert_t flags);
  43         struct request *(*dispatch_request)(struct blk_mq_hw_ctx *);
  44         bool (*has_work)(struct blk_mq_hw_ctx *);
  45         void (*completed_request)(struct request *, u64);
  46         void (*requeue_request)(struct request *);
  47         struct request *(*former_request)(struct request_queue *, struct request *);
  48         struct request *(*next_request)(struct request_queue *, struct request *);
  49         void (*init_icq)(struct io_cq *);
  50         void (*exit_icq)(struct io_cq *);
  51 };
  52
  53 #define ELV_NAME_MAX    (16)
  54
  55 struct elv_fs_entry {
  56         struct attribute attr;
  57         ssize_t (*show)(struct elevator_queue *, char *);
  58         ssize_t (*store)(struct elevator_queue *, const char *, size_t);
  59 };
  60
  61 /*
  62  * identifies an elevator type, such as AS or deadline
  63  */
  64 struct elevator_type
  65 {
  66         /* managed by elevator core */
  67         struct kmem_cache *icq_cache;
  68
  69         /* fields provided by elevator implementation */
  70         struct elevator_mq_ops ops;
  71
  72         size_t icq_size;        /* see iocontext.h */
  73         size_t icq_align;       /* ditto */
  74         struct elv_fs_entry *elevator_attrs;
  75         const char *elevator_name;
  76         const char *elevator_alias;
  77         const unsigned int elevator_features;
  78         struct module *elevator_owner;
  79 #ifdef CONFIG_BLK_DEBUG_FS
  80         const struct blk_mq_debugfs_attr *queue_debugfs_attrs;
  81         const struct blk_mq_debugfs_attr *hctx_debugfs_attrs;
  82 #endif
  83
  84         /* managed by elevator core */
  85         char icq_cache_name[ELV_NAME_MAX + 6];  /* elvname + "_io_cq" */
  86         struct list_head list;
  87 };
  88
  89 static inline bool elevator_tryget(struct elevator_type *e)
  90 {
  91         return try_module_get(e->elevator_owner);
  92 }
  93
  94 static inline void __elevator_get(struct elevator_type *e)
  95 {
  96         __module_get(e->elevator_owner);
  97 }
  98
  99 static inline void elevator_put(struct elevator_type *e)
 100 {
 101         module_put(e->elevator_owner);
 102 }
 103
 104 #define ELV_HASH_BITS 6
 105
 106 void elv_rqhash_del(struct request_queue *q, struct request *rq);
 107 void elv_rqhash_add(struct request_queue *q, struct request *rq);
 108 void elv_rqhash_reposition(struct request_queue *q, struct request *rq);
 109 struct request *elv_rqhash_find(struct request_queue *q, sector_t offset);
 110
 111 /*
 112  * each queue has an elevator_queue associated with it
 113  */
 114 struct elevator_queue
 115 {
 116         struct elevator_type *type;
 117         void *elevator_data;
 118         struct kobject kobj;
 119         struct mutex sysfs_lock;
 120         unsigned long flags;
 121         DECLARE_HASHTABLE(hash, ELV_HASH_BITS);
 122 };
 123
 124 #define ELEVATOR_FLAG_REGISTERED        0
 125 #define ELEVATOR_FLAG_DISABLE_WBT       1
 126
 127 /*
 128  * block elevator interface
 129  */
 130 extern enum elv_merge elv_merge(struct request_queue *, struct request **,
 131                 struct bio *);
 132 extern void elv_merge_requests(struct request_queue *, struct request *,
 133                                struct request *);
 134 extern void elv_merged_request(struct request_queue *, struct request *,
 135                 enum elv_merge);
 136 extern bool elv_attempt_insert_merge(struct request_queue *, struct request *,
 137                                      struct list_head *);
 138 extern struct request *elv_former_request(struct request_queue *, struct request *);
 139 extern struct request *elv_latter_request(struct request_queue *, struct request *);
 140 void elevator_init_mq(struct request_queue *q);
 141
 142 /*
 143  * io scheduler registration
 144  */
 145 extern int elv_register(struct elevator_type *);
 146 extern void elv_unregister(struct elevator_type *);
 147
 148 /*
 149  * io scheduler sysfs switching
 150  */
 151 extern ssize_t elv_iosched_show(struct request_queue *, char *);
 152 extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
 153
 154 extern bool elv_bio_merge_ok(struct request *, struct bio *);
 155 extern struct elevator_queue *elevator_alloc(struct request_queue *,
 156                                         struct elevator_type *);
 157
 158 /*
 159  * Helper functions.
 160  */
 161 extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
 162 extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);
 163
 164 /*
 165  * rb support functions.
 166  */
 167 extern void elv_rb_add(struct rb_root *, struct request *);
 168 extern void elv_rb_del(struct rb_root *, struct request *);
 169 extern struct request *elv_rb_find(struct rb_root *, sector_t);
 170
 171 /*
 172  * Insertion selection
 173  */
 174 #define ELEVATOR_INSERT_FRONT   1
 175 #define ELEVATOR_INSERT_BACK    2
 176 #define ELEVATOR_INSERT_SORT    3
 177 #define ELEVATOR_INSERT_REQUEUE 4
 178 #define ELEVATOR_INSERT_FLUSH   5
 179 #define ELEVATOR_INSERT_SORT_MERGE      6
 180
 181 #define rb_entry_rq(node)       rb_entry((node), struct request, rb_node)
 182
 183 #define rq_entry_fifo(ptr)      list_entry((ptr), struct request, queuelist)
 184 #define rq_fifo_clear(rq)       list_del_init(&(rq)->queuelist)
 185
 186 #endif /* _ELEVATOR_H */