1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * faulty.c : Multiple Devices driver for Linux 4 * 5 * Copyright (C) 2004 Neil Brown 6 * 7 * fautly-device-simulator personality for md 8 */ 9 10 11 /* 12 * The "faulty" personality causes some requests to fail. 13 * 14 * Possible failure modes are: 15 * reads fail "randomly" but succeed on retry 16 * writes fail "randomly" but succeed on retry 17 * reads for some address fail and then persist until a write 18 * reads for some address fail and then persist irrespective of write 19 * writes for some address fail and persist 20 * all writes fail 21 * 22 * Different modes can be active at a time, but only 23 * one can be set at array creation. Others can be added later. 24 * A mode can be one-shot or recurrent with the recurrence being 25 * once in every N requests. 26 * The bottom 5 bits of the "layout" indicate the mode. The 27 * remainder indicate a period, or 0 for one-shot. 28 * 29 * There is an implementation limit on the number of concurrently 30 * persisting-faulty blocks. When a new fault is requested that would 31 * exceed the limit, it is ignored. 32 * All current faults can be clear using a layout of "0". 33 * 34 * Requests are always sent to the device. If they are to fail, 35 * we clone the bio and insert a new b_end_io into the chain. 36 */ 37 38 #define WriteTransient 0 39 #define ReadTransient 1 40 #define WritePersistent 2 41 #define ReadPersistent 3 42 #define WriteAll 4 /* doesn't go to device */ 43 #define ReadFixable 5 44 #define Modes 6 45 46 #define ClearErrors 31 47 #define ClearFaults 30 48 49 #define AllPersist 100 /* internal use only */ 50 #define NoPersist 101 51 52 #define ModeMask 0x1f 53 #define ModeShift 5 54 55 #define MaxFault 50 56 #include <linux/blkdev.h> 57 #include <linux/module.h> 58 #include <linux/raid/md_u.h> 59 #include <linux/slab.h> 60 #include "md.h" 61 #include <linux/seq_file.h> 62 63 64 static void faulty_fail(struct bio *bio) 65 { 66 struct bio *b = bio->bi_private; 67 68 b->bi_iter.bi_size = bio->bi_iter.bi_size; 69 b->bi_iter.bi_sector = bio->bi_iter.bi_sector; 70 71 bio_put(bio); 72 73 bio_io_error(b); 74 } 75 76 struct faulty_conf { 77 int period[Modes]; 78 atomic_t counters[Modes]; 79 sector_t faults[MaxFault]; 80 int modes[MaxFault]; 81 int nfaults; 82 struct md_rdev *rdev; 83 }; 84 85 static int check_mode(struct faulty_conf *conf, int mode) 86 { 87 if (conf->period[mode] == 0 && 88 atomic_read(&conf->counters[mode]) <= 0) 89 return 0; /* no failure, no decrement */ 90 91 92 if (atomic_dec_and_test(&conf->counters[mode])) { 93 if (conf->period[mode]) 94 atomic_set(&conf->counters[mode], conf->period[mode]); 95 return 1; 96 } 97 return 0; 98 } 99 100 static int check_sector(struct faulty_conf *conf, sector_t start, sector_t end, int dir) 101 { 102 /* If we find a ReadFixable sector, we fix it ... */ 103 int i; 104 for (i=0; i<conf->nfaults; i++) 105 if (conf->faults[i] >= start && 106 conf->faults[i] < end) { 107 /* found it ... */ 108 switch (conf->modes[i] * 2 + dir) { 109 case WritePersistent*2+WRITE: return 1; 110 case ReadPersistent*2+READ: return 1; 111 case ReadFixable*2+READ: return 1; 112 case ReadFixable*2+WRITE: 113 conf->modes[i] = NoPersist; 114 return 0; 115 case AllPersist*2+READ: 116 case AllPersist*2+WRITE: return 1; 117 default: 118 return 0; 119 } 120 } 121 return 0; 122 } 123 124 static void add_sector(struct faulty_conf *conf, sector_t start, int mode) 125 { 126 int i; 127 int n = conf->nfaults; 128 for (i=0; i<conf->nfaults; i++) 129 if (conf->faults[i] == start) { 130 switch(mode) { 131 case NoPersist: conf->modes[i] = mode; return; 132 case WritePersistent: 133 if (conf->modes[i] == ReadPersistent || 134 conf->modes[i] == ReadFixable) 135 conf->modes[i] = AllPersist; 136 else 137 conf->modes[i] = WritePersistent; 138 return; 139 case ReadPersistent: 140 if (conf->modes[i] == WritePersistent) 141 conf->modes[i] = AllPersist; 142 else 143 conf->modes[i] = ReadPersistent; 144 return; 145 case ReadFixable: 146 if (conf->modes[i] == WritePersistent || 147 conf->modes[i] == ReadPersistent) 148 conf->modes[i] = AllPersist; 149 else 150 conf->modes[i] = ReadFixable; 151 return; 152 } 153 } else if (conf->modes[i] == NoPersist) 154 n = i; 155 156 if (n >= MaxFault) 157 return; 158 conf->faults[n] = start; 159 conf->modes[n] = mode; 160 if (conf->nfaults == n) 161 conf->nfaults = n+1; 162 } 163 164 static bool faulty_make_request(struct mddev *mddev, struct bio *bio) 165 { 166 struct faulty_conf *conf = mddev->private; 167 int failit = 0; 168 169 if (bio_data_dir(bio) == WRITE) { 170 /* write request */ 171 if (atomic_read(&conf->counters[WriteAll])) { 172 /* special case - don't decrement, don't submit_bio_noacct, 173 * just fail immediately 174 */ 175 bio_io_error(bio); 176 return true; 177 } 178 179 if (check_sector(conf, bio->bi_iter.bi_sector, 180 bio_end_sector(bio), WRITE)) 181 failit = 1; 182 if (check_mode(conf, WritePersistent)) { 183 add_sector(conf, bio->bi_iter.bi_sector, 184 WritePersistent); 185 failit = 1; 186 } 187 if (check_mode(conf, WriteTransient)) 188 failit = 1; 189 } else { 190 /* read request */ 191 if (check_sector(conf, bio->bi_iter.bi_sector, 192 bio_end_sector(bio), READ)) 193 failit = 1; 194 if (check_mode(conf, ReadTransient)) 195 failit = 1; 196 if (check_mode(conf, ReadPersistent)) { 197 add_sector(conf, bio->bi_iter.bi_sector, 198 ReadPersistent); 199 failit = 1; 200 } 201 if (check_mode(conf, ReadFixable)) { 202 add_sector(conf, bio->bi_iter.bi_sector, 203 ReadFixable); 204 failit = 1; 205 } 206 } 207 208 md_account_bio(mddev, &bio); 209 if (failit) { 210 struct bio *b = bio_alloc_clone(conf->rdev->bdev, bio, GFP_NOIO, 211 &mddev->bio_set); 212 213 b->bi_private = bio; 214 b->bi_end_io = faulty_fail; 215 bio = b; 216 } else 217 bio_set_dev(bio, conf->rdev->bdev); 218 219 submit_bio_noacct(bio); 220 return true; 221 } 222 223 static void faulty_status(struct seq_file *seq, struct mddev *mddev) 224 { 225 struct faulty_conf *conf = mddev->private; 226 int n; 227 228 if ((n=atomic_read(&conf->counters[WriteTransient])) != 0) 229 seq_printf(seq, " WriteTransient=%d(%d)", 230 n, conf->period[WriteTransient]); 231 232 if ((n=atomic_read(&conf->counters[ReadTransient])) != 0) 233 seq_printf(seq, " ReadTransient=%d(%d)", 234 n, conf->period[ReadTransient]); 235 236 if ((n=atomic_read(&conf->counters[WritePersistent])) != 0) 237 seq_printf(seq, " WritePersistent=%d(%d)", 238 n, conf->period[WritePersistent]); 239 240 if ((n=atomic_read(&conf->counters[ReadPersistent])) != 0) 241 seq_printf(seq, " ReadPersistent=%d(%d)", 242 n, conf->period[ReadPersistent]); 243 244 245 if ((n=atomic_read(&conf->counters[ReadFixable])) != 0) 246 seq_printf(seq, " ReadFixable=%d(%d)", 247 n, conf->period[ReadFixable]); 248 249 if ((n=atomic_read(&conf->counters[WriteAll])) != 0) 250 seq_printf(seq, " WriteAll"); 251 252 seq_printf(seq, " nfaults=%d", conf->nfaults); 253 } 254 255 256 static int faulty_reshape(struct mddev *mddev) 257 { 258 int mode = mddev->new_layout & ModeMask; 259 int count = mddev->new_layout >> ModeShift; 260 struct faulty_conf *conf = mddev->private; 261 262 if (mddev->new_layout < 0) 263 return 0; 264 265 /* new layout */ 266 if (mode == ClearFaults) 267 conf->nfaults = 0; 268 else if (mode == ClearErrors) { 269 int i; 270 for (i=0 ; i < Modes ; i++) { 271 conf->period[i] = 0; 272 atomic_set(&conf->counters[i], 0); 273 } 274 } else if (mode < Modes) { 275 conf->period[mode] = count; 276 if (!count) count++; 277 atomic_set(&conf->counters[mode], count); 278 } else 279 return -EINVAL; 280 mddev->new_layout = -1; 281 mddev->layout = -1; /* makes sure further changes come through */ 282 return 0; 283 } 284 285 static sector_t faulty_size(struct mddev *mddev, sector_t sectors, int raid_disks) 286 { 287 WARN_ONCE(raid_disks, 288 "%s does not support generic reshape\n", __func__); 289 290 if (sectors == 0) 291 return mddev->dev_sectors; 292 293 return sectors; 294 } 295 296 static int faulty_run(struct mddev *mddev) 297 { 298 struct md_rdev *rdev; 299 int i; 300 struct faulty_conf *conf; 301 302 if (md_check_no_bitmap(mddev)) 303 return -EINVAL; 304 305 conf = kmalloc(sizeof(*conf), GFP_KERNEL); 306 if (!conf) 307 return -ENOMEM; 308 309 for (i=0; i<Modes; i++) { 310 atomic_set(&conf->counters[i], 0); 311 conf->period[i] = 0; 312 } 313 conf->nfaults = 0; 314 315 rdev_for_each(rdev, mddev) { 316 conf->rdev = rdev; 317 disk_stack_limits(mddev->gendisk, rdev->bdev, 318 rdev->data_offset << 9); 319 } 320 321 md_set_array_sectors(mddev, faulty_size(mddev, 0, 0)); 322 mddev->private = conf; 323 324 faulty_reshape(mddev); 325 326 return 0; 327 } 328 329 static void faulty_free(struct mddev *mddev, void *priv) 330 { 331 struct faulty_conf *conf = priv; 332 333 kfree(conf); 334 } 335 336 static struct md_personality faulty_personality = 337 { 338 .name = "faulty", 339 .level = LEVEL_FAULTY, 340 .owner = THIS_MODULE, 341 .make_request = faulty_make_request, 342 .run = faulty_run, 343 .free = faulty_free, 344 .status = faulty_status, 345 .check_reshape = faulty_reshape, 346 .size = faulty_size, 347 }; 348 349 static int __init raid_init(void) 350 { 351 return register_md_personality(&faulty_personality); 352 } 353 354 static void raid_exit(void) 355 { 356 unregister_md_personality(&faulty_personality); 357 } 358 359 module_init(raid_init); 360 module_exit(raid_exit); 361 MODULE_LICENSE("GPL"); 362 MODULE_DESCRIPTION("Fault injection personality for MD (deprecated)"); 363 MODULE_ALIAS("md-personality-10"); /* faulty */ 364 MODULE_ALIAS("md-faulty"); 365 MODULE_ALIAS("md-level--5"); 366