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 
19 struct 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 
25 struct page_list {
26 	struct page_list *next;
27 	struct page *page;
28 };
29 
30 typedef void (*io_notify_fn)(unsigned int long error, void *context);
31 
32 enum 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 
39 struct 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 
52 struct 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  */
60 struct dm_io_client;
61 struct 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  */
74 struct dm_io_client *dm_io_client_create(void);
75 void 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  */
82 int 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 
85 #endif	/* __KERNEL__ */
86 #endif	/* _LINUX_DM_IO_H */
87