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_tags { 27 /* num. of hardware queues for which tags are allocated */ 28 unsigned int nr_hw_queues; 29 /* depth used while allocating tags */ 30 unsigned int nr_requests; 31 /* shared tag is stored at index 0 */ 32 struct blk_mq_tags *tags[]; 33 }; 34 35 struct elevator_resources { 36 /* holds elevator data */ 37 void *data; 38 /* holds elevator tags */ 39 struct elevator_tags *et; 40 }; 41 42 /* Holding context data for changing elevator */ 43 struct elv_change_ctx { 44 const char *name; 45 bool no_uevent; 46 47 /* for unregistering old elevator */ 48 struct elevator_queue *old; 49 /* for registering new elevator */ 50 struct elevator_queue *new; 51 /* store elevator type */ 52 struct elevator_type *type; 53 /* store elevator resources */ 54 struct elevator_resources res; 55 }; 56 57 struct elevator_mq_ops { 58 int (*init_sched)(struct request_queue *, struct elevator_queue *); 59 void (*exit_sched)(struct elevator_queue *); 60 int (*init_hctx)(struct blk_mq_hw_ctx *, unsigned int); 61 void (*exit_hctx)(struct blk_mq_hw_ctx *, unsigned int); 62 void (*depth_updated)(struct request_queue *); 63 void *(*alloc_sched_data)(struct request_queue *); 64 void (*free_sched_data)(void *); 65 66 bool (*allow_merge)(struct request_queue *, struct request *, struct bio *); 67 bool (*bio_merge)(struct request_queue *, struct bio *, unsigned int); 68 int (*request_merge)(struct request_queue *q, struct request **, struct bio *); 69 void (*request_merged)(struct request_queue *, struct request *, enum elv_merge); 70 void (*requests_merged)(struct request_queue *, struct request *, struct request *); 71 void (*limit_depth)(blk_opf_t, struct blk_mq_alloc_data *); 72 void (*prepare_request)(struct request *); 73 void (*finish_request)(struct request *); 74 void (*insert_requests)(struct blk_mq_hw_ctx *hctx, struct list_head *list, 75 blk_insert_t flags); 76 struct request *(*dispatch_request)(struct blk_mq_hw_ctx *); 77 bool (*has_work)(struct blk_mq_hw_ctx *); 78 void (*completed_request)(struct request *, u64); 79 void (*requeue_request)(struct request *); 80 struct request *(*former_request)(struct request_queue *, struct request *); 81 struct request *(*next_request)(struct request_queue *, struct request *); 82 void (*init_icq)(struct io_cq *); 83 void (*exit_icq)(struct io_cq *); 84 }; 85 86 #define ELV_NAME_MAX (16) 87 88 struct elv_fs_entry { 89 struct attribute attr; 90 ssize_t (*show)(struct elevator_queue *, char *); 91 ssize_t (*store)(struct elevator_queue *, const char *, size_t); 92 }; 93 94 /* 95 * identifies an elevator type, such as AS or deadline 96 */ 97 struct elevator_type 98 { 99 /* managed by elevator core */ 100 struct kmem_cache *icq_cache; 101 102 /* fields provided by elevator implementation */ 103 struct elevator_mq_ops ops; 104 105 size_t icq_size; /* see iocontext.h */ 106 size_t icq_align; /* ditto */ 107 const struct elv_fs_entry *elevator_attrs; 108 const char *elevator_name; 109 const char *elevator_alias; 110 struct module *elevator_owner; 111 #ifdef CONFIG_BLK_DEBUG_FS 112 const struct blk_mq_debugfs_attr *queue_debugfs_attrs; 113 const struct blk_mq_debugfs_attr *hctx_debugfs_attrs; 114 #endif 115 116 /* managed by elevator core */ 117 char icq_cache_name[ELV_NAME_MAX + 6]; /* elvname + "_io_cq" */ 118 struct list_head list; 119 }; 120 121 static inline bool elevator_tryget(struct elevator_type *e) 122 { 123 return try_module_get(e->elevator_owner); 124 } 125 126 static inline void __elevator_get(struct elevator_type *e) 127 { 128 __module_get(e->elevator_owner); 129 } 130 131 static inline void elevator_put(struct elevator_type *e) 132 { 133 module_put(e->elevator_owner); 134 } 135 136 #define ELV_HASH_BITS 6 137 138 void elv_rqhash_del(struct request_queue *q, struct request *rq); 139 void elv_rqhash_add(struct request_queue *q, struct request *rq); 140 void elv_rqhash_reposition(struct request_queue *q, struct request *rq); 141 struct request *elv_rqhash_find(struct request_queue *q, sector_t offset); 142 143 /* 144 * each queue has an elevator_queue associated with it 145 */ 146 struct elevator_queue 147 { 148 struct elevator_type *type; 149 struct elevator_tags *et; 150 void *elevator_data; 151 struct kobject kobj; 152 struct mutex sysfs_lock; 153 unsigned long flags; 154 DECLARE_HASHTABLE(hash, ELV_HASH_BITS); 155 }; 156 157 #define ELEVATOR_FLAG_REGISTERED 0 158 #define ELEVATOR_FLAG_DYING 1 159 160 /* 161 * block elevator interface 162 */ 163 extern enum elv_merge elv_merge(struct request_queue *, struct request **, 164 struct bio *); 165 extern void elv_merge_requests(struct request_queue *, struct request *, 166 struct request *); 167 extern void elv_merged_request(struct request_queue *, struct request *, 168 enum elv_merge); 169 extern bool elv_attempt_insert_merge(struct request_queue *, struct request *, 170 struct list_head *); 171 extern struct request *elv_former_request(struct request_queue *, struct request *); 172 extern struct request *elv_latter_request(struct request_queue *, struct request *); 173 174 /* 175 * io scheduler registration 176 */ 177 extern int elv_register(struct elevator_type *); 178 extern void elv_unregister(struct elevator_type *); 179 180 /* 181 * io scheduler sysfs switching 182 */ 183 ssize_t elv_iosched_show(struct gendisk *disk, char *page); 184 ssize_t elv_iosched_store(struct gendisk *disk, const char *page, size_t count); 185 186 extern bool elv_bio_merge_ok(struct request *, struct bio *); 187 struct elevator_queue *elevator_alloc(struct request_queue *, 188 struct elevator_type *, struct elevator_resources *); 189 190 /* 191 * Helper functions. 192 */ 193 extern struct request *elv_rb_former_request(struct request_queue *, struct request *); 194 extern struct request *elv_rb_latter_request(struct request_queue *, struct request *); 195 196 /* 197 * rb support functions. 198 */ 199 extern void elv_rb_add(struct rb_root *, struct request *); 200 extern void elv_rb_del(struct rb_root *, struct request *); 201 extern struct request *elv_rb_find(struct rb_root *, sector_t); 202 203 /* 204 * Insertion selection 205 */ 206 #define ELEVATOR_INSERT_FRONT 1 207 #define ELEVATOR_INSERT_BACK 2 208 #define ELEVATOR_INSERT_SORT 3 209 #define ELEVATOR_INSERT_REQUEUE 4 210 #define ELEVATOR_INSERT_FLUSH 5 211 #define ELEVATOR_INSERT_SORT_MERGE 6 212 213 #define rb_entry_rq(node) rb_entry((node), struct request, rb_node) 214 215 #define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist) 216 #define rq_fifo_clear(rq) list_del_init(&(rq)->queuelist) 217 218 void blk_mq_sched_reg_debugfs(struct request_queue *q); 219 void blk_mq_sched_unreg_debugfs(struct request_queue *q); 220 221 #endif /* _ELEVATOR_H */ 222