| 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 | |
| 173 | sc->chunk_size = chunk_size; |
| 174 | if (chunk_size & (chunk_size - 1)) |
| 175 | sc->chunk_size_shift = -1; |
| 176 | else |
| 177 | sc->chunk_size_shift = __ffs(chunk_size); |
| 178 | |
| 179 | /* |
| 180 | * Get the stripe destinations. |
| 181 | */ |
| 182 | for (i = 0; i < stripes; i++) { |
| 183 | argv += 2; |
| 184 | |
| 185 | r = get_stripe(ti, sc, i, argv); |
| 186 | if (r < 0) { |
| 187 | ti->error = "Couldn't parse stripe destination"; |
| 188 | while (i--) |
| 189 | dm_put_device(ti, sc->stripe[i].dev); |
| 190 | kfree(sc); |
| 191 | return r; |
| 192 | } |
| 193 | atomic_set(&(sc->stripe[i].error_count), 0); |
| 194 | } |
| 195 | |
| 196 | ti->private = sc; |
| 197 | |
| 198 | return 0; |
| 199 | } |
| 200 | |
| 201 | static void stripe_dtr(struct dm_target *ti) |
| 202 | { |
| 203 | unsigned int i; |
| 204 | struct stripe_c *sc = (struct stripe_c *) ti->private; |
| 205 | |
| 206 | for (i = 0; i < sc->stripes; i++) |
| 207 | dm_put_device(ti, sc->stripe[i].dev); |
| 208 | |
| 209 | flush_work(&sc->trigger_event); |
| 210 | kfree(sc); |
| 211 | } |
| 212 | |
| 213 | static void stripe_map_sector(struct stripe_c *sc, sector_t sector, |
| 214 | uint32_t *stripe, sector_t *result) |
| 215 | { |
| 216 | sector_t chunk = dm_target_offset(sc->ti, sector); |
| 217 | sector_t chunk_offset; |
| 218 | |
| 219 | if (sc->chunk_size_shift < 0) |
| 220 | chunk_offset = sector_div(chunk, sc->chunk_size); |
| 221 | else { |
| 222 | chunk_offset = chunk & (sc->chunk_size - 1); |
| 223 | chunk >>= sc->chunk_size_shift; |
| 224 | } |
| 225 | |
| 226 | if (sc->stripes_shift < 0) |
| 227 | *stripe = sector_div(chunk, sc->stripes); |
| 228 | else { |
| 229 | *stripe = chunk & (sc->stripes - 1); |
| 230 | chunk >>= sc->stripes_shift; |
| 231 | } |
| 232 | |
| 233 | if (sc->chunk_size_shift < 0) |
| 234 | chunk *= sc->chunk_size; |
| 235 | else |
| 236 | chunk <<= sc->chunk_size_shift; |
| 237 | |
| 238 | *result = chunk + chunk_offset; |
| 239 | } |
| 240 | |
| 241 | static void stripe_map_range_sector(struct stripe_c *sc, sector_t sector, |
| 242 | uint32_t target_stripe, sector_t *result) |
| 243 | { |
| 244 | uint32_t stripe; |
| 245 | |
| 246 | stripe_map_sector(sc, sector, &stripe, result); |
| 247 | if (stripe == target_stripe) |
| 248 | return; |
| 249 | |
| 250 | /* round down */ |
| 251 | sector = *result; |
| 252 | if (sc->chunk_size_shift < 0) |
| 253 | *result -= sector_div(sector, sc->chunk_size); |
| 254 | else |
| 255 | *result = sector & ~(sector_t)(sc->chunk_size - 1); |
| 256 | |
| 257 | if (target_stripe < stripe) |
| 258 | *result += sc->chunk_size; /* next chunk */ |
| 259 | } |
| 260 | |
| 261 | static int stripe_map_range(struct stripe_c *sc, struct bio *bio, |
| 262 | uint32_t target_stripe) |
| 263 | { |
| 264 | sector_t begin, end; |
| 265 | |
| 266 | stripe_map_range_sector(sc, bio->bi_iter.bi_sector, |
| 267 | target_stripe, &begin); |
| 268 | stripe_map_range_sector(sc, bio_end_sector(bio), |
| 269 | target_stripe, &end); |
| 270 | if (begin < end) { |
| 271 | bio->bi_bdev = sc->stripe[target_stripe].dev->bdev; |
| 272 | bio->bi_iter.bi_sector = begin + |
| 273 | sc->stripe[target_stripe].physical_start; |
| 274 | bio->bi_iter.bi_size = to_bytes(end - begin); |
| 275 | return DM_MAPIO_REMAPPED; |
| 276 | } else { |
| 277 | /* The range doesn't map to the target stripe */ |
| 278 | bio_endio(bio); |
| 279 | return DM_MAPIO_SUBMITTED; |
| 280 | } |
| 281 | } |
| 282 | |
| 283 | static int stripe_map(struct dm_target *ti, struct bio *bio) |
| 284 | { |
| 285 | struct stripe_c *sc = ti->private; |
| 286 | uint32_t stripe; |
| 287 | unsigned target_bio_nr; |
| 288 | |
| 289 | if (bio->bi_rw & REQ_FLUSH) { |
| 290 | target_bio_nr = dm_bio_get_target_bio_nr(bio); |
| 291 | BUG_ON(target_bio_nr >= sc->stripes); |
| 292 | bio->bi_bdev = sc->stripe[target_bio_nr].dev->bdev; |
| 293 | return DM_MAPIO_REMAPPED; |
| 294 | } |
| 295 | if (unlikely(bio->bi_rw & REQ_DISCARD) || |
| 296 | unlikely(bio->bi_rw & REQ_WRITE_SAME)) { |
| 297 | target_bio_nr = dm_bio_get_target_bio_nr(bio); |
| 298 | BUG_ON(target_bio_nr >= sc->stripes); |
| 299 | return stripe_map_range(sc, bio, target_bio_nr); |
| 300 | } |
| 301 | |
| 302 | stripe_map_sector(sc, bio->bi_iter.bi_sector, |
| 303 | &stripe, &bio->bi_iter.bi_sector); |
| 304 | |
| 305 | bio->bi_iter.bi_sector += sc->stripe[stripe].physical_start; |
| 306 | bio->bi_bdev = sc->stripe[stripe].dev->bdev; |
| 307 | |
| 308 | return DM_MAPIO_REMAPPED; |
| 309 | } |
| 310 | |
| 311 | /* |
| 312 | * Stripe status: |
| 313 | * |
| 314 | * INFO |
| 315 | * #stripes [stripe_name <stripe_name>] [group word count] |
| 316 | * [error count 'A|D' <error count 'A|D'>] |
| 317 | * |
| 318 | * TABLE |
| 319 | * #stripes [stripe chunk size] |
| 320 | * [stripe_name physical_start <stripe_name physical_start>] |
| 321 | * |
| 322 | */ |
| 323 | |
| 324 | static void stripe_status(struct dm_target *ti, status_type_t type, |
| 325 | unsigned status_flags, char *result, unsigned maxlen) |
| 326 | { |
| 327 | struct stripe_c *sc = (struct stripe_c *) ti->private; |
| 328 | char buffer[sc->stripes + 1]; |
| 329 | unsigned int sz = 0; |
| 330 | unsigned int i; |
| 331 | |
| 332 | switch (type) { |
| 333 | case STATUSTYPE_INFO: |
| 334 | DMEMIT("%d ", sc->stripes); |
| 335 | for (i = 0; i < sc->stripes; i++) { |
| 336 | DMEMIT("%s ", sc->stripe[i].dev->name); |
| 337 | buffer[i] = atomic_read(&(sc->stripe[i].error_count)) ? |
| 338 | 'D' : 'A'; |
| 339 | } |
| 340 | buffer[i] = '\0'; |
| 341 | DMEMIT("1 %s", buffer); |
| 342 | break; |
| 343 | |
| 344 | case STATUSTYPE_TABLE: |
| 345 | DMEMIT("%d %llu", sc->stripes, |
| 346 | (unsigned long long)sc->chunk_size); |
| 347 | for (i = 0; i < sc->stripes; i++) |
| 348 | DMEMIT(" %s %llu", sc->stripe[i].dev->name, |
| 349 | (unsigned long long)sc->stripe[i].physical_start); |
| 350 | break; |
| 351 | } |
| 352 | } |
| 353 | |
| 354 | static int stripe_end_io(struct dm_target *ti, struct bio *bio, int error) |
| 355 | { |
| 356 | unsigned i; |
| 357 | char major_minor[16]; |
| 358 | struct stripe_c *sc = ti->private; |
| 359 | |
| 360 | if (!error) |
| 361 | return 0; /* I/O complete */ |
| 362 | |
| 363 | if ((error == -EWOULDBLOCK) && (bio->bi_rw & REQ_RAHEAD)) |
| 364 | return error; |
| 365 | |
| 366 | if (error == -EOPNOTSUPP) |
| 367 | return error; |
| 368 | |
| 369 | memset(major_minor, 0, sizeof(major_minor)); |
| 370 | sprintf(major_minor, "%d:%d", |
| 371 | MAJOR(disk_devt(bio->bi_bdev->bd_disk)), |
| 372 | MINOR(disk_devt(bio->bi_bdev->bd_disk))); |
| 373 | |
| 374 | /* |
| 375 | * Test to see which stripe drive triggered the event |
| 376 | * and increment error count for all stripes on that device. |
| 377 | * If the error count for a given device exceeds the threshold |
| 378 | * value we will no longer trigger any further events. |
| 379 | */ |
| 380 | for (i = 0; i < sc->stripes; i++) |
| 381 | if (!strcmp(sc->stripe[i].dev->name, major_minor)) { |
| 382 | atomic_inc(&(sc->stripe[i].error_count)); |
| 383 | if (atomic_read(&(sc->stripe[i].error_count)) < |
| 384 | DM_IO_ERROR_THRESHOLD) |
| 385 | schedule_work(&sc->trigger_event); |
| 386 | } |
| 387 | |
| 388 | return error; |
| 389 | } |
| 390 | |
| 391 | static int stripe_iterate_devices(struct dm_target *ti, |
| 392 | iterate_devices_callout_fn fn, void *data) |
| 393 | { |
| 394 | struct stripe_c *sc = ti->private; |
| 395 | int ret = 0; |
| 396 | unsigned i = 0; |
| 397 | |
| 398 | do { |
| 399 | ret = fn(ti, sc->stripe[i].dev, |
| 400 | sc->stripe[i].physical_start, |
| 401 | sc->stripe_width, data); |
| 402 | } while (!ret && ++i < sc->stripes); |
| 403 | |
| 404 | return ret; |
| 405 | } |
| 406 | |
| 407 | static void stripe_io_hints(struct dm_target *ti, |
| 408 | struct queue_limits *limits) |
| 409 | { |
| 410 | struct stripe_c *sc = ti->private; |
| 411 | unsigned chunk_size = sc->chunk_size << SECTOR_SHIFT; |
| 412 | |
| 413 | blk_limits_io_min(limits, chunk_size); |
| 414 | blk_limits_io_opt(limits, chunk_size * sc->stripes); |
| 415 | } |
| 416 | |
| 417 | static struct target_type stripe_target = { |
| 418 | .name = "striped", |
| 419 | .version = {1, 5, 1}, |
| 420 | .module = THIS_MODULE, |
| 421 | .ctr = stripe_ctr, |
| 422 | .dtr = stripe_dtr, |
| 423 | .map = stripe_map, |
| 424 | .end_io = stripe_end_io, |
| 425 | .status = stripe_status, |
| 426 | .iterate_devices = stripe_iterate_devices, |
| 427 | .io_hints = stripe_io_hints, |
| 428 | }; |
| 429 | |
| 430 | int __init dm_stripe_init(void) |
| 431 | { |
| 432 | int r; |
| 433 | |
| 434 | r = dm_register_target(&stripe_target); |
| 435 | if (r < 0) |
| 436 | DMWARN("target registration failed"); |
| 437 | |
| 438 | return r; |
| 439 | } |
| 440 | |
| 441 | void dm_stripe_exit(void) |
| 442 | { |
| 443 | dm_unregister_target(&stripe_target); |
| 444 | } |