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