drivers/md/dm-stripe.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2001-2003 Sistina Software (UK) Limited.
   4  *
   5  * This file is released under the GPL.
   6  */
   7
   8 #include "dm.h"
   9 #include <linux/device-mapper.h>
  10
  11 #include <linux/module.h>
  12 #include <linux/init.h>
  13 #include <linux/blkdev.h>
  14 #include <linux/bio.h>
  15 #include <linux/dax.h>
  16 #include <linux/slab.h>
  17 #include <linux/log2.h>
  18
  19 static struct workqueue_struct *dm_stripe_wq;
  20
  21 #define DM_MSG_PREFIX "striped"
  22 #define DM_IO_ERROR_THRESHOLD 15
  23
  24 struct stripe {
  25         struct dm_dev *dev;
  26         sector_t physical_start;
  27
  28         atomic_t error_count;
  29 };
  30
  31 struct stripe_c {
  32         uint32_t stripes;
  33         int stripes_shift;
  34
  35         /* The size of this target / num. stripes */
  36         sector_t stripe_width;
  37
  38         uint32_t chunk_size;
  39         int chunk_size_shift;
  40
  41         /* Needed for handling events */
  42         struct dm_target *ti;
  43
  44         /* Work struct used for triggering events*/
  45         struct work_struct trigger_event;
  46
  47         struct stripe stripe[];
  48 };
  49
  50 /*
  51  * An event is triggered whenever a drive
  52  * drops out of a stripe volume.
  53  */
  54 static void trigger_event(struct work_struct *work)
  55 {
  56         struct stripe_c *sc = container_of(work, struct stripe_c,
  57                                            trigger_event);
  58         dm_table_event(sc->ti->table);
  59 }
  60
  61 /*
  62  * Parse a single <dev> <sector> pair
  63  */
  64 static int get_stripe(struct dm_target *ti, struct stripe_c *sc,
  65                       unsigned int stripe, char **argv)
  66 {
  67         unsigned long long start;
  68         char dummy;
  69         int ret;
  70
  71         if (sscanf(argv[1], "%llu%c", &start, &dummy) != 1)
  72                 return -EINVAL;
  73
  74         ret = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table),
  75                             &sc->stripe[stripe].dev);
  76         if (ret)
  77                 return ret;
  78
  79         sc->stripe[stripe].physical_start = start;
  80
  81         return 0;
  82 }
  83
  84 /*
  85  * Construct a striped mapping.
  86  * <number of stripes> <chunk size> [<dev_path> <offset>]+
  87  */
  88 static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
  89 {
  90         struct stripe_c *sc;
  91         sector_t width, tmp_len;
  92         uint32_t stripes;
  93         uint32_t chunk_size;
  94         int r;
  95         unsigned int i;
  96
  97         if (argc < 2) {
  98                 ti->error = "Not enough arguments";
  99                 return -EINVAL;
 100         }
 101
 102         if (kstrtouint(argv[0], 10, &stripes) || !stripes) {
 103                 ti->error = "Invalid stripe count";
 104                 return -EINVAL;
 105         }
 106
 107         if (kstrtouint(argv[1], 10, &chunk_size) || !chunk_size) {
 108                 ti->error = "Invalid chunk_size";
 109                 return -EINVAL;
 110         }
 111
 112         width = ti->len;
 113         if (sector_div(width, stripes)) {
 114                 ti->error = "Target length not divisible by number of stripes";
 115                 return -EINVAL;
 116         }
 117
 118         tmp_len = width;
 119         if (sector_div(tmp_len, chunk_size)) {
 120                 ti->error = "Target length not divisible by chunk size";
 121                 return -EINVAL;
 122         }
 123
 124         /*
 125          * Do we have enough arguments for that many stripes ?
 126          */
 127         if (argc != (2 + 2 * stripes)) {
 128                 ti->error = "Not enough destinations specified";
 129                 return -EINVAL;
 130         }
 131
 132         sc = kmalloc(struct_size(sc, stripe, stripes), GFP_KERNEL);
 133         if (!sc) {
 134                 ti->error = "Memory allocation for striped context failed";
 135                 return -ENOMEM;
 136         }
 137
 138         INIT_WORK(&sc->trigger_event, trigger_event);
 139
 140         /* Set pointer to dm target; used in trigger_event */
 141         sc->ti = ti;
 142         sc->stripes = stripes;
 143         sc->stripe_width = width;
 144
 145         if (stripes & (stripes - 1))
 146                 sc->stripes_shift = -1;
 147         else
 148                 sc->stripes_shift = __ffs(stripes);
 149
 150         r = dm_set_target_max_io_len(ti, chunk_size);
 151         if (r) {
 152                 kfree(sc);
 153                 return r;
 154         }
 155
 156         ti->num_flush_bios = stripes;
 157         ti->num_discard_bios = stripes;
 158         ti->num_secure_erase_bios = stripes;
 159         ti->num_write_zeroes_bios = stripes;
 160
 161         sc->chunk_size = chunk_size;
 162         if (chunk_size & (chunk_size - 1))
 163                 sc->chunk_size_shift = -1;
 164         else
 165                 sc->chunk_size_shift = __ffs(chunk_size);
 166
 167         /*
 168          * Get the stripe destinations.
 169          */
 170         for (i = 0; i < stripes; i++) {
 171                 argv += 2;
 172
 173                 r = get_stripe(ti, sc, i, argv);
 174                 if (r < 0) {
 175                         ti->error = "Couldn't parse stripe destination";
 176                         while (i--)
 177                                 dm_put_device(ti, sc->stripe[i].dev);
 178                         kfree(sc);
 179                         return r;
 180                 }
 181                 atomic_set(&(sc->stripe[i].error_count), 0);
 182         }
 183
 184         ti->private = sc;
 185
 186         return 0;
 187 }
 188
 189 static void stripe_dtr(struct dm_target *ti)
 190 {
 191         unsigned int i;
 192         struct stripe_c *sc = ti->private;
 193
 194         for (i = 0; i < sc->stripes; i++)
 195                 dm_put_device(ti, sc->stripe[i].dev);
 196
 197         flush_work(&sc->trigger_event);
 198         kfree(sc);
 199 }
 200
 201 static void stripe_map_sector(struct stripe_c *sc, sector_t sector,
 202                               uint32_t *stripe, sector_t *result)
 203 {
 204         sector_t chunk = dm_target_offset(sc->ti, sector);
 205         sector_t chunk_offset;
 206
 207         if (sc->chunk_size_shift < 0)
 208                 chunk_offset = sector_div(chunk, sc->chunk_size);
 209         else {
 210                 chunk_offset = chunk & (sc->chunk_size - 1);
 211                 chunk >>= sc->chunk_size_shift;
 212         }
 213
 214         if (sc->stripes_shift < 0)
 215                 *stripe = sector_div(chunk, sc->stripes);
 216         else {
 217                 *stripe = chunk & (sc->stripes - 1);
 218                 chunk >>= sc->stripes_shift;
 219         }
 220
 221         if (sc->chunk_size_shift < 0)
 222                 chunk *= sc->chunk_size;
 223         else
 224                 chunk <<= sc->chunk_size_shift;
 225
 226         *result = chunk + chunk_offset;
 227 }
 228
 229 static void stripe_map_range_sector(struct stripe_c *sc, sector_t sector,
 230                                     uint32_t target_stripe, sector_t *result)
 231 {
 232         uint32_t stripe;
 233
 234         stripe_map_sector(sc, sector, &stripe, result);
 235         if (stripe == target_stripe)
 236                 return;
 237
 238         /* round down */
 239         sector = *result;
 240         if (sc->chunk_size_shift < 0)
 241                 *result -= sector_div(sector, sc->chunk_size);
 242         else
 243                 *result = sector & ~(sector_t)(sc->chunk_size - 1);
 244
 245         if (target_stripe < stripe)
 246                 *result += sc->chunk_size;              /* next chunk */
 247 }
 248
 249 static int stripe_map_range(struct stripe_c *sc, struct bio *bio,
 250                             uint32_t target_stripe)
 251 {
 252         sector_t begin, end;
 253
 254         stripe_map_range_sector(sc, bio->bi_iter.bi_sector,
 255                                 target_stripe, &begin);
 256         stripe_map_range_sector(sc, bio_end_sector(bio),
 257                                 target_stripe, &end);
 258         if (begin < end) {
 259                 bio_set_dev(bio, sc->stripe[target_stripe].dev->bdev);
 260                 bio->bi_iter.bi_sector = begin +
 261                         sc->stripe[target_stripe].physical_start;
 262                 bio->bi_iter.bi_size = to_bytes(end - begin);
 263                 return DM_MAPIO_REMAPPED;
 264         }
 265
 266         /* The range doesn't map to the target stripe */
 267         bio_endio(bio);
 268         return DM_MAPIO_SUBMITTED;
 269 }
 270
 271 static int stripe_map(struct dm_target *ti, struct bio *bio)
 272 {
 273         struct stripe_c *sc = ti->private;
 274         uint32_t stripe;
 275         unsigned int target_bio_nr;
 276
 277         if (bio->bi_opf & REQ_PREFLUSH) {
 278                 target_bio_nr = dm_bio_get_target_bio_nr(bio);
 279                 BUG_ON(target_bio_nr >= sc->stripes);
 280                 bio_set_dev(bio, sc->stripe[target_bio_nr].dev->bdev);
 281                 return DM_MAPIO_REMAPPED;
 282         }
 283         if (unlikely(bio_op(bio) == REQ_OP_DISCARD) ||
 284             unlikely(bio_op(bio) == REQ_OP_SECURE_ERASE) ||
 285             unlikely(bio_op(bio) == REQ_OP_WRITE_ZEROES)) {
 286                 target_bio_nr = dm_bio_get_target_bio_nr(bio);
 287                 BUG_ON(target_bio_nr >= sc->stripes);
 288                 return stripe_map_range(sc, bio, target_bio_nr);
 289         }
 290
 291         stripe_map_sector(sc, bio->bi_iter.bi_sector,
 292                           &stripe, &bio->bi_iter.bi_sector);
 293
 294         bio->bi_iter.bi_sector += sc->stripe[stripe].physical_start;
 295         bio_set_dev(bio, sc->stripe[stripe].dev->bdev);
 296
 297         return DM_MAPIO_REMAPPED;
 298 }
 299
 300 #if IS_ENABLED(CONFIG_FS_DAX)
 301 static struct dax_device *stripe_dax_pgoff(struct dm_target *ti, pgoff_t *pgoff)
 302 {
 303         struct stripe_c *sc = ti->private;
 304         struct block_device *bdev;
 305         sector_t dev_sector;
 306         uint32_t stripe;
 307
 308         stripe_map_sector(sc, *pgoff * PAGE_SECTORS, &stripe, &dev_sector);
 309         dev_sector += sc->stripe[stripe].physical_start;
 310         bdev = sc->stripe[stripe].dev->bdev;
 311
 312         *pgoff = (get_start_sect(bdev) + dev_sector) >> PAGE_SECTORS_SHIFT;
 313         return sc->stripe[stripe].dev->dax_dev;
 314 }
 315
 316 static long stripe_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
 317                 long nr_pages, enum dax_access_mode mode, void **kaddr,
 318                 pfn_t *pfn)
 319 {
 320         struct dax_device *dax_dev = stripe_dax_pgoff(ti, &pgoff);
 321
 322         return dax_direct_access(dax_dev, pgoff, nr_pages, mode, kaddr, pfn);
 323 }
 324
 325 static int stripe_dax_zero_page_range(struct dm_target *ti, pgoff_t pgoff,
 326                                       size_t nr_pages)
 327 {
 328         struct dax_device *dax_dev = stripe_dax_pgoff(ti, &pgoff);
 329
 330         return dax_zero_page_range(dax_dev, pgoff, nr_pages);
 331 }
 332
 333 static size_t stripe_dax_recovery_write(struct dm_target *ti, pgoff_t pgoff,
 334                 void *addr, size_t bytes, struct iov_iter *i)
 335 {
 336         struct dax_device *dax_dev = stripe_dax_pgoff(ti, &pgoff);
 337
 338         return dax_recovery_write(dax_dev, pgoff, addr, bytes, i);
 339 }
 340
 341 #else
 342 #define stripe_dax_direct_access NULL
 343 #define stripe_dax_zero_page_range NULL
 344 #define stripe_dax_recovery_write NULL
 345 #endif
 346
 347 /*
 348  * Stripe status:
 349  *
 350  * INFO
 351  * #stripes [stripe_name <stripe_name>] [group word count]
 352  * [error count 'A|D' <error count 'A|D'>]
 353  *
 354  * TABLE
 355  * #stripes [stripe chunk size]
 356  * [stripe_name physical_start <stripe_name physical_start>]
 357  *
 358  */
 359
 360 static void stripe_status(struct dm_target *ti, status_type_t type,
 361                           unsigned int status_flags, char *result, unsigned int maxlen)
 362 {
 363         struct stripe_c *sc = ti->private;
 364         unsigned int sz = 0;
 365         unsigned int i;
 366
 367         switch (type) {
 368         case STATUSTYPE_INFO:
 369                 DMEMIT("%d ", sc->stripes);
 370                 for (i = 0; i < sc->stripes; i++)
 371                         DMEMIT("%s ", sc->stripe[i].dev->name);
 372
 373                 DMEMIT("1 ");
 374                 for (i = 0; i < sc->stripes; i++)
 375                         DMEMIT("%c", atomic_read(&(sc->stripe[i].error_count)) ?  'D' : 'A');
 376                 break;
 377
 378         case STATUSTYPE_TABLE:
 379                 DMEMIT("%d %llu", sc->stripes,
 380                         (unsigned long long)sc->chunk_size);
 381                 for (i = 0; i < sc->stripes; i++)
 382                         DMEMIT(" %s %llu", sc->stripe[i].dev->name,
 383                             (unsigned long long)sc->stripe[i].physical_start);
 384                 break;
 385
 386         case STATUSTYPE_IMA:
 387                 DMEMIT_TARGET_NAME_VERSION(ti->type);
 388                 DMEMIT(",stripes=%d,chunk_size=%llu", sc->stripes,
 389                        (unsigned long long)sc->chunk_size);
 390
 391                 for (i = 0; i < sc->stripes; i++) {
 392                         DMEMIT(",stripe_%d_device_name=%s", i, sc->stripe[i].dev->name);
 393                         DMEMIT(",stripe_%d_physical_start=%llu", i,
 394                                (unsigned long long)sc->stripe[i].physical_start);
 395                         DMEMIT(",stripe_%d_status=%c", i,
 396                                atomic_read(&(sc->stripe[i].error_count)) ? 'D' : 'A');
 397                 }
 398                 DMEMIT(";");
 399                 break;
 400         }
 401 }
 402
 403 static int stripe_end_io(struct dm_target *ti, struct bio *bio,
 404                 blk_status_t *error)
 405 {
 406         unsigned int i;
 407         char major_minor[16];
 408         struct stripe_c *sc = ti->private;
 409
 410         if (!*error)
 411                 return DM_ENDIO_DONE; /* I/O complete */
 412
 413         if (bio->bi_opf & REQ_RAHEAD)
 414                 return DM_ENDIO_DONE;
 415
 416         if (*error == BLK_STS_NOTSUPP)
 417                 return DM_ENDIO_DONE;
 418
 419         memset(major_minor, 0, sizeof(major_minor));
 420         sprintf(major_minor, "%d:%d", MAJOR(bio_dev(bio)), MINOR(bio_dev(bio)));
 421
 422         /*
 423          * Test to see which stripe drive triggered the event
 424          * and increment error count for all stripes on that device.
 425          * If the error count for a given device exceeds the threshold
 426          * value we will no longer trigger any further events.
 427          */
 428         for (i = 0; i < sc->stripes; i++)
 429                 if (!strcmp(sc->stripe[i].dev->name, major_minor)) {
 430                         atomic_inc(&(sc->stripe[i].error_count));
 431                         if (atomic_read(&(sc->stripe[i].error_count)) <
 432                             DM_IO_ERROR_THRESHOLD)
 433                                 queue_work(dm_stripe_wq, &sc->trigger_event);
 434                 }
 435
 436         return DM_ENDIO_DONE;
 437 }
 438
 439 static int stripe_iterate_devices(struct dm_target *ti,
 440                                   iterate_devices_callout_fn fn, void *data)
 441 {
 442         struct stripe_c *sc = ti->private;
 443         int ret = 0;
 444         unsigned int i = 0;
 445
 446         do {
 447                 ret = fn(ti, sc->stripe[i].dev,
 448                          sc->stripe[i].physical_start,
 449                          sc->stripe_width, data);
 450         } while (!ret && ++i < sc->stripes);
 451
 452         return ret;
 453 }
 454
 455 static void stripe_io_hints(struct dm_target *ti,
 456                             struct queue_limits *limits)
 457 {
 458         struct stripe_c *sc = ti->private;
 459         unsigned int chunk_size = sc->chunk_size << SECTOR_SHIFT;
 460
 461         blk_limits_io_min(limits, chunk_size);
 462         blk_limits_io_opt(limits, chunk_size * sc->stripes);
 463 }
 464
 465 static struct target_type stripe_target = {
 466         .name   = "striped",
 467         .version = {1, 6, 0},
 468         .features = DM_TARGET_PASSES_INTEGRITY | DM_TARGET_NOWAIT,
 469         .module = THIS_MODULE,
 470         .ctr    = stripe_ctr,
 471         .dtr    = stripe_dtr,
 472         .map    = stripe_map,
 473         .end_io = stripe_end_io,
 474         .status = stripe_status,
 475         .iterate_devices = stripe_iterate_devices,
 476         .io_hints = stripe_io_hints,
 477         .direct_access = stripe_dax_direct_access,
 478         .dax_zero_page_range = stripe_dax_zero_page_range,
 479         .dax_recovery_write = stripe_dax_recovery_write,
 480 };
 481
 482 int __init dm_stripe_init(void)
 483 {
 484         int r;
 485
 486         dm_stripe_wq = alloc_workqueue("dm_stripe_wq", 0, 0);
 487         if (!dm_stripe_wq)
 488                 return -ENOMEM;
 489         r = dm_register_target(&stripe_target);
 490         if (r < 0) {
 491                 destroy_workqueue(dm_stripe_wq);
 492                 DMWARN("target registration failed");
 493         }
 494
 495         return r;
 496 }
 497
 498 void dm_stripe_exit(void)
 499 {
 500         dm_unregister_target(&stripe_target);
 501         destroy_workqueue(dm_stripe_wq);
 502 }