2 * Copyright (C) 2003 Sistina Software (UK) Limited.
3 * Copyright (C) 2004, 2010 Red Hat, Inc. All rights reserved.
5 * This file is released under the GPL.
8 #include <linux/device-mapper.h>
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>
16 #define DM_MSG_PREFIX "flakey"
19 * Flakey: Used for testing only, simulates intermittent,
20 * catastrophic device failure.
24 unsigned long start_time;
27 unsigned down_interval;
31 * Construct a flakey mapping: <dev_path> <offset> <up interval> <down interval>
33 static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv)
36 unsigned long long tmp;
39 ti->error = "dm-flakey: Invalid argument count";
43 fc = kmalloc(sizeof(*fc), GFP_KERNEL);
45 ti->error = "dm-flakey: Cannot allocate linear context";
48 fc->start_time = jiffies;
50 if (sscanf(argv[1], "%llu", &tmp) != 1) {
51 ti->error = "dm-flakey: Invalid device sector";
56 if (sscanf(argv[2], "%u", &fc->up_interval) != 1) {
57 ti->error = "dm-flakey: Invalid up interval";
61 if (sscanf(argv[3], "%u", &fc->down_interval) != 1) {
62 ti->error = "dm-flakey: Invalid down interval";
66 if (!(fc->up_interval + fc->down_interval)) {
67 ti->error = "dm-flakey: Total (up + down) interval is zero";
71 if (fc->up_interval + fc->down_interval < fc->up_interval) {
72 ti->error = "dm-flakey: Interval overflow";
76 if (dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &fc->dev)) {
77 ti->error = "dm-flakey: Device lookup failed";
81 ti->num_flush_requests = 1;
82 ti->num_discard_requests = 1;
91 static void flakey_dtr(struct dm_target *ti)
93 struct flakey_c *fc = ti->private;
95 dm_put_device(ti, fc->dev);
99 static sector_t flakey_map_sector(struct dm_target *ti, sector_t bi_sector)
101 struct flakey_c *fc = ti->private;
103 return fc->start + dm_target_offset(ti, bi_sector);
106 static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
108 struct flakey_c *fc = ti->private;
110 bio->bi_bdev = fc->dev->bdev;
111 if (bio_sectors(bio))
112 bio->bi_sector = flakey_map_sector(ti, bio->bi_sector);
115 static int flakey_map(struct dm_target *ti, struct bio *bio,
116 union map_info *map_context)
118 struct flakey_c *fc = ti->private;
122 elapsed = (jiffies - fc->start_time) / HZ;
123 if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval)
126 flakey_map_bio(ti, bio);
128 return DM_MAPIO_REMAPPED;
131 static int flakey_status(struct dm_target *ti, status_type_t type,
132 char *result, unsigned int maxlen)
134 struct flakey_c *fc = ti->private;
137 case STATUSTYPE_INFO:
141 case STATUSTYPE_TABLE:
142 snprintf(result, maxlen, "%s %llu %u %u", fc->dev->name,
143 (unsigned long long)fc->start, fc->up_interval,
150 static int flakey_ioctl(struct dm_target *ti, unsigned int cmd, unsigned long arg)
152 struct flakey_c *fc = ti->private;
154 return __blkdev_driver_ioctl(fc->dev->bdev, fc->dev->mode, cmd, arg);
157 static int flakey_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
158 struct bio_vec *biovec, int max_size)
160 struct flakey_c *fc = ti->private;
161 struct request_queue *q = bdev_get_queue(fc->dev->bdev);
163 if (!q->merge_bvec_fn)
166 bvm->bi_bdev = fc->dev->bdev;
167 bvm->bi_sector = flakey_map_sector(ti, bvm->bi_sector);
169 return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
172 static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
174 struct flakey_c *fc = ti->private;
176 return fn(ti, fc->dev, fc->start, ti->len, data);
179 static struct target_type flakey_target = {
181 .version = {1, 1, 0},
182 .module = THIS_MODULE,
186 .status = flakey_status,
187 .ioctl = flakey_ioctl,
188 .merge = flakey_merge,
189 .iterate_devices = flakey_iterate_devices,
192 static int __init dm_flakey_init(void)
194 int r = dm_register_target(&flakey_target);
197 DMERR("register failed %d", r);
202 static void __exit dm_flakey_exit(void)
204 dm_unregister_target(&flakey_target);
208 module_init(dm_flakey_init);
209 module_exit(dm_flakey_exit);
211 MODULE_DESCRIPTION(DM_NAME " flakey target");
212 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
213 MODULE_LICENSE("GPL");