kernel/drivers/md/dm-stripe.c

   1 /*
   2  * Copyright (C) 2001-2003 Sistina Software (UK) Limited.
   3  *
   4  * This file is released under the GPL.
   5  */
   6
   7 #include "dm.h"
   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 #include <linux/log2.h>
  16
  17 #define DM_MSG_PREFIX "striped"
  18 #define DM_IO_ERROR_THRESHOLD 15
  19
  20 struct stripe {
  21         struct dm_dev *dev;
  22         sector_t physical_start;
  23
  24         atomic_t error_count;
  25 };
  26
  27 struct stripe_c {
  28         uint32_t stripes;
  29         int stripes_shift;
  30
  31         /* The size of this target / num. stripes */
  32         sector_t stripe_width;
  33
  34         uint32_t chunk_size;
  35         int chunk_size_shift;
  36
  37         /* Needed for handling events */
  38         struct dm_target *ti;
  39
  40         /* Work struct used for triggering events*/
  41         struct work_struct trigger_event;
  42
  43         struct stripe stripe[0];
  44 };
  45
  46 /*
  47  * An event is triggered whenever a drive
  48  * drops out of a stripe volume.
  49  */
  50 static void trigger_event(struct work_struct *work)
  51 {
  52         struct stripe_c *sc = container_of(work, struct stripe_c,
  53                                            trigger_event);
  54         dm_table_event(sc->ti->table);
  55 }
  56
  57 static inline struct stripe_c *alloc_context(unsigned int stripes)
  58 {
  59         size_t len;
  60
  61         if (dm_array_too_big(sizeof(struct stripe_c), sizeof(struct stripe),
  62                              stripes))
  63                 return NULL;
  64
  65         len = sizeof(struct stripe_c) + (sizeof(struct stripe) * stripes);
  66
  67         return kmalloc(len, GFP_KERNEL);
  68 }
  69
  70 /*
  71  * Parse a single <dev> <sector> pair
  72  */
  73 static int get_stripe(struct dm_target *ti, struct stripe_c *sc,
  74                       unsigned int stripe, char **argv)
  75 {
  76         unsigned long long start;
  77         char dummy;
  78
  79         if (sscanf(argv[1], "%llu%c", &start, &dummy) != 1)
  80                 return -EINVAL;
  81
  82         if (dm_get_device(ti, argv[0], dm_table_get_mode(ti->table),
  83                           &sc->stripe[stripe].dev))
  84                 return -ENXIO;
  85
  86         sc->stripe[stripe].physical_start = start;
  87
  88         return 0;
  89 }
  90
  91 /*
  92  * Construct a striped mapping.
  93  * <number of stripes> <chunk size> [<dev_path> <offset>]+
  94  */
  95 static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
  96 {
  97         struct stripe_c *sc;
  98         sector_t width, tmp_len;
  99         uint32_t stripes;
 100         uint32_t chunk_size;
 101         int r;
 102         unsigned int i;
 103
 104         if (argc < 2) {
 105                 ti->error = "Not enough arguments";
 106                 return -EINVAL;
 107         }
 108
 109         if (kstrtouint(argv[0], 10, &stripes) || !stripes) {
 110                 ti->error = "Invalid stripe count";
 111                 return -EINVAL;
 112         }
 113
 114         if (kstrtouint(argv[1], 10, &chunk_size) || !chunk_size) {
 115                 ti->error = "Invalid chunk_size";
 116                 return -EINVAL;
 117         }
 118
 119         width = ti->len;
 120         if (sector_div(width, stripes)) {
 121                 ti->error = "Target length not divisible by "
 122                     "number of stripes";
 123                 return -EINVAL;
 124         }
 125
 126         tmp_len = width;
 127         if (sector_div(tmp_len, chunk_size)) {
 128                 ti->error = "Target length not divisible by "
 129                     "chunk size";
 130                 return -EINVAL;
 131         }
 132
 133         /*
 134          * Do we have enough arguments for that many stripes ?
 135          */
 136         if (argc != (2 + 2 * stripes)) {
 137                 ti->error = "Not enough destinations "
 138                         "specified";
 139                 return -EINVAL;
 140         }
 141
 142         sc = alloc_context(stripes);
 143         if (!sc) {
 144                 ti->error = "Memory allocation for striped context "
 145                     "failed";
 146                 return -ENOMEM;
 147         }
 148
 149         INIT_WORK(&sc->trigger_event, trigger_event);
 150
 151         /* Set pointer to dm target; used in trigger_event */
 152         sc->ti = ti;
 153         sc->stripes = stripes;
 154         sc->stripe_width = width;
 155
 156         if (stripes & (stripes - 1))
 157                 sc->stripes_shift = -1;
 158         else
 159                 sc->stripes_shift = __ffs(stripes);
 160
 161         r = dm_set_target_max_io_len(ti, chunk_size);
 162         if (r) {
 163                 kfree(sc);
 164                 return r;
 165         }
 166
 167         ti->num_flush_bios = stripes;
 168         ti->num_discard_bios = stripes;
 169         ti->num_write_same_bios = stripes;
 170
 171         sc->chunk_size = chunk_size;
 172         if (chunk_size & (chunk_size - 1))
 173                 sc->chunk_size_shift = -1;
 174         else
 175                 sc->chunk_size_shift = __ffs(chunk_size);
 176
 177         /*
 178          * Get the stripe destinations.
 179          */
 180         for (i = 0; i < stripes; i++) {
 181                 argv += 2;
 182
 183                 r = get_stripe(ti, sc, i, argv);
 184                 if (r < 0) {
 185                         ti->error = "Couldn't parse stripe destination";
 186                         while (i--)
 187                                 dm_put_device(ti, sc->stripe[i].dev);
 188                         kfree(sc);
 189                         return r;
 190                 }
 191                 atomic_set(&(sc->stripe[i].error_count), 0);
 192         }
 193
 194         ti->private = sc;
 195
 196         return 0;
 197 }
 198
 199 static void stripe_dtr(struct dm_target *ti)
 200 {
 201         unsigned int i;
 202         struct stripe_c *sc = (struct stripe_c *) ti->private;
 203
 204         for (i = 0; i < sc->stripes; i++)
 205                 dm_put_device(ti, sc->stripe[i].dev);
 206
 207         flush_work(&sc->trigger_event);
 208         kfree(sc);
 209 }
 210
 211 static void stripe_map_sector(struct stripe_c *sc, sector_t sector,
 212                               uint32_t *stripe, sector_t *result)
 213 {
 214         sector_t chunk = dm_target_offset(sc->ti, sector);
 215         sector_t chunk_offset;
 216
 217         if (sc->chunk_size_shift < 0)
 218                 chunk_offset = sector_div(chunk, sc->chunk_size);
 219         else {
 220                 chunk_offset = chunk & (sc->chunk_size - 1);
 221                 chunk >>= sc->chunk_size_shift;
 222         }
 223
 224         if (sc->stripes_shift < 0)
 225                 *stripe = sector_div(chunk, sc->stripes);
 226         else {
 227                 *stripe = chunk & (sc->stripes - 1);
 228                 chunk >>= sc->stripes_shift;
 229         }
 230
 231         if (sc->chunk_size_shift < 0)
 232                 chunk *= sc->chunk_size;
 233         else
 234                 chunk <<= sc->chunk_size_shift;
 235
 236         *result = chunk + chunk_offset;
 237 }
 238
 239 static void stripe_map_range_sector(struct stripe_c *sc, sector_t sector,
 240                                     uint32_t target_stripe, sector_t *result)
 241 {
 242         uint32_t stripe;
 243
 244         stripe_map_sector(sc, sector, &stripe, result);
 245         if (stripe == target_stripe)
 246                 return;
 247
 248         /* round down */
 249         sector = *result;
 250         if (sc->chunk_size_shift < 0)
 251                 *result -= sector_div(sector, sc->chunk_size);
 252         else
 253                 *result = sector & ~(sector_t)(sc->chunk_size - 1);
 254
 255         if (target_stripe < stripe)
 256                 *result += sc->chunk_size;              /* next chunk */
 257 }
 258
 259 static int stripe_map_range(struct stripe_c *sc, struct bio *bio,
 260                             uint32_t target_stripe)
 261 {
 262         sector_t begin, end;
 263
 264         stripe_map_range_sector(sc, bio->bi_iter.bi_sector,
 265                                 target_stripe, &begin);
 266         stripe_map_range_sector(sc, bio_end_sector(bio),
 267                                 target_stripe, &end);
 268         if (begin < end) {
 269                 bio->bi_bdev = sc->stripe[target_stripe].dev->bdev;
 270                 bio->bi_iter.bi_sector = begin +
 271                         sc->stripe[target_stripe].physical_start;
 272                 bio->bi_iter.bi_size = to_bytes(end - begin);
 273                 return DM_MAPIO_REMAPPED;
 274         } else {
 275                 /* The range doesn't map to the target stripe */
 276                 bio_endio(bio, 0);
 277                 return DM_MAPIO_SUBMITTED;
 278         }
 279 }
 280
 281 static int stripe_map(struct dm_target *ti, struct bio *bio)
 282 {
 283         struct stripe_c *sc = ti->private;
 284         uint32_t stripe;
 285         unsigned target_bio_nr;
 286
 287         if (bio->bi_rw & REQ_FLUSH) {
 288                 target_bio_nr = dm_bio_get_target_bio_nr(bio);
 289                 BUG_ON(target_bio_nr >= sc->stripes);
 290                 bio->bi_bdev = sc->stripe[target_bio_nr].dev->bdev;
 291                 return DM_MAPIO_REMAPPED;
 292         }
 293         if (unlikely(bio->bi_rw & REQ_DISCARD) ||
 294             unlikely(bio->bi_rw & REQ_WRITE_SAME)) {
 295                 target_bio_nr = dm_bio_get_target_bio_nr(bio);
 296                 BUG_ON(target_bio_nr >= sc->stripes);
 297                 return stripe_map_range(sc, bio, target_bio_nr);
 298         }
 299
 300         stripe_map_sector(sc, bio->bi_iter.bi_sector,
 301                           &stripe, &bio->bi_iter.bi_sector);
 302
 303         bio->bi_iter.bi_sector += sc->stripe[stripe].physical_start;
 304         bio->bi_bdev = sc->stripe[stripe].dev->bdev;
 305
 306         return DM_MAPIO_REMAPPED;
 307 }
 308
 309 /*
 310  * Stripe status:
 311  *
 312  * INFO
 313  * #stripes [stripe_name <stripe_name>] [group word count]
 314  * [error count 'A|D' <error count 'A|D'>]
 315  *
 316  * TABLE
 317  * #stripes [stripe chunk size]
 318  * [stripe_name physical_start <stripe_name physical_start>]
 319  *
 320  */
 321
 322 static void stripe_status(struct dm_target *ti, status_type_t type,
 323                           unsigned status_flags, char *result, unsigned maxlen)
 324 {
 325         struct stripe_c *sc = (struct stripe_c *) ti->private;
 326         char buffer[sc->stripes + 1];
 327         unsigned int sz = 0;
 328         unsigned int i;
 329
 330         switch (type) {
 331         case STATUSTYPE_INFO:
 332                 DMEMIT("%d ", sc->stripes);
 333                 for (i = 0; i < sc->stripes; i++)  {
 334                         DMEMIT("%s ", sc->stripe[i].dev->name);
 335                         buffer[i] = atomic_read(&(sc->stripe[i].error_count)) ?
 336                                 'D' : 'A';
 337                 }
 338                 buffer[i] = '\0';
 339                 DMEMIT("1 %s", buffer);
 340                 break;
 341
 342         case STATUSTYPE_TABLE:
 343                 DMEMIT("%d %llu", sc->stripes,
 344                         (unsigned long long)sc->chunk_size);
 345                 for (i = 0; i < sc->stripes; i++)
 346                         DMEMIT(" %s %llu", sc->stripe[i].dev->name,
 347                             (unsigned long long)sc->stripe[i].physical_start);
 348                 break;
 349         }
 350 }
 351
 352 static int stripe_end_io(struct dm_target *ti, struct bio *bio, int error)
 353 {
 354         unsigned i;
 355         char major_minor[16];
 356         struct stripe_c *sc = ti->private;
 357
 358         if (!error)
 359                 return 0; /* I/O complete */
 360
 361         if ((error == -EWOULDBLOCK) && (bio->bi_rw & REQ_RAHEAD))
 362                 return error;
 363
 364         if (error == -EOPNOTSUPP)
 365                 return error;
 366
 367         memset(major_minor, 0, sizeof(major_minor));
 368         sprintf(major_minor, "%d:%d",
 369                 MAJOR(disk_devt(bio->bi_bdev->bd_disk)),
 370                 MINOR(disk_devt(bio->bi_bdev->bd_disk)));
 371
 372         /*
 373          * Test to see which stripe drive triggered the event
 374          * and increment error count for all stripes on that device.
 375          * If the error count for a given device exceeds the threshold
 376          * value we will no longer trigger any further events.
 377          */
 378         for (i = 0; i < sc->stripes; i++)
 379                 if (!strcmp(sc->stripe[i].dev->name, major_minor)) {
 380                         atomic_inc(&(sc->stripe[i].error_count));
 381                         if (atomic_read(&(sc->stripe[i].error_count)) <
 382                             DM_IO_ERROR_THRESHOLD)
 383                                 schedule_work(&sc->trigger_event);
 384                 }
 385
 386         return error;
 387 }
 388
 389 static int stripe_iterate_devices(struct dm_target *ti,
 390                                   iterate_devices_callout_fn fn, void *data)
 391 {
 392         struct stripe_c *sc = ti->private;
 393         int ret = 0;
 394         unsigned i = 0;
 395
 396         do {
 397                 ret = fn(ti, sc->stripe[i].dev,
 398                          sc->stripe[i].physical_start,
 399                          sc->stripe_width, data);
 400         } while (!ret && ++i < sc->stripes);
 401
 402         return ret;
 403 }
 404
 405 static void stripe_io_hints(struct dm_target *ti,
 406                             struct queue_limits *limits)
 407 {
 408         struct stripe_c *sc = ti->private;
 409         unsigned chunk_size = sc->chunk_size << SECTOR_SHIFT;
 410
 411         blk_limits_io_min(limits, chunk_size);
 412         blk_limits_io_opt(limits, chunk_size * sc->stripes);
 413 }
 414
 415 static int stripe_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
 416                         struct bio_vec *biovec, int max_size)
 417 {
 418         struct stripe_c *sc = ti->private;
 419         sector_t bvm_sector = bvm->bi_sector;
 420         uint32_t stripe;
 421         struct request_queue *q;
 422
 423         stripe_map_sector(sc, bvm_sector, &stripe, &bvm_sector);
 424
 425         q = bdev_get_queue(sc->stripe[stripe].dev->bdev);
 426         if (!q->merge_bvec_fn)
 427                 return max_size;
 428
 429         bvm->bi_bdev = sc->stripe[stripe].dev->bdev;
 430         bvm->bi_sector = sc->stripe[stripe].physical_start + bvm_sector;
 431
 432         return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
 433 }
 434
 435 static struct target_type stripe_target = {
 436         .name   = "striped",
 437         .version = {1, 5, 1},
 438         .module = THIS_MODULE,
 439         .ctr    = stripe_ctr,
 440         .dtr    = stripe_dtr,
 441         .map    = stripe_map,
 442         .end_io = stripe_end_io,
 443         .status = stripe_status,
 444         .iterate_devices = stripe_iterate_devices,
 445         .io_hints = stripe_io_hints,
 446         .merge  = stripe_merge,
 447 };
 448
 449 int __init dm_stripe_init(void)
 450 {
 451         int r;
 452
 453         r = dm_register_target(&stripe_target);
 454         if (r < 0) {
 455                 DMWARN("target registration failed");
 456                 return r;
 457         }
 458
 459         return r;
 460 }
 461
 462 void dm_stripe_exit(void)
 463 {
 464         dm_unregister_target(&stripe_target);
 465 }