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
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
|
/*
* Copyright (C) 2003 Sistina Software (UK) Limited.
* Copyright (C) 2004, 2010 Red Hat, Inc. All rights reserved.
*
* This file is released under the GPL.
*/
#include <linux/device-mapper.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/blkdev.h>
#include <linux/bio.h>
#include <linux/slab.h>
#define DM_MSG_PREFIX "flakey"
/*
* Flakey: Used for testing only, simulates intermittent,
* catastrophic device failure.
*/
struct flakey_c {
struct dm_dev *dev;
unsigned long start_time;
sector_t start;
unsigned up_interval;
unsigned down_interval;
};
/*
* Construct a flakey mapping: <dev_path> <offset> <up interval> <down interval>
*/
static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv)
{
struct flakey_c *fc;
unsigned long long tmp;
if (argc != 4) {
ti->error = "dm-flakey: Invalid argument count";
return -EINVAL;
}
fc = kmalloc(sizeof(*fc), GFP_KERNEL);
if (!fc) {
ti->error = "dm-flakey: Cannot allocate linear context";
return -ENOMEM;
}
fc->start_time = jiffies;
if (sscanf(argv[1], "%llu", &tmp) != 1) {
ti->error = "dm-flakey: Invalid device sector";
goto bad;
}
fc->start = tmp;
if (sscanf(argv[2], "%u", &fc->up_interval) != 1) {
ti->error = "dm-flakey: Invalid up interval";
goto bad;
}
if (sscanf(argv[3], "%u", &fc->down_interval) != 1) {
ti->error = "dm-flakey: Invalid down interval";
goto bad;
}
if (!(fc->up_interval + fc->down_interval)) {
ti->error = "dm-flakey: Total (up + down) interval is zero";
goto bad;
}
if (fc->up_interval + fc->down_interval < fc->up_interval) {
ti->error = "dm-flakey: Interval overflow";
goto bad;
}
if (dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &fc->dev)) {
ti->error = "dm-flakey: Device lookup failed";
goto bad;
}
ti->num_flush_requests = 1;
ti->private = fc;
return 0;
bad:
kfree(fc);
return -EINVAL;
}
static void flakey_dtr(struct dm_target *ti)
{
struct flakey_c *fc = ti->private;
dm_put_device(ti, fc->dev);
kfree(fc);
}
static sector_t flakey_map_sector(struct dm_target *ti, sector_t bi_sector)
{
struct flakey_c *fc = ti->private;
return fc->start + (bi_sector - ti->begin);
}
static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
{
struct flakey_c *fc = ti->private;
bio->bi_bdev = fc->dev->bdev;
if (bio_sectors(bio))
bio->bi_sector = flakey_map_sector(ti, bio->bi_sector);
}
static int flakey_map(struct dm_target *ti, struct bio *bio,
union map_info *map_context)
{
struct flakey_c *fc = ti->private;
unsigned elapsed;
/* Are we alive ? */
elapsed = (jiffies - fc->start_time) / HZ;
if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval)
return -EIO;
flakey_map_bio(ti, bio);
return DM_MAPIO_REMAPPED;
}
static int flakey_status(struct dm_target *ti, status_type_t type,
char *result, unsigned int maxlen)
{
struct flakey_c *fc = ti->private;
switch (type) {
case STATUSTYPE_INFO:
result[0] = '\0';
break;
case STATUSTYPE_TABLE:
snprintf(result, maxlen, "%s %llu %u %u", fc->dev->name,
(unsigned long long)fc->start, fc->up_interval,
fc->down_interval);
break;
}
return 0;
}
static int flakey_ioctl(struct dm_target *ti, unsigned int cmd, unsigned long arg)
{
struct flakey_c *fc = ti->private;
return __blkdev_driver_ioctl(fc->dev->bdev, fc->dev->mode, cmd, arg);
}
static int flakey_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
struct bio_vec *biovec, int max_size)
{
struct flakey_c *fc = ti->private;
struct request_queue *q = bdev_get_queue(fc->dev->bdev);
if (!q->merge_bvec_fn)
return max_size;
bvm->bi_bdev = fc->dev->bdev;
bvm->bi_sector = flakey_map_sector(ti, bvm->bi_sector);
return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
}
static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
{
struct flakey_c *fc = ti->private;
return fn(ti, fc->dev, fc->start, ti->len, data);
}
static struct target_type flakey_target = {
.name = "flakey",
.version = {1, 1, 0},
.module = THIS_MODULE,
.ctr = flakey_ctr,
.dtr = flakey_dtr,
.map = flakey_map,
.status = flakey_status,
.ioctl = flakey_ioctl,
.merge = flakey_merge,
.iterate_devices = flakey_iterate_devices,
};
static int __init dm_flakey_init(void)
{
int r = dm_register_target(&flakey_target);
if (r < 0)
DMERR("register failed %d", r);
return r;
}
static void __exit dm_flakey_exit(void)
{
dm_unregister_target(&flakey_target);
}
/* Module hooks */
module_init(dm_flakey_init);
module_exit(dm_flakey_exit);
MODULE_DESCRIPTION(DM_NAME " flakey target");
MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
MODULE_LICENSE("GPL");
|
