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