1 /* 2 * Copyright (C) 2001 Jens Axboe <axboe@kernel.dk> 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License version 2 as 6 * published by the Free Software Foundation. 7 * 8 * This program is distributed in the hope that it will be useful, 9 * but WITHOUT ANY WARRANTY; without even the implied warranty of 10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 11 * GNU General Public License for more details. 12 * 13 * You should have received a copy of the GNU General Public Licens 14 * along with this program; if not, write to the Free Software 15 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111- 16 * 17 */ 18 #include <linux/mm.h> 19 #include <linux/swap.h> 20 #include <linux/bio.h> 21 #include <linux/blkdev.h> 22 #include <linux/uio.h> 23 #include <linux/iocontext.h> 24 #include <linux/slab.h> 25 #include <linux/init.h> 26 #include <linux/kernel.h> 27 #include <linux/export.h> 28 #include <linux/mempool.h> 29 #include <linux/workqueue.h> 30 #include <linux/cgroup.h> 31 #include <linux/blk-cgroup.h> 32 33 #include <trace/events/block.h> 34 #include "blk.h" 35 #include "blk-rq-qos.h" 36 37 /* 38 * Test patch to inline a certain number of bi_io_vec's inside the bio 39 * itself, to shrink a bio data allocation from two mempool calls to one 40 */ 41 #define BIO_INLINE_VECS 4 42 43 /* 44 * if you change this list, also change bvec_alloc or things will 45 * break badly! cannot be bigger than what you can fit into an 46 * unsigned short 47 */ 48 #define BV(x, n) { .nr_vecs = x, .name = "biovec-"#n } 49 static struct biovec_slab bvec_slabs[BVEC_POOL_NR] __read_mostly = { 50 BV(1, 1), BV(4, 4), BV(16, 16), BV(64, 64), BV(128, 128), BV(BIO_MAX_PAGES, max), 51 }; 52 #undef BV 53 54 /* 55 * fs_bio_set is the bio_set containing bio and iovec memory pools used by 56 * IO code that does not need private memory pools. 57 */ 58 struct bio_set fs_bio_set; 59 EXPORT_SYMBOL(fs_bio_set); 60 61 /* 62 * Our slab pool management 63 */ 64 struct bio_slab { 65 struct kmem_cache *slab; 66 unsigned int slab_ref; 67 unsigned int slab_size; 68 char name[8]; 69 }; 70 static DEFINE_MUTEX(bio_slab_lock); 71 static struct bio_slab *bio_slabs; 72 static unsigned int bio_slab_nr, bio_slab_max; 73 74 static struct kmem_cache *bio_find_or_create_slab(unsigned int extra_size) 75 { 76 unsigned int sz = sizeof(struct bio) + extra_size; 77 struct kmem_cache *slab = NULL; 78 struct bio_slab *bslab, *new_bio_slabs; 79 unsigned int new_bio_slab_max; 80 unsigned int i, entry = -1; 81 82 mutex_lock(&bio_slab_lock); 83 84 i = 0; 85 while (i < bio_slab_nr) { 86 bslab = &bio_slabs[i]; 87 88 if (!bslab->slab && entry == -1) 89 entry = i; 90 else if (bslab->slab_size == sz) { 91 slab = bslab->slab; 92 bslab->slab_ref++; 93 break; 94 } 95 i++; 96 } 97 98 if (slab) 99 goto out_unlock; 100 101 if (bio_slab_nr == bio_slab_max && entry == -1) { 102 new_bio_slab_max = bio_slab_max << 1; 103 new_bio_slabs = krealloc(bio_slabs, 104 new_bio_slab_max * sizeof(struct bio_slab), 105 GFP_KERNEL); 106 if (!new_bio_slabs) 107 goto out_unlock; 108 bio_slab_max = new_bio_slab_max; 109 bio_slabs = new_bio_slabs; 110 } 111 if (entry == -1) 112 entry = bio_slab_nr++; 113 114 bslab = &bio_slabs[entry]; 115 116 snprintf(bslab->name, sizeof(bslab->name), "bio-%d", entry); 117 slab = kmem_cache_create(bslab->name, sz, ARCH_KMALLOC_MINALIGN, 118 SLAB_HWCACHE_ALIGN, NULL); 119 if (!slab) 120 goto out_unlock; 121 122 bslab->slab = slab; 123 bslab->slab_ref = 1; 124 bslab->slab_size = sz; 125 out_unlock: 126 mutex_unlock(&bio_slab_lock); 127 return slab; 128 } 129 130 static void bio_put_slab(struct bio_set *bs) 131 { 132 struct bio_slab *bslab = NULL; 133 unsigned int i; 134 135 mutex_lock(&bio_slab_lock); 136 137 for (i = 0; i < bio_slab_nr; i++) { 138 if (bs->bio_slab == bio_slabs[i].slab) { 139 bslab = &bio_slabs[i]; 140 break; 141 } 142 } 143 144 if (WARN(!bslab, KERN_ERR "bio: unable to find slab!\n")) 145 goto out; 146 147 WARN_ON(!bslab->slab_ref); 148 149 if (--bslab->slab_ref) 150 goto out; 151 152 kmem_cache_destroy(bslab->slab); 153 bslab->slab = NULL; 154 155 out: 156 mutex_unlock(&bio_slab_lock); 157 } 158 159 unsigned int bvec_nr_vecs(unsigned short idx) 160 { 161 return bvec_slabs[--idx].nr_vecs; 162 } 163 164 void bvec_free(mempool_t *pool, struct bio_vec *bv, unsigned int idx) 165 { 166 if (!idx) 167 return; 168 idx--; 169 170 BIO_BUG_ON(idx >= BVEC_POOL_NR); 171 172 if (idx == BVEC_POOL_MAX) { 173 mempool_free(bv, pool); 174 } else { 175 struct biovec_slab *bvs = bvec_slabs + idx; 176 177 kmem_cache_free(bvs->slab, bv); 178 } 179 } 180 181 struct bio_vec *bvec_alloc(gfp_t gfp_mask, int nr, unsigned long *idx, 182 mempool_t *pool) 183 { 184 struct bio_vec *bvl; 185 186 /* 187 * see comment near bvec_array define! 188 */ 189 switch (nr) { 190 case 1: 191 *idx = 0; 192 break; 193 case 2 ... 4: 194 *idx = 1; 195 break; 196 case 5 ... 16: 197 *idx = 2; 198 break; 199 case 17 ... 64: 200 *idx = 3; 201 break; 202 case 65 ... 128: 203 *idx = 4; 204 break; 205 case 129 ... BIO_MAX_PAGES: 206 *idx = 5; 207 break; 208 default: 209 return NULL; 210 } 211 212 /* 213 * idx now points to the pool we want to allocate from. only the 214 * 1-vec entry pool is mempool backed. 215 */ 216 if (*idx == BVEC_POOL_MAX) { 217 fallback: 218 bvl = mempool_alloc(pool, gfp_mask); 219 } else { 220 struct biovec_slab *bvs = bvec_slabs + *idx; 221 gfp_t __gfp_mask = gfp_mask & ~(__GFP_DIRECT_RECLAIM | __GFP_IO); 222 223 /* 224 * Make this allocation restricted and don't dump info on 225 * allocation failures, since we'll fallback to the mempool 226 * in case of failure. 227 */ 228 __gfp_mask |= __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN; 229 230 /* 231 * Try a slab allocation. If this fails and __GFP_DIRECT_RECLAIM 232 * is set, retry with the 1-entry mempool 233 */ 234 bvl = kmem_cache_alloc(bvs->slab, __gfp_mask); 235 if (unlikely(!bvl && (gfp_mask & __GFP_DIRECT_RECLAIM))) { 236 *idx = BVEC_POOL_MAX; 237 goto fallback; 238 } 239 } 240 241 (*idx)++; 242 return bvl; 243 } 244 245 void bio_uninit(struct bio *bio) 246 { 247 bio_disassociate_task(bio); 248 } 249 EXPORT_SYMBOL(bio_uninit); 250 251 static void bio_free(struct bio *bio) 252 { 253 struct bio_set *bs = bio->bi_pool; 254 void *p; 255 256 bio_uninit(bio); 257 258 if (bs) { 259 bvec_free(&bs->bvec_pool, bio->bi_io_vec, BVEC_POOL_IDX(bio)); 260 261 /* 262 * If we have front padding, adjust the bio pointer before freeing 263 */ 264 p = bio; 265 p -= bs->front_pad; 266 267 mempool_free(p, &bs->bio_pool); 268 } else { 269 /* Bio was allocated by bio_kmalloc() */ 270 kfree(bio); 271 } 272 } 273 274 /* 275 * Users of this function have their own bio allocation. Subsequently, 276 * they must remember to pair any call to bio_init() with bio_uninit() 277 * when IO has completed, or when the bio is released. 278 */ 279 void bio_init(struct bio *bio, struct bio_vec *table, 280 unsigned short max_vecs) 281 { 282 memset(bio, 0, sizeof(*bio)); 283 atomic_set(&bio->__bi_remaining, 1); 284 atomic_set(&bio->__bi_cnt, 1); 285 286 bio->bi_io_vec = table; 287 bio->bi_max_vecs = max_vecs; 288 } 289 EXPORT_SYMBOL(bio_init); 290 291 /** 292 * bio_reset - reinitialize a bio 293 * @bio: bio to reset 294 * 295 * Description: 296 * After calling bio_reset(), @bio will be in the same state as a freshly 297 * allocated bio returned bio bio_alloc_bioset() - the only fields that are 298 * preserved are the ones that are initialized by bio_alloc_bioset(). See 299 * comment in struct bio. 300 */ 301 void bio_reset(struct bio *bio) 302 { 303 unsigned long flags = bio->bi_flags & (~0UL << BIO_RESET_BITS); 304 305 bio_uninit(bio); 306 307 memset(bio, 0, BIO_RESET_BYTES); 308 bio->bi_flags = flags; 309 atomic_set(&bio->__bi_remaining, 1); 310 } 311 EXPORT_SYMBOL(bio_reset); 312 313 static struct bio *__bio_chain_endio(struct bio *bio) 314 { 315 struct bio *parent = bio->bi_private; 316 317 if (!parent->bi_status) 318 parent->bi_status = bio->bi_status; 319 bio_put(bio); 320 return parent; 321 } 322 323 static void bio_chain_endio(struct bio *bio) 324 { 325 bio_endio(__bio_chain_endio(bio)); 326 } 327 328 /** 329 * bio_chain - chain bio completions 330 * @bio: the target bio 331 * @parent: the @bio's parent bio 332 * 333 * The caller won't have a bi_end_io called when @bio completes - instead, 334 * @parent's bi_end_io won't be called until both @parent and @bio have 335 * completed; the chained bio will also be freed when it completes. 336 * 337 * The caller must not set bi_private or bi_end_io in @bio. 338 */ 339 void bio_chain(struct bio *bio, struct bio *parent) 340 { 341 BUG_ON(bio->bi_private || bio->bi_end_io); 342 343 bio->bi_private = parent; 344 bio->bi_end_io = bio_chain_endio; 345 bio_inc_remaining(parent); 346 } 347 EXPORT_SYMBOL(bio_chain); 348 349 static void bio_alloc_rescue(struct work_struct *work) 350 { 351 struct bio_set *bs = container_of(work, struct bio_set, rescue_work); 352 struct bio *bio; 353 354 while (1) { 355 spin_lock(&bs->rescue_lock); 356 bio = bio_list_pop(&bs->rescue_list); 357 spin_unlock(&bs->rescue_lock); 358 359 if (!bio) 360 break; 361 362 generic_make_request(bio); 363 } 364 } 365 366 static void punt_bios_to_rescuer(struct bio_set *bs) 367 { 368 struct bio_list punt, nopunt; 369 struct bio *bio; 370 371 if (WARN_ON_ONCE(!bs->rescue_workqueue)) 372 return; 373 /* 374 * In order to guarantee forward progress we must punt only bios that 375 * were allocated from this bio_set; otherwise, if there was a bio on 376 * there for a stacking driver higher up in the stack, processing it 377 * could require allocating bios from this bio_set, and doing that from 378 * our own rescuer would be bad. 379 * 380 * Since bio lists are singly linked, pop them all instead of trying to 381 * remove from the middle of the list: 382 */ 383 384 bio_list_init(&punt); 385 bio_list_init(&nopunt); 386 387 while ((bio = bio_list_pop(¤t->bio_list[0]))) 388 bio_list_add(bio->bi_pool == bs ? &punt : &nopunt, bio); 389 current->bio_list[0] = nopunt; 390 391 bio_list_init(&nopunt); 392 while ((bio = bio_list_pop(¤t->bio_list[1]))) 393 bio_list_add(bio->bi_pool == bs ? &punt : &nopunt, bio); 394 current->bio_list[1] = nopunt; 395 396 spin_lock(&bs->rescue_lock); 397 bio_list_merge(&bs->rescue_list, &punt); 398 spin_unlock(&bs->rescue_lock); 399 400 queue_work(bs->rescue_workqueue, &bs->rescue_work); 401 } 402 403 /** 404 * bio_alloc_bioset - allocate a bio for I/O 405 * @gfp_mask: the GFP_* mask given to the slab allocator 406 * @nr_iovecs: number of iovecs to pre-allocate 407 * @bs: the bio_set to allocate from. 408 * 409 * Description: 410 * If @bs is NULL, uses kmalloc() to allocate the bio; else the allocation is 411 * backed by the @bs's mempool. 412 * 413 * When @bs is not NULL, if %__GFP_DIRECT_RECLAIM is set then bio_alloc will 414 * always be able to allocate a bio. This is due to the mempool guarantees. 415 * To make this work, callers must never allocate more than 1 bio at a time 416 * from this pool. Callers that need to allocate more than 1 bio must always 417 * submit the previously allocated bio for IO before attempting to allocate 418 * a new one. Failure to do so can cause deadlocks under memory pressure. 419 * 420 * Note that when running under generic_make_request() (i.e. any block 421 * driver), bios are not submitted until after you return - see the code in 422 * generic_make_request() that converts recursion into iteration, to prevent 423 * stack overflows. 424 * 425 * This would normally mean allocating multiple bios under 426 * generic_make_request() would be susceptible to deadlocks, but we have 427 * deadlock avoidance code that resubmits any blocked bios from a rescuer 428 * thread. 429 * 430 * However, we do not guarantee forward progress for allocations from other 431 * mempools. Doing multiple allocations from the same mempool under 432 * generic_make_request() should be avoided - instead, use bio_set's front_pad 433 * for per bio allocations. 434 * 435 * RETURNS: 436 * Pointer to new bio on success, NULL on failure. 437 */ 438 struct bio *bio_alloc_bioset(gfp_t gfp_mask, unsigned int nr_iovecs, 439 struct bio_set *bs) 440 { 441 gfp_t saved_gfp = gfp_mask; 442 unsigned front_pad; 443 unsigned inline_vecs; 444 struct bio_vec *bvl = NULL; 445 struct bio *bio; 446 void *p; 447 448 if (!bs) { 449 if (nr_iovecs > UIO_MAXIOV) 450 return NULL; 451 452 p = kmalloc(sizeof(struct bio) + 453 nr_iovecs * sizeof(struct bio_vec), 454 gfp_mask); 455 front_pad = 0; 456 inline_vecs = nr_iovecs; 457 } else { 458 /* should not use nobvec bioset for nr_iovecs > 0 */ 459 if (WARN_ON_ONCE(!mempool_initialized(&bs->bvec_pool) && 460 nr_iovecs > 0)) 461 return NULL; 462 /* 463 * generic_make_request() converts recursion to iteration; this 464 * means if we're running beneath it, any bios we allocate and 465 * submit will not be submitted (and thus freed) until after we 466 * return. 467 * 468 * This exposes us to a potential deadlock if we allocate 469 * multiple bios from the same bio_set() while running 470 * underneath generic_make_request(). If we were to allocate 471 * multiple bios (say a stacking block driver that was splitting 472 * bios), we would deadlock if we exhausted the mempool's 473 * reserve. 474 * 475 * We solve this, and guarantee forward progress, with a rescuer 476 * workqueue per bio_set. If we go to allocate and there are 477 * bios on current->bio_list, we first try the allocation 478 * without __GFP_DIRECT_RECLAIM; if that fails, we punt those 479 * bios we would be blocking to the rescuer workqueue before 480 * we retry with the original gfp_flags. 481 */ 482 483 if (current->bio_list && 484 (!bio_list_empty(¤t->bio_list[0]) || 485 !bio_list_empty(¤t->bio_list[1])) && 486 bs->rescue_workqueue) 487 gfp_mask &= ~__GFP_DIRECT_RECLAIM; 488 489 p = mempool_alloc(&bs->bio_pool, gfp_mask); 490 if (!p && gfp_mask != saved_gfp) { 491 punt_bios_to_rescuer(bs); 492 gfp_mask = saved_gfp; 493 p = mempool_alloc(&bs->bio_pool, gfp_mask); 494 } 495 496 front_pad = bs->front_pad; 497 inline_vecs = BIO_INLINE_VECS; 498 } 499 500 if (unlikely(!p)) 501 return NULL; 502 503 bio = p + front_pad; 504 bio_init(bio, NULL, 0); 505 506 if (nr_iovecs > inline_vecs) { 507 unsigned long idx = 0; 508 509 bvl = bvec_alloc(gfp_mask, nr_iovecs, &idx, &bs->bvec_pool); 510 if (!bvl && gfp_mask != saved_gfp) { 511 punt_bios_to_rescuer(bs); 512 gfp_mask = saved_gfp; 513 bvl = bvec_alloc(gfp_mask, nr_iovecs, &idx, &bs->bvec_pool); 514 } 515 516 if (unlikely(!bvl)) 517 goto err_free; 518 519 bio->bi_flags |= idx << BVEC_POOL_OFFSET; 520 } else if (nr_iovecs) { 521 bvl = bio->bi_inline_vecs; 522 } 523 524 bio->bi_pool = bs; 525 bio->bi_max_vecs = nr_iovecs; 526 bio->bi_io_vec = bvl; 527 return bio; 528 529 err_free: 530 mempool_free(p, &bs->bio_pool); 531 return NULL; 532 } 533 EXPORT_SYMBOL(bio_alloc_bioset); 534 535 void zero_fill_bio_iter(struct bio *bio, struct bvec_iter start) 536 { 537 unsigned long flags; 538 struct bio_vec bv; 539 struct bvec_iter iter; 540 541 __bio_for_each_segment(bv, bio, iter, start) { 542 char *data = bvec_kmap_irq(&bv, &flags); 543 memset(data, 0, bv.bv_len); 544 flush_dcache_page(bv.bv_page); 545 bvec_kunmap_irq(data, &flags); 546 } 547 } 548 EXPORT_SYMBOL(zero_fill_bio_iter); 549 550 /** 551 * bio_put - release a reference to a bio 552 * @bio: bio to release reference to 553 * 554 * Description: 555 * Put a reference to a &struct bio, either one you have gotten with 556 * bio_alloc, bio_get or bio_clone_*. The last put of a bio will free it. 557 **/ 558 void bio_put(struct bio *bio) 559 { 560 if (!bio_flagged(bio, BIO_REFFED)) 561 bio_free(bio); 562 else { 563 BIO_BUG_ON(!atomic_read(&bio->__bi_cnt)); 564 565 /* 566 * last put frees it 567 */ 568 if (atomic_dec_and_test(&bio->__bi_cnt)) 569 bio_free(bio); 570 } 571 } 572 EXPORT_SYMBOL(bio_put); 573 574 inline int bio_phys_segments(struct request_queue *q, struct bio *bio) 575 { 576 if (unlikely(!bio_flagged(bio, BIO_SEG_VALID))) 577 blk_recount_segments(q, bio); 578 579 return bio->bi_phys_segments; 580 } 581 EXPORT_SYMBOL(bio_phys_segments); 582 583 /** 584 * __bio_clone_fast - clone a bio that shares the original bio's biovec 585 * @bio: destination bio 586 * @bio_src: bio to clone 587 * 588 * Clone a &bio. Caller will own the returned bio, but not 589 * the actual data it points to. Reference count of returned 590 * bio will be one. 591 * 592 * Caller must ensure that @bio_src is not freed before @bio. 593 */ 594 void __bio_clone_fast(struct bio *bio, struct bio *bio_src) 595 { 596 BUG_ON(bio->bi_pool && BVEC_POOL_IDX(bio)); 597 598 /* 599 * most users will be overriding ->bi_disk with a new target, 600 * so we don't set nor calculate new physical/hw segment counts here 601 */ 602 bio->bi_disk = bio_src->bi_disk; 603 bio->bi_partno = bio_src->bi_partno; 604 bio_set_flag(bio, BIO_CLONED); 605 if (bio_flagged(bio_src, BIO_THROTTLED)) 606 bio_set_flag(bio, BIO_THROTTLED); 607 bio->bi_opf = bio_src->bi_opf; 608 bio->bi_write_hint = bio_src->bi_write_hint; 609 bio->bi_iter = bio_src->bi_iter; 610 bio->bi_io_vec = bio_src->bi_io_vec; 611 612 bio_clone_blkcg_association(bio, bio_src); 613 } 614 EXPORT_SYMBOL(__bio_clone_fast); 615 616 /** 617 * bio_clone_fast - clone a bio that shares the original bio's biovec 618 * @bio: bio to clone 619 * @gfp_mask: allocation priority 620 * @bs: bio_set to allocate from 621 * 622 * Like __bio_clone_fast, only also allocates the returned bio 623 */ 624 struct bio *bio_clone_fast(struct bio *bio, gfp_t gfp_mask, struct bio_set *bs) 625 { 626 struct bio *b; 627 628 b = bio_alloc_bioset(gfp_mask, 0, bs); 629 if (!b) 630 return NULL; 631 632 __bio_clone_fast(b, bio); 633 634 if (bio_integrity(bio)) { 635 int ret; 636 637 ret = bio_integrity_clone(b, bio, gfp_mask); 638 639 if (ret < 0) { 640 bio_put(b); 641 return NULL; 642 } 643 } 644 645 return b; 646 } 647 EXPORT_SYMBOL(bio_clone_fast); 648 649 /** 650 * bio_add_pc_page - attempt to add page to bio 651 * @q: the target queue 652 * @bio: destination bio 653 * @page: page to add 654 * @len: vec entry length 655 * @offset: vec entry offset 656 * 657 * Attempt to add a page to the bio_vec maplist. This can fail for a 658 * number of reasons, such as the bio being full or target block device 659 * limitations. The target block device must allow bio's up to PAGE_SIZE, 660 * so it is always possible to add a single page to an empty bio. 661 * 662 * This should only be used by REQ_PC bios. 663 */ 664 int bio_add_pc_page(struct request_queue *q, struct bio *bio, struct page 665 *page, unsigned int len, unsigned int offset) 666 { 667 int retried_segments = 0; 668 struct bio_vec *bvec; 669 670 /* 671 * cloned bio must not modify vec list 672 */ 673 if (unlikely(bio_flagged(bio, BIO_CLONED))) 674 return 0; 675 676 if (((bio->bi_iter.bi_size + len) >> 9) > queue_max_hw_sectors(q)) 677 return 0; 678 679 /* 680 * For filesystems with a blocksize smaller than the pagesize 681 * we will often be called with the same page as last time and 682 * a consecutive offset. Optimize this special case. 683 */ 684 if (bio->bi_vcnt > 0) { 685 struct bio_vec *prev = &bio->bi_io_vec[bio->bi_vcnt - 1]; 686 687 if (page == prev->bv_page && 688 offset == prev->bv_offset + prev->bv_len) { 689 prev->bv_len += len; 690 bio->bi_iter.bi_size += len; 691 goto done; 692 } 693 694 /* 695 * If the queue doesn't support SG gaps and adding this 696 * offset would create a gap, disallow it. 697 */ 698 if (bvec_gap_to_prev(q, prev, offset)) 699 return 0; 700 } 701 702 if (bio_full(bio)) 703 return 0; 704 705 /* 706 * setup the new entry, we might clear it again later if we 707 * cannot add the page 708 */ 709 bvec = &bio->bi_io_vec[bio->bi_vcnt]; 710 bvec->bv_page = page; 711 bvec->bv_len = len; 712 bvec->bv_offset = offset; 713 bio->bi_vcnt++; 714 bio->bi_phys_segments++; 715 bio->bi_iter.bi_size += len; 716 717 /* 718 * Perform a recount if the number of segments is greater 719 * than queue_max_segments(q). 720 */ 721 722 while (bio->bi_phys_segments > queue_max_segments(q)) { 723 724 if (retried_segments) 725 goto failed; 726 727 retried_segments = 1; 728 blk_recount_segments(q, bio); 729 } 730 731 /* If we may be able to merge these biovecs, force a recount */ 732 if (bio->bi_vcnt > 1 && biovec_phys_mergeable(q, bvec - 1, bvec)) 733 bio_clear_flag(bio, BIO_SEG_VALID); 734 735 done: 736 return len; 737 738 failed: 739 bvec->bv_page = NULL; 740 bvec->bv_len = 0; 741 bvec->bv_offset = 0; 742 bio->bi_vcnt--; 743 bio->bi_iter.bi_size -= len; 744 blk_recount_segments(q, bio); 745 return 0; 746 } 747 EXPORT_SYMBOL(bio_add_pc_page); 748 749 /** 750 * __bio_try_merge_page - try appending data to an existing bvec. 751 * @bio: destination bio 752 * @page: page to add 753 * @len: length of the data to add 754 * @off: offset of the data in @page 755 * 756 * Try to add the data at @page + @off to the last bvec of @bio. This is a 757 * a useful optimisation for file systems with a block size smaller than the 758 * page size. 759 * 760 * Return %true on success or %false on failure. 761 */ 762 bool __bio_try_merge_page(struct bio *bio, struct page *page, 763 unsigned int len, unsigned int off) 764 { 765 if (WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED))) 766 return false; 767 768 if (bio->bi_vcnt > 0) { 769 struct bio_vec *bv = &bio->bi_io_vec[bio->bi_vcnt - 1]; 770 771 if (page == bv->bv_page && off == bv->bv_offset + bv->bv_len) { 772 bv->bv_len += len; 773 bio->bi_iter.bi_size += len; 774 return true; 775 } 776 } 777 return false; 778 } 779 EXPORT_SYMBOL_GPL(__bio_try_merge_page); 780 781 /** 782 * __bio_add_page - add page to a bio in a new segment 783 * @bio: destination bio 784 * @page: page to add 785 * @len: length of the data to add 786 * @off: offset of the data in @page 787 * 788 * Add the data at @page + @off to @bio as a new bvec. The caller must ensure 789 * that @bio has space for another bvec. 790 */ 791 void __bio_add_page(struct bio *bio, struct page *page, 792 unsigned int len, unsigned int off) 793 { 794 struct bio_vec *bv = &bio->bi_io_vec[bio->bi_vcnt]; 795 796 WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED)); 797 WARN_ON_ONCE(bio_full(bio)); 798 799 bv->bv_page = page; 800 bv->bv_offset = off; 801 bv->bv_len = len; 802 803 bio->bi_iter.bi_size += len; 804 bio->bi_vcnt++; 805 } 806 EXPORT_SYMBOL_GPL(__bio_add_page); 807 808 /** 809 * bio_add_page - attempt to add page to bio 810 * @bio: destination bio 811 * @page: page to add 812 * @len: vec entry length 813 * @offset: vec entry offset 814 * 815 * Attempt to add a page to the bio_vec maplist. This will only fail 816 * if either bio->bi_vcnt == bio->bi_max_vecs or it's a cloned bio. 817 */ 818 int bio_add_page(struct bio *bio, struct page *page, 819 unsigned int len, unsigned int offset) 820 { 821 if (!__bio_try_merge_page(bio, page, len, offset)) { 822 if (bio_full(bio)) 823 return 0; 824 __bio_add_page(bio, page, len, offset); 825 } 826 return len; 827 } 828 EXPORT_SYMBOL(bio_add_page); 829 830 #define PAGE_PTRS_PER_BVEC (sizeof(struct bio_vec) / sizeof(struct page *)) 831 832 /** 833 * __bio_iov_iter_get_pages - pin user or kernel pages and add them to a bio 834 * @bio: bio to add pages to 835 * @iter: iov iterator describing the region to be mapped 836 * 837 * Pins pages from *iter and appends them to @bio's bvec array. The 838 * pages will have to be released using put_page() when done. 839 * For multi-segment *iter, this function only adds pages from the 840 * the next non-empty segment of the iov iterator. 841 */ 842 static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter) 843 { 844 unsigned short nr_pages = bio->bi_max_vecs - bio->bi_vcnt; 845 unsigned short entries_left = bio->bi_max_vecs - bio->bi_vcnt; 846 struct bio_vec *bv = bio->bi_io_vec + bio->bi_vcnt; 847 struct page **pages = (struct page **)bv; 848 ssize_t size, left; 849 unsigned len, i; 850 size_t offset; 851 852 /* 853 * Move page array up in the allocated memory for the bio vecs as far as 854 * possible so that we can start filling biovecs from the beginning 855 * without overwriting the temporary page array. 856 */ 857 BUILD_BUG_ON(PAGE_PTRS_PER_BVEC < 2); 858 pages += entries_left * (PAGE_PTRS_PER_BVEC - 1); 859 860 size = iov_iter_get_pages(iter, pages, LONG_MAX, nr_pages, &offset); 861 if (unlikely(size <= 0)) 862 return size ? size : -EFAULT; 863 864 for (left = size, i = 0; left > 0; left -= len, i++) { 865 struct page *page = pages[i]; 866 867 len = min_t(size_t, PAGE_SIZE - offset, left); 868 if (WARN_ON_ONCE(bio_add_page(bio, page, len, offset) != len)) 869 return -EINVAL; 870 offset = 0; 871 } 872 873 iov_iter_advance(iter, size); 874 return 0; 875 } 876 877 /** 878 * bio_iov_iter_get_pages - pin user or kernel pages and add them to a bio 879 * @bio: bio to add pages to 880 * @iter: iov iterator describing the region to be mapped 881 * 882 * Pins pages from *iter and appends them to @bio's bvec array. The 883 * pages will have to be released using put_page() when done. 884 * The function tries, but does not guarantee, to pin as many pages as 885 * fit into the bio, or are requested in *iter, whatever is smaller. 886 * If MM encounters an error pinning the requested pages, it stops. 887 * Error is returned only if 0 pages could be pinned. 888 */ 889 int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter) 890 { 891 unsigned short orig_vcnt = bio->bi_vcnt; 892 893 do { 894 int ret = __bio_iov_iter_get_pages(bio, iter); 895 896 if (unlikely(ret)) 897 return bio->bi_vcnt > orig_vcnt ? 0 : ret; 898 899 } while (iov_iter_count(iter) && !bio_full(bio)); 900 901 return 0; 902 } 903 EXPORT_SYMBOL_GPL(bio_iov_iter_get_pages); 904 905 static void submit_bio_wait_endio(struct bio *bio) 906 { 907 complete(bio->bi_private); 908 } 909 910 /** 911 * submit_bio_wait - submit a bio, and wait until it completes 912 * @bio: The &struct bio which describes the I/O 913 * 914 * Simple wrapper around submit_bio(). Returns 0 on success, or the error from 915 * bio_endio() on failure. 916 * 917 * WARNING: Unlike to how submit_bio() is usually used, this function does not 918 * result in bio reference to be consumed. The caller must drop the reference 919 * on his own. 920 */ 921 int submit_bio_wait(struct bio *bio) 922 { 923 DECLARE_COMPLETION_ONSTACK_MAP(done, bio->bi_disk->lockdep_map); 924 925 bio->bi_private = &done; 926 bio->bi_end_io = submit_bio_wait_endio; 927 bio->bi_opf |= REQ_SYNC; 928 submit_bio(bio); 929 wait_for_completion_io(&done); 930 931 return blk_status_to_errno(bio->bi_status); 932 } 933 EXPORT_SYMBOL(submit_bio_wait); 934 935 /** 936 * bio_advance - increment/complete a bio by some number of bytes 937 * @bio: bio to advance 938 * @bytes: number of bytes to complete 939 * 940 * This updates bi_sector, bi_size and bi_idx; if the number of bytes to 941 * complete doesn't align with a bvec boundary, then bv_len and bv_offset will 942 * be updated on the last bvec as well. 943 * 944 * @bio will then represent the remaining, uncompleted portion of the io. 945 */ 946 void bio_advance(struct bio *bio, unsigned bytes) 947 { 948 if (bio_integrity(bio)) 949 bio_integrity_advance(bio, bytes); 950 951 bio_advance_iter(bio, &bio->bi_iter, bytes); 952 } 953 EXPORT_SYMBOL(bio_advance); 954 955 void bio_copy_data_iter(struct bio *dst, struct bvec_iter *dst_iter, 956 struct bio *src, struct bvec_iter *src_iter) 957 { 958 struct bio_vec src_bv, dst_bv; 959 void *src_p, *dst_p; 960 unsigned bytes; 961 962 while (src_iter->bi_size && dst_iter->bi_size) { 963 src_bv = bio_iter_iovec(src, *src_iter); 964 dst_bv = bio_iter_iovec(dst, *dst_iter); 965 966 bytes = min(src_bv.bv_len, dst_bv.bv_len); 967 968 src_p = kmap_atomic(src_bv.bv_page); 969 dst_p = kmap_atomic(dst_bv.bv_page); 970 971 memcpy(dst_p + dst_bv.bv_offset, 972 src_p + src_bv.bv_offset, 973 bytes); 974 975 kunmap_atomic(dst_p); 976 kunmap_atomic(src_p); 977 978 flush_dcache_page(dst_bv.bv_page); 979 980 bio_advance_iter(src, src_iter, bytes); 981 bio_advance_iter(dst, dst_iter, bytes); 982 } 983 } 984 EXPORT_SYMBOL(bio_copy_data_iter); 985 986 /** 987 * bio_copy_data - copy contents of data buffers from one bio to another 988 * @src: source bio 989 * @dst: destination bio 990 * 991 * Stops when it reaches the end of either @src or @dst - that is, copies 992 * min(src->bi_size, dst->bi_size) bytes (or the equivalent for lists of bios). 993 */ 994 void bio_copy_data(struct bio *dst, struct bio *src) 995 { 996 struct bvec_iter src_iter = src->bi_iter; 997 struct bvec_iter dst_iter = dst->bi_iter; 998 999 bio_copy_data_iter(dst, &dst_iter, src, &src_iter); 1000 } 1001 EXPORT_SYMBOL(bio_copy_data); 1002 1003 /** 1004 * bio_list_copy_data - copy contents of data buffers from one chain of bios to 1005 * another 1006 * @src: source bio list 1007 * @dst: destination bio list 1008 * 1009 * Stops when it reaches the end of either the @src list or @dst list - that is, 1010 * copies min(src->bi_size, dst->bi_size) bytes (or the equivalent for lists of 1011 * bios). 1012 */ 1013 void bio_list_copy_data(struct bio *dst, struct bio *src) 1014 { 1015 struct bvec_iter src_iter = src->bi_iter; 1016 struct bvec_iter dst_iter = dst->bi_iter; 1017 1018 while (1) { 1019 if (!src_iter.bi_size) { 1020 src = src->bi_next; 1021 if (!src) 1022 break; 1023 1024 src_iter = src->bi_iter; 1025 } 1026 1027 if (!dst_iter.bi_size) { 1028 dst = dst->bi_next; 1029 if (!dst) 1030 break; 1031 1032 dst_iter = dst->bi_iter; 1033 } 1034 1035 bio_copy_data_iter(dst, &dst_iter, src, &src_iter); 1036 } 1037 } 1038 EXPORT_SYMBOL(bio_list_copy_data); 1039 1040 struct bio_map_data { 1041 int is_our_pages; 1042 struct iov_iter iter; 1043 struct iovec iov[]; 1044 }; 1045 1046 static struct bio_map_data *bio_alloc_map_data(struct iov_iter *data, 1047 gfp_t gfp_mask) 1048 { 1049 struct bio_map_data *bmd; 1050 if (data->nr_segs > UIO_MAXIOV) 1051 return NULL; 1052 1053 bmd = kmalloc(sizeof(struct bio_map_data) + 1054 sizeof(struct iovec) * data->nr_segs, gfp_mask); 1055 if (!bmd) 1056 return NULL; 1057 memcpy(bmd->iov, data->iov, sizeof(struct iovec) * data->nr_segs); 1058 bmd->iter = *data; 1059 bmd->iter.iov = bmd->iov; 1060 return bmd; 1061 } 1062 1063 /** 1064 * bio_copy_from_iter - copy all pages from iov_iter to bio 1065 * @bio: The &struct bio which describes the I/O as destination 1066 * @iter: iov_iter as source 1067 * 1068 * Copy all pages from iov_iter to bio. 1069 * Returns 0 on success, or error on failure. 1070 */ 1071 static int bio_copy_from_iter(struct bio *bio, struct iov_iter *iter) 1072 { 1073 int i; 1074 struct bio_vec *bvec; 1075 1076 bio_for_each_segment_all(bvec, bio, i) { 1077 ssize_t ret; 1078 1079 ret = copy_page_from_iter(bvec->bv_page, 1080 bvec->bv_offset, 1081 bvec->bv_len, 1082 iter); 1083 1084 if (!iov_iter_count(iter)) 1085 break; 1086 1087 if (ret < bvec->bv_len) 1088 return -EFAULT; 1089 } 1090 1091 return 0; 1092 } 1093 1094 /** 1095 * bio_copy_to_iter - copy all pages from bio to iov_iter 1096 * @bio: The &struct bio which describes the I/O as source 1097 * @iter: iov_iter as destination 1098 * 1099 * Copy all pages from bio to iov_iter. 1100 * Returns 0 on success, or error on failure. 1101 */ 1102 static int bio_copy_to_iter(struct bio *bio, struct iov_iter iter) 1103 { 1104 int i; 1105 struct bio_vec *bvec; 1106 1107 bio_for_each_segment_all(bvec, bio, i) { 1108 ssize_t ret; 1109 1110 ret = copy_page_to_iter(bvec->bv_page, 1111 bvec->bv_offset, 1112 bvec->bv_len, 1113 &iter); 1114 1115 if (!iov_iter_count(&iter)) 1116 break; 1117 1118 if (ret < bvec->bv_len) 1119 return -EFAULT; 1120 } 1121 1122 return 0; 1123 } 1124 1125 void bio_free_pages(struct bio *bio) 1126 { 1127 struct bio_vec *bvec; 1128 int i; 1129 1130 bio_for_each_segment_all(bvec, bio, i) 1131 __free_page(bvec->bv_page); 1132 } 1133 EXPORT_SYMBOL(bio_free_pages); 1134 1135 /** 1136 * bio_uncopy_user - finish previously mapped bio 1137 * @bio: bio being terminated 1138 * 1139 * Free pages allocated from bio_copy_user_iov() and write back data 1140 * to user space in case of a read. 1141 */ 1142 int bio_uncopy_user(struct bio *bio) 1143 { 1144 struct bio_map_data *bmd = bio->bi_private; 1145 int ret = 0; 1146 1147 if (!bio_flagged(bio, BIO_NULL_MAPPED)) { 1148 /* 1149 * if we're in a workqueue, the request is orphaned, so 1150 * don't copy into a random user address space, just free 1151 * and return -EINTR so user space doesn't expect any data. 1152 */ 1153 if (!current->mm) 1154 ret = -EINTR; 1155 else if (bio_data_dir(bio) == READ) 1156 ret = bio_copy_to_iter(bio, bmd->iter); 1157 if (bmd->is_our_pages) 1158 bio_free_pages(bio); 1159 } 1160 kfree(bmd); 1161 bio_put(bio); 1162 return ret; 1163 } 1164 1165 /** 1166 * bio_copy_user_iov - copy user data to bio 1167 * @q: destination block queue 1168 * @map_data: pointer to the rq_map_data holding pages (if necessary) 1169 * @iter: iovec iterator 1170 * @gfp_mask: memory allocation flags 1171 * 1172 * Prepares and returns a bio for indirect user io, bouncing data 1173 * to/from kernel pages as necessary. Must be paired with 1174 * call bio_uncopy_user() on io completion. 1175 */ 1176 struct bio *bio_copy_user_iov(struct request_queue *q, 1177 struct rq_map_data *map_data, 1178 struct iov_iter *iter, 1179 gfp_t gfp_mask) 1180 { 1181 struct bio_map_data *bmd; 1182 struct page *page; 1183 struct bio *bio; 1184 int i = 0, ret; 1185 int nr_pages; 1186 unsigned int len = iter->count; 1187 unsigned int offset = map_data ? offset_in_page(map_data->offset) : 0; 1188 1189 bmd = bio_alloc_map_data(iter, gfp_mask); 1190 if (!bmd) 1191 return ERR_PTR(-ENOMEM); 1192 1193 /* 1194 * We need to do a deep copy of the iov_iter including the iovecs. 1195 * The caller provided iov might point to an on-stack or otherwise 1196 * shortlived one. 1197 */ 1198 bmd->is_our_pages = map_data ? 0 : 1; 1199 1200 nr_pages = DIV_ROUND_UP(offset + len, PAGE_SIZE); 1201 if (nr_pages > BIO_MAX_PAGES) 1202 nr_pages = BIO_MAX_PAGES; 1203 1204 ret = -ENOMEM; 1205 bio = bio_kmalloc(gfp_mask, nr_pages); 1206 if (!bio) 1207 goto out_bmd; 1208 1209 ret = 0; 1210 1211 if (map_data) { 1212 nr_pages = 1 << map_data->page_order; 1213 i = map_data->offset / PAGE_SIZE; 1214 } 1215 while (len) { 1216 unsigned int bytes = PAGE_SIZE; 1217 1218 bytes -= offset; 1219 1220 if (bytes > len) 1221 bytes = len; 1222 1223 if (map_data) { 1224 if (i == map_data->nr_entries * nr_pages) { 1225 ret = -ENOMEM; 1226 break; 1227 } 1228 1229 page = map_data->pages[i / nr_pages]; 1230 page += (i % nr_pages); 1231 1232 i++; 1233 } else { 1234 page = alloc_page(q->bounce_gfp | gfp_mask); 1235 if (!page) { 1236 ret = -ENOMEM; 1237 break; 1238 } 1239 } 1240 1241 if (bio_add_pc_page(q, bio, page, bytes, offset) < bytes) 1242 break; 1243 1244 len -= bytes; 1245 offset = 0; 1246 } 1247 1248 if (ret) 1249 goto cleanup; 1250 1251 if (map_data) 1252 map_data->offset += bio->bi_iter.bi_size; 1253 1254 /* 1255 * success 1256 */ 1257 if ((iov_iter_rw(iter) == WRITE && (!map_data || !map_data->null_mapped)) || 1258 (map_data && map_data->from_user)) { 1259 ret = bio_copy_from_iter(bio, iter); 1260 if (ret) 1261 goto cleanup; 1262 } else { 1263 iov_iter_advance(iter, bio->bi_iter.bi_size); 1264 } 1265 1266 bio->bi_private = bmd; 1267 if (map_data && map_data->null_mapped) 1268 bio_set_flag(bio, BIO_NULL_MAPPED); 1269 return bio; 1270 cleanup: 1271 if (!map_data) 1272 bio_free_pages(bio); 1273 bio_put(bio); 1274 out_bmd: 1275 kfree(bmd); 1276 return ERR_PTR(ret); 1277 } 1278 1279 /** 1280 * bio_map_user_iov - map user iovec into bio 1281 * @q: the struct request_queue for the bio 1282 * @iter: iovec iterator 1283 * @gfp_mask: memory allocation flags 1284 * 1285 * Map the user space address into a bio suitable for io to a block 1286 * device. Returns an error pointer in case of error. 1287 */ 1288 struct bio *bio_map_user_iov(struct request_queue *q, 1289 struct iov_iter *iter, 1290 gfp_t gfp_mask) 1291 { 1292 int j; 1293 struct bio *bio; 1294 int ret; 1295 struct bio_vec *bvec; 1296 1297 if (!iov_iter_count(iter)) 1298 return ERR_PTR(-EINVAL); 1299 1300 bio = bio_kmalloc(gfp_mask, iov_iter_npages(iter, BIO_MAX_PAGES)); 1301 if (!bio) 1302 return ERR_PTR(-ENOMEM); 1303 1304 while (iov_iter_count(iter)) { 1305 struct page **pages; 1306 ssize_t bytes; 1307 size_t offs, added = 0; 1308 int npages; 1309 1310 bytes = iov_iter_get_pages_alloc(iter, &pages, LONG_MAX, &offs); 1311 if (unlikely(bytes <= 0)) { 1312 ret = bytes ? bytes : -EFAULT; 1313 goto out_unmap; 1314 } 1315 1316 npages = DIV_ROUND_UP(offs + bytes, PAGE_SIZE); 1317 1318 if (unlikely(offs & queue_dma_alignment(q))) { 1319 ret = -EINVAL; 1320 j = 0; 1321 } else { 1322 for (j = 0; j < npages; j++) { 1323 struct page *page = pages[j]; 1324 unsigned int n = PAGE_SIZE - offs; 1325 unsigned short prev_bi_vcnt = bio->bi_vcnt; 1326 1327 if (n > bytes) 1328 n = bytes; 1329 1330 if (!bio_add_pc_page(q, bio, page, n, offs)) 1331 break; 1332 1333 /* 1334 * check if vector was merged with previous 1335 * drop page reference if needed 1336 */ 1337 if (bio->bi_vcnt == prev_bi_vcnt) 1338 put_page(page); 1339 1340 added += n; 1341 bytes -= n; 1342 offs = 0; 1343 } 1344 iov_iter_advance(iter, added); 1345 } 1346 /* 1347 * release the pages we didn't map into the bio, if any 1348 */ 1349 while (j < npages) 1350 put_page(pages[j++]); 1351 kvfree(pages); 1352 /* couldn't stuff something into bio? */ 1353 if (bytes) 1354 break; 1355 } 1356 1357 bio_set_flag(bio, BIO_USER_MAPPED); 1358 1359 /* 1360 * subtle -- if bio_map_user_iov() ended up bouncing a bio, 1361 * it would normally disappear when its bi_end_io is run. 1362 * however, we need it for the unmap, so grab an extra 1363 * reference to it 1364 */ 1365 bio_get(bio); 1366 return bio; 1367 1368 out_unmap: 1369 bio_for_each_segment_all(bvec, bio, j) { 1370 put_page(bvec->bv_page); 1371 } 1372 bio_put(bio); 1373 return ERR_PTR(ret); 1374 } 1375 1376 static void __bio_unmap_user(struct bio *bio) 1377 { 1378 struct bio_vec *bvec; 1379 int i; 1380 1381 /* 1382 * make sure we dirty pages we wrote to 1383 */ 1384 bio_for_each_segment_all(bvec, bio, i) { 1385 if (bio_data_dir(bio) == READ) 1386 set_page_dirty_lock(bvec->bv_page); 1387 1388 put_page(bvec->bv_page); 1389 } 1390 1391 bio_put(bio); 1392 } 1393 1394 /** 1395 * bio_unmap_user - unmap a bio 1396 * @bio: the bio being unmapped 1397 * 1398 * Unmap a bio previously mapped by bio_map_user_iov(). Must be called from 1399 * process context. 1400 * 1401 * bio_unmap_user() may sleep. 1402 */ 1403 void bio_unmap_user(struct bio *bio) 1404 { 1405 __bio_unmap_user(bio); 1406 bio_put(bio); 1407 } 1408 1409 static void bio_map_kern_endio(struct bio *bio) 1410 { 1411 bio_put(bio); 1412 } 1413 1414 /** 1415 * bio_map_kern - map kernel address into bio 1416 * @q: the struct request_queue for the bio 1417 * @data: pointer to buffer to map 1418 * @len: length in bytes 1419 * @gfp_mask: allocation flags for bio allocation 1420 * 1421 * Map the kernel address into a bio suitable for io to a block 1422 * device. Returns an error pointer in case of error. 1423 */ 1424 struct bio *bio_map_kern(struct request_queue *q, void *data, unsigned int len, 1425 gfp_t gfp_mask) 1426 { 1427 unsigned long kaddr = (unsigned long)data; 1428 unsigned long end = (kaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT; 1429 unsigned long start = kaddr >> PAGE_SHIFT; 1430 const int nr_pages = end - start; 1431 int offset, i; 1432 struct bio *bio; 1433 1434 bio = bio_kmalloc(gfp_mask, nr_pages); 1435 if (!bio) 1436 return ERR_PTR(-ENOMEM); 1437 1438 offset = offset_in_page(kaddr); 1439 for (i = 0; i < nr_pages; i++) { 1440 unsigned int bytes = PAGE_SIZE - offset; 1441 1442 if (len <= 0) 1443 break; 1444 1445 if (bytes > len) 1446 bytes = len; 1447 1448 if (bio_add_pc_page(q, bio, virt_to_page(data), bytes, 1449 offset) < bytes) { 1450 /* we don't support partial mappings */ 1451 bio_put(bio); 1452 return ERR_PTR(-EINVAL); 1453 } 1454 1455 data += bytes; 1456 len -= bytes; 1457 offset = 0; 1458 } 1459 1460 bio->bi_end_io = bio_map_kern_endio; 1461 return bio; 1462 } 1463 EXPORT_SYMBOL(bio_map_kern); 1464 1465 static void bio_copy_kern_endio(struct bio *bio) 1466 { 1467 bio_free_pages(bio); 1468 bio_put(bio); 1469 } 1470 1471 static void bio_copy_kern_endio_read(struct bio *bio) 1472 { 1473 char *p = bio->bi_private; 1474 struct bio_vec *bvec; 1475 int i; 1476 1477 bio_for_each_segment_all(bvec, bio, i) { 1478 memcpy(p, page_address(bvec->bv_page), bvec->bv_len); 1479 p += bvec->bv_len; 1480 } 1481 1482 bio_copy_kern_endio(bio); 1483 } 1484 1485 /** 1486 * bio_copy_kern - copy kernel address into bio 1487 * @q: the struct request_queue for the bio 1488 * @data: pointer to buffer to copy 1489 * @len: length in bytes 1490 * @gfp_mask: allocation flags for bio and page allocation 1491 * @reading: data direction is READ 1492 * 1493 * copy the kernel address into a bio suitable for io to a block 1494 * device. Returns an error pointer in case of error. 1495 */ 1496 struct bio *bio_copy_kern(struct request_queue *q, void *data, unsigned int len, 1497 gfp_t gfp_mask, int reading) 1498 { 1499 unsigned long kaddr = (unsigned long)data; 1500 unsigned long end = (kaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT; 1501 unsigned long start = kaddr >> PAGE_SHIFT; 1502 struct bio *bio; 1503 void *p = data; 1504 int nr_pages = 0; 1505 1506 /* 1507 * Overflow, abort 1508 */ 1509 if (end < start) 1510 return ERR_PTR(-EINVAL); 1511 1512 nr_pages = end - start; 1513 bio = bio_kmalloc(gfp_mask, nr_pages); 1514 if (!bio) 1515 return ERR_PTR(-ENOMEM); 1516 1517 while (len) { 1518 struct page *page; 1519 unsigned int bytes = PAGE_SIZE; 1520 1521 if (bytes > len) 1522 bytes = len; 1523 1524 page = alloc_page(q->bounce_gfp | gfp_mask); 1525 if (!page) 1526 goto cleanup; 1527 1528 if (!reading) 1529 memcpy(page_address(page), p, bytes); 1530 1531 if (bio_add_pc_page(q, bio, page, bytes, 0) < bytes) 1532 break; 1533 1534 len -= bytes; 1535 p += bytes; 1536 } 1537 1538 if (reading) { 1539 bio->bi_end_io = bio_copy_kern_endio_read; 1540 bio->bi_private = data; 1541 } else { 1542 bio->bi_end_io = bio_copy_kern_endio; 1543 } 1544 1545 return bio; 1546 1547 cleanup: 1548 bio_free_pages(bio); 1549 bio_put(bio); 1550 return ERR_PTR(-ENOMEM); 1551 } 1552 1553 /* 1554 * bio_set_pages_dirty() and bio_check_pages_dirty() are support functions 1555 * for performing direct-IO in BIOs. 1556 * 1557 * The problem is that we cannot run set_page_dirty() from interrupt context 1558 * because the required locks are not interrupt-safe. So what we can do is to 1559 * mark the pages dirty _before_ performing IO. And in interrupt context, 1560 * check that the pages are still dirty. If so, fine. If not, redirty them 1561 * in process context. 1562 * 1563 * We special-case compound pages here: normally this means reads into hugetlb 1564 * pages. The logic in here doesn't really work right for compound pages 1565 * because the VM does not uniformly chase down the head page in all cases. 1566 * But dirtiness of compound pages is pretty meaningless anyway: the VM doesn't 1567 * handle them at all. So we skip compound pages here at an early stage. 1568 * 1569 * Note that this code is very hard to test under normal circumstances because 1570 * direct-io pins the pages with get_user_pages(). This makes 1571 * is_page_cache_freeable return false, and the VM will not clean the pages. 1572 * But other code (eg, flusher threads) could clean the pages if they are mapped 1573 * pagecache. 1574 * 1575 * Simply disabling the call to bio_set_pages_dirty() is a good way to test the 1576 * deferred bio dirtying paths. 1577 */ 1578 1579 /* 1580 * bio_set_pages_dirty() will mark all the bio's pages as dirty. 1581 */ 1582 void bio_set_pages_dirty(struct bio *bio) 1583 { 1584 struct bio_vec *bvec; 1585 int i; 1586 1587 bio_for_each_segment_all(bvec, bio, i) { 1588 if (!PageCompound(bvec->bv_page)) 1589 set_page_dirty_lock(bvec->bv_page); 1590 } 1591 } 1592 EXPORT_SYMBOL_GPL(bio_set_pages_dirty); 1593 1594 static void bio_release_pages(struct bio *bio) 1595 { 1596 struct bio_vec *bvec; 1597 int i; 1598 1599 bio_for_each_segment_all(bvec, bio, i) 1600 put_page(bvec->bv_page); 1601 } 1602 1603 /* 1604 * bio_check_pages_dirty() will check that all the BIO's pages are still dirty. 1605 * If they are, then fine. If, however, some pages are clean then they must 1606 * have been written out during the direct-IO read. So we take another ref on 1607 * the BIO and re-dirty the pages in process context. 1608 * 1609 * It is expected that bio_check_pages_dirty() will wholly own the BIO from 1610 * here on. It will run one put_page() against each page and will run one 1611 * bio_put() against the BIO. 1612 */ 1613 1614 static void bio_dirty_fn(struct work_struct *work); 1615 1616 static DECLARE_WORK(bio_dirty_work, bio_dirty_fn); 1617 static DEFINE_SPINLOCK(bio_dirty_lock); 1618 static struct bio *bio_dirty_list; 1619 1620 /* 1621 * This runs in process context 1622 */ 1623 static void bio_dirty_fn(struct work_struct *work) 1624 { 1625 struct bio *bio, *next; 1626 1627 spin_lock_irq(&bio_dirty_lock); 1628 next = bio_dirty_list; 1629 bio_dirty_list = NULL; 1630 spin_unlock_irq(&bio_dirty_lock); 1631 1632 while ((bio = next) != NULL) { 1633 next = bio->bi_private; 1634 1635 bio_set_pages_dirty(bio); 1636 bio_release_pages(bio); 1637 bio_put(bio); 1638 } 1639 } 1640 1641 void bio_check_pages_dirty(struct bio *bio) 1642 { 1643 struct bio_vec *bvec; 1644 unsigned long flags; 1645 int i; 1646 1647 bio_for_each_segment_all(bvec, bio, i) { 1648 if (!PageDirty(bvec->bv_page) && !PageCompound(bvec->bv_page)) 1649 goto defer; 1650 } 1651 1652 bio_release_pages(bio); 1653 bio_put(bio); 1654 return; 1655 defer: 1656 spin_lock_irqsave(&bio_dirty_lock, flags); 1657 bio->bi_private = bio_dirty_list; 1658 bio_dirty_list = bio; 1659 spin_unlock_irqrestore(&bio_dirty_lock, flags); 1660 schedule_work(&bio_dirty_work); 1661 } 1662 EXPORT_SYMBOL_GPL(bio_check_pages_dirty); 1663 1664 void generic_start_io_acct(struct request_queue *q, int op, 1665 unsigned long sectors, struct hd_struct *part) 1666 { 1667 const int sgrp = op_stat_group(op); 1668 int cpu = part_stat_lock(); 1669 1670 part_round_stats(q, cpu, part); 1671 part_stat_inc(cpu, part, ios[sgrp]); 1672 part_stat_add(cpu, part, sectors[sgrp], sectors); 1673 part_inc_in_flight(q, part, op_is_write(op)); 1674 1675 part_stat_unlock(); 1676 } 1677 EXPORT_SYMBOL(generic_start_io_acct); 1678 1679 void generic_end_io_acct(struct request_queue *q, int req_op, 1680 struct hd_struct *part, unsigned long start_time) 1681 { 1682 unsigned long duration = jiffies - start_time; 1683 const int sgrp = op_stat_group(req_op); 1684 int cpu = part_stat_lock(); 1685 1686 part_stat_add(cpu, part, nsecs[sgrp], jiffies_to_nsecs(duration)); 1687 part_round_stats(q, cpu, part); 1688 part_dec_in_flight(q, part, op_is_write(req_op)); 1689 1690 part_stat_unlock(); 1691 } 1692 EXPORT_SYMBOL(generic_end_io_acct); 1693 1694 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 1695 void bio_flush_dcache_pages(struct bio *bi) 1696 { 1697 struct bio_vec bvec; 1698 struct bvec_iter iter; 1699 1700 bio_for_each_segment(bvec, bi, iter) 1701 flush_dcache_page(bvec.bv_page); 1702 } 1703 EXPORT_SYMBOL(bio_flush_dcache_pages); 1704 #endif 1705 1706 static inline bool bio_remaining_done(struct bio *bio) 1707 { 1708 /* 1709 * If we're not chaining, then ->__bi_remaining is always 1 and 1710 * we always end io on the first invocation. 1711 */ 1712 if (!bio_flagged(bio, BIO_CHAIN)) 1713 return true; 1714 1715 BUG_ON(atomic_read(&bio->__bi_remaining) <= 0); 1716 1717 if (atomic_dec_and_test(&bio->__bi_remaining)) { 1718 bio_clear_flag(bio, BIO_CHAIN); 1719 return true; 1720 } 1721 1722 return false; 1723 } 1724 1725 /** 1726 * bio_endio - end I/O on a bio 1727 * @bio: bio 1728 * 1729 * Description: 1730 * bio_endio() will end I/O on the whole bio. bio_endio() is the preferred 1731 * way to end I/O on a bio. No one should call bi_end_io() directly on a 1732 * bio unless they own it and thus know that it has an end_io function. 1733 * 1734 * bio_endio() can be called several times on a bio that has been chained 1735 * using bio_chain(). The ->bi_end_io() function will only be called the 1736 * last time. At this point the BLK_TA_COMPLETE tracing event will be 1737 * generated if BIO_TRACE_COMPLETION is set. 1738 **/ 1739 void bio_endio(struct bio *bio) 1740 { 1741 again: 1742 if (!bio_remaining_done(bio)) 1743 return; 1744 if (!bio_integrity_endio(bio)) 1745 return; 1746 1747 if (bio->bi_disk) 1748 rq_qos_done_bio(bio->bi_disk->queue, bio); 1749 1750 /* 1751 * Need to have a real endio function for chained bios, otherwise 1752 * various corner cases will break (like stacking block devices that 1753 * save/restore bi_end_io) - however, we want to avoid unbounded 1754 * recursion and blowing the stack. Tail call optimization would 1755 * handle this, but compiling with frame pointers also disables 1756 * gcc's sibling call optimization. 1757 */ 1758 if (bio->bi_end_io == bio_chain_endio) { 1759 bio = __bio_chain_endio(bio); 1760 goto again; 1761 } 1762 1763 if (bio->bi_disk && bio_flagged(bio, BIO_TRACE_COMPLETION)) { 1764 trace_block_bio_complete(bio->bi_disk->queue, bio, 1765 blk_status_to_errno(bio->bi_status)); 1766 bio_clear_flag(bio, BIO_TRACE_COMPLETION); 1767 } 1768 1769 blk_throtl_bio_endio(bio); 1770 /* release cgroup info */ 1771 bio_uninit(bio); 1772 if (bio->bi_end_io) 1773 bio->bi_end_io(bio); 1774 } 1775 EXPORT_SYMBOL(bio_endio); 1776 1777 /** 1778 * bio_split - split a bio 1779 * @bio: bio to split 1780 * @sectors: number of sectors to split from the front of @bio 1781 * @gfp: gfp mask 1782 * @bs: bio set to allocate from 1783 * 1784 * Allocates and returns a new bio which represents @sectors from the start of 1785 * @bio, and updates @bio to represent the remaining sectors. 1786 * 1787 * Unless this is a discard request the newly allocated bio will point 1788 * to @bio's bi_io_vec; it is the caller's responsibility to ensure that 1789 * @bio is not freed before the split. 1790 */ 1791 struct bio *bio_split(struct bio *bio, int sectors, 1792 gfp_t gfp, struct bio_set *bs) 1793 { 1794 struct bio *split; 1795 1796 BUG_ON(sectors <= 0); 1797 BUG_ON(sectors >= bio_sectors(bio)); 1798 1799 split = bio_clone_fast(bio, gfp, bs); 1800 if (!split) 1801 return NULL; 1802 1803 split->bi_iter.bi_size = sectors << 9; 1804 1805 if (bio_integrity(split)) 1806 bio_integrity_trim(split); 1807 1808 bio_advance(bio, split->bi_iter.bi_size); 1809 1810 if (bio_flagged(bio, BIO_TRACE_COMPLETION)) 1811 bio_set_flag(split, BIO_TRACE_COMPLETION); 1812 1813 return split; 1814 } 1815 EXPORT_SYMBOL(bio_split); 1816 1817 /** 1818 * bio_trim - trim a bio 1819 * @bio: bio to trim 1820 * @offset: number of sectors to trim from the front of @bio 1821 * @size: size we want to trim @bio to, in sectors 1822 */ 1823 void bio_trim(struct bio *bio, int offset, int size) 1824 { 1825 /* 'bio' is a cloned bio which we need to trim to match 1826 * the given offset and size. 1827 */ 1828 1829 size <<= 9; 1830 if (offset == 0 && size == bio->bi_iter.bi_size) 1831 return; 1832 1833 bio_clear_flag(bio, BIO_SEG_VALID); 1834 1835 bio_advance(bio, offset << 9); 1836 1837 bio->bi_iter.bi_size = size; 1838 1839 if (bio_integrity(bio)) 1840 bio_integrity_trim(bio); 1841 1842 } 1843 EXPORT_SYMBOL_GPL(bio_trim); 1844 1845 /* 1846 * create memory pools for biovec's in a bio_set. 1847 * use the global biovec slabs created for general use. 1848 */ 1849 int biovec_init_pool(mempool_t *pool, int pool_entries) 1850 { 1851 struct biovec_slab *bp = bvec_slabs + BVEC_POOL_MAX; 1852 1853 return mempool_init_slab_pool(pool, pool_entries, bp->slab); 1854 } 1855 1856 /* 1857 * bioset_exit - exit a bioset initialized with bioset_init() 1858 * 1859 * May be called on a zeroed but uninitialized bioset (i.e. allocated with 1860 * kzalloc()). 1861 */ 1862 void bioset_exit(struct bio_set *bs) 1863 { 1864 if (bs->rescue_workqueue) 1865 destroy_workqueue(bs->rescue_workqueue); 1866 bs->rescue_workqueue = NULL; 1867 1868 mempool_exit(&bs->bio_pool); 1869 mempool_exit(&bs->bvec_pool); 1870 1871 bioset_integrity_free(bs); 1872 if (bs->bio_slab) 1873 bio_put_slab(bs); 1874 bs->bio_slab = NULL; 1875 } 1876 EXPORT_SYMBOL(bioset_exit); 1877 1878 /** 1879 * bioset_init - Initialize a bio_set 1880 * @bs: pool to initialize 1881 * @pool_size: Number of bio and bio_vecs to cache in the mempool 1882 * @front_pad: Number of bytes to allocate in front of the returned bio 1883 * @flags: Flags to modify behavior, currently %BIOSET_NEED_BVECS 1884 * and %BIOSET_NEED_RESCUER 1885 * 1886 * Description: 1887 * Set up a bio_set to be used with @bio_alloc_bioset. Allows the caller 1888 * to ask for a number of bytes to be allocated in front of the bio. 1889 * Front pad allocation is useful for embedding the bio inside 1890 * another structure, to avoid allocating extra data to go with the bio. 1891 * Note that the bio must be embedded at the END of that structure always, 1892 * or things will break badly. 1893 * If %BIOSET_NEED_BVECS is set in @flags, a separate pool will be allocated 1894 * for allocating iovecs. This pool is not needed e.g. for bio_clone_fast(). 1895 * If %BIOSET_NEED_RESCUER is set, a workqueue is created which can be used to 1896 * dispatch queued requests when the mempool runs out of space. 1897 * 1898 */ 1899 int bioset_init(struct bio_set *bs, 1900 unsigned int pool_size, 1901 unsigned int front_pad, 1902 int flags) 1903 { 1904 unsigned int back_pad = BIO_INLINE_VECS * sizeof(struct bio_vec); 1905 1906 bs->front_pad = front_pad; 1907 1908 spin_lock_init(&bs->rescue_lock); 1909 bio_list_init(&bs->rescue_list); 1910 INIT_WORK(&bs->rescue_work, bio_alloc_rescue); 1911 1912 bs->bio_slab = bio_find_or_create_slab(front_pad + back_pad); 1913 if (!bs->bio_slab) 1914 return -ENOMEM; 1915 1916 if (mempool_init_slab_pool(&bs->bio_pool, pool_size, bs->bio_slab)) 1917 goto bad; 1918 1919 if ((flags & BIOSET_NEED_BVECS) && 1920 biovec_init_pool(&bs->bvec_pool, pool_size)) 1921 goto bad; 1922 1923 if (!(flags & BIOSET_NEED_RESCUER)) 1924 return 0; 1925 1926 bs->rescue_workqueue = alloc_workqueue("bioset", WQ_MEM_RECLAIM, 0); 1927 if (!bs->rescue_workqueue) 1928 goto bad; 1929 1930 return 0; 1931 bad: 1932 bioset_exit(bs); 1933 return -ENOMEM; 1934 } 1935 EXPORT_SYMBOL(bioset_init); 1936 1937 /* 1938 * Initialize and setup a new bio_set, based on the settings from 1939 * another bio_set. 1940 */ 1941 int bioset_init_from_src(struct bio_set *bs, struct bio_set *src) 1942 { 1943 int flags; 1944 1945 flags = 0; 1946 if (src->bvec_pool.min_nr) 1947 flags |= BIOSET_NEED_BVECS; 1948 if (src->rescue_workqueue) 1949 flags |= BIOSET_NEED_RESCUER; 1950 1951 return bioset_init(bs, src->bio_pool.min_nr, src->front_pad, flags); 1952 } 1953 EXPORT_SYMBOL(bioset_init_from_src); 1954 1955 #ifdef CONFIG_BLK_CGROUP 1956 1957 #ifdef CONFIG_MEMCG 1958 /** 1959 * bio_associate_blkcg_from_page - associate a bio with the page's blkcg 1960 * @bio: target bio 1961 * @page: the page to lookup the blkcg from 1962 * 1963 * Associate @bio with the blkcg from @page's owning memcg. This works like 1964 * every other associate function wrt references. 1965 */ 1966 int bio_associate_blkcg_from_page(struct bio *bio, struct page *page) 1967 { 1968 struct cgroup_subsys_state *blkcg_css; 1969 1970 if (unlikely(bio->bi_css)) 1971 return -EBUSY; 1972 if (!page->mem_cgroup) 1973 return 0; 1974 blkcg_css = cgroup_get_e_css(page->mem_cgroup->css.cgroup, 1975 &io_cgrp_subsys); 1976 bio->bi_css = blkcg_css; 1977 return 0; 1978 } 1979 #endif /* CONFIG_MEMCG */ 1980 1981 /** 1982 * bio_associate_blkcg - associate a bio with the specified blkcg 1983 * @bio: target bio 1984 * @blkcg_css: css of the blkcg to associate 1985 * 1986 * Associate @bio with the blkcg specified by @blkcg_css. Block layer will 1987 * treat @bio as if it were issued by a task which belongs to the blkcg. 1988 * 1989 * This function takes an extra reference of @blkcg_css which will be put 1990 * when @bio is released. The caller must own @bio and is responsible for 1991 * synchronizing calls to this function. 1992 */ 1993 int bio_associate_blkcg(struct bio *bio, struct cgroup_subsys_state *blkcg_css) 1994 { 1995 if (unlikely(bio->bi_css)) 1996 return -EBUSY; 1997 css_get(blkcg_css); 1998 bio->bi_css = blkcg_css; 1999 return 0; 2000 } 2001 EXPORT_SYMBOL_GPL(bio_associate_blkcg); 2002 2003 /** 2004 * bio_associate_blkg - associate a bio with the specified blkg 2005 * @bio: target bio 2006 * @blkg: the blkg to associate 2007 * 2008 * Associate @bio with the blkg specified by @blkg. This is the queue specific 2009 * blkcg information associated with the @bio, a reference will be taken on the 2010 * @blkg and will be freed when the bio is freed. 2011 */ 2012 int bio_associate_blkg(struct bio *bio, struct blkcg_gq *blkg) 2013 { 2014 if (unlikely(bio->bi_blkg)) 2015 return -EBUSY; 2016 if (!blkg_try_get(blkg)) 2017 return -ENODEV; 2018 bio->bi_blkg = blkg; 2019 return 0; 2020 } 2021 2022 /** 2023 * bio_disassociate_task - undo bio_associate_current() 2024 * @bio: target bio 2025 */ 2026 void bio_disassociate_task(struct bio *bio) 2027 { 2028 if (bio->bi_ioc) { 2029 put_io_context(bio->bi_ioc); 2030 bio->bi_ioc = NULL; 2031 } 2032 if (bio->bi_css) { 2033 css_put(bio->bi_css); 2034 bio->bi_css = NULL; 2035 } 2036 if (bio->bi_blkg) { 2037 blkg_put(bio->bi_blkg); 2038 bio->bi_blkg = NULL; 2039 } 2040 } 2041 2042 /** 2043 * bio_clone_blkcg_association - clone blkcg association from src to dst bio 2044 * @dst: destination bio 2045 * @src: source bio 2046 */ 2047 void bio_clone_blkcg_association(struct bio *dst, struct bio *src) 2048 { 2049 if (src->bi_css) 2050 WARN_ON(bio_associate_blkcg(dst, src->bi_css)); 2051 } 2052 EXPORT_SYMBOL_GPL(bio_clone_blkcg_association); 2053 #endif /* CONFIG_BLK_CGROUP */ 2054 2055 static void __init biovec_init_slabs(void) 2056 { 2057 int i; 2058 2059 for (i = 0; i < BVEC_POOL_NR; i++) { 2060 int size; 2061 struct biovec_slab *bvs = bvec_slabs + i; 2062 2063 if (bvs->nr_vecs <= BIO_INLINE_VECS) { 2064 bvs->slab = NULL; 2065 continue; 2066 } 2067 2068 size = bvs->nr_vecs * sizeof(struct bio_vec); 2069 bvs->slab = kmem_cache_create(bvs->name, size, 0, 2070 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); 2071 } 2072 } 2073 2074 static int __init init_bio(void) 2075 { 2076 bio_slab_max = 2; 2077 bio_slab_nr = 0; 2078 bio_slabs = kcalloc(bio_slab_max, sizeof(struct bio_slab), 2079 GFP_KERNEL); 2080 if (!bio_slabs) 2081 panic("bio: can't allocate bios\n"); 2082 2083 bio_integrity_init(); 2084 biovec_init_slabs(); 2085 2086 if (bioset_init(&fs_bio_set, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS)) 2087 panic("bio: can't allocate bios\n"); 2088 2089 if (bioset_integrity_create(&fs_bio_set, BIO_POOL_SIZE)) 2090 panic("bio: can't create integrity pool\n"); 2091 2092 return 0; 2093 } 2094 subsys_initcall(init_bio); 2095