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 generic_make_request, 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 if (failit) { 208 struct bio *b = bio_clone_fast(bio, GFP_NOIO, &mddev->bio_set); 209 210 bio_set_dev(b, conf->rdev->bdev); 211 b->bi_private = bio; 212 b->bi_end_io = faulty_fail; 213 bio = b; 214 } else 215 bio_set_dev(bio, conf->rdev->bdev); 216 217 generic_make_request(bio); 218 return true; 219 } 220 221 static void faulty_status(struct seq_file *seq, struct mddev *mddev) 222 { 223 struct faulty_conf *conf = mddev->private; 224 int n; 225 226 if ((n=atomic_read(&conf->counters[WriteTransient])) != 0) 227 seq_printf(seq, " WriteTransient=%d(%d)", 228 n, conf->period[WriteTransient]); 229 230 if ((n=atomic_read(&conf->counters[ReadTransient])) != 0) 231 seq_printf(seq, " ReadTransient=%d(%d)", 232 n, conf->period[ReadTransient]); 233 234 if ((n=atomic_read(&conf->counters[WritePersistent])) != 0) 235 seq_printf(seq, " WritePersistent=%d(%d)", 236 n, conf->period[WritePersistent]); 237 238 if ((n=atomic_read(&conf->counters[ReadPersistent])) != 0) 239 seq_printf(seq, " ReadPersistent=%d(%d)", 240 n, conf->period[ReadPersistent]); 241 242 243 if ((n=atomic_read(&conf->counters[ReadFixable])) != 0) 244 seq_printf(seq, " ReadFixable=%d(%d)", 245 n, conf->period[ReadFixable]); 246 247 if ((n=atomic_read(&conf->counters[WriteAll])) != 0) 248 seq_printf(seq, " WriteAll"); 249 250 seq_printf(seq, " nfaults=%d", conf->nfaults); 251 } 252 253 254 static int faulty_reshape(struct mddev *mddev) 255 { 256 int mode = mddev->new_layout & ModeMask; 257 int count = mddev->new_layout >> ModeShift; 258 struct faulty_conf *conf = mddev->private; 259 260 if (mddev->new_layout < 0) 261 return 0; 262 263 /* new layout */ 264 if (mode == ClearFaults) 265 conf->nfaults = 0; 266 else if (mode == ClearErrors) { 267 int i; 268 for (i=0 ; i < Modes ; i++) { 269 conf->period[i] = 0; 270 atomic_set(&conf->counters[i], 0); 271 } 272 } else if (mode < Modes) { 273 conf->period[mode] = count; 274 if (!count) count++; 275 atomic_set(&conf->counters[mode], count); 276 } else 277 return -EINVAL; 278 mddev->new_layout = -1; 279 mddev->layout = -1; /* makes sure further changes come through */ 280 return 0; 281 } 282 283 static sector_t faulty_size(struct mddev *mddev, sector_t sectors, int raid_disks) 284 { 285 WARN_ONCE(raid_disks, 286 "%s does not support generic reshape\n", __func__); 287 288 if (sectors == 0) 289 return mddev->dev_sectors; 290 291 return sectors; 292 } 293 294 static int faulty_run(struct mddev *mddev) 295 { 296 struct md_rdev *rdev; 297 int i; 298 struct faulty_conf *conf; 299 300 if (md_check_no_bitmap(mddev)) 301 return -EINVAL; 302 303 conf = kmalloc(sizeof(*conf), GFP_KERNEL); 304 if (!conf) 305 return -ENOMEM; 306 307 for (i=0; i<Modes; i++) { 308 atomic_set(&conf->counters[i], 0); 309 conf->period[i] = 0; 310 } 311 conf->nfaults = 0; 312 313 rdev_for_each(rdev, mddev) { 314 conf->rdev = rdev; 315 disk_stack_limits(mddev->gendisk, rdev->bdev, 316 rdev->data_offset << 9); 317 } 318 319 md_set_array_sectors(mddev, faulty_size(mddev, 0, 0)); 320 mddev->private = conf; 321 322 faulty_reshape(mddev); 323 324 return 0; 325 } 326 327 static void faulty_free(struct mddev *mddev, void *priv) 328 { 329 struct faulty_conf *conf = priv; 330 331 kfree(conf); 332 } 333 334 static struct md_personality faulty_personality = 335 { 336 .name = "faulty", 337 .level = LEVEL_FAULTY, 338 .owner = THIS_MODULE, 339 .make_request = faulty_make_request, 340 .run = faulty_run, 341 .free = faulty_free, 342 .status = faulty_status, 343 .check_reshape = faulty_reshape, 344 .size = faulty_size, 345 }; 346 347 static int __init raid_init(void) 348 { 349 return register_md_personality(&faulty_personality); 350 } 351 352 static void raid_exit(void) 353 { 354 unregister_md_personality(&faulty_personality); 355 } 356 357 module_init(raid_init); 358 module_exit(raid_exit); 359 MODULE_LICENSE("GPL"); 360 MODULE_DESCRIPTION("Fault injection personality for MD"); 361 MODULE_ALIAS("md-personality-10"); /* faulty */ 362 MODULE_ALIAS("md-faulty"); 363 MODULE_ALIAS("md-level--5"); 364