1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
|
// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2001 Sistina Software (UK) Limited
*
* This file is released under the GPL.
*/
#include "dm-core.h"
#include <linux/module.h>
#include <linux/init.h>
#include <linux/kmod.h>
#include <linux/bio.h>
#include <linux/dax.h>
#define DM_MSG_PREFIX "target"
static LIST_HEAD(_targets);
static DECLARE_RWSEM(_lock);
static inline struct target_type *__find_target_type(const char *name)
{
struct target_type *tt;
list_for_each_entry(tt, &_targets, list)
if (!strcmp(name, tt->name))
return tt;
return NULL;
}
static struct target_type *get_target_type(const char *name)
{
struct target_type *tt;
down_read(&_lock);
tt = __find_target_type(name);
if (tt && !try_module_get(tt->module))
tt = NULL;
up_read(&_lock);
return tt;
}
static void load_module(const char *name)
{
request_module("dm-%s", name);
}
struct target_type *dm_get_target_type(const char *name)
{
struct target_type *tt = get_target_type(name);
if (!tt) {
load_module(name);
tt = get_target_type(name);
}
return tt;
}
void dm_put_target_type(struct target_type *tt)
{
down_read(&_lock);
module_put(tt->module);
up_read(&_lock);
}
int dm_target_iterate(void (*iter_func)(struct target_type *tt,
void *param), void *param)
{
struct target_type *tt;
down_read(&_lock);
list_for_each_entry(tt, &_targets, list)
iter_func(tt, param);
up_read(&_lock);
return 0;
}
int dm_register_target(struct target_type *tt)
{
int rv = 0;
down_write(&_lock);
if (__find_target_type(tt->name)) {
DMERR("%s: '%s' target already registered",
__func__, tt->name);
rv = -EEXIST;
} else {
list_add(&tt->list, &_targets);
}
up_write(&_lock);
return rv;
}
EXPORT_SYMBOL(dm_register_target);
void dm_unregister_target(struct target_type *tt)
{
down_write(&_lock);
if (!__find_target_type(tt->name)) {
DMCRIT("Unregistering unrecognised target: %s", tt->name);
BUG();
}
list_del(&tt->list);
up_write(&_lock);
}
EXPORT_SYMBOL(dm_unregister_target);
/*
* io-err: always fails an io, useful for bringing
* up LVs that have holes in them.
*/
static int io_err_ctr(struct dm_target *tt, unsigned int argc, char **args)
{
/*
* Return error for discards instead of -EOPNOTSUPP
*/
tt->num_discard_bios = 1;
tt->discards_supported = true;
return 0;
}
static void io_err_dtr(struct dm_target *tt)
{
/* empty */
}
static int io_err_map(struct dm_target *tt, struct bio *bio)
{
return DM_MAPIO_KILL;
}
static int io_err_clone_and_map_rq(struct dm_target *ti, struct request *rq,
union map_info *map_context,
struct request **clone)
{
return DM_MAPIO_KILL;
}
static void io_err_release_clone_rq(struct request *clone,
union map_info *map_context)
{
}
static void io_err_io_hints(struct dm_target *ti, struct queue_limits *limits)
{
limits->max_discard_sectors = UINT_MAX;
limits->max_hw_discard_sectors = UINT_MAX;
limits->discard_granularity = 512;
}
static long io_err_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
long nr_pages, enum dax_access_mode mode, void **kaddr,
pfn_t *pfn)
{
return -EIO;
}
static struct target_type error_target = {
.name = "error",
.version = {1, 6, 0},
.features = DM_TARGET_WILDCARD,
.ctr = io_err_ctr,
.dtr = io_err_dtr,
.map = io_err_map,
.clone_and_map_rq = io_err_clone_and_map_rq,
.release_clone_rq = io_err_release_clone_rq,
.io_hints = io_err_io_hints,
.direct_access = io_err_dax_direct_access,
};
int __init dm_target_init(void)
{
return dm_register_target(&error_target);
}
void dm_target_exit(void)
{
dm_unregister_target(&error_target);
}
|
