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