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