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-core.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 int ret; 53 54 client = kzalloc(sizeof(*client), GFP_KERNEL); 55 if (!client) 56 return ERR_PTR(-ENOMEM); 57 58 ret = mempool_init_slab_pool(&client->pool, min_ios, _dm_io_cache); 59 if (ret) 60 goto bad; 61 62 ret = bioset_init(&client->bios, min_ios, 0, BIOSET_NEED_BVECS); 63 if (ret) 64 goto bad; 65 66 return client; 67 68 bad: 69 mempool_exit(&client->pool); 70 kfree(client); 71 return ERR_PTR(ret); 72 } 73 EXPORT_SYMBOL(dm_io_client_create); 74 75 void dm_io_client_destroy(struct dm_io_client *client) 76 { 77 mempool_exit(&client->pool); 78 bioset_exit(&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, blk_status_t 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) 138 { 139 struct io *io; 140 unsigned region; 141 blk_status_t error; 142 143 if (bio->bi_status && bio_data_dir(bio) == READ) 144 zero_fill_bio(bio); 145 146 /* 147 * The bio destructor in bio_put() may use the io object. 148 */ 149 retrieve_io_and_region_from_bio(bio, &io, ®ion); 150 151 error = bio->bi_status; 152 bio_put(bio); 153 154 dec_count(io, region, error); 155 } 156 157 /*----------------------------------------------------------------- 158 * These little objects provide an abstraction for getting a new 159 * destination page for io. 160 *---------------------------------------------------------------*/ 161 struct dpages { 162 void (*get_page)(struct dpages *dp, 163 struct page **p, unsigned long *len, unsigned *offset); 164 void (*next_page)(struct dpages *dp); 165 166 union { 167 unsigned context_u; 168 struct bvec_iter context_bi; 169 }; 170 void *context_ptr; 171 172 void *vma_invalidate_address; 173 unsigned long vma_invalidate_size; 174 }; 175 176 /* 177 * Functions for getting the pages from a list. 178 */ 179 static void list_get_page(struct dpages *dp, 180 struct page **p, unsigned long *len, unsigned *offset) 181 { 182 unsigned o = dp->context_u; 183 struct page_list *pl = (struct page_list *) dp->context_ptr; 184 185 *p = pl->page; 186 *len = PAGE_SIZE - o; 187 *offset = o; 188 } 189 190 static void list_next_page(struct dpages *dp) 191 { 192 struct page_list *pl = (struct page_list *) dp->context_ptr; 193 dp->context_ptr = pl->next; 194 dp->context_u = 0; 195 } 196 197 static void list_dp_init(struct dpages *dp, struct page_list *pl, unsigned offset) 198 { 199 dp->get_page = list_get_page; 200 dp->next_page = list_next_page; 201 dp->context_u = offset; 202 dp->context_ptr = pl; 203 } 204 205 /* 206 * Functions for getting the pages from a bvec. 207 */ 208 static void bio_get_page(struct dpages *dp, struct page **p, 209 unsigned long *len, unsigned *offset) 210 { 211 struct bio_vec bvec = bvec_iter_bvec((struct bio_vec *)dp->context_ptr, 212 dp->context_bi); 213 214 *p = bvec.bv_page; 215 *len = bvec.bv_len; 216 *offset = bvec.bv_offset; 217 218 /* avoid figuring it out again in bio_next_page() */ 219 dp->context_bi.bi_sector = (sector_t)bvec.bv_len; 220 } 221 222 static void bio_next_page(struct dpages *dp) 223 { 224 unsigned int len = (unsigned int)dp->context_bi.bi_sector; 225 226 bvec_iter_advance((struct bio_vec *)dp->context_ptr, 227 &dp->context_bi, len); 228 } 229 230 static void bio_dp_init(struct dpages *dp, struct bio *bio) 231 { 232 dp->get_page = bio_get_page; 233 dp->next_page = bio_next_page; 234 235 /* 236 * We just use bvec iterator to retrieve pages, so it is ok to 237 * access the bvec table directly here 238 */ 239 dp->context_ptr = bio->bi_io_vec; 240 dp->context_bi = bio->bi_iter; 241 } 242 243 /* 244 * Functions for getting the pages from a VMA. 245 */ 246 static void vm_get_page(struct dpages *dp, 247 struct page **p, unsigned long *len, unsigned *offset) 248 { 249 *p = vmalloc_to_page(dp->context_ptr); 250 *offset = dp->context_u; 251 *len = PAGE_SIZE - dp->context_u; 252 } 253 254 static void vm_next_page(struct dpages *dp) 255 { 256 dp->context_ptr += PAGE_SIZE - dp->context_u; 257 dp->context_u = 0; 258 } 259 260 static void vm_dp_init(struct dpages *dp, void *data) 261 { 262 dp->get_page = vm_get_page; 263 dp->next_page = vm_next_page; 264 dp->context_u = offset_in_page(data); 265 dp->context_ptr = data; 266 } 267 268 /* 269 * Functions for getting the pages from kernel memory. 270 */ 271 static void km_get_page(struct dpages *dp, struct page **p, unsigned long *len, 272 unsigned *offset) 273 { 274 *p = virt_to_page(dp->context_ptr); 275 *offset = dp->context_u; 276 *len = PAGE_SIZE - dp->context_u; 277 } 278 279 static void km_next_page(struct dpages *dp) 280 { 281 dp->context_ptr += PAGE_SIZE - dp->context_u; 282 dp->context_u = 0; 283 } 284 285 static void km_dp_init(struct dpages *dp, void *data) 286 { 287 dp->get_page = km_get_page; 288 dp->next_page = km_next_page; 289 dp->context_u = offset_in_page(data); 290 dp->context_ptr = data; 291 } 292 293 /*----------------------------------------------------------------- 294 * IO routines that accept a list of pages. 295 *---------------------------------------------------------------*/ 296 static void do_region(int op, int op_flags, unsigned region, 297 struct dm_io_region *where, struct dpages *dp, 298 struct io *io) 299 { 300 struct bio *bio; 301 struct page *page; 302 unsigned long len; 303 unsigned offset; 304 unsigned num_bvecs; 305 sector_t remaining = where->count; 306 struct request_queue *q = bdev_get_queue(where->bdev); 307 sector_t num_sectors; 308 unsigned int special_cmd_max_sectors; 309 310 /* 311 * Reject unsupported discard and write same requests. 312 */ 313 if (op == REQ_OP_DISCARD) 314 special_cmd_max_sectors = q->limits.max_discard_sectors; 315 else if (op == REQ_OP_WRITE_ZEROES) 316 special_cmd_max_sectors = q->limits.max_write_zeroes_sectors; 317 if ((op == REQ_OP_DISCARD || op == REQ_OP_WRITE_ZEROES) && 318 special_cmd_max_sectors == 0) { 319 atomic_inc(&io->count); 320 dec_count(io, region, BLK_STS_NOTSUPP); 321 return; 322 } 323 324 /* 325 * where->count may be zero if op holds a flush and we need to 326 * send a zero-sized flush. 327 */ 328 do { 329 /* 330 * Allocate a suitably sized-bio. 331 */ 332 switch (op) { 333 case REQ_OP_DISCARD: 334 case REQ_OP_WRITE_ZEROES: 335 num_bvecs = 0; 336 break; 337 default: 338 num_bvecs = bio_max_segs(dm_sector_div_up(remaining, 339 (PAGE_SIZE >> SECTOR_SHIFT))); 340 } 341 342 bio = bio_alloc_bioset(where->bdev, num_bvecs, op | op_flags, 343 GFP_NOIO, &io->client->bios); 344 bio->bi_iter.bi_sector = where->sector + (where->count - remaining); 345 bio->bi_end_io = endio; 346 store_io_and_region_in_bio(bio, io, region); 347 348 if (op == REQ_OP_DISCARD || op == REQ_OP_WRITE_ZEROES) { 349 num_sectors = min_t(sector_t, special_cmd_max_sectors, remaining); 350 bio->bi_iter.bi_size = num_sectors << SECTOR_SHIFT; 351 remaining -= num_sectors; 352 } else while (remaining) { 353 /* 354 * Try and add as many pages as possible. 355 */ 356 dp->get_page(dp, &page, &len, &offset); 357 len = min(len, to_bytes(remaining)); 358 if (!bio_add_page(bio, page, len, offset)) 359 break; 360 361 offset = 0; 362 remaining -= to_sector(len); 363 dp->next_page(dp); 364 } 365 366 atomic_inc(&io->count); 367 submit_bio(bio); 368 } while (remaining); 369 } 370 371 static void dispatch_io(int op, int op_flags, unsigned int num_regions, 372 struct dm_io_region *where, struct dpages *dp, 373 struct io *io, int sync) 374 { 375 int i; 376 struct dpages old_pages = *dp; 377 378 BUG_ON(num_regions > DM_IO_MAX_REGIONS); 379 380 if (sync) 381 op_flags |= REQ_SYNC; 382 383 /* 384 * For multiple regions we need to be careful to rewind 385 * the dp object for each call to do_region. 386 */ 387 for (i = 0; i < num_regions; i++) { 388 *dp = old_pages; 389 if (where[i].count || (op_flags & REQ_PREFLUSH)) 390 do_region(op, op_flags, i, where + i, dp, io); 391 } 392 393 /* 394 * Drop the extra reference that we were holding to avoid 395 * the io being completed too early. 396 */ 397 dec_count(io, 0, 0); 398 } 399 400 struct sync_io { 401 unsigned long error_bits; 402 struct completion wait; 403 }; 404 405 static void sync_io_complete(unsigned long error, void *context) 406 { 407 struct sync_io *sio = context; 408 409 sio->error_bits = error; 410 complete(&sio->wait); 411 } 412 413 static int sync_io(struct dm_io_client *client, unsigned int num_regions, 414 struct dm_io_region *where, int op, int op_flags, 415 struct dpages *dp, unsigned long *error_bits) 416 { 417 struct io *io; 418 struct sync_io sio; 419 420 if (num_regions > 1 && !op_is_write(op)) { 421 WARN_ON(1); 422 return -EIO; 423 } 424 425 init_completion(&sio.wait); 426 427 io = mempool_alloc(&client->pool, GFP_NOIO); 428 io->error_bits = 0; 429 atomic_set(&io->count, 1); /* see dispatch_io() */ 430 io->client = client; 431 io->callback = sync_io_complete; 432 io->context = &sio; 433 434 io->vma_invalidate_address = dp->vma_invalidate_address; 435 io->vma_invalidate_size = dp->vma_invalidate_size; 436 437 dispatch_io(op, op_flags, num_regions, where, dp, io, 1); 438 439 wait_for_completion_io(&sio.wait); 440 441 if (error_bits) 442 *error_bits = sio.error_bits; 443 444 return sio.error_bits ? -EIO : 0; 445 } 446 447 static int async_io(struct dm_io_client *client, unsigned int num_regions, 448 struct dm_io_region *where, int op, int op_flags, 449 struct dpages *dp, io_notify_fn fn, void *context) 450 { 451 struct io *io; 452 453 if (num_regions > 1 && !op_is_write(op)) { 454 WARN_ON(1); 455 fn(1, context); 456 return -EIO; 457 } 458 459 io = mempool_alloc(&client->pool, GFP_NOIO); 460 io->error_bits = 0; 461 atomic_set(&io->count, 1); /* see dispatch_io() */ 462 io->client = client; 463 io->callback = fn; 464 io->context = context; 465 466 io->vma_invalidate_address = dp->vma_invalidate_address; 467 io->vma_invalidate_size = dp->vma_invalidate_size; 468 469 dispatch_io(op, op_flags, num_regions, where, dp, io, 0); 470 return 0; 471 } 472 473 static int dp_init(struct dm_io_request *io_req, struct dpages *dp, 474 unsigned long size) 475 { 476 /* Set up dpages based on memory type */ 477 478 dp->vma_invalidate_address = NULL; 479 dp->vma_invalidate_size = 0; 480 481 switch (io_req->mem.type) { 482 case DM_IO_PAGE_LIST: 483 list_dp_init(dp, io_req->mem.ptr.pl, io_req->mem.offset); 484 break; 485 486 case DM_IO_BIO: 487 bio_dp_init(dp, io_req->mem.ptr.bio); 488 break; 489 490 case DM_IO_VMA: 491 flush_kernel_vmap_range(io_req->mem.ptr.vma, size); 492 if (io_req->bi_op == REQ_OP_READ) { 493 dp->vma_invalidate_address = io_req->mem.ptr.vma; 494 dp->vma_invalidate_size = size; 495 } 496 vm_dp_init(dp, io_req->mem.ptr.vma); 497 break; 498 499 case DM_IO_KMEM: 500 km_dp_init(dp, io_req->mem.ptr.addr); 501 break; 502 503 default: 504 return -EINVAL; 505 } 506 507 return 0; 508 } 509 510 int dm_io(struct dm_io_request *io_req, unsigned num_regions, 511 struct dm_io_region *where, unsigned long *sync_error_bits) 512 { 513 int r; 514 struct dpages dp; 515 516 r = dp_init(io_req, &dp, (unsigned long)where->count << SECTOR_SHIFT); 517 if (r) 518 return r; 519 520 if (!io_req->notify.fn) 521 return sync_io(io_req->client, num_regions, where, 522 io_req->bi_op, io_req->bi_op_flags, &dp, 523 sync_error_bits); 524 525 return async_io(io_req->client, num_regions, where, io_req->bi_op, 526 io_req->bi_op_flags, &dp, io_req->notify.fn, 527 io_req->notify.context); 528 } 529 EXPORT_SYMBOL(dm_io); 530 531 int __init dm_io_init(void) 532 { 533 _dm_io_cache = KMEM_CACHE(io, 0); 534 if (!_dm_io_cache) 535 return -ENOMEM; 536 537 return 0; 538 } 539 540 void dm_io_exit(void) 541 { 542 kmem_cache_destroy(_dm_io_cache); 543 _dm_io_cache = NULL; 544 } 545