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[] __counted_by(stripes);
  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         ti->flush_bypasses_map = true;
 161
 162         sc->chunk_size = chunk_size;
 163         if (chunk_size & (chunk_size - 1))
 164                 sc->chunk_size_shift = -1;
 165         else
 166                 sc->chunk_size_shift = __ffs(chunk_size);
 167
 168         /*
 169          * Get the stripe destinations.
 170          */
 171         for (i = 0; i < stripes; i++) {
 172                 argv += 2;
 173
 174                 r = get_stripe(ti, sc, i, argv);
 175                 if (r < 0) {
 176                         ti->error = "Couldn't parse stripe destination";
 177                         while (i--)
 178                                 dm_put_device(ti, sc->stripe[i].dev);
 179                         kfree(sc);
 180                         return r;
 181                 }
 182                 atomic_set(&(sc->stripe[i].error_count), 0);
 183         }
 184
 185         ti->private = sc;
 186
 187         return 0;
 188 }
 189
 190 static void stripe_dtr(struct dm_target *ti)
 191 {
 192         unsigned int i;
 193         struct stripe_c *sc = ti->private;
 194
 195         for (i = 0; i < sc->stripes; i++)
 196                 dm_put_device(ti, sc->stripe[i].dev);
 197
 198         flush_work(&sc->trigger_event);
 199         kfree(sc);
 200 }
 201
 202 static void stripe_map_sector(struct stripe_c *sc, sector_t sector,
 203                               uint32_t *stripe, sector_t *result)
 204 {
 205         sector_t chunk = dm_target_offset(sc->ti, sector);
 206         sector_t chunk_offset;
 207
 208         if (sc->chunk_size_shift < 0)
 209                 chunk_offset = sector_div(chunk, sc->chunk_size);
 210         else {
 211                 chunk_offset = chunk & (sc->chunk_size - 1);
 212                 chunk >>= sc->chunk_size_shift;
 213         }
 214
 215         if (sc->stripes_shift < 0)
 216                 *stripe = sector_div(chunk, sc->stripes);
 217         else {
 218                 *stripe = chunk & (sc->stripes - 1);
 219                 chunk >>= sc->stripes_shift;
 220         }
 221
 222         if (sc->chunk_size_shift < 0)
 223                 chunk *= sc->chunk_size;
 224         else
 225                 chunk <<= sc->chunk_size_shift;
 226
 227         *result = chunk + chunk_offset;
 228 }
 229
 230 static void stripe_map_range_sector(struct stripe_c *sc, sector_t sector,
 231                                     uint32_t target_stripe, sector_t *result)
 232 {
 233         uint32_t stripe;
 234
 235         stripe_map_sector(sc, sector, &stripe, result);
 236         if (stripe == target_stripe)
 237                 return;
 238
 239         /* round down */
 240         sector = *result;
 241         if (sc->chunk_size_shift < 0)
 242                 *result -= sector_div(sector, sc->chunk_size);
 243         else
 244                 *result = sector & ~(sector_t)(sc->chunk_size - 1);
 245
 246         if (target_stripe < stripe)
 247                 *result += sc->chunk_size;              /* next chunk */
 248 }
 249
 250 static int stripe_map_range(struct stripe_c *sc, struct bio *bio,
 251                             uint32_t target_stripe)
 252 {
 253         sector_t begin, end;
 254
 255         stripe_map_range_sector(sc, bio->bi_iter.bi_sector,
 256                                 target_stripe, &begin);
 257         stripe_map_range_sector(sc, bio_end_sector(bio),
 258                                 target_stripe, &end);
 259         if (begin < end) {
 260                 bio_set_dev(bio, sc->stripe[target_stripe].dev->bdev);
 261                 bio->bi_iter.bi_sector = begin +
 262                         sc->stripe[target_stripe].physical_start;
 263                 bio->bi_iter.bi_size = to_bytes(end - begin);
 264                 return DM_MAPIO_REMAPPED;
 265         }
 266
 267         /* The range doesn't map to the target stripe */
 268         bio_endio(bio);
 269         return DM_MAPIO_SUBMITTED;
 270 }
 271
 272 int stripe_map(struct dm_target *ti, struct bio *bio)
 273 {
 274         struct stripe_c *sc = ti->private;
 275         uint32_t stripe;
 276         unsigned int target_bio_nr;
 277
 278         if (bio->bi_opf & REQ_PREFLUSH) {
 279                 target_bio_nr = dm_bio_get_target_bio_nr(bio);
 280                 BUG_ON(target_bio_nr >= sc->stripes);
 281                 bio_set_dev(bio, sc->stripe[target_bio_nr].dev->bdev);
 282                 return DM_MAPIO_REMAPPED;
 283         }
 284         if (unlikely(bio_op(bio) == REQ_OP_DISCARD) ||
 285             unlikely(bio_op(bio) == REQ_OP_SECURE_ERASE) ||
 286             unlikely(bio_op(bio) == REQ_OP_WRITE_ZEROES)) {
 287                 target_bio_nr = dm_bio_get_target_bio_nr(bio);
 288                 BUG_ON(target_bio_nr >= sc->stripes);
 289                 return stripe_map_range(sc, bio, target_bio_nr);
 290         }
 291
 292         stripe_map_sector(sc, bio->bi_iter.bi_sector,
 293                           &stripe, &bio->bi_iter.bi_sector);
 294
 295         bio->bi_iter.bi_sector += sc->stripe[stripe].physical_start;
 296         bio_set_dev(bio, sc->stripe[stripe].dev->bdev);
 297
 298         return DM_MAPIO_REMAPPED;
 299 }
 300
 301 #if IS_ENABLED(CONFIG_FS_DAX)
 302 static struct dax_device *stripe_dax_pgoff(struct dm_target *ti, pgoff_t *pgoff)
 303 {
 304         struct stripe_c *sc = ti->private;
 305         struct block_device *bdev;
 306         sector_t dev_sector;
 307         uint32_t stripe;
 308
 309         stripe_map_sector(sc, *pgoff * PAGE_SECTORS, &stripe, &dev_sector);
 310         dev_sector += sc->stripe[stripe].physical_start;
 311         bdev = sc->stripe[stripe].dev->bdev;
 312
 313         *pgoff = (get_start_sect(bdev) + dev_sector) >> PAGE_SECTORS_SHIFT;
 314         return sc->stripe[stripe].dev->dax_dev;
 315 }
 316
 317 static long stripe_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
 318                 long nr_pages, enum dax_access_mode mode, void **kaddr,
 319                 pfn_t *pfn)
 320 {
 321         struct dax_device *dax_dev = stripe_dax_pgoff(ti, &pgoff);
 322
 323         return dax_direct_access(dax_dev, pgoff, nr_pages, mode, kaddr, pfn);
 324 }
 325
 326 static int stripe_dax_zero_page_range(struct dm_target *ti, pgoff_t pgoff,
 327                                       size_t nr_pages)
 328 {
 329         struct dax_device *dax_dev = stripe_dax_pgoff(ti, &pgoff);
 330
 331         return dax_zero_page_range(dax_dev, pgoff, nr_pages);
 332 }
 333
 334 static size_t stripe_dax_recovery_write(struct dm_target *ti, pgoff_t pgoff,
 335                 void *addr, size_t bytes, struct iov_iter *i)
 336 {
 337         struct dax_device *dax_dev = stripe_dax_pgoff(ti, &pgoff);
 338
 339         return dax_recovery_write(dax_dev, pgoff, addr, bytes, i);
 340 }
 341
 342 #else
 343 #define stripe_dax_direct_access NULL
 344 #define stripe_dax_zero_page_range NULL
 345 #define stripe_dax_recovery_write NULL
 346 #endif
 347
 348 /*
 349  * Stripe status:
 350  *
 351  * INFO
 352  * #stripes [stripe_name <stripe_name>] [group word count]
 353  * [error count 'A|D' <error count 'A|D'>]
 354  *
 355  * TABLE
 356  * #stripes [stripe chunk size]
 357  * [stripe_name physical_start <stripe_name physical_start>]
 358  *
 359  */
 360
 361 static void stripe_status(struct dm_target *ti, status_type_t type,
 362                           unsigned int status_flags, char *result, unsigned int maxlen)
 363 {
 364         struct stripe_c *sc = ti->private;
 365         unsigned int sz = 0;
 366         unsigned int i;
 367
 368         switch (type) {
 369         case STATUSTYPE_INFO:
 370                 DMEMIT("%d ", sc->stripes);
 371                 for (i = 0; i < sc->stripes; i++)
 372                         DMEMIT("%s ", sc->stripe[i].dev->name);
 373
 374                 DMEMIT("1 ");
 375                 for (i = 0; i < sc->stripes; i++)
 376                         DMEMIT("%c", atomic_read(&(sc->stripe[i].error_count)) ?  'D' : 'A');
 377                 break;
 378
 379         case STATUSTYPE_TABLE:
 380                 DMEMIT("%d %llu", sc->stripes,
 381                         (unsigned long long)sc->chunk_size);
 382                 for (i = 0; i < sc->stripes; i++)
 383                         DMEMIT(" %s %llu", sc->stripe[i].dev->name,
 384                             (unsigned long long)sc->stripe[i].physical_start);
 385                 break;
 386
 387         case STATUSTYPE_IMA:
 388                 DMEMIT_TARGET_NAME_VERSION(ti->type);
 389                 DMEMIT(",stripes=%d,chunk_size=%llu", sc->stripes,
 390                        (unsigned long long)sc->chunk_size);
 391
 392                 for (i = 0; i < sc->stripes; i++) {
 393                         DMEMIT(",stripe_%d_device_name=%s", i, sc->stripe[i].dev->name);
 394                         DMEMIT(",stripe_%d_physical_start=%llu", i,
 395                                (unsigned long long)sc->stripe[i].physical_start);
 396                         DMEMIT(",stripe_%d_status=%c", i,
 397                                atomic_read(&(sc->stripe[i].error_count)) ? 'D' : 'A');
 398                 }
 399                 DMEMIT(";");
 400                 break;
 401         }
 402 }
 403
 404 static int stripe_end_io(struct dm_target *ti, struct bio *bio,
 405                 blk_status_t *error)
 406 {
 407         unsigned int i;
 408         char major_minor[16];
 409         struct stripe_c *sc = ti->private;
 410
 411         if (!*error)
 412                 return DM_ENDIO_DONE; /* I/O complete */
 413
 414         if (bio->bi_opf & REQ_RAHEAD)
 415                 return DM_ENDIO_DONE;
 416
 417         if (*error == BLK_STS_NOTSUPP)
 418                 return DM_ENDIO_DONE;
 419
 420         memset(major_minor, 0, sizeof(major_minor));
 421         sprintf(major_minor, "%d:%d", MAJOR(bio_dev(bio)), MINOR(bio_dev(bio)));
 422
 423         /*
 424          * Test to see which stripe drive triggered the event
 425          * and increment error count for all stripes on that device.
 426          * If the error count for a given device exceeds the threshold
 427          * value we will no longer trigger any further events.
 428          */
 429         for (i = 0; i < sc->stripes; i++)
 430                 if (!strcmp(sc->stripe[i].dev->name, major_minor)) {
 431                         atomic_inc(&(sc->stripe[i].error_count));
 432                         if (atomic_read(&(sc->stripe[i].error_count)) <
 433                             DM_IO_ERROR_THRESHOLD)
 434                                 queue_work(dm_stripe_wq, &sc->trigger_event);
 435                 }
 436
 437         return DM_ENDIO_DONE;
 438 }
 439
 440 static int stripe_iterate_devices(struct dm_target *ti,
 441                                   iterate_devices_callout_fn fn, void *data)
 442 {
 443         struct stripe_c *sc = ti->private;
 444         int ret = 0;
 445         unsigned int i = 0;
 446
 447         do {
 448                 ret = fn(ti, sc->stripe[i].dev,
 449                          sc->stripe[i].physical_start,
 450                          sc->stripe_width, data);
 451         } while (!ret && ++i < sc->stripes);
 452
 453         return ret;
 454 }
 455
 456 static void stripe_io_hints(struct dm_target *ti,
 457                             struct queue_limits *limits)
 458 {
 459         struct stripe_c *sc = ti->private;
 460         unsigned int chunk_size = sc->chunk_size << SECTOR_SHIFT;
 461
 462         limits->io_min = chunk_size;
 463         limits->io_opt = chunk_size * sc->stripes;
 464 }
 465
 466 static struct target_type stripe_target = {
 467         .name   = "striped",
 468         .version = {1, 6, 0},
 469         .features = DM_TARGET_PASSES_INTEGRITY | DM_TARGET_NOWAIT,
 470         .module = THIS_MODULE,
 471         .ctr    = stripe_ctr,
 472         .dtr    = stripe_dtr,
 473         .map    = stripe_map,
 474         .end_io = stripe_end_io,
 475         .status = stripe_status,
 476         .iterate_devices = stripe_iterate_devices,
 477         .io_hints = stripe_io_hints,
 478         .direct_access = stripe_dax_direct_access,
 479         .dax_zero_page_range = stripe_dax_zero_page_range,
 480         .dax_recovery_write = stripe_dax_recovery_write,
 481 };
 482
 483 int __init dm_stripe_init(void)
 484 {
 485         int r;
 486
 487         dm_stripe_wq = alloc_workqueue("dm_stripe_wq", 0, 0);
 488         if (!dm_stripe_wq)
 489                 return -ENOMEM;
 490         r = dm_register_target(&stripe_target);
 491         if (r < 0) {
 492                 destroy_workqueue(dm_stripe_wq);
 493                 DMWARN("target registration failed");
 494         }
 495
 496         return r;
 497 }
 498
 499 void dm_stripe_exit(void)
 500 {
 501         dm_unregister_target(&stripe_target);
 502         destroy_workqueue(dm_stripe_wq);
 503 }