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 <scsi/sg.h>		/* for struct sg_iovec */
  32
  33#include <trace/events/block.h>
  34
  35/*
  36 * Test patch to inline a certain number of bi_io_vec's inside the bio
  37 * itself, to shrink a bio data allocation from two mempool calls to one
  38 */
  39#define BIO_INLINE_VECS		4
  40
 
 
  41/*
  42 * if you change this list, also change bvec_alloc or things will
  43 * break badly! cannot be bigger than what you can fit into an
  44 * unsigned short
  45 */
  46#define BV(x) { .nr_vecs = x, .name = "biovec-"__stringify(x) }
  47static struct biovec_slab bvec_slabs[BIOVEC_NR_POOLS] __read_mostly = {
  48	BV(1), BV(4), BV(16), BV(64), BV(128), BV(BIO_MAX_PAGES),
  49};
  50#undef BV
  51
  52/*
  53 * fs_bio_set is the bio_set containing bio and iovec memory pools used by
  54 * IO code that does not need private memory pools.
  55 */
  56struct bio_set *fs_bio_set;
  57EXPORT_SYMBOL(fs_bio_set);
  58
  59/*
  60 * Our slab pool management
  61 */
  62struct bio_slab {
  63	struct kmem_cache *slab;
  64	unsigned int slab_ref;
  65	unsigned int slab_size;
  66	char name[8];
  67};
  68static DEFINE_MUTEX(bio_slab_lock);
  69static struct bio_slab *bio_slabs;
  70static unsigned int bio_slab_nr, bio_slab_max;
  71
  72static struct kmem_cache *bio_find_or_create_slab(unsigned int extra_size)
  73{
  74	unsigned int sz = sizeof(struct bio) + extra_size;
  75	struct kmem_cache *slab = NULL;
  76	struct bio_slab *bslab, *new_bio_slabs;
  77	unsigned int new_bio_slab_max;
  78	unsigned int i, entry = -1;
  79
  80	mutex_lock(&bio_slab_lock);
  81
  82	i = 0;
  83	while (i < bio_slab_nr) {
  84		bslab = &bio_slabs[i];
  85
  86		if (!bslab->slab && entry == -1)
  87			entry = i;
  88		else if (bslab->slab_size == sz) {
  89			slab = bslab->slab;
  90			bslab->slab_ref++;
  91			break;
  92		}
  93		i++;
  94	}
  95
  96	if (slab)
  97		goto out_unlock;
  98
  99	if (bio_slab_nr == bio_slab_max && entry == -1) {
 100		new_bio_slab_max = bio_slab_max << 1;
 101		new_bio_slabs = krealloc(bio_slabs,
 102					 new_bio_slab_max * sizeof(struct bio_slab),
 103					 GFP_KERNEL);
 104		if (!new_bio_slabs)
 105			goto out_unlock;
 106		bio_slab_max = new_bio_slab_max;
 107		bio_slabs = new_bio_slabs;
 108	}
 109	if (entry == -1)
 110		entry = bio_slab_nr++;
 111
 112	bslab = &bio_slabs[entry];
 113
 114	snprintf(bslab->name, sizeof(bslab->name), "bio-%d", entry);
 115	slab = kmem_cache_create(bslab->name, sz, 0, 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;
 122out_unlock:
 123	mutex_unlock(&bio_slab_lock);
 124	return slab;
 125}
 126
 127static 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
 152out:
 153	mutex_unlock(&bio_slab_lock);
 154}
 155
 156unsigned int bvec_nr_vecs(unsigned short idx)
 157{
 158	return bvec_slabs[idx].nr_vecs;
 159}
 160
 161void 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
 174struct 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) {
 210fallback:
 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_WAIT | __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_WAIT
 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_WAIT))) {
 229			*idx = BIOVEC_MAX_IDX;
 230			goto fallback;
 231		}
 232	}
 233
 234	return bvl;
 235}
 236
 237static 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
 245static 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
 269void bio_init(struct bio *bio)
 270{
 271	memset(bio, 0, sizeof(*bio));
 272	bio->bi_flags = 1 << BIO_UPTODATE;
 273	atomic_set(&bio->bi_remaining, 1);
 274	atomic_set(&bio->bi_cnt, 1);
 275}
 276EXPORT_SYMBOL(bio_init);
 277
 278/**
 279 * bio_reset - reinitialize a bio
 280 * @bio:	bio to reset
 
 
 281 *
 282 * Description:
 283 *   After calling bio_reset(), @bio will be in the same state as a freshly
 284 *   allocated bio returned bio bio_alloc_bioset() - the only fields that are
 285 *   preserved are the ones that are initialized by bio_alloc_bioset(). See
 286 *   comment in struct bio.
 287 */
 288void bio_reset(struct bio *bio)
 
 
 
 289{
 290	unsigned long flags = bio->bi_flags & (~0UL << BIO_RESET_BITS);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 291
 292	__bio_free(bio);
 
 
 
 
 
 
 293
 294	memset(bio, 0, BIO_RESET_BYTES);
 295	bio->bi_flags = flags|(1 << BIO_UPTODATE);
 296	atomic_set(&bio->bi_remaining, 1);
 297}
 298EXPORT_SYMBOL(bio_reset);
 299
 300static void bio_chain_endio(struct bio *bio, int error)
 301{
 302	bio_endio(bio->bi_private, error);
 303	bio_put(bio);
 304}
 305
 306/**
 307 * bio_chain - chain bio completions
 
 
 
 
 
 
 308 *
 309 * The caller won't have a bi_end_io called when @bio completes - instead,
 310 * @parent's bi_end_io won't be called until both @parent and @bio have
 311 * completed; the chained bio will also be freed when it completes.
 
 
 
 312 *
 313 * The caller must not set bi_private or bi_end_io in @bio.
 
 314 */
 315void bio_chain(struct bio *bio, struct bio *parent)
 316{
 317	BUG_ON(bio->bi_private || bio->bi_end_io);
 318
 319	bio->bi_private = parent;
 320	bio->bi_end_io	= bio_chain_endio;
 321	atomic_inc(&parent->bi_remaining);
 322}
 323EXPORT_SYMBOL(bio_chain);
 324
 325static void bio_alloc_rescue(struct work_struct *work)
 326{
 327	struct bio_set *bs = container_of(work, struct bio_set, rescue_work);
 328	struct bio *bio;
 329
 330	while (1) {
 331		spin_lock(&bs->rescue_lock);
 332		bio = bio_list_pop(&bs->rescue_list);
 333		spin_unlock(&bs->rescue_lock);
 334
 335		if (!bio)
 336			break;
 337
 338		generic_make_request(bio);
 339	}
 340}
 
 341
 342static void punt_bios_to_rescuer(struct bio_set *bs)
 343{
 344	struct bio_list punt, nopunt;
 345	struct bio *bio;
 346
 347	/*
 348	 * In order to guarantee forward progress we must punt only bios that
 349	 * were allocated from this bio_set; otherwise, if there was a bio on
 350	 * there for a stacking driver higher up in the stack, processing it
 351	 * could require allocating bios from this bio_set, and doing that from
 352	 * our own rescuer would be bad.
 353	 *
 354	 * Since bio lists are singly linked, pop them all instead of trying to
 355	 * remove from the middle of the list:
 356	 */
 357
 358	bio_list_init(&punt);
 359	bio_list_init(&nopunt);
 360
 361	while ((bio = bio_list_pop(current->bio_list)))
 362		bio_list_add(bio->bi_pool == bs ? &punt : &nopunt, bio);
 363
 364	*current->bio_list = nopunt;
 365
 366	spin_lock(&bs->rescue_lock);
 367	bio_list_merge(&bs->rescue_list, &punt);
 368	spin_unlock(&bs->rescue_lock);
 369
 370	queue_work(bs->rescue_workqueue, &bs->rescue_work);
 371}
 372
 373/**
 374 * bio_alloc_bioset - allocate a bio for I/O
 375 * @gfp_mask:   the GFP_ mask given to the slab allocator
 376 * @nr_iovecs:	number of iovecs to pre-allocate
 377 * @bs:		the bio_set to allocate from.
 378 *
 379 * Description:
 380 *   If @bs is NULL, uses kmalloc() to allocate the bio; else the allocation is
 381 *   backed by the @bs's mempool.
 382 *
 383 *   When @bs is not NULL, if %__GFP_WAIT is set then bio_alloc will always be
 384 *   able to allocate a bio. This is due to the mempool guarantees. To make this
 385 *   work, callers must never allocate more than 1 bio at a time from this pool.
 386 *   Callers that need to allocate more than 1 bio must always submit the
 387 *   previously allocated bio for IO before attempting to allocate a new one.
 388 *   Failure to do so can cause deadlocks under memory pressure.
 389 *
 390 *   Note that when running under generic_make_request() (i.e. any block
 391 *   driver), bios are not submitted until after you return - see the code in
 392 *   generic_make_request() that converts recursion into iteration, to prevent
 393 *   stack overflows.
 394 *
 395 *   This would normally mean allocating multiple bios under
 396 *   generic_make_request() would be susceptible to deadlocks, but we have
 397 *   deadlock avoidance code that resubmits any blocked bios from a rescuer
 398 *   thread.
 399 *
 400 *   However, we do not guarantee forward progress for allocations from other
 401 *   mempools. Doing multiple allocations from the same mempool under
 402 *   generic_make_request() should be avoided - instead, use bio_set's front_pad
 403 *   for per bio allocations.
 404 *
 405 *   RETURNS:
 406 *   Pointer to new bio on success, NULL on failure.
 407 */
 408struct bio *bio_alloc_bioset(gfp_t gfp_mask, int nr_iovecs, struct bio_set *bs)
 409{
 410	gfp_t saved_gfp = gfp_mask;
 411	unsigned front_pad;
 412	unsigned inline_vecs;
 413	unsigned long idx = BIO_POOL_NONE;
 414	struct bio_vec *bvl = NULL;
 415	struct bio *bio;
 416	void *p;
 417
 418	if (!bs) {
 419		if (nr_iovecs > UIO_MAXIOV)
 420			return NULL;
 421
 422		p = kmalloc(sizeof(struct bio) +
 423			    nr_iovecs * sizeof(struct bio_vec),
 424			    gfp_mask);
 425		front_pad = 0;
 426		inline_vecs = nr_iovecs;
 427	} else {
 428		/*
 429		 * generic_make_request() converts recursion to iteration; this
 430		 * means if we're running beneath it, any bios we allocate and
 431		 * submit will not be submitted (and thus freed) until after we
 432		 * return.
 433		 *
 434		 * This exposes us to a potential deadlock if we allocate
 435		 * multiple bios from the same bio_set() while running
 436		 * underneath generic_make_request(). If we were to allocate
 437		 * multiple bios (say a stacking block driver that was splitting
 438		 * bios), we would deadlock if we exhausted the mempool's
 439		 * reserve.
 440		 *
 441		 * We solve this, and guarantee forward progress, with a rescuer
 442		 * workqueue per bio_set. If we go to allocate and there are
 443		 * bios on current->bio_list, we first try the allocation
 444		 * without __GFP_WAIT; if that fails, we punt those bios we
 445		 * would be blocking to the rescuer workqueue before we retry
 446		 * with the original gfp_flags.
 447		 */
 448
 449		if (current->bio_list && !bio_list_empty(current->bio_list))
 450			gfp_mask &= ~__GFP_WAIT;
 451
 452		p = mempool_alloc(bs->bio_pool, gfp_mask);
 453		if (!p && gfp_mask != saved_gfp) {
 454			punt_bios_to_rescuer(bs);
 455			gfp_mask = saved_gfp;
 456			p = mempool_alloc(bs->bio_pool, gfp_mask);
 457		}
 458
 459		front_pad = bs->front_pad;
 460		inline_vecs = BIO_INLINE_VECS;
 461	}
 462
 463	if (unlikely(!p))
 
 
 464		return NULL;
 465
 466	bio = p + front_pad;
 467	bio_init(bio);
 468
 469	if (nr_iovecs > inline_vecs) {
 470		bvl = bvec_alloc(gfp_mask, nr_iovecs, &idx, bs->bvec_pool);
 471		if (!bvl && gfp_mask != saved_gfp) {
 472			punt_bios_to_rescuer(bs);
 473			gfp_mask = saved_gfp;
 474			bvl = bvec_alloc(gfp_mask, nr_iovecs, &idx, bs->bvec_pool);
 475		}
 476
 477		if (unlikely(!bvl))
 478			goto err_free;
 479
 480		bio->bi_flags |= 1 << BIO_OWNS_VEC;
 481	} else if (nr_iovecs) {
 482		bvl = bio->bi_inline_vecs;
 483	}
 484
 485	bio->bi_pool = bs;
 486	bio->bi_flags |= idx << BIO_POOL_OFFSET;
 487	bio->bi_max_vecs = nr_iovecs;
 488	bio->bi_io_vec = bvl;
 489	return bio;
 490
 491err_free:
 492	mempool_free(p, bs->bio_pool);
 493	return NULL;
 494}
 495EXPORT_SYMBOL(bio_alloc_bioset);
 496
 497void zero_fill_bio(struct bio *bio)
 498{
 499	unsigned long flags;
 500	struct bio_vec bv;
 501	struct bvec_iter iter;
 502
 503	bio_for_each_segment(bv, bio, iter) {
 504		char *data = bvec_kmap_irq(&bv, &flags);
 505		memset(data, 0, bv.bv_len);
 506		flush_dcache_page(bv.bv_page);
 507		bvec_kunmap_irq(data, &flags);
 508	}
 509}
 510EXPORT_SYMBOL(zero_fill_bio);
 511
 512/**
 513 * bio_put - release a reference to a bio
 514 * @bio:   bio to release reference to
 515 *
 516 * Description:
 517 *   Put a reference to a &struct bio, either one you have gotten with
 518 *   bio_alloc, bio_get or bio_clone. The last put of a bio will free it.
 519 **/
 520void bio_put(struct bio *bio)
 521{
 522	BIO_BUG_ON(!atomic_read(&bio->bi_cnt));
 523
 524	/*
 525	 * last put frees it
 526	 */
 527	if (atomic_dec_and_test(&bio->bi_cnt))
 528		bio_free(bio);
 
 
 
 529}
 530EXPORT_SYMBOL(bio_put);
 531
 532inline int bio_phys_segments(struct request_queue *q, struct bio *bio)
 533{
 534	if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
 535		blk_recount_segments(q, bio);
 536
 537	return bio->bi_phys_segments;
 538}
 539EXPORT_SYMBOL(bio_phys_segments);
 540
 541/**
 542 * 	__bio_clone_fast - clone a bio that shares the original bio's biovec
 543 * 	@bio: destination bio
 544 * 	@bio_src: bio to clone
 545 *
 546 *	Clone a &bio. Caller will own the returned bio, but not
 547 *	the actual data it points to. Reference count of returned
 548 * 	bio will be one.
 549 *
 550 * 	Caller must ensure that @bio_src is not freed before @bio.
 551 */
 552void __bio_clone_fast(struct bio *bio, struct bio *bio_src)
 553{
 554	BUG_ON(bio->bi_pool && BIO_POOL_IDX(bio) != BIO_POOL_NONE);
 
 555
 556	/*
 557	 * most users will be overriding ->bi_bdev with a new target,
 558	 * so we don't set nor calculate new physical/hw segment counts here
 559	 */
 
 560	bio->bi_bdev = bio_src->bi_bdev;
 561	bio->bi_flags |= 1 << BIO_CLONED;
 562	bio->bi_rw = bio_src->bi_rw;
 563	bio->bi_iter = bio_src->bi_iter;
 564	bio->bi_io_vec = bio_src->bi_io_vec;
 
 565}
 566EXPORT_SYMBOL(__bio_clone_fast);
 567
 568/**
 569 *	bio_clone_fast - clone a bio that shares the original bio's biovec
 570 *	@bio: bio to clone
 571 *	@gfp_mask: allocation priority
 572 *	@bs: bio_set to allocate from
 573 *
 574 * 	Like __bio_clone_fast, only also allocates the returned bio
 575 */
 576struct bio *bio_clone_fast(struct bio *bio, gfp_t gfp_mask, struct bio_set *bs)
 577{
 578	struct bio *b;
 579
 580	b = bio_alloc_bioset(gfp_mask, 0, bs);
 581	if (!b)
 582		return NULL;
 583
 584	__bio_clone_fast(b, bio);
 
 585
 586	if (bio_integrity(bio)) {
 587		int ret;
 588
 589		ret = bio_integrity_clone(b, bio, gfp_mask);
 590
 591		if (ret < 0) {
 592			bio_put(b);
 593			return NULL;
 594		}
 595	}
 596
 597	return b;
 598}
 599EXPORT_SYMBOL(bio_clone_fast);
 600
 601/**
 602 * 	bio_clone_bioset - clone a bio
 603 * 	@bio_src: bio to clone
 604 *	@gfp_mask: allocation priority
 605 *	@bs: bio_set to allocate from
 606 *
 607 *	Clone bio. Caller will own the returned bio, but not the actual data it
 608 *	points to. Reference count of returned bio will be one.
 609 */
 610struct bio *bio_clone_bioset(struct bio *bio_src, gfp_t gfp_mask,
 611			     struct bio_set *bs)
 612{
 613	struct bvec_iter iter;
 614	struct bio_vec bv;
 615	struct bio *bio;
 616
 617	/*
 618	 * Pre immutable biovecs, __bio_clone() used to just do a memcpy from
 619	 * bio_src->bi_io_vec to bio->bi_io_vec.
 620	 *
 621	 * We can't do that anymore, because:
 622	 *
 623	 *  - The point of cloning the biovec is to produce a bio with a biovec
 624	 *    the caller can modify: bi_idx and bi_bvec_done should be 0.
 625	 *
 626	 *  - The original bio could've had more than BIO_MAX_PAGES biovecs; if
 627	 *    we tried to clone the whole thing bio_alloc_bioset() would fail.
 628	 *    But the clone should succeed as long as the number of biovecs we
 629	 *    actually need to allocate is fewer than BIO_MAX_PAGES.
 630	 *
 631	 *  - Lastly, bi_vcnt should not be looked at or relied upon by code
 632	 *    that does not own the bio - reason being drivers don't use it for
 633	 *    iterating over the biovec anymore, so expecting it to be kept up
 634	 *    to date (i.e. for clones that share the parent biovec) is just
 635	 *    asking for trouble and would force extra work on
 636	 *    __bio_clone_fast() anyways.
 637	 */
 638
 639	bio = bio_alloc_bioset(gfp_mask, bio_segments(bio_src), bs);
 640	if (!bio)
 641		return NULL;
 642
 643	bio->bi_bdev		= bio_src->bi_bdev;
 644	bio->bi_rw		= bio_src->bi_rw;
 645	bio->bi_iter.bi_sector	= bio_src->bi_iter.bi_sector;
 646	bio->bi_iter.bi_size	= bio_src->bi_iter.bi_size;
 647
 648	if (bio->bi_rw & REQ_DISCARD)
 649		goto integrity_clone;
 650
 651	if (bio->bi_rw & REQ_WRITE_SAME) {
 652		bio->bi_io_vec[bio->bi_vcnt++] = bio_src->bi_io_vec[0];
 653		goto integrity_clone;
 654	}
 655
 656	bio_for_each_segment(bv, bio_src, iter)
 657		bio->bi_io_vec[bio->bi_vcnt++] = bv;
 658
 659integrity_clone:
 660	if (bio_integrity(bio_src)) {
 661		int ret;
 662
 663		ret = bio_integrity_clone(bio, bio_src, gfp_mask);
 664		if (ret < 0) {
 665			bio_put(bio);
 666			return NULL;
 667		}
 668	}
 669
 670	return bio;
 671}
 672EXPORT_SYMBOL(bio_clone_bioset);
 673
 674/**
 675 *	bio_get_nr_vecs		- return approx number of vecs
 676 *	@bdev:  I/O target
 677 *
 678 *	Return the approximate number of pages we can send to this target.
 679 *	There's no guarantee that you will be able to fit this number of pages
 680 *	into a bio, it does not account for dynamic restrictions that vary
 681 *	on offset.
 682 */
 683int bio_get_nr_vecs(struct block_device *bdev)
 684{
 685	struct request_queue *q = bdev_get_queue(bdev);
 686	int nr_pages;
 687
 688	nr_pages = min_t(unsigned,
 689		     queue_max_segments(q),
 690		     queue_max_sectors(q) / (PAGE_SIZE >> 9) + 1);
 691
 692	return min_t(unsigned, nr_pages, BIO_MAX_PAGES);
 693
 694}
 695EXPORT_SYMBOL(bio_get_nr_vecs);
 696
 697static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page
 698			  *page, unsigned int len, unsigned int offset,
 699			  unsigned int max_sectors)
 700{
 701	int retried_segments = 0;
 702	struct bio_vec *bvec;
 703
 704	/*
 705	 * cloned bio must not modify vec list
 706	 */
 707	if (unlikely(bio_flagged(bio, BIO_CLONED)))
 708		return 0;
 709
 710	if (((bio->bi_iter.bi_size + len) >> 9) > max_sectors)
 711		return 0;
 712
 713	/*
 714	 * For filesystems with a blocksize smaller than the pagesize
 715	 * we will often be called with the same page as last time and
 716	 * a consecutive offset.  Optimize this special case.
 717	 */
 718	if (bio->bi_vcnt > 0) {
 719		struct bio_vec *prev = &bio->bi_io_vec[bio->bi_vcnt - 1];
 720
 721		if (page == prev->bv_page &&
 722		    offset == prev->bv_offset + prev->bv_len) {
 723			unsigned int prev_bv_len = prev->bv_len;
 724			prev->bv_len += len;
 725
 726			if (q->merge_bvec_fn) {
 727				struct bvec_merge_data bvm = {
 728					/* prev_bvec is already charged in
 729					   bi_size, discharge it in order to
 730					   simulate merging updated prev_bvec
 731					   as new bvec. */
 732					.bi_bdev = bio->bi_bdev,
 733					.bi_sector = bio->bi_iter.bi_sector,
 734					.bi_size = bio->bi_iter.bi_size -
 735						prev_bv_len,
 736					.bi_rw = bio->bi_rw,
 737				};
 738
 739				if (q->merge_bvec_fn(q, &bvm, prev) < prev->bv_len) {
 740					prev->bv_len -= len;
 741					return 0;
 742				}
 743			}
 744
 745			goto done;
 746		}
 747	}
 748
 749	if (bio->bi_vcnt >= bio->bi_max_vecs)
 750		return 0;
 751
 752	/*
 753	 * we might lose a segment or two here, but rather that than
 754	 * make this too complex.
 755	 */
 756
 757	while (bio->bi_phys_segments >= queue_max_segments(q)) {
 758
 759		if (retried_segments)
 760			return 0;
 761
 762		retried_segments = 1;
 763		blk_recount_segments(q, bio);
 764	}
 765
 766	/*
 767	 * setup the new entry, we might clear it again later if we
 768	 * cannot add the page
 769	 */
 770	bvec = &bio->bi_io_vec[bio->bi_vcnt];
 771	bvec->bv_page = page;
 772	bvec->bv_len = len;
 773	bvec->bv_offset = offset;
 774
 775	/*
 776	 * if queue has other restrictions (eg varying max sector size
 777	 * depending on offset), it can specify a merge_bvec_fn in the
 778	 * queue to get further control
 779	 */
 780	if (q->merge_bvec_fn) {
 781		struct bvec_merge_data bvm = {
 782			.bi_bdev = bio->bi_bdev,
 783			.bi_sector = bio->bi_iter.bi_sector,
 784			.bi_size = bio->bi_iter.bi_size,
 785			.bi_rw = bio->bi_rw,
 786		};
 787
 788		/*
 789		 * merge_bvec_fn() returns number of bytes it can accept
 790		 * at this offset
 791		 */
 792		if (q->merge_bvec_fn(q, &bvm, bvec) < bvec->bv_len) {
 793			bvec->bv_page = NULL;
 794			bvec->bv_len = 0;
 795			bvec->bv_offset = 0;
 796			return 0;
 797		}
 798	}
 799
 800	/* If we may be able to merge these biovecs, force a recount */
 801	if (bio->bi_vcnt && (BIOVEC_PHYS_MERGEABLE(bvec-1, bvec)))
 802		bio->bi_flags &= ~(1 << BIO_SEG_VALID);
 803
 804	bio->bi_vcnt++;
 805	bio->bi_phys_segments++;
 806 done:
 807	bio->bi_iter.bi_size += len;
 808	return len;
 809}
 810
 811/**
 812 *	bio_add_pc_page	-	attempt to add page to bio
 813 *	@q: the target queue
 814 *	@bio: destination bio
 815 *	@page: page to add
 816 *	@len: vec entry length
 817 *	@offset: vec entry offset
 818 *
 819 *	Attempt to add a page to the bio_vec maplist. This can fail for a
 820 *	number of reasons, such as the bio being full or target block device
 821 *	limitations. The target block device must allow bio's up to PAGE_SIZE,
 822 *	so it is always possible to add a single page to an empty bio.
 823 *
 824 *	This should only be used by REQ_PC bios.
 825 */
 826int bio_add_pc_page(struct request_queue *q, struct bio *bio, struct page *page,
 827		    unsigned int len, unsigned int offset)
 828{
 829	return __bio_add_page(q, bio, page, len, offset,
 830			      queue_max_hw_sectors(q));
 831}
 832EXPORT_SYMBOL(bio_add_pc_page);
 833
 834/**
 835 *	bio_add_page	-	attempt to add page to bio
 836 *	@bio: destination bio
 837 *	@page: page to add
 838 *	@len: vec entry length
 839 *	@offset: vec entry offset
 840 *
 841 *	Attempt to add a page to the bio_vec maplist. This can fail for a
 842 *	number of reasons, such as the bio being full or target block device
 843 *	limitations. The target block device must allow bio's up to PAGE_SIZE,
 844 *	so it is always possible to add a single page to an empty bio.
 845 */
 846int bio_add_page(struct bio *bio, struct page *page, unsigned int len,
 847		 unsigned int offset)
 848{
 849	struct request_queue *q = bdev_get_queue(bio->bi_bdev);
 850	return __bio_add_page(q, bio, page, len, offset, queue_max_sectors(q));
 851}
 852EXPORT_SYMBOL(bio_add_page);
 853
 854struct submit_bio_ret {
 855	struct completion event;
 856	int error;
 857};
 858
 859static void submit_bio_wait_endio(struct bio *bio, int error)
 860{
 861	struct submit_bio_ret *ret = bio->bi_private;
 862
 863	ret->error = error;
 864	complete(&ret->event);
 865}
 866
 867/**
 868 * submit_bio_wait - submit a bio, and wait until it completes
 869 * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead)
 870 * @bio: The &struct bio which describes the I/O
 871 *
 872 * Simple wrapper around submit_bio(). Returns 0 on success, or the error from
 873 * bio_endio() on failure.
 874 */
 875int submit_bio_wait(int rw, struct bio *bio)
 876{
 877	struct submit_bio_ret ret;
 878
 879	rw |= REQ_SYNC;
 880	init_completion(&ret.event);
 881	bio->bi_private = &ret;
 882	bio->bi_end_io = submit_bio_wait_endio;
 883	submit_bio(rw, bio);
 884	wait_for_completion(&ret.event);
 885
 886	return ret.error;
 887}
 888EXPORT_SYMBOL(submit_bio_wait);
 889
 890/**
 891 * bio_advance - increment/complete a bio by some number of bytes
 892 * @bio:	bio to advance
 893 * @bytes:	number of bytes to complete
 894 *
 895 * This updates bi_sector, bi_size and bi_idx; if the number of bytes to
 896 * complete doesn't align with a bvec boundary, then bv_len and bv_offset will
 897 * be updated on the last bvec as well.
 898 *
 899 * @bio will then represent the remaining, uncompleted portion of the io.
 900 */
 901void bio_advance(struct bio *bio, unsigned bytes)
 902{
 903	if (bio_integrity(bio))
 904		bio_integrity_advance(bio, bytes);
 905
 906	bio_advance_iter(bio, &bio->bi_iter, bytes);
 907}
 908EXPORT_SYMBOL(bio_advance);
 909
 910/**
 911 * bio_alloc_pages - allocates a single page for each bvec in a bio
 912 * @bio: bio to allocate pages for
 913 * @gfp_mask: flags for allocation
 914 *
 915 * Allocates pages up to @bio->bi_vcnt.
 916 *
 917 * Returns 0 on success, -ENOMEM on failure. On failure, any allocated pages are
 918 * freed.
 919 */
 920int bio_alloc_pages(struct bio *bio, gfp_t gfp_mask)
 921{
 922	int i;
 923	struct bio_vec *bv;
 924
 925	bio_for_each_segment_all(bv, bio, i) {
 926		bv->bv_page = alloc_page(gfp_mask);
 927		if (!bv->bv_page) {
 928			while (--bv >= bio->bi_io_vec)
 929				__free_page(bv->bv_page);
 930			return -ENOMEM;
 931		}
 932	}
 933
 934	return 0;
 935}
 936EXPORT_SYMBOL(bio_alloc_pages);
 937
 938/**
 939 * bio_copy_data - copy contents of data buffers from one chain of bios to
 940 * another
 941 * @src: source bio list
 942 * @dst: destination bio list
 943 *
 944 * If @src and @dst are single bios, bi_next must be NULL - otherwise, treats
 945 * @src and @dst as linked lists of bios.
 946 *
 947 * Stops when it reaches the end of either @src or @dst - that is, copies
 948 * min(src->bi_size, dst->bi_size) bytes (or the equivalent for lists of bios).
 949 */
 950void bio_copy_data(struct bio *dst, struct bio *src)
 951{
 952	struct bvec_iter src_iter, dst_iter;
 953	struct bio_vec src_bv, dst_bv;
 954	void *src_p, *dst_p;
 955	unsigned bytes;
 956
 957	src_iter = src->bi_iter;
 958	dst_iter = dst->bi_iter;
 959
 960	while (1) {
 961		if (!src_iter.bi_size) {
 962			src = src->bi_next;
 963			if (!src)
 964				break;
 965
 966			src_iter = src->bi_iter;
 967		}
 968
 969		if (!dst_iter.bi_size) {
 970			dst = dst->bi_next;
 971			if (!dst)
 972				break;
 973
 974			dst_iter = dst->bi_iter;
 975		}
 976
 977		src_bv = bio_iter_iovec(src, src_iter);
 978		dst_bv = bio_iter_iovec(dst, dst_iter);
 979
 980		bytes = min(src_bv.bv_len, dst_bv.bv_len);
 981
 982		src_p = kmap_atomic(src_bv.bv_page);
 983		dst_p = kmap_atomic(dst_bv.bv_page);
 984
 985		memcpy(dst_p + dst_bv.bv_offset,
 986		       src_p + src_bv.bv_offset,
 987		       bytes);
 988
 989		kunmap_atomic(dst_p);
 990		kunmap_atomic(src_p);
 991
 992		bio_advance_iter(src, &src_iter, bytes);
 993		bio_advance_iter(dst, &dst_iter, bytes);
 994	}
 995}
 996EXPORT_SYMBOL(bio_copy_data);
 997
 998struct bio_map_data {
 
 
 999	int nr_sgvecs;
1000	int is_our_pages;
1001	struct sg_iovec sgvecs[];
1002};
1003
1004static void bio_set_map_data(struct bio_map_data *bmd, struct bio *bio,
1005			     const struct sg_iovec *iov, int iov_count,
1006			     int is_our_pages)
1007{
 
1008	memcpy(bmd->sgvecs, iov, sizeof(struct sg_iovec) * iov_count);
1009	bmd->nr_sgvecs = iov_count;
1010	bmd->is_our_pages = is_our_pages;
1011	bio->bi_private = bmd;
1012}
1013
 
 
 
 
 
 
 
1014static struct bio_map_data *bio_alloc_map_data(int nr_segs,
1015					       unsigned int iov_count,
1016					       gfp_t gfp_mask)
1017{
 
 
1018	if (iov_count > UIO_MAXIOV)
1019		return NULL;
1020
1021	return kmalloc(sizeof(struct bio_map_data) +
1022		       sizeof(struct sg_iovec) * iov_count, gfp_mask);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1023}
1024
1025static int __bio_copy_iov(struct bio *bio, const struct sg_iovec *iov, int iov_count,
 
1026			  int to_user, int from_user, int do_free_page)
1027{
1028	int ret = 0, i;
1029	struct bio_vec *bvec;
1030	int iov_idx = 0;
1031	unsigned int iov_off = 0;
1032
1033	bio_for_each_segment_all(bvec, bio, i) {
1034		char *bv_addr = page_address(bvec->bv_page);
1035		unsigned int bv_len = bvec->bv_len;
1036
1037		while (bv_len && iov_idx < iov_count) {
1038			unsigned int bytes;
1039			char __user *iov_addr;
1040
1041			bytes = min_t(unsigned int,
1042				      iov[iov_idx].iov_len - iov_off, bv_len);
1043			iov_addr = iov[iov_idx].iov_base + iov_off;
1044
1045			if (!ret) {
1046				if (to_user)
1047					ret = copy_to_user(iov_addr, bv_addr,
1048							   bytes);
1049
1050				if (from_user)
1051					ret = copy_from_user(bv_addr, iov_addr,
1052							     bytes);
1053
1054				if (ret)
1055					ret = -EFAULT;
1056			}
1057
1058			bv_len -= bytes;
1059			bv_addr += bytes;
1060			iov_addr += bytes;
1061			iov_off += bytes;
1062
1063			if (iov[iov_idx].iov_len == iov_off) {
1064				iov_idx++;
1065				iov_off = 0;
1066			}
1067		}
1068
1069		if (do_free_page)
1070			__free_page(bvec->bv_page);
1071	}
1072
1073	return ret;
1074}
1075
1076/**
1077 *	bio_uncopy_user	-	finish previously mapped bio
1078 *	@bio: bio being terminated
1079 *
1080 *	Free pages allocated from bio_copy_user() and write back data
1081 *	to user space in case of a read.
1082 */
1083int bio_uncopy_user(struct bio *bio)
1084{
1085	struct bio_map_data *bmd = bio->bi_private;
1086	struct bio_vec *bvec;
1087	int ret = 0, i;
1088
1089	if (!bio_flagged(bio, BIO_NULL_MAPPED)) {
1090		/*
1091		 * if we're in a workqueue, the request is orphaned, so
1092		 * don't copy into a random user address space, just free.
1093		 */
1094		if (current->mm)
1095			ret = __bio_copy_iov(bio, bmd->sgvecs, bmd->nr_sgvecs,
1096					     bio_data_dir(bio) == READ,
1097					     0, bmd->is_our_pages);
1098		else if (bmd->is_our_pages)
1099			bio_for_each_segment_all(bvec, bio, i)
1100				__free_page(bvec->bv_page);
1101	}
1102	kfree(bmd);
1103	bio_put(bio);
1104	return ret;
1105}
1106EXPORT_SYMBOL(bio_uncopy_user);
1107
1108/**
1109 *	bio_copy_user_iov	-	copy user data to bio
1110 *	@q: destination block queue
1111 *	@map_data: pointer to the rq_map_data holding pages (if necessary)
1112 *	@iov:	the iovec.
1113 *	@iov_count: number of elements in the iovec
1114 *	@write_to_vm: bool indicating writing to pages or not
1115 *	@gfp_mask: memory allocation flags
1116 *
1117 *	Prepares and returns a bio for indirect user io, bouncing data
1118 *	to/from kernel pages as necessary. Must be paired with
1119 *	call bio_uncopy_user() on io completion.
1120 */
1121struct bio *bio_copy_user_iov(struct request_queue *q,
1122			      struct rq_map_data *map_data,
1123			      const struct sg_iovec *iov, int iov_count,
1124			      int write_to_vm, gfp_t gfp_mask)
1125{
1126	struct bio_map_data *bmd;
1127	struct bio_vec *bvec;
1128	struct page *page;
1129	struct bio *bio;
1130	int i, ret;
1131	int nr_pages = 0;
1132	unsigned int len = 0;
1133	unsigned int offset = map_data ? map_data->offset & ~PAGE_MASK : 0;
1134
1135	for (i = 0; i < iov_count; i++) {
1136		unsigned long uaddr;
1137		unsigned long end;
1138		unsigned long start;
1139
1140		uaddr = (unsigned long)iov[i].iov_base;
1141		end = (uaddr + iov[i].iov_len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1142		start = uaddr >> PAGE_SHIFT;
1143
1144		/*
1145		 * Overflow, abort
1146		 */
1147		if (end < start)
1148			return ERR_PTR(-EINVAL);
1149
1150		nr_pages += end - start;
1151		len += iov[i].iov_len;
1152	}
1153
1154	if (offset)
1155		nr_pages++;
1156
1157	bmd = bio_alloc_map_data(nr_pages, iov_count, gfp_mask);
1158	if (!bmd)
1159		return ERR_PTR(-ENOMEM);
1160
1161	ret = -ENOMEM;
1162	bio = bio_kmalloc(gfp_mask, nr_pages);
1163	if (!bio)
1164		goto out_bmd;
1165
1166	if (!write_to_vm)
1167		bio->bi_rw |= REQ_WRITE;
1168
1169	ret = 0;
1170
1171	if (map_data) {
1172		nr_pages = 1 << map_data->page_order;
1173		i = map_data->offset / PAGE_SIZE;
1174	}
1175	while (len) {
1176		unsigned int bytes = PAGE_SIZE;
1177
1178		bytes -= offset;
1179
1180		if (bytes > len)
1181			bytes = len;
1182
1183		if (map_data) {
1184			if (i == map_data->nr_entries * nr_pages) {
1185				ret = -ENOMEM;
1186				break;
1187			}
1188
1189			page = map_data->pages[i / nr_pages];
1190			page += (i % nr_pages);
1191
1192			i++;
1193		} else {
1194			page = alloc_page(q->bounce_gfp | gfp_mask);
1195			if (!page) {
1196				ret = -ENOMEM;
1197				break;
1198			}
1199		}
1200
1201		if (bio_add_pc_page(q, bio, page, bytes, offset) < bytes)
1202			break;
1203
1204		len -= bytes;
1205		offset = 0;
1206	}
1207
1208	if (ret)
1209		goto cleanup;
1210
1211	/*
1212	 * success
1213	 */
1214	if ((!write_to_vm && (!map_data || !map_data->null_mapped)) ||
1215	    (map_data && map_data->from_user)) {
1216		ret = __bio_copy_iov(bio, iov, iov_count, 0, 1, 0);
1217		if (ret)
1218			goto cleanup;
1219	}
1220
1221	bio_set_map_data(bmd, bio, iov, iov_count, map_data ? 0 : 1);
1222	return bio;
1223cleanup:
1224	if (!map_data)
1225		bio_for_each_segment_all(bvec, bio, i)
1226			__free_page(bvec->bv_page);
1227
1228	bio_put(bio);
1229out_bmd:
1230	kfree(bmd);
1231	return ERR_PTR(ret);
1232}
1233
1234/**
1235 *	bio_copy_user	-	copy user data to bio
1236 *	@q: destination block queue
1237 *	@map_data: pointer to the rq_map_data holding pages (if necessary)
1238 *	@uaddr: start of user address
1239 *	@len: length in bytes
1240 *	@write_to_vm: bool indicating writing to pages or not
1241 *	@gfp_mask: memory allocation flags
1242 *
1243 *	Prepares and returns a bio for indirect user io, bouncing data
1244 *	to/from kernel pages as necessary. Must be paired with
1245 *	call bio_uncopy_user() on io completion.
1246 */
1247struct bio *bio_copy_user(struct request_queue *q, struct rq_map_data *map_data,
1248			  unsigned long uaddr, unsigned int len,
1249			  int write_to_vm, gfp_t gfp_mask)
1250{
1251	struct sg_iovec iov;
1252
1253	iov.iov_base = (void __user *)uaddr;
1254	iov.iov_len = len;
1255
1256	return bio_copy_user_iov(q, map_data, &iov, 1, write_to_vm, gfp_mask);
1257}
1258EXPORT_SYMBOL(bio_copy_user);
1259
1260static struct bio *__bio_map_user_iov(struct request_queue *q,
1261				      struct block_device *bdev,
1262				      const struct sg_iovec *iov, int iov_count,
1263				      int write_to_vm, gfp_t gfp_mask)
1264{
1265	int i, j;
1266	int nr_pages = 0;
1267	struct page **pages;
1268	struct bio *bio;
1269	int cur_page = 0;
1270	int ret, offset;
1271
1272	for (i = 0; i < iov_count; i++) {
1273		unsigned long uaddr = (unsigned long)iov[i].iov_base;
1274		unsigned long len = iov[i].iov_len;
1275		unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1276		unsigned long start = uaddr >> PAGE_SHIFT;
1277
1278		/*
1279		 * Overflow, abort
1280		 */
1281		if (end < start)
1282			return ERR_PTR(-EINVAL);
1283
1284		nr_pages += end - start;
1285		/*
1286		 * buffer must be aligned to at least hardsector size for now
1287		 */
1288		if (uaddr & queue_dma_alignment(q))
1289			return ERR_PTR(-EINVAL);
1290	}
1291
1292	if (!nr_pages)
1293		return ERR_PTR(-EINVAL);
1294
1295	bio = bio_kmalloc(gfp_mask, nr_pages);
1296	if (!bio)
1297		return ERR_PTR(-ENOMEM);
1298
1299	ret = -ENOMEM;
1300	pages = kcalloc(nr_pages, sizeof(struct page *), gfp_mask);
1301	if (!pages)
1302		goto out;
1303
1304	for (i = 0; i < iov_count; i++) {
1305		unsigned long uaddr = (unsigned long)iov[i].iov_base;
1306		unsigned long len = iov[i].iov_len;
1307		unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1308		unsigned long start = uaddr >> PAGE_SHIFT;
1309		const int local_nr_pages = end - start;
1310		const int page_limit = cur_page + local_nr_pages;
1311
1312		ret = get_user_pages_fast(uaddr, local_nr_pages,
1313				write_to_vm, &pages[cur_page]);
1314		if (ret < local_nr_pages) {
1315			ret = -EFAULT;
1316			goto out_unmap;
1317		}
1318
1319		offset = uaddr & ~PAGE_MASK;
1320		for (j = cur_page; j < page_limit; j++) {
1321			unsigned int bytes = PAGE_SIZE - offset;
1322
1323			if (len <= 0)
1324				break;
1325			
1326			if (bytes > len)
1327				bytes = len;
1328
1329			/*
1330			 * sorry...
1331			 */
1332			if (bio_add_pc_page(q, bio, pages[j], bytes, offset) <
1333					    bytes)
1334				break;
1335
1336			len -= bytes;
1337			offset = 0;
1338		}
1339
1340		cur_page = j;
1341		/*
1342		 * release the pages we didn't map into the bio, if any
1343		 */
1344		while (j < page_limit)
1345			page_cache_release(pages[j++]);
1346	}
1347
1348	kfree(pages);
1349
1350	/*
1351	 * set data direction, and check if mapped pages need bouncing
1352	 */
1353	if (!write_to_vm)
1354		bio->bi_rw |= REQ_WRITE;
1355
1356	bio->bi_bdev = bdev;
1357	bio->bi_flags |= (1 << BIO_USER_MAPPED);
1358	return bio;
1359
1360 out_unmap:
1361	for (i = 0; i < nr_pages; i++) {
1362		if(!pages[i])
1363			break;
1364		page_cache_release(pages[i]);
1365	}
1366 out:
1367	kfree(pages);
1368	bio_put(bio);
1369	return ERR_PTR(ret);
1370}
1371
1372/**
1373 *	bio_map_user	-	map user address into bio
1374 *	@q: the struct request_queue for the bio
1375 *	@bdev: destination block device
1376 *	@uaddr: start of user address
1377 *	@len: length in bytes
1378 *	@write_to_vm: bool indicating writing to pages or not
1379 *	@gfp_mask: memory allocation flags
1380 *
1381 *	Map the user space address into a bio suitable for io to a block
1382 *	device. Returns an error pointer in case of error.
1383 */
1384struct bio *bio_map_user(struct request_queue *q, struct block_device *bdev,
1385			 unsigned long uaddr, unsigned int len, int write_to_vm,
1386			 gfp_t gfp_mask)
1387{
1388	struct sg_iovec iov;
1389
1390	iov.iov_base = (void __user *)uaddr;
1391	iov.iov_len = len;
1392
1393	return bio_map_user_iov(q, bdev, &iov, 1, write_to_vm, gfp_mask);
1394}
1395EXPORT_SYMBOL(bio_map_user);
1396
1397/**
1398 *	bio_map_user_iov - map user sg_iovec table into bio
1399 *	@q: the struct request_queue for the bio
1400 *	@bdev: destination block device
1401 *	@iov:	the iovec.
1402 *	@iov_count: number of elements in the iovec
1403 *	@write_to_vm: bool indicating writing to pages or not
1404 *	@gfp_mask: memory allocation flags
1405 *
1406 *	Map the user space address into a bio suitable for io to a block
1407 *	device. Returns an error pointer in case of error.
1408 */
1409struct bio *bio_map_user_iov(struct request_queue *q, struct block_device *bdev,
1410			     const struct sg_iovec *iov, int iov_count,
1411			     int write_to_vm, gfp_t gfp_mask)
1412{
1413	struct bio *bio;
1414
1415	bio = __bio_map_user_iov(q, bdev, iov, iov_count, write_to_vm,
1416				 gfp_mask);
1417	if (IS_ERR(bio))
1418		return bio;
1419
1420	/*
1421	 * subtle -- if __bio_map_user() ended up bouncing a bio,
1422	 * it would normally disappear when its bi_end_io is run.
1423	 * however, we need it for the unmap, so grab an extra
1424	 * reference to it
1425	 */
1426	bio_get(bio);
1427
1428	return bio;
1429}
1430
1431static void __bio_unmap_user(struct bio *bio)
1432{
1433	struct bio_vec *bvec;
1434	int i;
1435
1436	/*
1437	 * make sure we dirty pages we wrote to
1438	 */
1439	bio_for_each_segment_all(bvec, bio, i) {
1440		if (bio_data_dir(bio) == READ)
1441			set_page_dirty_lock(bvec->bv_page);
1442
1443		page_cache_release(bvec->bv_page);
1444	}
1445
1446	bio_put(bio);
1447}
1448
1449/**
1450 *	bio_unmap_user	-	unmap a bio
1451 *	@bio:		the bio being unmapped
1452 *
1453 *	Unmap a bio previously mapped by bio_map_user(). Must be called with
1454 *	a process context.
1455 *
1456 *	bio_unmap_user() may sleep.
1457 */
1458void bio_unmap_user(struct bio *bio)
1459{
1460	__bio_unmap_user(bio);
1461	bio_put(bio);
1462}
1463EXPORT_SYMBOL(bio_unmap_user);
1464
1465static void bio_map_kern_endio(struct bio *bio, int err)
1466{
1467	bio_put(bio);
1468}
1469
1470static struct bio *__bio_map_kern(struct request_queue *q, void *data,
1471				  unsigned int len, gfp_t gfp_mask)
1472{
1473	unsigned long kaddr = (unsigned long)data;
1474	unsigned long end = (kaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1475	unsigned long start = kaddr >> PAGE_SHIFT;
1476	const int nr_pages = end - start;
1477	int offset, i;
1478	struct bio *bio;
1479
1480	bio = bio_kmalloc(gfp_mask, nr_pages);
1481	if (!bio)
1482		return ERR_PTR(-ENOMEM);
1483
1484	offset = offset_in_page(kaddr);
1485	for (i = 0; i < nr_pages; i++) {
1486		unsigned int bytes = PAGE_SIZE - offset;
1487
1488		if (len <= 0)
1489			break;
1490
1491		if (bytes > len)
1492			bytes = len;
1493
1494		if (bio_add_pc_page(q, bio, virt_to_page(data), bytes,
1495				    offset) < bytes)
1496			break;
1497
1498		data += bytes;
1499		len -= bytes;
1500		offset = 0;
1501	}
1502
1503	bio->bi_end_io = bio_map_kern_endio;
1504	return bio;
1505}
1506
1507/**
1508 *	bio_map_kern	-	map kernel address into bio
1509 *	@q: the struct request_queue for the bio
1510 *	@data: pointer to buffer to map
1511 *	@len: length in bytes
1512 *	@gfp_mask: allocation flags for bio allocation
1513 *
1514 *	Map the kernel address into a bio suitable for io to a block
1515 *	device. Returns an error pointer in case of error.
1516 */
1517struct bio *bio_map_kern(struct request_queue *q, void *data, unsigned int len,
1518			 gfp_t gfp_mask)
1519{
1520	struct bio *bio;
1521
1522	bio = __bio_map_kern(q, data, len, gfp_mask);
1523	if (IS_ERR(bio))
1524		return bio;
1525
1526	if (bio->bi_iter.bi_size == len)
1527		return bio;
1528
1529	/*
1530	 * Don't support partial mappings.
1531	 */
1532	bio_put(bio);
1533	return ERR_PTR(-EINVAL);
1534}
1535EXPORT_SYMBOL(bio_map_kern);
1536
1537static void bio_copy_kern_endio(struct bio *bio, int err)
1538{
1539	struct bio_vec *bvec;
1540	const int read = bio_data_dir(bio) == READ;
1541	struct bio_map_data *bmd = bio->bi_private;
1542	int i;
1543	char *p = bmd->sgvecs[0].iov_base;
1544
1545	bio_for_each_segment_all(bvec, bio, i) {
1546		char *addr = page_address(bvec->bv_page);
 
1547
1548		if (read)
1549			memcpy(p, addr, bvec->bv_len);
1550
1551		__free_page(bvec->bv_page);
1552		p += bvec->bv_len;
1553	}
1554
1555	kfree(bmd);
1556	bio_put(bio);
1557}
1558
1559/**
1560 *	bio_copy_kern	-	copy kernel address into bio
1561 *	@q: the struct request_queue for the bio
1562 *	@data: pointer to buffer to copy
1563 *	@len: length in bytes
1564 *	@gfp_mask: allocation flags for bio and page allocation
1565 *	@reading: data direction is READ
1566 *
1567 *	copy the kernel address into a bio suitable for io to a block
1568 *	device. Returns an error pointer in case of error.
1569 */
1570struct bio *bio_copy_kern(struct request_queue *q, void *data, unsigned int len,
1571			  gfp_t gfp_mask, int reading)
1572{
1573	struct bio *bio;
1574	struct bio_vec *bvec;
1575	int i;
1576
1577	bio = bio_copy_user(q, NULL, (unsigned long)data, len, 1, gfp_mask);
1578	if (IS_ERR(bio))
1579		return bio;
1580
1581	if (!reading) {
1582		void *p = data;
1583
1584		bio_for_each_segment_all(bvec, bio, i) {
1585			char *addr = page_address(bvec->bv_page);
1586
1587			memcpy(addr, p, bvec->bv_len);
1588			p += bvec->bv_len;
1589		}
1590	}
1591
1592	bio->bi_end_io = bio_copy_kern_endio;
1593
1594	return bio;
1595}
1596EXPORT_SYMBOL(bio_copy_kern);
1597
1598/*
1599 * bio_set_pages_dirty() and bio_check_pages_dirty() are support functions
1600 * for performing direct-IO in BIOs.
1601 *
1602 * The problem is that we cannot run set_page_dirty() from interrupt context
1603 * because the required locks are not interrupt-safe.  So what we can do is to
1604 * mark the pages dirty _before_ performing IO.  And in interrupt context,
1605 * check that the pages are still dirty.   If so, fine.  If not, redirty them
1606 * in process context.
1607 *
1608 * We special-case compound pages here: normally this means reads into hugetlb
1609 * pages.  The logic in here doesn't really work right for compound pages
1610 * because the VM does not uniformly chase down the head page in all cases.
1611 * But dirtiness of compound pages is pretty meaningless anyway: the VM doesn't
1612 * handle them at all.  So we skip compound pages here at an early stage.
1613 *
1614 * Note that this code is very hard to test under normal circumstances because
1615 * direct-io pins the pages with get_user_pages().  This makes
1616 * is_page_cache_freeable return false, and the VM will not clean the pages.
1617 * But other code (eg, flusher threads) could clean the pages if they are mapped
1618 * pagecache.
1619 *
1620 * Simply disabling the call to bio_set_pages_dirty() is a good way to test the
1621 * deferred bio dirtying paths.
1622 */
1623
1624/*
1625 * bio_set_pages_dirty() will mark all the bio's pages as dirty.
1626 */
1627void bio_set_pages_dirty(struct bio *bio)
1628{
1629	struct bio_vec *bvec;
1630	int i;
1631
1632	bio_for_each_segment_all(bvec, bio, i) {
1633		struct page *page = bvec->bv_page;
1634
1635		if (page && !PageCompound(page))
1636			set_page_dirty_lock(page);
1637	}
1638}
1639
1640static void bio_release_pages(struct bio *bio)
1641{
1642	struct bio_vec *bvec;
1643	int i;
1644
1645	bio_for_each_segment_all(bvec, bio, i) {
1646		struct page *page = bvec->bv_page;
1647
1648		if (page)
1649			put_page(page);
1650	}
1651}
1652
1653/*
1654 * bio_check_pages_dirty() will check that all the BIO's pages are still dirty.
1655 * If they are, then fine.  If, however, some pages are clean then they must
1656 * have been written out during the direct-IO read.  So we take another ref on
1657 * the BIO and the offending pages and re-dirty the pages in process context.
1658 *
1659 * It is expected that bio_check_pages_dirty() will wholly own the BIO from
1660 * here on.  It will run one page_cache_release() against each page and will
1661 * run one bio_put() against the BIO.
1662 */
1663
1664static void bio_dirty_fn(struct work_struct *work);
1665
1666static DECLARE_WORK(bio_dirty_work, bio_dirty_fn);
1667static DEFINE_SPINLOCK(bio_dirty_lock);
1668static struct bio *bio_dirty_list;
1669
1670/*
1671 * This runs in process context
1672 */
1673static void bio_dirty_fn(struct work_struct *work)
1674{
1675	unsigned long flags;
1676	struct bio *bio;
1677
1678	spin_lock_irqsave(&bio_dirty_lock, flags);
1679	bio = bio_dirty_list;
1680	bio_dirty_list = NULL;
1681	spin_unlock_irqrestore(&bio_dirty_lock, flags);
1682
1683	while (bio) {
1684		struct bio *next = bio->bi_private;
1685
1686		bio_set_pages_dirty(bio);
1687		bio_release_pages(bio);
1688		bio_put(bio);
1689		bio = next;
1690	}
1691}
1692
1693void bio_check_pages_dirty(struct bio *bio)
1694{
1695	struct bio_vec *bvec;
1696	int nr_clean_pages = 0;
1697	int i;
1698
1699	bio_for_each_segment_all(bvec, bio, i) {
1700		struct page *page = bvec->bv_page;
1701
1702		if (PageDirty(page) || PageCompound(page)) {
1703			page_cache_release(page);
1704			bvec->bv_page = NULL;
1705		} else {
1706			nr_clean_pages++;
1707		}
1708	}
1709
1710	if (nr_clean_pages) {
1711		unsigned long flags;
1712
1713		spin_lock_irqsave(&bio_dirty_lock, flags);
1714		bio->bi_private = bio_dirty_list;
1715		bio_dirty_list = bio;
1716		spin_unlock_irqrestore(&bio_dirty_lock, flags);
1717		schedule_work(&bio_dirty_work);
1718	} else {
1719		bio_put(bio);
1720	}
1721}
1722
1723#if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
1724void bio_flush_dcache_pages(struct bio *bi)
1725{
1726	struct bio_vec bvec;
1727	struct bvec_iter iter;
1728
1729	bio_for_each_segment(bvec, bi, iter)
1730		flush_dcache_page(bvec.bv_page);
1731}
1732EXPORT_SYMBOL(bio_flush_dcache_pages);
1733#endif
1734
1735/**
1736 * bio_endio - end I/O on a bio
1737 * @bio:	bio
1738 * @error:	error, if any
1739 *
1740 * Description:
1741 *   bio_endio() will end I/O on the whole bio. bio_endio() is the
1742 *   preferred way to end I/O on a bio, it takes care of clearing
1743 *   BIO_UPTODATE on error. @error is 0 on success, and and one of the
1744 *   established -Exxxx (-EIO, for instance) error values in case
1745 *   something went wrong. No one should call bi_end_io() directly on a
1746 *   bio unless they own it and thus know that it has an end_io
1747 *   function.
1748 **/
1749void bio_endio(struct bio *bio, int error)
1750{
1751	while (bio) {
1752		BUG_ON(atomic_read(&bio->bi_remaining) <= 0);
 
 
1753
1754		if (error)
1755			clear_bit(BIO_UPTODATE, &bio->bi_flags);
1756		else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
1757			error = -EIO;
1758
1759		if (!atomic_dec_and_test(&bio->bi_remaining))
1760			return;
 
 
1761
1762		/*
1763		 * Need to have a real endio function for chained bios,
1764		 * otherwise various corner cases will break (like stacking
1765		 * block devices that save/restore bi_end_io) - however, we want
1766		 * to avoid unbounded recursion and blowing the stack. Tail call
1767		 * optimization would handle this, but compiling with frame
1768		 * pointers also disables gcc's sibling call optimization.
1769		 */
1770		if (bio->bi_end_io == bio_chain_endio) {
1771			struct bio *parent = bio->bi_private;
1772			bio_put(bio);
1773			bio = parent;
1774		} else {
1775			if (bio->bi_end_io)
1776				bio->bi_end_io(bio, error);
1777			bio = NULL;
1778		}
1779	}
1780}
1781EXPORT_SYMBOL(bio_endio);
1782
1783/**
1784 * bio_endio_nodec - end I/O on a bio, without decrementing bi_remaining
1785 * @bio:	bio
1786 * @error:	error, if any
1787 *
1788 * For code that has saved and restored bi_end_io; thing hard before using this
1789 * function, probably you should've cloned the entire bio.
1790 **/
1791void bio_endio_nodec(struct bio *bio, int error)
1792{
1793	atomic_inc(&bio->bi_remaining);
1794	bio_endio(bio, error);
 
 
 
 
1795}
1796EXPORT_SYMBOL(bio_endio_nodec);
1797
1798/**
1799 * bio_split - split a bio
1800 * @bio:	bio to split
1801 * @sectors:	number of sectors to split from the front of @bio
1802 * @gfp:	gfp mask
1803 * @bs:		bio set to allocate from
1804 *
1805 * Allocates and returns a new bio which represents @sectors from the start of
1806 * @bio, and updates @bio to represent the remaining sectors.
1807 *
1808 * The newly allocated bio will point to @bio's bi_io_vec; it is the caller's
1809 * responsibility to ensure that @bio is not freed before the split.
1810 */
1811struct bio *bio_split(struct bio *bio, int sectors,
1812		      gfp_t gfp, struct bio_set *bs)
1813{
1814	struct bio *split = NULL;
1815
1816	BUG_ON(sectors <= 0);
1817	BUG_ON(sectors >= bio_sectors(bio));
1818
1819	split = bio_clone_fast(bio, gfp, bs);
1820	if (!split)
1821		return NULL;
1822
1823	split->bi_iter.bi_size = sectors << 9;
 
 
 
 
 
 
 
 
1824
1825	if (bio_integrity(split))
1826		bio_integrity_trim(split, 0, sectors);
 
 
 
1827
1828	bio_advance(bio, split->bi_iter.bi_size);
 
1829
1830	return split;
 
 
 
 
 
 
 
 
 
 
 
 
1831}
1832EXPORT_SYMBOL(bio_split);
1833
1834/**
1835 * bio_trim - trim a bio
1836 * @bio:	bio to trim
1837 * @offset:	number of sectors to trim from the front of @bio
1838 * @size:	size we want to trim @bio to, in sectors
 
 
 
 
1839 */
1840void bio_trim(struct bio *bio, int offset, int size)
 
1841{
1842	/* 'bio' is a cloned bio which we need to trim to match
1843	 * the given offset and size.
1844	 */
 
 
 
 
1845
1846	size <<= 9;
1847	if (offset == 0 && size == bio->bi_iter.bi_size)
1848		return;
1849
1850	clear_bit(BIO_SEG_VALID, &bio->bi_flags);
 
 
 
 
 
1851
1852	bio_advance(bio, offset << 9);
 
1853
1854	bio->bi_iter.bi_size = size;
1855}
1856EXPORT_SYMBOL_GPL(bio_trim);
1857
1858/*
1859 * create memory pools for biovec's in a bio_set.
1860 * use the global biovec slabs created for general use.
1861 */
1862mempool_t *biovec_create_pool(struct bio_set *bs, int pool_entries)
1863{
1864	struct biovec_slab *bp = bvec_slabs + BIOVEC_MAX_IDX;
1865
1866	return mempool_create_slab_pool(pool_entries, bp->slab);
 
 
 
 
1867}
1868
1869void bioset_free(struct bio_set *bs)
1870{
1871	if (bs->rescue_workqueue)
1872		destroy_workqueue(bs->rescue_workqueue);
1873
 
 
1874	if (bs->bio_pool)
1875		mempool_destroy(bs->bio_pool);
1876
1877	if (bs->bvec_pool)
1878		mempool_destroy(bs->bvec_pool);
1879
1880	bioset_integrity_free(bs);
 
1881	bio_put_slab(bs);
1882
1883	kfree(bs);
1884}
1885EXPORT_SYMBOL(bioset_free);
1886
1887/**
1888 * bioset_create  - Create a bio_set
1889 * @pool_size:	Number of bio and bio_vecs to cache in the mempool
1890 * @front_pad:	Number of bytes to allocate in front of the returned bio
1891 *
1892 * Description:
1893 *    Set up a bio_set to be used with @bio_alloc_bioset. Allows the caller
1894 *    to ask for a number of bytes to be allocated in front of the bio.
1895 *    Front pad allocation is useful for embedding the bio inside
1896 *    another structure, to avoid allocating extra data to go with the bio.
1897 *    Note that the bio must be embedded at the END of that structure always,
1898 *    or things will break badly.
1899 */
1900struct bio_set *bioset_create(unsigned int pool_size, unsigned int front_pad)
1901{
1902	unsigned int back_pad = BIO_INLINE_VECS * sizeof(struct bio_vec);
1903	struct bio_set *bs;
1904
1905	bs = kzalloc(sizeof(*bs), GFP_KERNEL);
1906	if (!bs)
1907		return NULL;
1908
1909	bs->front_pad = front_pad;
1910
1911	spin_lock_init(&bs->rescue_lock);
1912	bio_list_init(&bs->rescue_list);
1913	INIT_WORK(&bs->rescue_work, bio_alloc_rescue);
1914
1915	bs->bio_slab = bio_find_or_create_slab(front_pad + back_pad);
1916	if (!bs->bio_slab) {
1917		kfree(bs);
1918		return NULL;
1919	}
1920
1921	bs->bio_pool = mempool_create_slab_pool(pool_size, bs->bio_slab);
1922	if (!bs->bio_pool)
1923		goto bad;
1924
1925	bs->bvec_pool = biovec_create_pool(bs, pool_size);
1926	if (!bs->bvec_pool)
1927		goto bad;
1928
1929	bs->rescue_workqueue = alloc_workqueue("bioset", WQ_MEM_RECLAIM, 0);
1930	if (!bs->rescue_workqueue)
1931		goto bad;
1932
1933	return bs;
1934bad:
1935	bioset_free(bs);
1936	return NULL;
1937}
1938EXPORT_SYMBOL(bioset_create);
1939
1940#ifdef CONFIG_BLK_CGROUP
1941/**
1942 * bio_associate_current - associate a bio with %current
1943 * @bio: target bio
1944 *
1945 * Associate @bio with %current if it hasn't been associated yet.  Block
1946 * layer will treat @bio as if it were issued by %current no matter which
1947 * task actually issues it.
1948 *
1949 * This function takes an extra reference of @task's io_context and blkcg
1950 * which will be put when @bio is released.  The caller must own @bio,
1951 * ensure %current->io_context exists, and is responsible for synchronizing
1952 * calls to this function.
1953 */
1954int bio_associate_current(struct bio *bio)
1955{
1956	struct io_context *ioc;
1957	struct cgroup_subsys_state *css;
1958
1959	if (bio->bi_ioc)
1960		return -EBUSY;
1961
1962	ioc = current->io_context;
1963	if (!ioc)
1964		return -ENOENT;
1965
1966	/* acquire active ref on @ioc and associate */
1967	get_io_context_active(ioc);
1968	bio->bi_ioc = ioc;
1969
1970	/* associate blkcg if exists */
1971	rcu_read_lock();
1972	css = task_css(current, blkio_cgrp_id);
1973	if (css && css_tryget(css))
1974		bio->bi_css = css;
1975	rcu_read_unlock();
1976
1977	return 0;
1978}
1979
1980/**
1981 * bio_disassociate_task - undo bio_associate_current()
1982 * @bio: target bio
1983 */
1984void bio_disassociate_task(struct bio *bio)
1985{
1986	if (bio->bi_ioc) {
1987		put_io_context(bio->bi_ioc);
1988		bio->bi_ioc = NULL;
1989	}
1990	if (bio->bi_css) {
1991		css_put(bio->bi_css);
1992		bio->bi_css = NULL;
1993	}
1994}
1995
1996#endif /* CONFIG_BLK_CGROUP */
1997
1998static void __init biovec_init_slabs(void)
1999{
2000	int i;
2001
2002	for (i = 0; i < BIOVEC_NR_POOLS; i++) {
2003		int size;
2004		struct biovec_slab *bvs = bvec_slabs + i;
2005
2006		if (bvs->nr_vecs <= BIO_INLINE_VECS) {
2007			bvs->slab = NULL;
2008			continue;
2009		}
2010
2011		size = bvs->nr_vecs * sizeof(struct bio_vec);
2012		bvs->slab = kmem_cache_create(bvs->name, size, 0,
2013                                SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
2014	}
2015}
2016
2017static int __init init_bio(void)
2018{
2019	bio_slab_max = 2;
2020	bio_slab_nr = 0;
2021	bio_slabs = kzalloc(bio_slab_max * sizeof(struct bio_slab), GFP_KERNEL);
2022	if (!bio_slabs)
2023		panic("bio: can't allocate bios\n");
2024
2025	bio_integrity_init();
2026	biovec_init_slabs();
2027
2028	fs_bio_set = bioset_create(BIO_POOL_SIZE, 0);
2029	if (!fs_bio_set)
2030		panic("bio: can't allocate bios\n");
2031
2032	if (bioset_integrity_create(fs_bio_set, BIO_POOL_SIZE))
2033		panic("bio: can't create integrity pool\n");
 
 
 
 
 
2034
2035	return 0;
2036}
2037subsys_initcall(init_bio);