1 /* 2 * faulty.c : Multiple Devices driver for Linux 3 * 4 * Copyright (C) 2004 Neil Brown 5 * 6 * fautly-device-simulator personality for md 7 * 8 * 9 * This program is free software; you can redistribute it and/or modify 10 * it under the terms of the GNU General Public License as published by 11 * the Free Software Foundation; either version 2, or (at your option) 12 * any later version. 13 * 14 * You should have received a copy of the GNU General Public License 15 * (for example /usr/src/linux/COPYING); if not, write to the Free 16 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 17 */ 18 19 20 /* 21 * The "faulty" personality causes some requests to fail. 22 * 23 * Possible failure modes are: 24 * reads fail "randomly" but succeed on retry 25 * writes fail "randomly" but succeed on retry 26 * reads for some address fail and then persist until a write 27 * reads for some address fail and then persist irrespective of write 28 * writes for some address fail and persist 29 * all writes fail 30 * 31 * Different modes can be active at a time, but only 32 * one can be set at array creation. Others can be added later. 33 * A mode can be one-shot or recurrent with the recurrence being 34 * once in every N requests. 35 * The bottom 5 bits of the "layout" indicate the mode. The 36 * remainder indicate a period, or 0 for one-shot. 37 * 38 * There is an implementation limit on the number of concurrently 39 * persisting-faulty blocks. When a new fault is requested that would 40 * exceed the limit, it is ignored. 41 * All current faults can be clear using a layout of "0". 42 * 43 * Requests are always sent to the device. If they are to fail, 44 * we clone the bio and insert a new b_end_io into the chain. 45 */ 46 47 #define WriteTransient 0 48 #define ReadTransient 1 49 #define WritePersistent 2 50 #define ReadPersistent 3 51 #define WriteAll 4 /* doesn't go to device */ 52 #define ReadFixable 5 53 #define Modes 6 54 55 #define ClearErrors 31 56 #define ClearFaults 30 57 58 #define AllPersist 100 /* internal use only */ 59 #define NoPersist 101 60 61 #define ModeMask 0x1f 62 #define ModeShift 5 63 64 #define MaxFault 50 65 #include <linux/blkdev.h> 66 #include <linux/module.h> 67 #include <linux/raid/md_u.h> 68 #include <linux/slab.h> 69 #include "md.h" 70 #include <linux/seq_file.h> 71 72 73 static void faulty_fail(struct bio *bio) 74 { 75 struct bio *b = bio->bi_private; 76 77 b->bi_iter.bi_size = bio->bi_iter.bi_size; 78 b->bi_iter.bi_sector = bio->bi_iter.bi_sector; 79 80 bio_put(bio); 81 82 bio_io_error(b); 83 } 84 85 struct faulty_conf { 86 int period[Modes]; 87 atomic_t counters[Modes]; 88 sector_t faults[MaxFault]; 89 int modes[MaxFault]; 90 int nfaults; 91 struct md_rdev *rdev; 92 }; 93 94 static int check_mode(struct faulty_conf *conf, int mode) 95 { 96 if (conf->period[mode] == 0 && 97 atomic_read(&conf->counters[mode]) <= 0) 98 return 0; /* no failure, no decrement */ 99 100 101 if (atomic_dec_and_test(&conf->counters[mode])) { 102 if (conf->period[mode]) 103 atomic_set(&conf->counters[mode], conf->period[mode]); 104 return 1; 105 } 106 return 0; 107 } 108 109 static int check_sector(struct faulty_conf *conf, sector_t start, sector_t end, int dir) 110 { 111 /* If we find a ReadFixable sector, we fix it ... */ 112 int i; 113 for (i=0; i<conf->nfaults; i++) 114 if (conf->faults[i] >= start && 115 conf->faults[i] < end) { 116 /* found it ... */ 117 switch (conf->modes[i] * 2 + dir) { 118 case WritePersistent*2+WRITE: return 1; 119 case ReadPersistent*2+READ: return 1; 120 case ReadFixable*2+READ: return 1; 121 case ReadFixable*2+WRITE: 122 conf->modes[i] = NoPersist; 123 return 0; 124 case AllPersist*2+READ: 125 case AllPersist*2+WRITE: return 1; 126 default: 127 return 0; 128 } 129 } 130 return 0; 131 } 132 133 static void add_sector(struct faulty_conf *conf, sector_t start, int mode) 134 { 135 int i; 136 int n = conf->nfaults; 137 for (i=0; i<conf->nfaults; i++) 138 if (conf->faults[i] == start) { 139 switch(mode) { 140 case NoPersist: conf->modes[i] = mode; return; 141 case WritePersistent: 142 if (conf->modes[i] == ReadPersistent || 143 conf->modes[i] == ReadFixable) 144 conf->modes[i] = AllPersist; 145 else 146 conf->modes[i] = WritePersistent; 147 return; 148 case ReadPersistent: 149 if (conf->modes[i] == WritePersistent) 150 conf->modes[i] = AllPersist; 151 else 152 conf->modes[i] = ReadPersistent; 153 return; 154 case ReadFixable: 155 if (conf->modes[i] == WritePersistent || 156 conf->modes[i] == ReadPersistent) 157 conf->modes[i] = AllPersist; 158 else 159 conf->modes[i] = ReadFixable; 160 return; 161 } 162 } else if (conf->modes[i] == NoPersist) 163 n = i; 164 165 if (n >= MaxFault) 166 return; 167 conf->faults[n] = start; 168 conf->modes[n] = mode; 169 if (conf->nfaults == n) 170 conf->nfaults = n+1; 171 } 172 173 static bool faulty_make_request(struct mddev *mddev, struct bio *bio) 174 { 175 struct faulty_conf *conf = mddev->private; 176 int failit = 0; 177 178 if (bio_data_dir(bio) == WRITE) { 179 /* write request */ 180 if (atomic_read(&conf->counters[WriteAll])) { 181 /* special case - don't decrement, don't generic_make_request, 182 * just fail immediately 183 */ 184 bio_io_error(bio); 185 return true; 186 } 187 188 if (check_sector(conf, bio->bi_iter.bi_sector, 189 bio_end_sector(bio), WRITE)) 190 failit = 1; 191 if (check_mode(conf, WritePersistent)) { 192 add_sector(conf, bio->bi_iter.bi_sector, 193 WritePersistent); 194 failit = 1; 195 } 196 if (check_mode(conf, WriteTransient)) 197 failit = 1; 198 } else { 199 /* read request */ 200 if (check_sector(conf, bio->bi_iter.bi_sector, 201 bio_end_sector(bio), READ)) 202 failit = 1; 203 if (check_mode(conf, ReadTransient)) 204 failit = 1; 205 if (check_mode(conf, ReadPersistent)) { 206 add_sector(conf, bio->bi_iter.bi_sector, 207 ReadPersistent); 208 failit = 1; 209 } 210 if (check_mode(conf, ReadFixable)) { 211 add_sector(conf, bio->bi_iter.bi_sector, 212 ReadFixable); 213 failit = 1; 214 } 215 } 216 if (failit) { 217 struct bio *b = bio_clone_fast(bio, GFP_NOIO, mddev->bio_set); 218 219 bio_set_dev(b, conf->rdev->bdev); 220 b->bi_private = bio; 221 b->bi_end_io = faulty_fail; 222 bio = b; 223 } else 224 bio_set_dev(bio, conf->rdev->bdev); 225 226 generic_make_request(bio); 227 return true; 228 } 229 230 static void faulty_status(struct seq_file *seq, struct mddev *mddev) 231 { 232 struct faulty_conf *conf = mddev->private; 233 int n; 234 235 if ((n=atomic_read(&conf->counters[WriteTransient])) != 0) 236 seq_printf(seq, " WriteTransient=%d(%d)", 237 n, conf->period[WriteTransient]); 238 239 if ((n=atomic_read(&conf->counters[ReadTransient])) != 0) 240 seq_printf(seq, " ReadTransient=%d(%d)", 241 n, conf->period[ReadTransient]); 242 243 if ((n=atomic_read(&conf->counters[WritePersistent])) != 0) 244 seq_printf(seq, " WritePersistent=%d(%d)", 245 n, conf->period[WritePersistent]); 246 247 if ((n=atomic_read(&conf->counters[ReadPersistent])) != 0) 248 seq_printf(seq, " ReadPersistent=%d(%d)", 249 n, conf->period[ReadPersistent]); 250 251 252 if ((n=atomic_read(&conf->counters[ReadFixable])) != 0) 253 seq_printf(seq, " ReadFixable=%d(%d)", 254 n, conf->period[ReadFixable]); 255 256 if ((n=atomic_read(&conf->counters[WriteAll])) != 0) 257 seq_printf(seq, " WriteAll"); 258 259 seq_printf(seq, " nfaults=%d", conf->nfaults); 260 } 261 262 263 static int faulty_reshape(struct mddev *mddev) 264 { 265 int mode = mddev->new_layout & ModeMask; 266 int count = mddev->new_layout >> ModeShift; 267 struct faulty_conf *conf = mddev->private; 268 269 if (mddev->new_layout < 0) 270 return 0; 271 272 /* new layout */ 273 if (mode == ClearFaults) 274 conf->nfaults = 0; 275 else if (mode == ClearErrors) { 276 int i; 277 for (i=0 ; i < Modes ; i++) { 278 conf->period[i] = 0; 279 atomic_set(&conf->counters[i], 0); 280 } 281 } else if (mode < Modes) { 282 conf->period[mode] = count; 283 if (!count) count++; 284 atomic_set(&conf->counters[mode], count); 285 } else 286 return -EINVAL; 287 mddev->new_layout = -1; 288 mddev->layout = -1; /* makes sure further changes come through */ 289 return 0; 290 } 291 292 static sector_t faulty_size(struct mddev *mddev, sector_t sectors, int raid_disks) 293 { 294 WARN_ONCE(raid_disks, 295 "%s does not support generic reshape\n", __func__); 296 297 if (sectors == 0) 298 return mddev->dev_sectors; 299 300 return sectors; 301 } 302 303 static int faulty_run(struct mddev *mddev) 304 { 305 struct md_rdev *rdev; 306 int i; 307 struct faulty_conf *conf; 308 309 if (md_check_no_bitmap(mddev)) 310 return -EINVAL; 311 312 conf = kmalloc(sizeof(*conf), GFP_KERNEL); 313 if (!conf) 314 return -ENOMEM; 315 316 for (i=0; i<Modes; i++) { 317 atomic_set(&conf->counters[i], 0); 318 conf->period[i] = 0; 319 } 320 conf->nfaults = 0; 321 322 rdev_for_each(rdev, mddev) { 323 conf->rdev = rdev; 324 disk_stack_limits(mddev->gendisk, rdev->bdev, 325 rdev->data_offset << 9); 326 } 327 328 md_set_array_sectors(mddev, faulty_size(mddev, 0, 0)); 329 mddev->private = conf; 330 331 faulty_reshape(mddev); 332 333 return 0; 334 } 335 336 static void faulty_free(struct mddev *mddev, void *priv) 337 { 338 struct faulty_conf *conf = priv; 339 340 kfree(conf); 341 } 342 343 static struct md_personality faulty_personality = 344 { 345 .name = "faulty", 346 .level = LEVEL_FAULTY, 347 .owner = THIS_MODULE, 348 .make_request = faulty_make_request, 349 .run = faulty_run, 350 .free = faulty_free, 351 .status = faulty_status, 352 .check_reshape = faulty_reshape, 353 .size = faulty_size, 354 }; 355 356 static int __init raid_init(void) 357 { 358 return register_md_personality(&faulty_personality); 359 } 360 361 static void raid_exit(void) 362 { 363 unregister_md_personality(&faulty_personality); 364 } 365 366 module_init(raid_init); 367 module_exit(raid_exit); 368 MODULE_LICENSE("GPL"); 369 MODULE_DESCRIPTION("Fault injection personality for MD"); 370 MODULE_ALIAS("md-personality-10"); /* faulty */ 371 MODULE_ALIAS("md-faulty"); 372 MODULE_ALIAS("md-level--5"); 373