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