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(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 /** 831 * __bio_iov_iter_get_pages - pin user or kernel pages and add them to a bio 832 * @bio: bio to add pages to 833 * @iter: iov iterator describing the region to be mapped 834 * 835 * Pins pages from *iter and appends them to @bio's bvec array. The 836 * pages will have to be released using put_page() when done. 837 * For multi-segment *iter, this function only adds pages from the 838 * the next non-empty segment of the iov iterator. 839 */ 840 static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter) 841 { 842 unsigned short nr_pages = bio->bi_max_vecs - bio->bi_vcnt, idx; 843 struct bio_vec *bv = bio->bi_io_vec + bio->bi_vcnt; 844 struct page **pages = (struct page **)bv; 845 size_t offset; 846 ssize_t size; 847 848 size = iov_iter_get_pages(iter, pages, LONG_MAX, nr_pages, &offset); 849 if (unlikely(size <= 0)) 850 return size ? size : -EFAULT; 851 idx = nr_pages = (size + offset + PAGE_SIZE - 1) / PAGE_SIZE; 852 853 /* 854 * Deep magic below: We need to walk the pinned pages backwards 855 * because we are abusing the space allocated for the bio_vecs 856 * for the page array. Because the bio_vecs are larger than the 857 * page pointers by definition this will always work. But it also 858 * means we can't use bio_add_page, so any changes to it's semantics 859 * need to be reflected here as well. 860 */ 861 bio->bi_iter.bi_size += size; 862 bio->bi_vcnt += nr_pages; 863 864 while (idx--) { 865 bv[idx].bv_page = pages[idx]; 866 bv[idx].bv_len = PAGE_SIZE; 867 bv[idx].bv_offset = 0; 868 } 869 870 bv[0].bv_offset += offset; 871 bv[0].bv_len -= offset; 872 bv[nr_pages - 1].bv_len -= nr_pages * PAGE_SIZE - offset - size; 873 874 iov_iter_advance(iter, size); 875 return 0; 876 } 877 878 /** 879 * bio_iov_iter_get_pages - pin user or kernel pages and add them to a bio 880 * @bio: bio to add pages to 881 * @iter: iov iterator describing the region to be mapped 882 * 883 * Pins pages from *iter and appends them to @bio's bvec array. The 884 * pages will have to be released using put_page() when done. 885 * The function tries, but does not guarantee, to pin as many pages as 886 * fit into the bio, or are requested in *iter, whatever is smaller. 887 * If MM encounters an error pinning the requested pages, it stops. 888 * Error is returned only if 0 pages could be pinned. 889 */ 890 int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter) 891 { 892 unsigned short orig_vcnt = bio->bi_vcnt; 893 894 do { 895 int ret = __bio_iov_iter_get_pages(bio, iter); 896 897 if (unlikely(ret)) 898 return bio->bi_vcnt > orig_vcnt ? 0 : ret; 899 900 } while (iov_iter_count(iter) && !bio_full(bio)); 901 902 return 0; 903 } 904 EXPORT_SYMBOL_GPL(bio_iov_iter_get_pages); 905 906 static void submit_bio_wait_endio(struct bio *bio) 907 { 908 complete(bio->bi_private); 909 } 910 911 /** 912 * submit_bio_wait - submit a bio, and wait until it completes 913 * @bio: The &struct bio which describes the I/O 914 * 915 * Simple wrapper around submit_bio(). Returns 0 on success, or the error from 916 * bio_endio() on failure. 917 * 918 * WARNING: Unlike to how submit_bio() is usually used, this function does not 919 * result in bio reference to be consumed. The caller must drop the reference 920 * on his own. 921 */ 922 int submit_bio_wait(struct bio *bio) 923 { 924 DECLARE_COMPLETION_ONSTACK_MAP(done, bio->bi_disk->lockdep_map); 925 926 bio->bi_private = &done; 927 bio->bi_end_io = submit_bio_wait_endio; 928 bio->bi_opf |= REQ_SYNC; 929 submit_bio(bio); 930 wait_for_completion_io(&done); 931 932 return blk_status_to_errno(bio->bi_status); 933 } 934 EXPORT_SYMBOL(submit_bio_wait); 935 936 /** 937 * bio_advance - increment/complete a bio by some number of bytes 938 * @bio: bio to advance 939 * @bytes: number of bytes to complete 940 * 941 * This updates bi_sector, bi_size and bi_idx; if the number of bytes to 942 * complete doesn't align with a bvec boundary, then bv_len and bv_offset will 943 * be updated on the last bvec as well. 944 * 945 * @bio will then represent the remaining, uncompleted portion of the io. 946 */ 947 void bio_advance(struct bio *bio, unsigned bytes) 948 { 949 if (bio_integrity(bio)) 950 bio_integrity_advance(bio, bytes); 951 952 bio_advance_iter(bio, &bio->bi_iter, bytes); 953 } 954 EXPORT_SYMBOL(bio_advance); 955 956 void bio_copy_data_iter(struct bio *dst, struct bvec_iter *dst_iter, 957 struct bio *src, struct bvec_iter *src_iter) 958 { 959 struct bio_vec src_bv, dst_bv; 960 void *src_p, *dst_p; 961 unsigned bytes; 962 963 while (src_iter->bi_size && dst_iter->bi_size) { 964 src_bv = bio_iter_iovec(src, *src_iter); 965 dst_bv = bio_iter_iovec(dst, *dst_iter); 966 967 bytes = min(src_bv.bv_len, dst_bv.bv_len); 968 969 src_p = kmap_atomic(src_bv.bv_page); 970 dst_p = kmap_atomic(dst_bv.bv_page); 971 972 memcpy(dst_p + dst_bv.bv_offset, 973 src_p + src_bv.bv_offset, 974 bytes); 975 976 kunmap_atomic(dst_p); 977 kunmap_atomic(src_p); 978 979 flush_dcache_page(dst_bv.bv_page); 980 981 bio_advance_iter(src, src_iter, bytes); 982 bio_advance_iter(dst, dst_iter, bytes); 983 } 984 } 985 EXPORT_SYMBOL(bio_copy_data_iter); 986 987 /** 988 * bio_copy_data - copy contents of data buffers from one bio to another 989 * @src: source bio 990 * @dst: destination bio 991 * 992 * Stops when it reaches the end of either @src or @dst - that is, copies 993 * min(src->bi_size, dst->bi_size) bytes (or the equivalent for lists of bios). 994 */ 995 void bio_copy_data(struct bio *dst, struct bio *src) 996 { 997 struct bvec_iter src_iter = src->bi_iter; 998 struct bvec_iter dst_iter = dst->bi_iter; 999 1000 bio_copy_data_iter(dst, &dst_iter, src, &src_iter); 1001 } 1002 EXPORT_SYMBOL(bio_copy_data); 1003 1004 /** 1005 * bio_list_copy_data - copy contents of data buffers from one chain of bios to 1006 * another 1007 * @src: source bio list 1008 * @dst: destination bio list 1009 * 1010 * Stops when it reaches the end of either the @src list or @dst list - that is, 1011 * copies min(src->bi_size, dst->bi_size) bytes (or the equivalent for lists of 1012 * bios). 1013 */ 1014 void bio_list_copy_data(struct bio *dst, struct bio *src) 1015 { 1016 struct bvec_iter src_iter = src->bi_iter; 1017 struct bvec_iter dst_iter = dst->bi_iter; 1018 1019 while (1) { 1020 if (!src_iter.bi_size) { 1021 src = src->bi_next; 1022 if (!src) 1023 break; 1024 1025 src_iter = src->bi_iter; 1026 } 1027 1028 if (!dst_iter.bi_size) { 1029 dst = dst->bi_next; 1030 if (!dst) 1031 break; 1032 1033 dst_iter = dst->bi_iter; 1034 } 1035 1036 bio_copy_data_iter(dst, &dst_iter, src, &src_iter); 1037 } 1038 } 1039 EXPORT_SYMBOL(bio_list_copy_data); 1040 1041 struct bio_map_data { 1042 int is_our_pages; 1043 struct iov_iter iter; 1044 struct iovec iov[]; 1045 }; 1046 1047 static struct bio_map_data *bio_alloc_map_data(struct iov_iter *data, 1048 gfp_t gfp_mask) 1049 { 1050 struct bio_map_data *bmd; 1051 if (data->nr_segs > UIO_MAXIOV) 1052 return NULL; 1053 1054 bmd = kmalloc(sizeof(struct bio_map_data) + 1055 sizeof(struct iovec) * data->nr_segs, gfp_mask); 1056 if (!bmd) 1057 return NULL; 1058 memcpy(bmd->iov, data->iov, sizeof(struct iovec) * data->nr_segs); 1059 bmd->iter = *data; 1060 bmd->iter.iov = bmd->iov; 1061 return bmd; 1062 } 1063 1064 /** 1065 * bio_copy_from_iter - copy all pages from iov_iter to bio 1066 * @bio: The &struct bio which describes the I/O as destination 1067 * @iter: iov_iter as source 1068 * 1069 * Copy all pages from iov_iter to bio. 1070 * Returns 0 on success, or error on failure. 1071 */ 1072 static int bio_copy_from_iter(struct bio *bio, struct iov_iter *iter) 1073 { 1074 int i; 1075 struct bio_vec *bvec; 1076 1077 bio_for_each_segment_all(bvec, bio, i) { 1078 ssize_t ret; 1079 1080 ret = copy_page_from_iter(bvec->bv_page, 1081 bvec->bv_offset, 1082 bvec->bv_len, 1083 iter); 1084 1085 if (!iov_iter_count(iter)) 1086 break; 1087 1088 if (ret < bvec->bv_len) 1089 return -EFAULT; 1090 } 1091 1092 return 0; 1093 } 1094 1095 /** 1096 * bio_copy_to_iter - copy all pages from bio to iov_iter 1097 * @bio: The &struct bio which describes the I/O as source 1098 * @iter: iov_iter as destination 1099 * 1100 * Copy all pages from bio to iov_iter. 1101 * Returns 0 on success, or error on failure. 1102 */ 1103 static int bio_copy_to_iter(struct bio *bio, struct iov_iter iter) 1104 { 1105 int i; 1106 struct bio_vec *bvec; 1107 1108 bio_for_each_segment_all(bvec, bio, i) { 1109 ssize_t ret; 1110 1111 ret = copy_page_to_iter(bvec->bv_page, 1112 bvec->bv_offset, 1113 bvec->bv_len, 1114 &iter); 1115 1116 if (!iov_iter_count(&iter)) 1117 break; 1118 1119 if (ret < bvec->bv_len) 1120 return -EFAULT; 1121 } 1122 1123 return 0; 1124 } 1125 1126 void bio_free_pages(struct bio *bio) 1127 { 1128 struct bio_vec *bvec; 1129 int i; 1130 1131 bio_for_each_segment_all(bvec, bio, i) 1132 __free_page(bvec->bv_page); 1133 } 1134 EXPORT_SYMBOL(bio_free_pages); 1135 1136 /** 1137 * bio_uncopy_user - finish previously mapped bio 1138 * @bio: bio being terminated 1139 * 1140 * Free pages allocated from bio_copy_user_iov() and write back data 1141 * to user space in case of a read. 1142 */ 1143 int bio_uncopy_user(struct bio *bio) 1144 { 1145 struct bio_map_data *bmd = bio->bi_private; 1146 int ret = 0; 1147 1148 if (!bio_flagged(bio, BIO_NULL_MAPPED)) { 1149 /* 1150 * if we're in a workqueue, the request is orphaned, so 1151 * don't copy into a random user address space, just free 1152 * and return -EINTR so user space doesn't expect any data. 1153 */ 1154 if (!current->mm) 1155 ret = -EINTR; 1156 else if (bio_data_dir(bio) == READ) 1157 ret = bio_copy_to_iter(bio, bmd->iter); 1158 if (bmd->is_our_pages) 1159 bio_free_pages(bio); 1160 } 1161 kfree(bmd); 1162 bio_put(bio); 1163 return ret; 1164 } 1165 1166 /** 1167 * bio_copy_user_iov - copy user data to bio 1168 * @q: destination block queue 1169 * @map_data: pointer to the rq_map_data holding pages (if necessary) 1170 * @iter: iovec iterator 1171 * @gfp_mask: memory allocation flags 1172 * 1173 * Prepares and returns a bio for indirect user io, bouncing data 1174 * to/from kernel pages as necessary. Must be paired with 1175 * call bio_uncopy_user() on io completion. 1176 */ 1177 struct bio *bio_copy_user_iov(struct request_queue *q, 1178 struct rq_map_data *map_data, 1179 struct iov_iter *iter, 1180 gfp_t gfp_mask) 1181 { 1182 struct bio_map_data *bmd; 1183 struct page *page; 1184 struct bio *bio; 1185 int i = 0, ret; 1186 int nr_pages; 1187 unsigned int len = iter->count; 1188 unsigned int offset = map_data ? offset_in_page(map_data->offset) : 0; 1189 1190 bmd = bio_alloc_map_data(iter, gfp_mask); 1191 if (!bmd) 1192 return ERR_PTR(-ENOMEM); 1193 1194 /* 1195 * We need to do a deep copy of the iov_iter including the iovecs. 1196 * The caller provided iov might point to an on-stack or otherwise 1197 * shortlived one. 1198 */ 1199 bmd->is_our_pages = map_data ? 0 : 1; 1200 1201 nr_pages = DIV_ROUND_UP(offset + len, PAGE_SIZE); 1202 if (nr_pages > BIO_MAX_PAGES) 1203 nr_pages = BIO_MAX_PAGES; 1204 1205 ret = -ENOMEM; 1206 bio = bio_kmalloc(gfp_mask, nr_pages); 1207 if (!bio) 1208 goto out_bmd; 1209 1210 ret = 0; 1211 1212 if (map_data) { 1213 nr_pages = 1 << map_data->page_order; 1214 i = map_data->offset / PAGE_SIZE; 1215 } 1216 while (len) { 1217 unsigned int bytes = PAGE_SIZE; 1218 1219 bytes -= offset; 1220 1221 if (bytes > len) 1222 bytes = len; 1223 1224 if (map_data) { 1225 if (i == map_data->nr_entries * nr_pages) { 1226 ret = -ENOMEM; 1227 break; 1228 } 1229 1230 page = map_data->pages[i / nr_pages]; 1231 page += (i % nr_pages); 1232 1233 i++; 1234 } else { 1235 page = alloc_page(q->bounce_gfp | gfp_mask); 1236 if (!page) { 1237 ret = -ENOMEM; 1238 break; 1239 } 1240 } 1241 1242 if (bio_add_pc_page(q, bio, page, bytes, offset) < bytes) 1243 break; 1244 1245 len -= bytes; 1246 offset = 0; 1247 } 1248 1249 if (ret) 1250 goto cleanup; 1251 1252 if (map_data) 1253 map_data->offset += bio->bi_iter.bi_size; 1254 1255 /* 1256 * success 1257 */ 1258 if (((iter->type & WRITE) && (!map_data || !map_data->null_mapped)) || 1259 (map_data && map_data->from_user)) { 1260 ret = bio_copy_from_iter(bio, iter); 1261 if (ret) 1262 goto cleanup; 1263 } else { 1264 iov_iter_advance(iter, bio->bi_iter.bi_size); 1265 } 1266 1267 bio->bi_private = bmd; 1268 if (map_data && map_data->null_mapped) 1269 bio_set_flag(bio, BIO_NULL_MAPPED); 1270 return bio; 1271 cleanup: 1272 if (!map_data) 1273 bio_free_pages(bio); 1274 bio_put(bio); 1275 out_bmd: 1276 kfree(bmd); 1277 return ERR_PTR(ret); 1278 } 1279 1280 /** 1281 * bio_map_user_iov - map user iovec into bio 1282 * @q: the struct request_queue for the bio 1283 * @iter: iovec iterator 1284 * @gfp_mask: memory allocation flags 1285 * 1286 * Map the user space address into a bio suitable for io to a block 1287 * device. Returns an error pointer in case of error. 1288 */ 1289 struct bio *bio_map_user_iov(struct request_queue *q, 1290 struct iov_iter *iter, 1291 gfp_t gfp_mask) 1292 { 1293 int j; 1294 struct bio *bio; 1295 int ret; 1296 struct bio_vec *bvec; 1297 1298 if (!iov_iter_count(iter)) 1299 return ERR_PTR(-EINVAL); 1300 1301 bio = bio_kmalloc(gfp_mask, iov_iter_npages(iter, BIO_MAX_PAGES)); 1302 if (!bio) 1303 return ERR_PTR(-ENOMEM); 1304 1305 while (iov_iter_count(iter)) { 1306 struct page **pages; 1307 ssize_t bytes; 1308 size_t offs, added = 0; 1309 int npages; 1310 1311 bytes = iov_iter_get_pages_alloc(iter, &pages, LONG_MAX, &offs); 1312 if (unlikely(bytes <= 0)) { 1313 ret = bytes ? bytes : -EFAULT; 1314 goto out_unmap; 1315 } 1316 1317 npages = DIV_ROUND_UP(offs + bytes, PAGE_SIZE); 1318 1319 if (unlikely(offs & queue_dma_alignment(q))) { 1320 ret = -EINVAL; 1321 j = 0; 1322 } else { 1323 for (j = 0; j < npages; j++) { 1324 struct page *page = pages[j]; 1325 unsigned int n = PAGE_SIZE - offs; 1326 unsigned short prev_bi_vcnt = bio->bi_vcnt; 1327 1328 if (n > bytes) 1329 n = bytes; 1330 1331 if (!bio_add_pc_page(q, bio, page, n, offs)) 1332 break; 1333 1334 /* 1335 * check if vector was merged with previous 1336 * drop page reference if needed 1337 */ 1338 if (bio->bi_vcnt == prev_bi_vcnt) 1339 put_page(page); 1340 1341 added += n; 1342 bytes -= n; 1343 offs = 0; 1344 } 1345 iov_iter_advance(iter, added); 1346 } 1347 /* 1348 * release the pages we didn't map into the bio, if any 1349 */ 1350 while (j < npages) 1351 put_page(pages[j++]); 1352 kvfree(pages); 1353 /* couldn't stuff something into bio? */ 1354 if (bytes) 1355 break; 1356 } 1357 1358 bio_set_flag(bio, BIO_USER_MAPPED); 1359 1360 /* 1361 * subtle -- if bio_map_user_iov() ended up bouncing a bio, 1362 * it would normally disappear when its bi_end_io is run. 1363 * however, we need it for the unmap, so grab an extra 1364 * reference to it 1365 */ 1366 bio_get(bio); 1367 return bio; 1368 1369 out_unmap: 1370 bio_for_each_segment_all(bvec, bio, j) { 1371 put_page(bvec->bv_page); 1372 } 1373 bio_put(bio); 1374 return ERR_PTR(ret); 1375 } 1376 1377 static void __bio_unmap_user(struct bio *bio) 1378 { 1379 struct bio_vec *bvec; 1380 int i; 1381 1382 /* 1383 * make sure we dirty pages we wrote to 1384 */ 1385 bio_for_each_segment_all(bvec, bio, i) { 1386 if (bio_data_dir(bio) == READ) 1387 set_page_dirty_lock(bvec->bv_page); 1388 1389 put_page(bvec->bv_page); 1390 } 1391 1392 bio_put(bio); 1393 } 1394 1395 /** 1396 * bio_unmap_user - unmap a bio 1397 * @bio: the bio being unmapped 1398 * 1399 * Unmap a bio previously mapped by bio_map_user_iov(). Must be called from 1400 * process context. 1401 * 1402 * bio_unmap_user() may sleep. 1403 */ 1404 void bio_unmap_user(struct bio *bio) 1405 { 1406 __bio_unmap_user(bio); 1407 bio_put(bio); 1408 } 1409 1410 static void bio_map_kern_endio(struct bio *bio) 1411 { 1412 bio_put(bio); 1413 } 1414 1415 /** 1416 * bio_map_kern - map kernel address into bio 1417 * @q: the struct request_queue for the bio 1418 * @data: pointer to buffer to map 1419 * @len: length in bytes 1420 * @gfp_mask: allocation flags for bio allocation 1421 * 1422 * Map the kernel address into a bio suitable for io to a block 1423 * device. Returns an error pointer in case of error. 1424 */ 1425 struct bio *bio_map_kern(struct request_queue *q, void *data, unsigned int len, 1426 gfp_t gfp_mask) 1427 { 1428 unsigned long kaddr = (unsigned long)data; 1429 unsigned long end = (kaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT; 1430 unsigned long start = kaddr >> PAGE_SHIFT; 1431 const int nr_pages = end - start; 1432 int offset, i; 1433 struct bio *bio; 1434 1435 bio = bio_kmalloc(gfp_mask, nr_pages); 1436 if (!bio) 1437 return ERR_PTR(-ENOMEM); 1438 1439 offset = offset_in_page(kaddr); 1440 for (i = 0; i < nr_pages; i++) { 1441 unsigned int bytes = PAGE_SIZE - offset; 1442 1443 if (len <= 0) 1444 break; 1445 1446 if (bytes > len) 1447 bytes = len; 1448 1449 if (bio_add_pc_page(q, bio, virt_to_page(data), bytes, 1450 offset) < bytes) { 1451 /* we don't support partial mappings */ 1452 bio_put(bio); 1453 return ERR_PTR(-EINVAL); 1454 } 1455 1456 data += bytes; 1457 len -= bytes; 1458 offset = 0; 1459 } 1460 1461 bio->bi_end_io = bio_map_kern_endio; 1462 return bio; 1463 } 1464 EXPORT_SYMBOL(bio_map_kern); 1465 1466 static void bio_copy_kern_endio(struct bio *bio) 1467 { 1468 bio_free_pages(bio); 1469 bio_put(bio); 1470 } 1471 1472 static void bio_copy_kern_endio_read(struct bio *bio) 1473 { 1474 char *p = bio->bi_private; 1475 struct bio_vec *bvec; 1476 int i; 1477 1478 bio_for_each_segment_all(bvec, bio, i) { 1479 memcpy(p, page_address(bvec->bv_page), bvec->bv_len); 1480 p += bvec->bv_len; 1481 } 1482 1483 bio_copy_kern_endio(bio); 1484 } 1485 1486 /** 1487 * bio_copy_kern - copy kernel address into bio 1488 * @q: the struct request_queue for the bio 1489 * @data: pointer to buffer to copy 1490 * @len: length in bytes 1491 * @gfp_mask: allocation flags for bio and page allocation 1492 * @reading: data direction is READ 1493 * 1494 * copy the kernel address into a bio suitable for io to a block 1495 * device. Returns an error pointer in case of error. 1496 */ 1497 struct bio *bio_copy_kern(struct request_queue *q, void *data, unsigned int len, 1498 gfp_t gfp_mask, int reading) 1499 { 1500 unsigned long kaddr = (unsigned long)data; 1501 unsigned long end = (kaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT; 1502 unsigned long start = kaddr >> PAGE_SHIFT; 1503 struct bio *bio; 1504 void *p = data; 1505 int nr_pages = 0; 1506 1507 /* 1508 * Overflow, abort 1509 */ 1510 if (end < start) 1511 return ERR_PTR(-EINVAL); 1512 1513 nr_pages = end - start; 1514 bio = bio_kmalloc(gfp_mask, nr_pages); 1515 if (!bio) 1516 return ERR_PTR(-ENOMEM); 1517 1518 while (len) { 1519 struct page *page; 1520 unsigned int bytes = PAGE_SIZE; 1521 1522 if (bytes > len) 1523 bytes = len; 1524 1525 page = alloc_page(q->bounce_gfp | gfp_mask); 1526 if (!page) 1527 goto cleanup; 1528 1529 if (!reading) 1530 memcpy(page_address(page), p, bytes); 1531 1532 if (bio_add_pc_page(q, bio, page, bytes, 0) < bytes) 1533 break; 1534 1535 len -= bytes; 1536 p += bytes; 1537 } 1538 1539 if (reading) { 1540 bio->bi_end_io = bio_copy_kern_endio_read; 1541 bio->bi_private = data; 1542 } else { 1543 bio->bi_end_io = bio_copy_kern_endio; 1544 } 1545 1546 return bio; 1547 1548 cleanup: 1549 bio_free_pages(bio); 1550 bio_put(bio); 1551 return ERR_PTR(-ENOMEM); 1552 } 1553 1554 /* 1555 * bio_set_pages_dirty() and bio_check_pages_dirty() are support functions 1556 * for performing direct-IO in BIOs. 1557 * 1558 * The problem is that we cannot run set_page_dirty() from interrupt context 1559 * because the required locks are not interrupt-safe. So what we can do is to 1560 * mark the pages dirty _before_ performing IO. And in interrupt context, 1561 * check that the pages are still dirty. If so, fine. If not, redirty them 1562 * in process context. 1563 * 1564 * We special-case compound pages here: normally this means reads into hugetlb 1565 * pages. The logic in here doesn't really work right for compound pages 1566 * because the VM does not uniformly chase down the head page in all cases. 1567 * But dirtiness of compound pages is pretty meaningless anyway: the VM doesn't 1568 * handle them at all. So we skip compound pages here at an early stage. 1569 * 1570 * Note that this code is very hard to test under normal circumstances because 1571 * direct-io pins the pages with get_user_pages(). This makes 1572 * is_page_cache_freeable return false, and the VM will not clean the pages. 1573 * But other code (eg, flusher threads) could clean the pages if they are mapped 1574 * pagecache. 1575 * 1576 * Simply disabling the call to bio_set_pages_dirty() is a good way to test the 1577 * deferred bio dirtying paths. 1578 */ 1579 1580 /* 1581 * bio_set_pages_dirty() will mark all the bio's pages as dirty. 1582 */ 1583 void bio_set_pages_dirty(struct bio *bio) 1584 { 1585 struct bio_vec *bvec; 1586 int i; 1587 1588 bio_for_each_segment_all(bvec, bio, i) { 1589 if (!PageCompound(bvec->bv_page)) 1590 set_page_dirty_lock(bvec->bv_page); 1591 } 1592 } 1593 EXPORT_SYMBOL_GPL(bio_set_pages_dirty); 1594 1595 static void bio_release_pages(struct bio *bio) 1596 { 1597 struct bio_vec *bvec; 1598 int i; 1599 1600 bio_for_each_segment_all(bvec, bio, i) 1601 put_page(bvec->bv_page); 1602 } 1603 1604 /* 1605 * bio_check_pages_dirty() will check that all the BIO's pages are still dirty. 1606 * If they are, then fine. If, however, some pages are clean then they must 1607 * have been written out during the direct-IO read. So we take another ref on 1608 * the BIO and re-dirty the pages in process context. 1609 * 1610 * It is expected that bio_check_pages_dirty() will wholly own the BIO from 1611 * here on. It will run one put_page() against each page and will run one 1612 * bio_put() against the BIO. 1613 */ 1614 1615 static void bio_dirty_fn(struct work_struct *work); 1616 1617 static DECLARE_WORK(bio_dirty_work, bio_dirty_fn); 1618 static DEFINE_SPINLOCK(bio_dirty_lock); 1619 static struct bio *bio_dirty_list; 1620 1621 /* 1622 * This runs in process context 1623 */ 1624 static void bio_dirty_fn(struct work_struct *work) 1625 { 1626 struct bio *bio, *next; 1627 1628 spin_lock_irq(&bio_dirty_lock); 1629 next = bio_dirty_list; 1630 bio_dirty_list = NULL; 1631 spin_unlock_irq(&bio_dirty_lock); 1632 1633 while ((bio = next) != NULL) { 1634 next = bio->bi_private; 1635 1636 bio_set_pages_dirty(bio); 1637 bio_release_pages(bio); 1638 bio_put(bio); 1639 } 1640 } 1641 1642 void bio_check_pages_dirty(struct bio *bio) 1643 { 1644 struct bio_vec *bvec; 1645 unsigned long flags; 1646 int i; 1647 1648 bio_for_each_segment_all(bvec, bio, i) { 1649 if (!PageDirty(bvec->bv_page) && !PageCompound(bvec->bv_page)) 1650 goto defer; 1651 } 1652 1653 bio_release_pages(bio); 1654 bio_put(bio); 1655 return; 1656 defer: 1657 spin_lock_irqsave(&bio_dirty_lock, flags); 1658 bio->bi_private = bio_dirty_list; 1659 bio_dirty_list = bio; 1660 spin_unlock_irqrestore(&bio_dirty_lock, flags); 1661 schedule_work(&bio_dirty_work); 1662 } 1663 EXPORT_SYMBOL_GPL(bio_check_pages_dirty); 1664 1665 void generic_start_io_acct(struct request_queue *q, int op, 1666 unsigned long sectors, struct hd_struct *part) 1667 { 1668 const int sgrp = op_stat_group(op); 1669 int cpu = part_stat_lock(); 1670 1671 part_round_stats(q, cpu, part); 1672 part_stat_inc(cpu, part, ios[sgrp]); 1673 part_stat_add(cpu, part, sectors[sgrp], sectors); 1674 part_inc_in_flight(q, part, op_is_write(op)); 1675 1676 part_stat_unlock(); 1677 } 1678 EXPORT_SYMBOL(generic_start_io_acct); 1679 1680 void generic_end_io_acct(struct request_queue *q, int req_op, 1681 struct hd_struct *part, unsigned long start_time) 1682 { 1683 unsigned long duration = jiffies - start_time; 1684 const int sgrp = op_stat_group(req_op); 1685 int cpu = part_stat_lock(); 1686 1687 part_stat_add(cpu, part, nsecs[sgrp], jiffies_to_nsecs(duration)); 1688 part_round_stats(q, cpu, part); 1689 part_dec_in_flight(q, part, op_is_write(req_op)); 1690 1691 part_stat_unlock(); 1692 } 1693 EXPORT_SYMBOL(generic_end_io_acct); 1694 1695 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 1696 void bio_flush_dcache_pages(struct bio *bi) 1697 { 1698 struct bio_vec bvec; 1699 struct bvec_iter iter; 1700 1701 bio_for_each_segment(bvec, bi, iter) 1702 flush_dcache_page(bvec.bv_page); 1703 } 1704 EXPORT_SYMBOL(bio_flush_dcache_pages); 1705 #endif 1706 1707 static inline bool bio_remaining_done(struct bio *bio) 1708 { 1709 /* 1710 * If we're not chaining, then ->__bi_remaining is always 1 and 1711 * we always end io on the first invocation. 1712 */ 1713 if (!bio_flagged(bio, BIO_CHAIN)) 1714 return true; 1715 1716 BUG_ON(atomic_read(&bio->__bi_remaining) <= 0); 1717 1718 if (atomic_dec_and_test(&bio->__bi_remaining)) { 1719 bio_clear_flag(bio, BIO_CHAIN); 1720 return true; 1721 } 1722 1723 return false; 1724 } 1725 1726 /** 1727 * bio_endio - end I/O on a bio 1728 * @bio: bio 1729 * 1730 * Description: 1731 * bio_endio() will end I/O on the whole bio. bio_endio() is the preferred 1732 * way to end I/O on a bio. No one should call bi_end_io() directly on a 1733 * bio unless they own it and thus know that it has an end_io function. 1734 * 1735 * bio_endio() can be called several times on a bio that has been chained 1736 * using bio_chain(). The ->bi_end_io() function will only be called the 1737 * last time. At this point the BLK_TA_COMPLETE tracing event will be 1738 * generated if BIO_TRACE_COMPLETION is set. 1739 **/ 1740 void bio_endio(struct bio *bio) 1741 { 1742 again: 1743 if (!bio_remaining_done(bio)) 1744 return; 1745 if (!bio_integrity_endio(bio)) 1746 return; 1747 1748 if (bio->bi_disk) 1749 rq_qos_done_bio(bio->bi_disk->queue, bio); 1750 1751 /* 1752 * Need to have a real endio function for chained bios, otherwise 1753 * various corner cases will break (like stacking block devices that 1754 * save/restore bi_end_io) - however, we want to avoid unbounded 1755 * recursion and blowing the stack. Tail call optimization would 1756 * handle this, but compiling with frame pointers also disables 1757 * gcc's sibling call optimization. 1758 */ 1759 if (bio->bi_end_io == bio_chain_endio) { 1760 bio = __bio_chain_endio(bio); 1761 goto again; 1762 } 1763 1764 if (bio->bi_disk && bio_flagged(bio, BIO_TRACE_COMPLETION)) { 1765 trace_block_bio_complete(bio->bi_disk->queue, bio, 1766 blk_status_to_errno(bio->bi_status)); 1767 bio_clear_flag(bio, BIO_TRACE_COMPLETION); 1768 } 1769 1770 blk_throtl_bio_endio(bio); 1771 /* release cgroup info */ 1772 bio_uninit(bio); 1773 if (bio->bi_end_io) 1774 bio->bi_end_io(bio); 1775 } 1776 EXPORT_SYMBOL(bio_endio); 1777 1778 /** 1779 * bio_split - split a bio 1780 * @bio: bio to split 1781 * @sectors: number of sectors to split from the front of @bio 1782 * @gfp: gfp mask 1783 * @bs: bio set to allocate from 1784 * 1785 * Allocates and returns a new bio which represents @sectors from the start of 1786 * @bio, and updates @bio to represent the remaining sectors. 1787 * 1788 * Unless this is a discard request the newly allocated bio will point 1789 * to @bio's bi_io_vec; it is the caller's responsibility to ensure that 1790 * @bio is not freed before the split. 1791 */ 1792 struct bio *bio_split(struct bio *bio, int sectors, 1793 gfp_t gfp, struct bio_set *bs) 1794 { 1795 struct bio *split; 1796 1797 BUG_ON(sectors <= 0); 1798 BUG_ON(sectors >= bio_sectors(bio)); 1799 1800 split = bio_clone_fast(bio, gfp, bs); 1801 if (!split) 1802 return NULL; 1803 1804 split->bi_iter.bi_size = sectors << 9; 1805 1806 if (bio_integrity(split)) 1807 bio_integrity_trim(split); 1808 1809 bio_advance(bio, split->bi_iter.bi_size); 1810 bio->bi_iter.bi_done = 0; 1811 1812 if (bio_flagged(bio, BIO_TRACE_COMPLETION)) 1813 bio_set_flag(split, BIO_TRACE_COMPLETION); 1814 1815 return split; 1816 } 1817 EXPORT_SYMBOL(bio_split); 1818 1819 /** 1820 * bio_trim - trim a bio 1821 * @bio: bio to trim 1822 * @offset: number of sectors to trim from the front of @bio 1823 * @size: size we want to trim @bio to, in sectors 1824 */ 1825 void bio_trim(struct bio *bio, int offset, int size) 1826 { 1827 /* 'bio' is a cloned bio which we need to trim to match 1828 * the given offset and size. 1829 */ 1830 1831 size <<= 9; 1832 if (offset == 0 && size == bio->bi_iter.bi_size) 1833 return; 1834 1835 bio_clear_flag(bio, BIO_SEG_VALID); 1836 1837 bio_advance(bio, offset << 9); 1838 1839 bio->bi_iter.bi_size = size; 1840 1841 if (bio_integrity(bio)) 1842 bio_integrity_trim(bio); 1843 1844 } 1845 EXPORT_SYMBOL_GPL(bio_trim); 1846 1847 /* 1848 * create memory pools for biovec's in a bio_set. 1849 * use the global biovec slabs created for general use. 1850 */ 1851 int biovec_init_pool(mempool_t *pool, int pool_entries) 1852 { 1853 struct biovec_slab *bp = bvec_slabs + BVEC_POOL_MAX; 1854 1855 return mempool_init_slab_pool(pool, pool_entries, bp->slab); 1856 } 1857 1858 /* 1859 * bioset_exit - exit a bioset initialized with bioset_init() 1860 * 1861 * May be called on a zeroed but uninitialized bioset (i.e. allocated with 1862 * kzalloc()). 1863 */ 1864 void bioset_exit(struct bio_set *bs) 1865 { 1866 if (bs->rescue_workqueue) 1867 destroy_workqueue(bs->rescue_workqueue); 1868 bs->rescue_workqueue = NULL; 1869 1870 mempool_exit(&bs->bio_pool); 1871 mempool_exit(&bs->bvec_pool); 1872 1873 bioset_integrity_free(bs); 1874 if (bs->bio_slab) 1875 bio_put_slab(bs); 1876 bs->bio_slab = NULL; 1877 } 1878 EXPORT_SYMBOL(bioset_exit); 1879 1880 /** 1881 * bioset_init - Initialize a bio_set 1882 * @bs: pool to initialize 1883 * @pool_size: Number of bio and bio_vecs to cache in the mempool 1884 * @front_pad: Number of bytes to allocate in front of the returned bio 1885 * @flags: Flags to modify behavior, currently %BIOSET_NEED_BVECS 1886 * and %BIOSET_NEED_RESCUER 1887 * 1888 * Description: 1889 * Set up a bio_set to be used with @bio_alloc_bioset. Allows the caller 1890 * to ask for a number of bytes to be allocated in front of the bio. 1891 * Front pad allocation is useful for embedding the bio inside 1892 * another structure, to avoid allocating extra data to go with the bio. 1893 * Note that the bio must be embedded at the END of that structure always, 1894 * or things will break badly. 1895 * If %BIOSET_NEED_BVECS is set in @flags, a separate pool will be allocated 1896 * for allocating iovecs. This pool is not needed e.g. for bio_clone_fast(). 1897 * If %BIOSET_NEED_RESCUER is set, a workqueue is created which can be used to 1898 * dispatch queued requests when the mempool runs out of space. 1899 * 1900 */ 1901 int bioset_init(struct bio_set *bs, 1902 unsigned int pool_size, 1903 unsigned int front_pad, 1904 int flags) 1905 { 1906 unsigned int back_pad = BIO_INLINE_VECS * sizeof(struct bio_vec); 1907 1908 bs->front_pad = front_pad; 1909 1910 spin_lock_init(&bs->rescue_lock); 1911 bio_list_init(&bs->rescue_list); 1912 INIT_WORK(&bs->rescue_work, bio_alloc_rescue); 1913 1914 bs->bio_slab = bio_find_or_create_slab(front_pad + back_pad); 1915 if (!bs->bio_slab) 1916 return -ENOMEM; 1917 1918 if (mempool_init_slab_pool(&bs->bio_pool, pool_size, bs->bio_slab)) 1919 goto bad; 1920 1921 if ((flags & BIOSET_NEED_BVECS) && 1922 biovec_init_pool(&bs->bvec_pool, pool_size)) 1923 goto bad; 1924 1925 if (!(flags & BIOSET_NEED_RESCUER)) 1926 return 0; 1927 1928 bs->rescue_workqueue = alloc_workqueue("bioset", WQ_MEM_RECLAIM, 0); 1929 if (!bs->rescue_workqueue) 1930 goto bad; 1931 1932 return 0; 1933 bad: 1934 bioset_exit(bs); 1935 return -ENOMEM; 1936 } 1937 EXPORT_SYMBOL(bioset_init); 1938 1939 /* 1940 * Initialize and setup a new bio_set, based on the settings from 1941 * another bio_set. 1942 */ 1943 int bioset_init_from_src(struct bio_set *bs, struct bio_set *src) 1944 { 1945 int flags; 1946 1947 flags = 0; 1948 if (src->bvec_pool.min_nr) 1949 flags |= BIOSET_NEED_BVECS; 1950 if (src->rescue_workqueue) 1951 flags |= BIOSET_NEED_RESCUER; 1952 1953 return bioset_init(bs, src->bio_pool.min_nr, src->front_pad, flags); 1954 } 1955 EXPORT_SYMBOL(bioset_init_from_src); 1956 1957 #ifdef CONFIG_BLK_CGROUP 1958 1959 #ifdef CONFIG_MEMCG 1960 /** 1961 * bio_associate_blkcg_from_page - associate a bio with the page's blkcg 1962 * @bio: target bio 1963 * @page: the page to lookup the blkcg from 1964 * 1965 * Associate @bio with the blkcg from @page's owning memcg. This works like 1966 * every other associate function wrt references. 1967 */ 1968 int bio_associate_blkcg_from_page(struct bio *bio, struct page *page) 1969 { 1970 struct cgroup_subsys_state *blkcg_css; 1971 1972 if (unlikely(bio->bi_css)) 1973 return -EBUSY; 1974 if (!page->mem_cgroup) 1975 return 0; 1976 blkcg_css = cgroup_get_e_css(page->mem_cgroup->css.cgroup, 1977 &io_cgrp_subsys); 1978 bio->bi_css = blkcg_css; 1979 return 0; 1980 } 1981 #endif /* CONFIG_MEMCG */ 1982 1983 /** 1984 * bio_associate_blkcg - associate a bio with the specified blkcg 1985 * @bio: target bio 1986 * @blkcg_css: css of the blkcg to associate 1987 * 1988 * Associate @bio with the blkcg specified by @blkcg_css. Block layer will 1989 * treat @bio as if it were issued by a task which belongs to the blkcg. 1990 * 1991 * This function takes an extra reference of @blkcg_css which will be put 1992 * when @bio is released. The caller must own @bio and is responsible for 1993 * synchronizing calls to this function. 1994 */ 1995 int bio_associate_blkcg(struct bio *bio, struct cgroup_subsys_state *blkcg_css) 1996 { 1997 if (unlikely(bio->bi_css)) 1998 return -EBUSY; 1999 css_get(blkcg_css); 2000 bio->bi_css = blkcg_css; 2001 return 0; 2002 } 2003 EXPORT_SYMBOL_GPL(bio_associate_blkcg); 2004 2005 /** 2006 * bio_associate_blkg - associate a bio with the specified blkg 2007 * @bio: target bio 2008 * @blkg: the blkg to associate 2009 * 2010 * Associate @bio with the blkg specified by @blkg. This is the queue specific 2011 * blkcg information associated with the @bio, a reference will be taken on the 2012 * @blkg and will be freed when the bio is freed. 2013 */ 2014 int bio_associate_blkg(struct bio *bio, struct blkcg_gq *blkg) 2015 { 2016 if (unlikely(bio->bi_blkg)) 2017 return -EBUSY; 2018 if (!blkg_try_get(blkg)) 2019 return -ENODEV; 2020 bio->bi_blkg = blkg; 2021 return 0; 2022 } 2023 2024 /** 2025 * bio_disassociate_task - undo bio_associate_current() 2026 * @bio: target bio 2027 */ 2028 void bio_disassociate_task(struct bio *bio) 2029 { 2030 if (bio->bi_ioc) { 2031 put_io_context(bio->bi_ioc); 2032 bio->bi_ioc = NULL; 2033 } 2034 if (bio->bi_css) { 2035 css_put(bio->bi_css); 2036 bio->bi_css = NULL; 2037 } 2038 if (bio->bi_blkg) { 2039 blkg_put(bio->bi_blkg); 2040 bio->bi_blkg = NULL; 2041 } 2042 } 2043 2044 /** 2045 * bio_clone_blkcg_association - clone blkcg association from src to dst bio 2046 * @dst: destination bio 2047 * @src: source bio 2048 */ 2049 void bio_clone_blkcg_association(struct bio *dst, struct bio *src) 2050 { 2051 if (src->bi_css) 2052 WARN_ON(bio_associate_blkcg(dst, src->bi_css)); 2053 } 2054 EXPORT_SYMBOL_GPL(bio_clone_blkcg_association); 2055 #endif /* CONFIG_BLK_CGROUP */ 2056 2057 static void __init biovec_init_slabs(void) 2058 { 2059 int i; 2060 2061 for (i = 0; i < BVEC_POOL_NR; i++) { 2062 int size; 2063 struct biovec_slab *bvs = bvec_slabs + i; 2064 2065 if (bvs->nr_vecs <= BIO_INLINE_VECS) { 2066 bvs->slab = NULL; 2067 continue; 2068 } 2069 2070 size = bvs->nr_vecs * sizeof(struct bio_vec); 2071 bvs->slab = kmem_cache_create(bvs->name, size, 0, 2072 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); 2073 } 2074 } 2075 2076 static int __init init_bio(void) 2077 { 2078 bio_slab_max = 2; 2079 bio_slab_nr = 0; 2080 bio_slabs = kcalloc(bio_slab_max, sizeof(struct bio_slab), 2081 GFP_KERNEL); 2082 if (!bio_slabs) 2083 panic("bio: can't allocate bios\n"); 2084 2085 bio_integrity_init(); 2086 biovec_init_slabs(); 2087 2088 if (bioset_init(&fs_bio_set, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS)) 2089 panic("bio: can't allocate bios\n"); 2090 2091 if (bioset_integrity_create(&fs_bio_set, BIO_POOL_SIZE)) 2092 panic("bio: can't create integrity pool\n"); 2093 2094 return 0; 2095 } 2096 subsys_initcall(init_bio); 2097