block: move elevator.h to block/

Except for the features passed to blk_queue_required_elevator_features,
elevator.h is only needed internally to the block layer.  Move the
ELEVATOR_F_* definitions to blkdev.h, and the move elevator.h to
block/, dropping all the spurious includes outside of that.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20210920123328.1399408-13-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 166 insertions, 0 deletions

diff --git a/block/elevator.h b/block/elevator.h
new file mode 100644
index 000000000000..16cd8bdedb7e
--- /dev/null
+++ b/block/elevator.h
@@ -0,0 +1,166 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ELEVATOR_H
+#define _ELEVATOR_H
+
+#include <linux/percpu.h>
+#include <linux/hashtable.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)(unsigned int, struct blk_mq_alloc_data *);
+	void (*prepare_request)(struct request *);
+	void (*finish_request)(struct request *);
+	void (*insert_requests)(struct blk_mq_hw_ctx *, struct list_head *, bool);
+	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;
+};
+
+#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 int registered:1;
+	DECLARE_HASHTABLE(hash, ELV_HASH_BITS);
+};
+
+/*
+ * 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 */