drivers/md/md-faulty.c

   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");