1 /* 2 * Copyright (C) 2003 Sistina Software 3 * Copyright (C) 2006 Red Hat GmbH 4 * 5 * This file is released under the GPL. 6 */ 7 8 #include "dm.h" 9 10 #include <linux/device-mapper.h> 11 12 #include <linux/bio.h> 13 #include <linux/completion.h> 14 #include <linux/mempool.h> 15 #include <linux/module.h> 16 #include <linux/sched.h> 17 #include <linux/slab.h> 18 #include <linux/dm-io.h> 19 20 #define DM_MSG_PREFIX "io" 21 22 #define DM_IO_MAX_REGIONS BITS_PER_LONG 23 24 struct dm_io_client { 25 mempool_t *pool; 26 struct bio_set *bios; 27 }; 28 29 /* 30 * Aligning 'struct io' reduces the number of bits required to store 31 * its address. Refer to store_io_and_region_in_bio() below. 32 */ 33 struct io { 34 unsigned long error_bits; 35 atomic_t count; 36 struct dm_io_client *client; 37 io_notify_fn callback; 38 void *context; 39 void *vma_invalidate_address; 40 unsigned long vma_invalidate_size; 41 } __attribute__((aligned(DM_IO_MAX_REGIONS))); 42 43 static struct kmem_cache *_dm_io_cache; 44 45 /* 46 * Create a client with mempool and bioset. 47 */ 48 struct dm_io_client *dm_io_client_create(void) 49 { 50 struct dm_io_client *client; 51 unsigned min_ios = dm_get_reserved_bio_based_ios(); 52 53 client = kmalloc(sizeof(*client), GFP_KERNEL); 54 if (!client) 55 return ERR_PTR(-ENOMEM); 56 57 client->pool = mempool_create_slab_pool(min_ios, _dm_io_cache); 58 if (!client->pool) 59 goto bad; 60 61 client->bios = bioset_create(min_ios, 0); 62 if (!client->bios) 63 goto bad; 64 65 return client; 66 67 bad: 68 if (client->pool) 69 mempool_destroy(client->pool); 70 kfree(client); 71 return ERR_PTR(-ENOMEM); 72 } 73 EXPORT_SYMBOL(dm_io_client_create); 74 75 void dm_io_client_destroy(struct dm_io_client *client) 76 { 77 mempool_destroy(client->pool); 78 bioset_free(client->bios); 79 kfree(client); 80 } 81 EXPORT_SYMBOL(dm_io_client_destroy); 82 83 /*----------------------------------------------------------------- 84 * We need to keep track of which region a bio is doing io for. 85 * To avoid a memory allocation to store just 5 or 6 bits, we 86 * ensure the 'struct io' pointer is aligned so enough low bits are 87 * always zero and then combine it with the region number directly in 88 * bi_private. 89 *---------------------------------------------------------------*/ 90 static void store_io_and_region_in_bio(struct bio *bio, struct io *io, 91 unsigned region) 92 { 93 if (unlikely(!IS_ALIGNED((unsigned long)io, DM_IO_MAX_REGIONS))) { 94 DMCRIT("Unaligned struct io pointer %p", io); 95 BUG(); 96 } 97 98 bio->bi_private = (void *)((unsigned long)io | region); 99 } 100 101 static void retrieve_io_and_region_from_bio(struct bio *bio, struct io **io, 102 unsigned *region) 103 { 104 unsigned long val = (unsigned long)bio->bi_private; 105 106 *io = (void *)(val & -(unsigned long)DM_IO_MAX_REGIONS); 107 *region = val & (DM_IO_MAX_REGIONS - 1); 108 } 109 110 /*----------------------------------------------------------------- 111 * We need an io object to keep track of the number of bios that 112 * have been dispatched for a particular io. 113 *---------------------------------------------------------------*/ 114 static void complete_io(struct io *io) 115 { 116 unsigned long error_bits = io->error_bits; 117 io_notify_fn fn = io->callback; 118 void *context = io->context; 119 120 if (io->vma_invalidate_size) 121 invalidate_kernel_vmap_range(io->vma_invalidate_address, 122 io->vma_invalidate_size); 123 124 mempool_free(io, io->client->pool); 125 fn(error_bits, context); 126 } 127 128 static void dec_count(struct io *io, unsigned int region, int error) 129 { 130 if (error) 131 set_bit(region, &io->error_bits); 132 133 if (atomic_dec_and_test(&io->count)) 134 complete_io(io); 135 } 136 137 static void endio(struct bio *bio, int error) 138 { 139 struct io *io; 140 unsigned region; 141 142 if (error && bio_data_dir(bio) == READ) 143 zero_fill_bio(bio); 144 145 /* 146 * The bio destructor in bio_put() may use the io object. 147 */ 148 retrieve_io_and_region_from_bio(bio, &io, ®ion); 149 150 bio_put(bio); 151 152 dec_count(io, region, error); 153 } 154 155 /*----------------------------------------------------------------- 156 * These little objects provide an abstraction for getting a new 157 * destination page for io. 158 *---------------------------------------------------------------*/ 159 struct dpages { 160 void (*get_page)(struct dpages *dp, 161 struct page **p, unsigned long *len, unsigned *offset); 162 void (*next_page)(struct dpages *dp); 163 164 unsigned context_u; 165 void *context_ptr; 166 167 void *vma_invalidate_address; 168 unsigned long vma_invalidate_size; 169 }; 170 171 /* 172 * Functions for getting the pages from a list. 173 */ 174 static void list_get_page(struct dpages *dp, 175 struct page **p, unsigned long *len, unsigned *offset) 176 { 177 unsigned o = dp->context_u; 178 struct page_list *pl = (struct page_list *) dp->context_ptr; 179 180 *p = pl->page; 181 *len = PAGE_SIZE - o; 182 *offset = o; 183 } 184 185 static void list_next_page(struct dpages *dp) 186 { 187 struct page_list *pl = (struct page_list *) dp->context_ptr; 188 dp->context_ptr = pl->next; 189 dp->context_u = 0; 190 } 191 192 static void list_dp_init(struct dpages *dp, struct page_list *pl, unsigned offset) 193 { 194 dp->get_page = list_get_page; 195 dp->next_page = list_next_page; 196 dp->context_u = offset; 197 dp->context_ptr = pl; 198 } 199 200 /* 201 * Functions for getting the pages from a bvec. 202 */ 203 static void bio_get_page(struct dpages *dp, struct page **p, 204 unsigned long *len, unsigned *offset) 205 { 206 struct bio_vec *bvec = dp->context_ptr; 207 *p = bvec->bv_page; 208 *len = bvec->bv_len - dp->context_u; 209 *offset = bvec->bv_offset + dp->context_u; 210 } 211 212 static void bio_next_page(struct dpages *dp) 213 { 214 struct bio_vec *bvec = dp->context_ptr; 215 dp->context_ptr = bvec + 1; 216 dp->context_u = 0; 217 } 218 219 static void bio_dp_init(struct dpages *dp, struct bio *bio) 220 { 221 dp->get_page = bio_get_page; 222 dp->next_page = bio_next_page; 223 dp->context_ptr = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter); 224 dp->context_u = bio->bi_iter.bi_bvec_done; 225 } 226 227 /* 228 * Functions for getting the pages from a VMA. 229 */ 230 static void vm_get_page(struct dpages *dp, 231 struct page **p, unsigned long *len, unsigned *offset) 232 { 233 *p = vmalloc_to_page(dp->context_ptr); 234 *offset = dp->context_u; 235 *len = PAGE_SIZE - dp->context_u; 236 } 237 238 static void vm_next_page(struct dpages *dp) 239 { 240 dp->context_ptr += PAGE_SIZE - dp->context_u; 241 dp->context_u = 0; 242 } 243 244 static void vm_dp_init(struct dpages *dp, void *data) 245 { 246 dp->get_page = vm_get_page; 247 dp->next_page = vm_next_page; 248 dp->context_u = ((unsigned long) data) & (PAGE_SIZE - 1); 249 dp->context_ptr = data; 250 } 251 252 /* 253 * Functions for getting the pages from kernel memory. 254 */ 255 static void km_get_page(struct dpages *dp, struct page **p, unsigned long *len, 256 unsigned *offset) 257 { 258 *p = virt_to_page(dp->context_ptr); 259 *offset = dp->context_u; 260 *len = PAGE_SIZE - dp->context_u; 261 } 262 263 static void km_next_page(struct dpages *dp) 264 { 265 dp->context_ptr += PAGE_SIZE - dp->context_u; 266 dp->context_u = 0; 267 } 268 269 static void km_dp_init(struct dpages *dp, void *data) 270 { 271 dp->get_page = km_get_page; 272 dp->next_page = km_next_page; 273 dp->context_u = ((unsigned long) data) & (PAGE_SIZE - 1); 274 dp->context_ptr = data; 275 } 276 277 /*----------------------------------------------------------------- 278 * IO routines that accept a list of pages. 279 *---------------------------------------------------------------*/ 280 static void do_region(int rw, unsigned region, struct dm_io_region *where, 281 struct dpages *dp, struct io *io) 282 { 283 struct bio *bio; 284 struct page *page; 285 unsigned long len; 286 unsigned offset; 287 unsigned num_bvecs; 288 sector_t remaining = where->count; 289 struct request_queue *q = bdev_get_queue(where->bdev); 290 unsigned short logical_block_size = queue_logical_block_size(q); 291 sector_t num_sectors; 292 unsigned int uninitialized_var(special_cmd_max_sectors); 293 294 /* 295 * Reject unsupported discard and write same requests. 296 */ 297 if (rw & REQ_DISCARD) 298 special_cmd_max_sectors = q->limits.max_discard_sectors; 299 else if (rw & REQ_WRITE_SAME) 300 special_cmd_max_sectors = q->limits.max_write_same_sectors; 301 if ((rw & (REQ_DISCARD | REQ_WRITE_SAME)) && special_cmd_max_sectors == 0) { 302 dec_count(io, region, -EOPNOTSUPP); 303 return; 304 } 305 306 /* 307 * where->count may be zero if rw holds a flush and we need to 308 * send a zero-sized flush. 309 */ 310 do { 311 /* 312 * Allocate a suitably sized-bio. 313 */ 314 if ((rw & REQ_DISCARD) || (rw & REQ_WRITE_SAME)) 315 num_bvecs = 1; 316 else 317 num_bvecs = min_t(int, bio_get_nr_vecs(where->bdev), 318 dm_sector_div_up(remaining, (PAGE_SIZE >> SECTOR_SHIFT))); 319 320 bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, io->client->bios); 321 bio->bi_iter.bi_sector = where->sector + (where->count - remaining); 322 bio->bi_bdev = where->bdev; 323 bio->bi_end_io = endio; 324 store_io_and_region_in_bio(bio, io, region); 325 326 if (rw & REQ_DISCARD) { 327 num_sectors = min_t(sector_t, special_cmd_max_sectors, remaining); 328 bio->bi_iter.bi_size = num_sectors << SECTOR_SHIFT; 329 remaining -= num_sectors; 330 } else if (rw & REQ_WRITE_SAME) { 331 /* 332 * WRITE SAME only uses a single page. 333 */ 334 dp->get_page(dp, &page, &len, &offset); 335 bio_add_page(bio, page, logical_block_size, offset); 336 num_sectors = min_t(sector_t, special_cmd_max_sectors, remaining); 337 bio->bi_iter.bi_size = num_sectors << SECTOR_SHIFT; 338 339 offset = 0; 340 remaining -= num_sectors; 341 dp->next_page(dp); 342 } else while (remaining) { 343 /* 344 * Try and add as many pages as possible. 345 */ 346 dp->get_page(dp, &page, &len, &offset); 347 len = min(len, to_bytes(remaining)); 348 if (!bio_add_page(bio, page, len, offset)) 349 break; 350 351 offset = 0; 352 remaining -= to_sector(len); 353 dp->next_page(dp); 354 } 355 356 atomic_inc(&io->count); 357 submit_bio(rw, bio); 358 } while (remaining); 359 } 360 361 static void dispatch_io(int rw, unsigned int num_regions, 362 struct dm_io_region *where, struct dpages *dp, 363 struct io *io, int sync) 364 { 365 int i; 366 struct dpages old_pages = *dp; 367 368 BUG_ON(num_regions > DM_IO_MAX_REGIONS); 369 370 if (sync) 371 rw |= REQ_SYNC; 372 373 /* 374 * For multiple regions we need to be careful to rewind 375 * the dp object for each call to do_region. 376 */ 377 for (i = 0; i < num_regions; i++) { 378 *dp = old_pages; 379 if (where[i].count || (rw & REQ_FLUSH)) 380 do_region(rw, i, where + i, dp, io); 381 } 382 383 /* 384 * Drop the extra reference that we were holding to avoid 385 * the io being completed too early. 386 */ 387 dec_count(io, 0, 0); 388 } 389 390 struct sync_io { 391 unsigned long error_bits; 392 struct completion wait; 393 }; 394 395 static void sync_io_complete(unsigned long error, void *context) 396 { 397 struct sync_io *sio = context; 398 399 sio->error_bits = error; 400 complete(&sio->wait); 401 } 402 403 static int sync_io(struct dm_io_client *client, unsigned int num_regions, 404 struct dm_io_region *where, int rw, struct dpages *dp, 405 unsigned long *error_bits) 406 { 407 struct io *io; 408 struct sync_io sio; 409 410 if (num_regions > 1 && (rw & RW_MASK) != WRITE) { 411 WARN_ON(1); 412 return -EIO; 413 } 414 415 init_completion(&sio.wait); 416 417 io = mempool_alloc(client->pool, GFP_NOIO); 418 io->error_bits = 0; 419 atomic_set(&io->count, 1); /* see dispatch_io() */ 420 io->client = client; 421 io->callback = sync_io_complete; 422 io->context = &sio; 423 424 io->vma_invalidate_address = dp->vma_invalidate_address; 425 io->vma_invalidate_size = dp->vma_invalidate_size; 426 427 dispatch_io(rw, num_regions, where, dp, io, 1); 428 429 wait_for_completion_io(&sio.wait); 430 431 if (error_bits) 432 *error_bits = sio.error_bits; 433 434 return sio.error_bits ? -EIO : 0; 435 } 436 437 static int async_io(struct dm_io_client *client, unsigned int num_regions, 438 struct dm_io_region *where, int rw, struct dpages *dp, 439 io_notify_fn fn, void *context) 440 { 441 struct io *io; 442 443 if (num_regions > 1 && (rw & RW_MASK) != WRITE) { 444 WARN_ON(1); 445 fn(1, context); 446 return -EIO; 447 } 448 449 io = mempool_alloc(client->pool, GFP_NOIO); 450 io->error_bits = 0; 451 atomic_set(&io->count, 1); /* see dispatch_io() */ 452 io->client = client; 453 io->callback = fn; 454 io->context = context; 455 456 io->vma_invalidate_address = dp->vma_invalidate_address; 457 io->vma_invalidate_size = dp->vma_invalidate_size; 458 459 dispatch_io(rw, num_regions, where, dp, io, 0); 460 return 0; 461 } 462 463 static int dp_init(struct dm_io_request *io_req, struct dpages *dp, 464 unsigned long size) 465 { 466 /* Set up dpages based on memory type */ 467 468 dp->vma_invalidate_address = NULL; 469 dp->vma_invalidate_size = 0; 470 471 switch (io_req->mem.type) { 472 case DM_IO_PAGE_LIST: 473 list_dp_init(dp, io_req->mem.ptr.pl, io_req->mem.offset); 474 break; 475 476 case DM_IO_BIO: 477 bio_dp_init(dp, io_req->mem.ptr.bio); 478 break; 479 480 case DM_IO_VMA: 481 flush_kernel_vmap_range(io_req->mem.ptr.vma, size); 482 if ((io_req->bi_rw & RW_MASK) == READ) { 483 dp->vma_invalidate_address = io_req->mem.ptr.vma; 484 dp->vma_invalidate_size = size; 485 } 486 vm_dp_init(dp, io_req->mem.ptr.vma); 487 break; 488 489 case DM_IO_KMEM: 490 km_dp_init(dp, io_req->mem.ptr.addr); 491 break; 492 493 default: 494 return -EINVAL; 495 } 496 497 return 0; 498 } 499 500 /* 501 * New collapsed (a)synchronous interface. 502 * 503 * If the IO is asynchronous (i.e. it has notify.fn), you must either unplug 504 * the queue with blk_unplug() some time later or set REQ_SYNC in io_req->bi_rw. 505 * If you fail to do one of these, the IO will be submitted to the disk after 506 * q->unplug_delay, which defaults to 3ms in blk-settings.c. 507 */ 508 int dm_io(struct dm_io_request *io_req, unsigned num_regions, 509 struct dm_io_region *where, unsigned long *sync_error_bits) 510 { 511 int r; 512 struct dpages dp; 513 514 r = dp_init(io_req, &dp, (unsigned long)where->count << SECTOR_SHIFT); 515 if (r) 516 return r; 517 518 if (!io_req->notify.fn) 519 return sync_io(io_req->client, num_regions, where, 520 io_req->bi_rw, &dp, sync_error_bits); 521 522 return async_io(io_req->client, num_regions, where, io_req->bi_rw, 523 &dp, io_req->notify.fn, io_req->notify.context); 524 } 525 EXPORT_SYMBOL(dm_io); 526 527 int __init dm_io_init(void) 528 { 529 _dm_io_cache = KMEM_CACHE(io, 0); 530 if (!_dm_io_cache) 531 return -ENOMEM; 532 533 return 0; 534 } 535 536 void dm_io_exit(void) 537 { 538 kmem_cache_destroy(_dm_io_cache); 539 _dm_io_cache = NULL; 540 } 541