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 ti->num_write_zeroes_bios = stripes; 173 174 sc->chunk_size = chunk_size; 175 if (chunk_size & (chunk_size - 1)) 176 sc->chunk_size_shift = -1; 177 else 178 sc->chunk_size_shift = __ffs(chunk_size); 179 180 /* 181 * Get the stripe destinations. 182 */ 183 for (i = 0; i < stripes; i++) { 184 argv += 2; 185 186 r = get_stripe(ti, sc, i, argv); 187 if (r < 0) { 188 ti->error = "Couldn't parse stripe destination"; 189 while (i--) 190 dm_put_device(ti, sc->stripe[i].dev); 191 kfree(sc); 192 return r; 193 } 194 atomic_set(&(sc->stripe[i].error_count), 0); 195 } 196 197 ti->private = sc; 198 199 return 0; 200 } 201 202 static void stripe_dtr(struct dm_target *ti) 203 { 204 unsigned int i; 205 struct stripe_c *sc = (struct stripe_c *) ti->private; 206 207 for (i = 0; i < sc->stripes; i++) 208 dm_put_device(ti, sc->stripe[i].dev); 209 210 flush_work(&sc->trigger_event); 211 kfree(sc); 212 } 213 214 static void stripe_map_sector(struct stripe_c *sc, sector_t sector, 215 uint32_t *stripe, sector_t *result) 216 { 217 sector_t chunk = dm_target_offset(sc->ti, sector); 218 sector_t chunk_offset; 219 220 if (sc->chunk_size_shift < 0) 221 chunk_offset = sector_div(chunk, sc->chunk_size); 222 else { 223 chunk_offset = chunk & (sc->chunk_size - 1); 224 chunk >>= sc->chunk_size_shift; 225 } 226 227 if (sc->stripes_shift < 0) 228 *stripe = sector_div(chunk, sc->stripes); 229 else { 230 *stripe = chunk & (sc->stripes - 1); 231 chunk >>= sc->stripes_shift; 232 } 233 234 if (sc->chunk_size_shift < 0) 235 chunk *= sc->chunk_size; 236 else 237 chunk <<= sc->chunk_size_shift; 238 239 *result = chunk + chunk_offset; 240 } 241 242 static void stripe_map_range_sector(struct stripe_c *sc, sector_t sector, 243 uint32_t target_stripe, sector_t *result) 244 { 245 uint32_t stripe; 246 247 stripe_map_sector(sc, sector, &stripe, result); 248 if (stripe == target_stripe) 249 return; 250 251 /* round down */ 252 sector = *result; 253 if (sc->chunk_size_shift < 0) 254 *result -= sector_div(sector, sc->chunk_size); 255 else 256 *result = sector & ~(sector_t)(sc->chunk_size - 1); 257 258 if (target_stripe < stripe) 259 *result += sc->chunk_size; /* next chunk */ 260 } 261 262 static int stripe_map_range(struct stripe_c *sc, struct bio *bio, 263 uint32_t target_stripe) 264 { 265 sector_t begin, end; 266 267 stripe_map_range_sector(sc, bio->bi_iter.bi_sector, 268 target_stripe, &begin); 269 stripe_map_range_sector(sc, bio_end_sector(bio), 270 target_stripe, &end); 271 if (begin < end) { 272 bio->bi_bdev = sc->stripe[target_stripe].dev->bdev; 273 bio->bi_iter.bi_sector = begin + 274 sc->stripe[target_stripe].physical_start; 275 bio->bi_iter.bi_size = to_bytes(end - begin); 276 return DM_MAPIO_REMAPPED; 277 } else { 278 /* The range doesn't map to the target stripe */ 279 bio_endio(bio); 280 return DM_MAPIO_SUBMITTED; 281 } 282 } 283 284 static int stripe_map(struct dm_target *ti, struct bio *bio) 285 { 286 struct stripe_c *sc = ti->private; 287 uint32_t stripe; 288 unsigned target_bio_nr; 289 290 if (bio->bi_opf & REQ_PREFLUSH) { 291 target_bio_nr = dm_bio_get_target_bio_nr(bio); 292 BUG_ON(target_bio_nr >= sc->stripes); 293 bio->bi_bdev = sc->stripe[target_bio_nr].dev->bdev; 294 return DM_MAPIO_REMAPPED; 295 } 296 if (unlikely(bio_op(bio) == REQ_OP_DISCARD) || 297 unlikely(bio_op(bio) == REQ_OP_WRITE_ZEROES) || 298 unlikely(bio_op(bio) == REQ_OP_WRITE_SAME)) { 299 target_bio_nr = dm_bio_get_target_bio_nr(bio); 300 BUG_ON(target_bio_nr >= sc->stripes); 301 return stripe_map_range(sc, bio, target_bio_nr); 302 } 303 304 stripe_map_sector(sc, bio->bi_iter.bi_sector, 305 &stripe, &bio->bi_iter.bi_sector); 306 307 bio->bi_iter.bi_sector += sc->stripe[stripe].physical_start; 308 bio->bi_bdev = sc->stripe[stripe].dev->bdev; 309 310 return DM_MAPIO_REMAPPED; 311 } 312 313 static long stripe_direct_access(struct dm_target *ti, sector_t sector, 314 void **kaddr, pfn_t *pfn, long size) 315 { 316 struct stripe_c *sc = ti->private; 317 uint32_t stripe; 318 struct block_device *bdev; 319 struct blk_dax_ctl dax = { 320 .size = size, 321 }; 322 long ret; 323 324 stripe_map_sector(sc, sector, &stripe, &dax.sector); 325 326 dax.sector += sc->stripe[stripe].physical_start; 327 bdev = sc->stripe[stripe].dev->bdev; 328 329 ret = bdev_direct_access(bdev, &dax); 330 *kaddr = dax.addr; 331 *pfn = dax.pfn; 332 333 return ret; 334 } 335 336 /* 337 * Stripe status: 338 * 339 * INFO 340 * #stripes [stripe_name <stripe_name>] [group word count] 341 * [error count 'A|D' <error count 'A|D'>] 342 * 343 * TABLE 344 * #stripes [stripe chunk size] 345 * [stripe_name physical_start <stripe_name physical_start>] 346 * 347 */ 348 349 static void stripe_status(struct dm_target *ti, status_type_t type, 350 unsigned status_flags, char *result, unsigned maxlen) 351 { 352 struct stripe_c *sc = (struct stripe_c *) ti->private; 353 char buffer[sc->stripes + 1]; 354 unsigned int sz = 0; 355 unsigned int i; 356 357 switch (type) { 358 case STATUSTYPE_INFO: 359 DMEMIT("%d ", sc->stripes); 360 for (i = 0; i < sc->stripes; i++) { 361 DMEMIT("%s ", sc->stripe[i].dev->name); 362 buffer[i] = atomic_read(&(sc->stripe[i].error_count)) ? 363 'D' : 'A'; 364 } 365 buffer[i] = '\0'; 366 DMEMIT("1 %s", buffer); 367 break; 368 369 case STATUSTYPE_TABLE: 370 DMEMIT("%d %llu", sc->stripes, 371 (unsigned long long)sc->chunk_size); 372 for (i = 0; i < sc->stripes; i++) 373 DMEMIT(" %s %llu", sc->stripe[i].dev->name, 374 (unsigned long long)sc->stripe[i].physical_start); 375 break; 376 } 377 } 378 379 static int stripe_end_io(struct dm_target *ti, struct bio *bio, int error) 380 { 381 unsigned i; 382 char major_minor[16]; 383 struct stripe_c *sc = ti->private; 384 385 if (!error) 386 return 0; /* I/O complete */ 387 388 if ((error == -EWOULDBLOCK) && (bio->bi_opf & REQ_RAHEAD)) 389 return error; 390 391 if (error == -EOPNOTSUPP) 392 return error; 393 394 memset(major_minor, 0, sizeof(major_minor)); 395 sprintf(major_minor, "%d:%d", 396 MAJOR(disk_devt(bio->bi_bdev->bd_disk)), 397 MINOR(disk_devt(bio->bi_bdev->bd_disk))); 398 399 /* 400 * Test to see which stripe drive triggered the event 401 * and increment error count for all stripes on that device. 402 * If the error count for a given device exceeds the threshold 403 * value we will no longer trigger any further events. 404 */ 405 for (i = 0; i < sc->stripes; i++) 406 if (!strcmp(sc->stripe[i].dev->name, major_minor)) { 407 atomic_inc(&(sc->stripe[i].error_count)); 408 if (atomic_read(&(sc->stripe[i].error_count)) < 409 DM_IO_ERROR_THRESHOLD) 410 schedule_work(&sc->trigger_event); 411 } 412 413 return error; 414 } 415 416 static int stripe_iterate_devices(struct dm_target *ti, 417 iterate_devices_callout_fn fn, void *data) 418 { 419 struct stripe_c *sc = ti->private; 420 int ret = 0; 421 unsigned i = 0; 422 423 do { 424 ret = fn(ti, sc->stripe[i].dev, 425 sc->stripe[i].physical_start, 426 sc->stripe_width, data); 427 } while (!ret && ++i < sc->stripes); 428 429 return ret; 430 } 431 432 static void stripe_io_hints(struct dm_target *ti, 433 struct queue_limits *limits) 434 { 435 struct stripe_c *sc = ti->private; 436 unsigned chunk_size = sc->chunk_size << SECTOR_SHIFT; 437 438 blk_limits_io_min(limits, chunk_size); 439 blk_limits_io_opt(limits, chunk_size * sc->stripes); 440 } 441 442 static struct target_type stripe_target = { 443 .name = "striped", 444 .version = {1, 6, 0}, 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_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