1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2003 Sistina Software 4 * Copyright (C) 2006 Red Hat GmbH 5 * 6 * This file is released under the GPL. 7 */ 8 9 #include "dm-core.h" 10 11 #include <linux/device-mapper.h> 12 13 #include <linux/bio.h> 14 #include <linux/completion.h> 15 #include <linux/mempool.h> 16 #include <linux/module.h> 17 #include <linux/sched.h> 18 #include <linux/slab.h> 19 #include <linux/dm-io.h> 20 21 #define DM_MSG_PREFIX "io" 22 23 #define DM_IO_MAX_REGIONS BITS_PER_LONG 24 25 struct dm_io_client { 26 mempool_t pool; 27 struct bio_set bios; 28 }; 29 30 /* 31 * Aligning 'struct io' reduces the number of bits required to store 32 * its address. Refer to store_io_and_region_in_bio() below. 33 */ 34 struct io { 35 unsigned long error_bits; 36 atomic_t count; 37 struct dm_io_client *client; 38 io_notify_fn callback; 39 void *context; 40 void *vma_invalidate_address; 41 unsigned long vma_invalidate_size; 42 } __aligned(DM_IO_MAX_REGIONS); 43 44 static struct kmem_cache *_dm_io_cache; 45 46 /* 47 * Create a client with mempool and bioset. 48 */ 49 struct dm_io_client *dm_io_client_create(void) 50 { 51 struct dm_io_client *client; 52 unsigned int min_ios = dm_get_reserved_bio_based_ios(); 53 int ret; 54 55 client = kzalloc(sizeof(*client), GFP_KERNEL); 56 if (!client) 57 return ERR_PTR(-ENOMEM); 58 59 ret = mempool_init_slab_pool(&client->pool, min_ios, _dm_io_cache); 60 if (ret) 61 goto bad; 62 63 ret = bioset_init(&client->bios, min_ios, 0, BIOSET_NEED_BVECS); 64 if (ret) 65 goto bad; 66 67 return client; 68 69 bad: 70 mempool_exit(&client->pool); 71 kfree(client); 72 return ERR_PTR(ret); 73 } 74 EXPORT_SYMBOL(dm_io_client_create); 75 76 void dm_io_client_destroy(struct dm_io_client *client) 77 { 78 mempool_exit(&client->pool); 79 bioset_exit(&client->bios); 80 kfree(client); 81 } 82 EXPORT_SYMBOL(dm_io_client_destroy); 83 84 /* 85 *------------------------------------------------------------------- 86 * We need to keep track of which region a bio is doing io for. 87 * To avoid a memory allocation to store just 5 or 6 bits, we 88 * ensure the 'struct io' pointer is aligned so enough low bits are 89 * always zero and then combine it with the region number directly in 90 * bi_private. 91 *------------------------------------------------------------------- 92 */ 93 static void store_io_and_region_in_bio(struct bio *bio, struct io *io, 94 unsigned int region) 95 { 96 if (unlikely(!IS_ALIGNED((unsigned long)io, DM_IO_MAX_REGIONS))) { 97 DMCRIT("Unaligned struct io pointer %p", io); 98 BUG(); 99 } 100 101 bio->bi_private = (void *)((unsigned long)io | region); 102 } 103 104 static void retrieve_io_and_region_from_bio(struct bio *bio, struct io **io, 105 unsigned int *region) 106 { 107 unsigned long val = (unsigned long)bio->bi_private; 108 109 *io = (void *)(val & -(unsigned long)DM_IO_MAX_REGIONS); 110 *region = val & (DM_IO_MAX_REGIONS - 1); 111 } 112 113 /* 114 *-------------------------------------------------------------- 115 * We need an io object to keep track of the number of bios that 116 * have been dispatched for a particular io. 117 *-------------------------------------------------------------- 118 */ 119 static void complete_io(struct io *io) 120 { 121 unsigned long error_bits = io->error_bits; 122 io_notify_fn fn = io->callback; 123 void *context = io->context; 124 125 if (io->vma_invalidate_size) 126 invalidate_kernel_vmap_range(io->vma_invalidate_address, 127 io->vma_invalidate_size); 128 129 mempool_free(io, &io->client->pool); 130 fn(error_bits, context); 131 } 132 133 static void dec_count(struct io *io, unsigned int region, blk_status_t error) 134 { 135 if (error) 136 set_bit(region, &io->error_bits); 137 138 if (atomic_dec_and_test(&io->count)) 139 complete_io(io); 140 } 141 142 static void endio(struct bio *bio) 143 { 144 struct io *io; 145 unsigned int region; 146 blk_status_t error; 147 148 if (bio->bi_status && bio_data_dir(bio) == READ) 149 zero_fill_bio(bio); 150 151 /* 152 * The bio destructor in bio_put() may use the io object. 153 */ 154 retrieve_io_and_region_from_bio(bio, &io, ®ion); 155 156 error = bio->bi_status; 157 bio_put(bio); 158 159 dec_count(io, region, error); 160 } 161 162 /* 163 *-------------------------------------------------------------- 164 * These little objects provide an abstraction for getting a new 165 * destination page for io. 166 *-------------------------------------------------------------- 167 */ 168 struct dpages { 169 void (*get_page)(struct dpages *dp, 170 struct page **p, unsigned long *len, unsigned int *offset); 171 void (*next_page)(struct dpages *dp); 172 173 union { 174 unsigned int context_u; 175 struct bvec_iter context_bi; 176 }; 177 void *context_ptr; 178 179 void *vma_invalidate_address; 180 unsigned long vma_invalidate_size; 181 }; 182 183 /* 184 * Functions for getting the pages from a list. 185 */ 186 static void list_get_page(struct dpages *dp, 187 struct page **p, unsigned long *len, unsigned int *offset) 188 { 189 unsigned int o = dp->context_u; 190 struct page_list *pl = (struct page_list *) dp->context_ptr; 191 192 *p = pl->page; 193 *len = PAGE_SIZE - o; 194 *offset = o; 195 } 196 197 static void list_next_page(struct dpages *dp) 198 { 199 struct page_list *pl = (struct page_list *) dp->context_ptr; 200 201 dp->context_ptr = pl->next; 202 dp->context_u = 0; 203 } 204 205 static void list_dp_init(struct dpages *dp, struct page_list *pl, unsigned int offset) 206 { 207 dp->get_page = list_get_page; 208 dp->next_page = list_next_page; 209 dp->context_u = offset; 210 dp->context_ptr = pl; 211 } 212 213 /* 214 * Functions for getting the pages from a bvec. 215 */ 216 static void bio_get_page(struct dpages *dp, struct page **p, 217 unsigned long *len, unsigned int *offset) 218 { 219 struct bio_vec bvec = bvec_iter_bvec((struct bio_vec *)dp->context_ptr, 220 dp->context_bi); 221 222 *p = bvec.bv_page; 223 *len = bvec.bv_len; 224 *offset = bvec.bv_offset; 225 226 /* avoid figuring it out again in bio_next_page() */ 227 dp->context_bi.bi_sector = (sector_t)bvec.bv_len; 228 } 229 230 static void bio_next_page(struct dpages *dp) 231 { 232 unsigned int len = (unsigned int)dp->context_bi.bi_sector; 233 234 bvec_iter_advance((struct bio_vec *)dp->context_ptr, 235 &dp->context_bi, len); 236 } 237 238 static void bio_dp_init(struct dpages *dp, struct bio *bio) 239 { 240 dp->get_page = bio_get_page; 241 dp->next_page = bio_next_page; 242 243 /* 244 * We just use bvec iterator to retrieve pages, so it is ok to 245 * access the bvec table directly here 246 */ 247 dp->context_ptr = bio->bi_io_vec; 248 dp->context_bi = bio->bi_iter; 249 } 250 251 /* 252 * Functions for getting the pages from a VMA. 253 */ 254 static void vm_get_page(struct dpages *dp, 255 struct page **p, unsigned long *len, unsigned int *offset) 256 { 257 *p = vmalloc_to_page(dp->context_ptr); 258 *offset = dp->context_u; 259 *len = PAGE_SIZE - dp->context_u; 260 } 261 262 static void vm_next_page(struct dpages *dp) 263 { 264 dp->context_ptr += PAGE_SIZE - dp->context_u; 265 dp->context_u = 0; 266 } 267 268 static void vm_dp_init(struct dpages *dp, void *data) 269 { 270 dp->get_page = vm_get_page; 271 dp->next_page = vm_next_page; 272 dp->context_u = offset_in_page(data); 273 dp->context_ptr = data; 274 } 275 276 /* 277 * Functions for getting the pages from kernel memory. 278 */ 279 static void km_get_page(struct dpages *dp, struct page **p, unsigned long *len, 280 unsigned int *offset) 281 { 282 *p = virt_to_page(dp->context_ptr); 283 *offset = dp->context_u; 284 *len = PAGE_SIZE - dp->context_u; 285 } 286 287 static void km_next_page(struct dpages *dp) 288 { 289 dp->context_ptr += PAGE_SIZE - dp->context_u; 290 dp->context_u = 0; 291 } 292 293 static void km_dp_init(struct dpages *dp, void *data) 294 { 295 dp->get_page = km_get_page; 296 dp->next_page = km_next_page; 297 dp->context_u = offset_in_page(data); 298 dp->context_ptr = data; 299 } 300 301 /* 302 *--------------------------------------------------------------- 303 * IO routines that accept a list of pages. 304 *--------------------------------------------------------------- 305 */ 306 static void do_region(const blk_opf_t opf, unsigned int region, 307 struct dm_io_region *where, struct dpages *dp, 308 struct io *io) 309 { 310 struct bio *bio; 311 struct page *page; 312 unsigned long len; 313 unsigned int offset; 314 unsigned int num_bvecs; 315 sector_t remaining = where->count; 316 struct request_queue *q = bdev_get_queue(where->bdev); 317 sector_t num_sectors; 318 unsigned int special_cmd_max_sectors; 319 const enum req_op op = opf & REQ_OP_MASK; 320 321 /* 322 * Reject unsupported discard and write same requests. 323 */ 324 if (op == REQ_OP_DISCARD) 325 special_cmd_max_sectors = bdev_max_discard_sectors(where->bdev); 326 else if (op == REQ_OP_WRITE_ZEROES) 327 special_cmd_max_sectors = q->limits.max_write_zeroes_sectors; 328 if ((op == REQ_OP_DISCARD || op == REQ_OP_WRITE_ZEROES) && 329 special_cmd_max_sectors == 0) { 330 atomic_inc(&io->count); 331 dec_count(io, region, BLK_STS_NOTSUPP); 332 return; 333 } 334 335 /* 336 * where->count may be zero if op holds a flush and we need to 337 * send a zero-sized flush. 338 */ 339 do { 340 /* 341 * Allocate a suitably sized-bio. 342 */ 343 switch (op) { 344 case REQ_OP_DISCARD: 345 case REQ_OP_WRITE_ZEROES: 346 num_bvecs = 0; 347 break; 348 default: 349 num_bvecs = bio_max_segs(dm_sector_div_up(remaining, 350 (PAGE_SIZE >> SECTOR_SHIFT))); 351 } 352 353 bio = bio_alloc_bioset(where->bdev, num_bvecs, opf, GFP_NOIO, 354 &io->client->bios); 355 bio->bi_iter.bi_sector = where->sector + (where->count - remaining); 356 bio->bi_end_io = endio; 357 store_io_and_region_in_bio(bio, io, region); 358 359 if (op == REQ_OP_DISCARD || op == REQ_OP_WRITE_ZEROES) { 360 num_sectors = min_t(sector_t, special_cmd_max_sectors, remaining); 361 bio->bi_iter.bi_size = num_sectors << SECTOR_SHIFT; 362 remaining -= num_sectors; 363 } else { 364 while (remaining) { 365 /* 366 * Try and add as many pages as possible. 367 */ 368 dp->get_page(dp, &page, &len, &offset); 369 len = min(len, to_bytes(remaining)); 370 if (!bio_add_page(bio, page, len, offset)) 371 break; 372 373 offset = 0; 374 remaining -= to_sector(len); 375 dp->next_page(dp); 376 } 377 } 378 379 atomic_inc(&io->count); 380 submit_bio(bio); 381 } while (remaining); 382 } 383 384 static void dispatch_io(blk_opf_t opf, unsigned int num_regions, 385 struct dm_io_region *where, struct dpages *dp, 386 struct io *io, int sync) 387 { 388 int i; 389 struct dpages old_pages = *dp; 390 391 BUG_ON(num_regions > DM_IO_MAX_REGIONS); 392 393 if (sync) 394 opf |= REQ_SYNC; 395 396 /* 397 * For multiple regions we need to be careful to rewind 398 * the dp object for each call to do_region. 399 */ 400 for (i = 0; i < num_regions; i++) { 401 *dp = old_pages; 402 if (where[i].count || (opf & REQ_PREFLUSH)) 403 do_region(opf, i, where + i, dp, io); 404 } 405 406 /* 407 * Drop the extra reference that we were holding to avoid 408 * the io being completed too early. 409 */ 410 dec_count(io, 0, 0); 411 } 412 413 struct sync_io { 414 unsigned long error_bits; 415 struct completion wait; 416 }; 417 418 static void sync_io_complete(unsigned long error, void *context) 419 { 420 struct sync_io *sio = context; 421 422 sio->error_bits = error; 423 complete(&sio->wait); 424 } 425 426 static int sync_io(struct dm_io_client *client, unsigned int num_regions, 427 struct dm_io_region *where, blk_opf_t opf, struct dpages *dp, 428 unsigned long *error_bits) 429 { 430 struct io *io; 431 struct sync_io sio; 432 433 if (num_regions > 1 && !op_is_write(opf)) { 434 WARN_ON(1); 435 return -EIO; 436 } 437 438 init_completion(&sio.wait); 439 440 io = mempool_alloc(&client->pool, GFP_NOIO); 441 io->error_bits = 0; 442 atomic_set(&io->count, 1); /* see dispatch_io() */ 443 io->client = client; 444 io->callback = sync_io_complete; 445 io->context = &sio; 446 447 io->vma_invalidate_address = dp->vma_invalidate_address; 448 io->vma_invalidate_size = dp->vma_invalidate_size; 449 450 dispatch_io(opf, num_regions, where, dp, io, 1); 451 452 wait_for_completion_io(&sio.wait); 453 454 if (error_bits) 455 *error_bits = sio.error_bits; 456 457 return sio.error_bits ? -EIO : 0; 458 } 459 460 static int async_io(struct dm_io_client *client, unsigned int num_regions, 461 struct dm_io_region *where, blk_opf_t opf, 462 struct dpages *dp, io_notify_fn fn, void *context) 463 { 464 struct io *io; 465 466 if (num_regions > 1 && !op_is_write(opf)) { 467 WARN_ON(1); 468 fn(1, context); 469 return -EIO; 470 } 471 472 io = mempool_alloc(&client->pool, GFP_NOIO); 473 io->error_bits = 0; 474 atomic_set(&io->count, 1); /* see dispatch_io() */ 475 io->client = client; 476 io->callback = fn; 477 io->context = context; 478 479 io->vma_invalidate_address = dp->vma_invalidate_address; 480 io->vma_invalidate_size = dp->vma_invalidate_size; 481 482 dispatch_io(opf, num_regions, where, dp, io, 0); 483 return 0; 484 } 485 486 static int dp_init(struct dm_io_request *io_req, struct dpages *dp, 487 unsigned long size) 488 { 489 /* Set up dpages based on memory type */ 490 491 dp->vma_invalidate_address = NULL; 492 dp->vma_invalidate_size = 0; 493 494 switch (io_req->mem.type) { 495 case DM_IO_PAGE_LIST: 496 list_dp_init(dp, io_req->mem.ptr.pl, io_req->mem.offset); 497 break; 498 499 case DM_IO_BIO: 500 bio_dp_init(dp, io_req->mem.ptr.bio); 501 break; 502 503 case DM_IO_VMA: 504 flush_kernel_vmap_range(io_req->mem.ptr.vma, size); 505 if ((io_req->bi_opf & REQ_OP_MASK) == REQ_OP_READ) { 506 dp->vma_invalidate_address = io_req->mem.ptr.vma; 507 dp->vma_invalidate_size = size; 508 } 509 vm_dp_init(dp, io_req->mem.ptr.vma); 510 break; 511 512 case DM_IO_KMEM: 513 km_dp_init(dp, io_req->mem.ptr.addr); 514 break; 515 516 default: 517 return -EINVAL; 518 } 519 520 return 0; 521 } 522 523 int dm_io(struct dm_io_request *io_req, unsigned int num_regions, 524 struct dm_io_region *where, unsigned long *sync_error_bits) 525 { 526 int r; 527 struct dpages dp; 528 529 r = dp_init(io_req, &dp, (unsigned long)where->count << SECTOR_SHIFT); 530 if (r) 531 return r; 532 533 if (!io_req->notify.fn) 534 return sync_io(io_req->client, num_regions, where, 535 io_req->bi_opf, &dp, sync_error_bits); 536 537 return async_io(io_req->client, num_regions, where, 538 io_req->bi_opf, &dp, io_req->notify.fn, 539 io_req->notify.context); 540 } 541 EXPORT_SYMBOL(dm_io); 542 543 int __init dm_io_init(void) 544 { 545 _dm_io_cache = KMEM_CACHE(io, 0); 546 if (!_dm_io_cache) 547 return -ENOMEM; 548 549 return 0; 550 } 551 552 void dm_io_exit(void) 553 { 554 kmem_cache_destroy(_dm_io_cache); 555 _dm_io_cache = NULL; 556 } 557