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