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"); 213