1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * Copyright (C) 2003 Sistina Software
4 * Copyright (C) 2004 - 2008 Red Hat, Inc. All rights reserved.
5 *
6 * Device-Mapper low-level I/O.
7 *
8 * This file is released under the GPL.
9 */
10
11#ifndef _LINUX_DM_IO_H
12#define _LINUX_DM_IO_H
13
14#ifdef __KERNEL__
15
16#include <linux/types.h>
17#include <linux/blk_types.h>
18
19struct dm_io_region {
20	struct block_device *bdev;
21	sector_t sector;
22	sector_t count;		/* If this is zero the region is ignored. */
23};
24
25struct page_list {
26	struct page_list *next;
27	struct page *page;
28};
29
30typedef void (*io_notify_fn)(unsigned int long error, void *context);
31
32enum dm_io_mem_type {
33	DM_IO_PAGE_LIST,/* Page list */
34	DM_IO_BIO,	/* Bio vector */
35	DM_IO_VMA,	/* Virtual memory area */
36	DM_IO_KMEM,	/* Kernel memory */
37};
38
39struct dm_io_memory {
40	enum dm_io_mem_type type;
41
42	unsigned int offset;
43
44	union {
45		struct page_list *pl;
46		struct bio *bio;
47		void *vma;
48		void *addr;
49	} ptr;
50};
51
52struct dm_io_notify {
53	io_notify_fn fn;	/* Callback for asynchronous requests */
54	void *context;		/* Passed to callback */
55};
56
57/*
58 * IO request structure
59 */
60struct dm_io_client;
61struct dm_io_request {
62	blk_opf_t	    bi_opf;	/* Request type and flags */
63	struct dm_io_memory mem;	/* Memory to use for io */
64	struct dm_io_notify notify;	/* Synchronous if notify.fn is NULL */
65	struct dm_io_client *client;	/* Client memory handler */
66};
67
68/*
69 * For async io calls, users can alternatively use the dm_io() function below
70 * and dm_io_client_create() to create private mempools for the client.
71 *
72 * Create/destroy may block.
73 */
74struct dm_io_client *dm_io_client_create(void);
75void dm_io_client_destroy(struct dm_io_client *client);
76
77/*
78 * IO interface using private per-client pools.
79 * Each bit in the optional 'sync_error_bits' bitset indicates whether an
80 * error occurred doing io to the corresponding region.
81 */
82int dm_io(struct dm_io_request *io_req, unsigned int num_regions,
83	  struct dm_io_region *region, unsigned int long *sync_error_bits,
84	  unsigned short ioprio);
85
86#endif	/* __KERNEL__ */
87#endif	/* _LINUX_DM_IO_H */
88