Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
dm: add flakey target
This target is the same as the linear target except that it returns I/O
errors periodically. It's been found useful in simulating failing
devices for testing purposes.
I needed a dm target to do some failure testing on btrfs's raid code, and
Mike pointed me at this.
Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
authored by Josef Bacik and committed by Alasdair G Kergon 3407ef52 024d37e9
+17
Documentation/device-mapper/dm-flakey.txt
+17
Documentation/device-mapper/dm-flakey.txt
···
1
+
dm-flakey
2
+
=========
3
+
4
+
This target is the same as the linear target except that it returns I/O
5
+
errors periodically. It's been found useful in simulating failing
6
+
devices for testing purposes.
7
+
8
+
Starting from the time the table is loaded, the device is available for
9
+
<up interval> seconds, then returns errors for <down interval> seconds,
10
+
and then this cycle repeats.
11
+
12
+
Parameters: <dev path> <offset> <up interval> <down interval>
13
+
<dev path>: Full pathname to the underlying block-device, or a
14
+
"major:minor" device-number.
15
+
<offset>: Starting sector within the device.
16
+
<up interval>: Number of seconds device is available.
17
+
<down interval>: Number of seconds device returns errors.
+6
drivers/md/Kconfig
+6
drivers/md/Kconfig
+1
drivers/md/Makefile
+1
drivers/md/Makefile
···
29
29
obj-$(CONFIG_BLK_DEV_DM) += dm-mod.o
30
30
obj-$(CONFIG_DM_CRYPT) += dm-crypt.o
31
31
obj-$(CONFIG_DM_DELAY) += dm-delay.o
32
+
obj-$(CONFIG_DM_FLAKEY) += dm-flakey.o
32
33
obj-$(CONFIG_DM_MULTIPATH) += dm-multipath.o dm-round-robin.o
33
34
obj-$(CONFIG_DM_MULTIPATH_QL) += dm-queue-length.o
34
35
obj-$(CONFIG_DM_MULTIPATH_ST) += dm-service-time.o
+212
drivers/md/dm-flakey.c
+212
drivers/md/dm-flakey.c
···
1
+
/*
2
+
* Copyright (C) 2003 Sistina Software (UK) Limited.
3
+
* Copyright (C) 2004, 2010 Red Hat, Inc. All rights reserved.
4
+
*
5
+
* This file is released under the GPL.
6
+
*/
7
+
8
+
#include <linux/device-mapper.h>
9
+
10
+
#include <linux/module.h>
11
+
#include <linux/init.h>
12
+
#include <linux/blkdev.h>
13
+
#include <linux/bio.h>
14
+
#include <linux/slab.h>
15
+
16
+
#define DM_MSG_PREFIX "flakey"
17
+
18
+
/*
19
+
* Flakey: Used for testing only, simulates intermittent,
20
+
* catastrophic device failure.
21
+
*/
22
+
struct flakey_c {
23
+
struct dm_dev *dev;
24
+
unsigned long start_time;
25
+
sector_t start;
26
+
unsigned up_interval;
27
+
unsigned down_interval;
28
+
};
29
+
30
+
/*
31
+
* Construct a flakey mapping: <dev_path> <offset> <up interval> <down interval>
32
+
*/
33
+
static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv)
34
+
{
35
+
struct flakey_c *fc;
36
+
unsigned long long tmp;
37
+
38
+
if (argc != 4) {
39
+
ti->error = "dm-flakey: Invalid argument count";
40
+
return -EINVAL;
41
+
}
42
+
43
+
fc = kmalloc(sizeof(*fc), GFP_KERNEL);
44
+
if (!fc) {
45
+
ti->error = "dm-flakey: Cannot allocate linear context";
46
+
return -ENOMEM;
47
+
}
48
+
fc->start_time = jiffies;
49
+
50
+
if (sscanf(argv[1], "%llu", &tmp) != 1) {
51
+
ti->error = "dm-flakey: Invalid device sector";
52
+
goto bad;
53
+
}
54
+
fc->start = tmp;
55
+
56
+
if (sscanf(argv[2], "%u", &fc->up_interval) != 1) {
57
+
ti->error = "dm-flakey: Invalid up interval";
58
+
goto bad;
59
+
}
60
+
61
+
if (sscanf(argv[3], "%u", &fc->down_interval) != 1) {
62
+
ti->error = "dm-flakey: Invalid down interval";
63
+
goto bad;
64
+
}
65
+
66
+
if (!(fc->up_interval + fc->down_interval)) {
67
+
ti->error = "dm-flakey: Total (up + down) interval is zero";
68
+
goto bad;
69
+
}
70
+
71
+
if (fc->up_interval + fc->down_interval < fc->up_interval) {
72
+
ti->error = "dm-flakey: Interval overflow";
73
+
goto bad;
74
+
}
75
+
76
+
if (dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &fc->dev)) {
77
+
ti->error = "dm-flakey: Device lookup failed";
78
+
goto bad;
79
+
}
80
+
81
+
ti->num_flush_requests = 1;
82
+
ti->private = fc;
83
+
return 0;
84
+
85
+
bad:
86
+
kfree(fc);
87
+
return -EINVAL;
88
+
}
89
+
90
+
static void flakey_dtr(struct dm_target *ti)
91
+
{
92
+
struct flakey_c *fc = ti->private;
93
+
94
+
dm_put_device(ti, fc->dev);
95
+
kfree(fc);
96
+
}
97
+
98
+
static sector_t flakey_map_sector(struct dm_target *ti, sector_t bi_sector)
99
+
{
100
+
struct flakey_c *fc = ti->private;
101
+
102
+
return fc->start + (bi_sector - ti->begin);
103
+
}
104
+
105
+
static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
106
+
{
107
+
struct flakey_c *fc = ti->private;
108
+
109
+
bio->bi_bdev = fc->dev->bdev;
110
+
if (bio_sectors(bio))
111
+
bio->bi_sector = flakey_map_sector(ti, bio->bi_sector);
112
+
}
113
+
114
+
static int flakey_map(struct dm_target *ti, struct bio *bio,
115
+
union map_info *map_context)
116
+
{
117
+
struct flakey_c *fc = ti->private;
118
+
unsigned elapsed;
119
+
120
+
/* Are we alive ? */
121
+
elapsed = (jiffies - fc->start_time) / HZ;
122
+
if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval)
123
+
return -EIO;
124
+
125
+
flakey_map_bio(ti, bio);
126
+
127
+
return DM_MAPIO_REMAPPED;
128
+
}
129
+
130
+
static int flakey_status(struct dm_target *ti, status_type_t type,
131
+
char *result, unsigned int maxlen)
132
+
{
133
+
struct flakey_c *fc = ti->private;
134
+
135
+
switch (type) {
136
+
case STATUSTYPE_INFO:
137
+
result[0] = '\0';
138
+
break;
139
+
140
+
case STATUSTYPE_TABLE:
141
+
snprintf(result, maxlen, "%s %llu %u %u", fc->dev->name,
142
+
(unsigned long long)fc->start, fc->up_interval,
143
+
fc->down_interval);
144
+
break;
145
+
}
146
+
return 0;
147
+
}
148
+
149
+
static int flakey_ioctl(struct dm_target *ti, unsigned int cmd, unsigned long arg)
150
+
{
151
+
struct flakey_c *fc = ti->private;
152
+
153
+
return __blkdev_driver_ioctl(fc->dev->bdev, fc->dev->mode, cmd, arg);
154
+
}
155
+
156
+
static int flakey_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
157
+
struct bio_vec *biovec, int max_size)
158
+
{
159
+
struct flakey_c *fc = ti->private;
160
+
struct request_queue *q = bdev_get_queue(fc->dev->bdev);
161
+
162
+
if (!q->merge_bvec_fn)
163
+
return max_size;
164
+
165
+
bvm->bi_bdev = fc->dev->bdev;
166
+
bvm->bi_sector = flakey_map_sector(ti, bvm->bi_sector);
167
+
168
+
return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
169
+
}
170
+
171
+
static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
172
+
{
173
+
struct flakey_c *fc = ti->private;
174
+
175
+
return fn(ti, fc->dev, fc->start, ti->len, data);
176
+
}
177
+
178
+
static struct target_type flakey_target = {
179
+
.name = "flakey",
180
+
.version = {1, 1, 0},
181
+
.module = THIS_MODULE,
182
+
.ctr = flakey_ctr,
183
+
.dtr = flakey_dtr,
184
+
.map = flakey_map,
185
+
.status = flakey_status,
186
+
.ioctl = flakey_ioctl,
187
+
.merge = flakey_merge,
188
+
.iterate_devices = flakey_iterate_devices,
189
+
};
190
+
191
+
static int __init dm_flakey_init(void)
192
+
{
193
+
int r = dm_register_target(&flakey_target);
194
+
195
+
if (r < 0)
196
+
DMERR("register failed %d", r);
197
+
198
+
return r;
199
+
}
200
+
201
+
static void __exit dm_flakey_exit(void)
202
+
{
203
+
dm_unregister_target(&flakey_target);
204
+
}
205
+
206
+
/* Module hooks */
207
+
module_init(dm_flakey_init);
208
+
module_exit(dm_flakey_exit);
209
+
210
+
MODULE_DESCRIPTION(DM_NAME " flakey target");
211
+
MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
212
+
MODULE_LICENSE("GPL");