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-rw-r--r--block/elevator.h186
1 files changed, 186 insertions, 0 deletions
diff --git a/block/elevator.h b/block/elevator.h
new file mode 100644
index 0000000000..7ca3d7b6ed
--- /dev/null
+++ b/block/elevator.h
@@ -0,0 +1,186 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ELEVATOR_H
+#define _ELEVATOR_H
+
+#include <linux/percpu.h>
+#include <linux/hashtable.h>
+#include "blk-mq.h"
+
+struct io_cq;
+struct elevator_type;
+struct blk_mq_debugfs_attr;
+
+/*
+ * Return values from elevator merger
+ */
+enum elv_merge {
+ ELEVATOR_NO_MERGE = 0,
+ ELEVATOR_FRONT_MERGE = 1,
+ ELEVATOR_BACK_MERGE = 2,
+ ELEVATOR_DISCARD_MERGE = 3,
+};
+
+struct blk_mq_alloc_data;
+struct blk_mq_hw_ctx;
+
+struct elevator_mq_ops {
+ int (*init_sched)(struct request_queue *, struct elevator_type *);
+ void (*exit_sched)(struct elevator_queue *);
+ int (*init_hctx)(struct blk_mq_hw_ctx *, unsigned int);
+ void (*exit_hctx)(struct blk_mq_hw_ctx *, unsigned int);
+ void (*depth_updated)(struct blk_mq_hw_ctx *);
+
+ bool (*allow_merge)(struct request_queue *, struct request *, struct bio *);
+ bool (*bio_merge)(struct request_queue *, struct bio *, unsigned int);
+ int (*request_merge)(struct request_queue *q, struct request **, struct bio *);
+ void (*request_merged)(struct request_queue *, struct request *, enum elv_merge);
+ void (*requests_merged)(struct request_queue *, struct request *, struct request *);
+ void (*limit_depth)(blk_opf_t, struct blk_mq_alloc_data *);
+ void (*prepare_request)(struct request *);
+ void (*finish_request)(struct request *);
+ void (*insert_requests)(struct blk_mq_hw_ctx *hctx, struct list_head *list,
+ blk_insert_t flags);
+ struct request *(*dispatch_request)(struct blk_mq_hw_ctx *);
+ bool (*has_work)(struct blk_mq_hw_ctx *);
+ void (*completed_request)(struct request *, u64);
+ void (*requeue_request)(struct request *);
+ struct request *(*former_request)(struct request_queue *, struct request *);
+ struct request *(*next_request)(struct request_queue *, struct request *);
+ void (*init_icq)(struct io_cq *);
+ void (*exit_icq)(struct io_cq *);
+};
+
+#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_mq_ops ops;
+
+ size_t icq_size; /* see iocontext.h */
+ size_t icq_align; /* ditto */
+ struct elv_fs_entry *elevator_attrs;
+ const char *elevator_name;
+ const char *elevator_alias;
+ const unsigned int elevator_features;
+ struct module *elevator_owner;
+#ifdef CONFIG_BLK_DEBUG_FS
+ const struct blk_mq_debugfs_attr *queue_debugfs_attrs;
+ const struct blk_mq_debugfs_attr *hctx_debugfs_attrs;
+#endif
+
+ /* managed by elevator core */
+ char icq_cache_name[ELV_NAME_MAX + 6]; /* elvname + "_io_cq" */
+ struct list_head list;
+};
+
+static inline bool elevator_tryget(struct elevator_type *e)
+{
+ return try_module_get(e->elevator_owner);
+}
+
+static inline void __elevator_get(struct elevator_type *e)
+{
+ __module_get(e->elevator_owner);
+}
+
+static inline void elevator_put(struct elevator_type *e)
+{
+ module_put(e->elevator_owner);
+}
+
+#define ELV_HASH_BITS 6
+
+void elv_rqhash_del(struct request_queue *q, struct request *rq);
+void elv_rqhash_add(struct request_queue *q, struct request *rq);
+void elv_rqhash_reposition(struct request_queue *q, struct request *rq);
+struct request *elv_rqhash_find(struct request_queue *q, sector_t offset);
+
+/*
+ * 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 long flags;
+ DECLARE_HASHTABLE(hash, ELV_HASH_BITS);
+};
+
+#define ELEVATOR_FLAG_REGISTERED 0
+#define ELEVATOR_FLAG_DISABLE_WBT 1
+
+/*
+ * block elevator interface
+ */
+extern enum elv_merge 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 *,
+ enum elv_merge);
+extern bool elv_attempt_insert_merge(struct request_queue *, struct request *,
+ struct list_head *);
+extern struct request *elv_former_request(struct request_queue *, struct request *);
+extern struct request *elv_latter_request(struct request_queue *, struct request *);
+void elevator_init_mq(struct request_queue *q);
+
+/*
+ * io scheduler registration
+ */
+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 bool elv_bio_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);
+
+/*
+ * 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
+
+#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)
+
+#endif /* _ELEVATOR_H */