개념 설명 전체 · v6.6 / block/bio.c

    1 // SPDX-License-Identifier: GPL-2.0
    2 /*
    3  * Copyright (C) 2001 Jens Axboe <[email protected]>
    4  */
    5 #include <linux/mm.h>
    6 #include <linux/swap.h>
    7 #include <linux/bio.h>
    8 #include <linux/blkdev.h>
    9 #include <linux/uio.h>
   10 #include <linux/iocontext.h>
   11 #include <linux/slab.h>
   12 #include <linux/init.h>
   13 #include <linux/kernel.h>
   14 #include <linux/export.h>
   15 #include <linux/mempool.h>
   16 #include <linux/workqueue.h>
   17 #include <linux/cgroup.h>
   18 #include <linux/highmem.h>
   19 #include <linux/sched/sysctl.h>
   20 #include <linux/blk-crypto.h>
   21 #include <linux/xarray.h>
   22 
   23 #include <trace/events/block.h>
   24 #include "blk.h"
   25 #include "blk-rq-qos.h"
   26 #include "blk-cgroup.h"
   27 
   28 #define ALLOC_CACHE_THRESHOLD	16
   29 #define ALLOC_CACHE_MAX		256
   30 
   31 struct bio_alloc_cache {
   32 	struct bio		*free_list;
   33 	struct bio		*free_list_irq;
   34 	unsigned int		nr;
   35 	unsigned int		nr_irq;
   36 };
   37 
   38 static struct biovec_slab {
   39 	int nr_vecs;
   40 	char *name;
   41 	struct kmem_cache *slab;
   42 } bvec_slabs[] __read_mostly = {
   43 	{ .nr_vecs = 16, .name = "biovec-16" },
   44 	{ .nr_vecs = 64, .name = "biovec-64" },
   45 	{ .nr_vecs = 128, .name = "biovec-128" },
   46 	{ .nr_vecs = BIO_MAX_VECS, .name = "biovec-max" },
   47 };
   48 
   49 static struct biovec_slab *biovec_slab(unsigned short nr_vecs)
   50 {
   51 	switch (nr_vecs) {
   52 	/* smaller bios use inline vecs */
   53 	case 5 ... 16:
   54 		return &bvec_slabs[0];
   55 	case 17 ... 64:
   56 		return &bvec_slabs[1];
   57 	case 65 ... 128:
   58 		return &bvec_slabs[2];
   59 	case 129 ... BIO_MAX_VECS:
   60 		return &bvec_slabs[3];
   61 	default:
   62 		BUG();
   63 		return NULL;
   64 	}
   65 }
   66 
   67 /*
   68  * fs_bio_set is the bio_set containing bio and iovec memory pools used by
   69  * IO code that does not need private memory pools.
   70  */
   71 struct bio_set fs_bio_set;
   72 EXPORT_SYMBOL(fs_bio_set);
   73 
   74 /*
   75  * Our slab pool management
   76  */
   77 struct bio_slab {
   78 	struct kmem_cache *slab;
   79 	unsigned int slab_ref;
   80 	unsigned int slab_size;
   81 	char name[8];
   82 };
   83 static DEFINE_MUTEX(bio_slab_lock);
   84 static DEFINE_XARRAY(bio_slabs);
   85 
   86 static struct bio_slab *create_bio_slab(unsigned int size)
   87 {
   88 	struct bio_slab *bslab = kzalloc(sizeof(*bslab), GFP_KERNEL);
   89 
   90 	if (!bslab)
   91 		return NULL;
   92 
   93 	snprintf(bslab->name, sizeof(bslab->name), "bio-%d", size);
   94 	bslab->slab = kmem_cache_create(bslab->name, size,
   95 			ARCH_KMALLOC_MINALIGN,
   96 			SLAB_HWCACHE_ALIGN | SLAB_TYPESAFE_BY_RCU, NULL);
   97 	if (!bslab->slab)
   98 		goto fail_alloc_slab;
   99 
  100 	bslab->slab_ref = 1;
  101 	bslab->slab_size = size;
  102 
  103 	if (!xa_err(xa_store(&bio_slabs, size, bslab, GFP_KERNEL)))
  104 		return bslab;
  105 
  106 	kmem_cache_destroy(bslab->slab);
  107 
  108 fail_alloc_slab:
  109 	kfree(bslab);
  110 	return NULL;
  111 }
  112 
  113 static inline unsigned int bs_bio_slab_size(struct bio_set *bs)
  114 {
  115 	return bs->front_pad + sizeof(struct bio) + bs->back_pad;
  116 }
  117 
  118 static struct kmem_cache *bio_find_or_create_slab(struct bio_set *bs)
  119 {
  120 	unsigned int size = bs_bio_slab_size(bs);
  121 	struct bio_slab *bslab;
  122 
  123 	mutex_lock(&bio_slab_lock);
  124 	bslab = xa_load(&bio_slabs, size);
  125 	if (bslab)
  126 		bslab->slab_ref++;
  127 	else
  128 		bslab = create_bio_slab(size);
  129 	mutex_unlock(&bio_slab_lock);
  130 
  131 	if (bslab)
  132 		return bslab->slab;
  133 	return NULL;
  134 }
  135 
  136 static void bio_put_slab(struct bio_set *bs)
  137 {
  138 	struct bio_slab *bslab = NULL;
  139 	unsigned int slab_size = bs_bio_slab_size(bs);
  140 
  141 	mutex_lock(&bio_slab_lock);
  142 
  143 	bslab = xa_load(&bio_slabs, slab_size);
  144 	if (WARN(!bslab, KERN_ERR "bio: unable to find slab!\n"))
  145 		goto out;
  146 
  147 	WARN_ON_ONCE(bslab->slab != bs->bio_slab);
  148 
  149 	WARN_ON(!bslab->slab_ref);
  150 
  151 	if (--bslab->slab_ref)
  152 		goto out;
  153 
  154 	xa_erase(&bio_slabs, slab_size);
  155 
  156 	kmem_cache_destroy(bslab->slab);
  157 	kfree(bslab);
  158 
  159 out:
  160 	mutex_unlock(&bio_slab_lock);
  161 }
  162 
  163 void bvec_free(mempool_t *pool, struct bio_vec *bv, unsigned short nr_vecs)
  164 {
  165 	BUG_ON(nr_vecs > BIO_MAX_VECS);
  166 
  167 	if (nr_vecs == BIO_MAX_VECS)
  168 		mempool_free(bv, pool);
  169 	else if (nr_vecs > BIO_INLINE_VECS)
  170 		kmem_cache_free(biovec_slab(nr_vecs)->slab, bv);
  171 }
  172 
  173 /*
  174  * Make the first allocation restricted and don't dump info on allocation
  175  * failures, since we'll fall back to the mempool in case of failure.
  176  */
  177 static inline gfp_t bvec_alloc_gfp(gfp_t gfp)
  178 {
  179 	return (gfp & ~(__GFP_DIRECT_RECLAIM | __GFP_IO)) |
  180 		__GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN;
  181 }
  182 
  183 struct bio_vec *bvec_alloc(mempool_t *pool, unsigned short *nr_vecs,
  184 		gfp_t gfp_mask)
  185 {
  186 	struct biovec_slab *bvs = biovec_slab(*nr_vecs);
  187 
  188 	if (WARN_ON_ONCE(!bvs))
  189 		return NULL;
  190 
  191 	/*
  192 	 * Upgrade the nr_vecs request to take full advantage of the allocation.
  193 	 * We also rely on this in the bvec_free path.
  194 	 */
  195 	*nr_vecs = bvs->nr_vecs;
  196 
  197 	/*
  198 	 * Try a slab allocation first for all smaller allocations.  If that
  199 	 * fails and __GFP_DIRECT_RECLAIM is set retry with the mempool.
  200 	 * The mempool is sized to handle up to BIO_MAX_VECS entries.
  201 	 */
  202 	if (*nr_vecs < BIO_MAX_VECS) {
  203 		struct bio_vec *bvl;
  204 
  205 		bvl = kmem_cache_alloc(bvs->slab, bvec_alloc_gfp(gfp_mask));
  206 		if (likely(bvl) || !(gfp_mask & __GFP_DIRECT_RECLAIM))
  207 			return bvl;
  208 		*nr_vecs = BIO_MAX_VECS;
  209 	}
  210 
  211 	return mempool_alloc(pool, gfp_mask);
  212 }
  213 
  214 void bio_uninit(struct bio *bio)
  215 {
  216 #ifdef CONFIG_BLK_CGROUP
  217 	if (bio->bi_blkg) {
  218 		blkg_put(bio->bi_blkg);
  219 		bio->bi_blkg = NULL;
  220 	}
  221 #endif
  222 	if (bio_integrity(bio))
  223 		bio_integrity_free(bio);
  224 
  225 	bio_crypt_free_ctx(bio);
  226 }
  227 EXPORT_SYMBOL(bio_uninit);
  228 
  229 static void bio_free(struct bio *bio)
  230 {
  231 	struct bio_set *bs = bio->bi_pool;
  232 	void *p = bio;
  233 
  234 	WARN_ON_ONCE(!bs);
  235 
  236 	bio_uninit(bio);
  237 	bvec_free(&bs->bvec_pool, bio->bi_io_vec, bio->bi_max_vecs);
  238 	mempool_free(p - bs->front_pad, &bs->bio_pool);
  239 }
  240 
  241 /*
  242  * Users of this function have their own bio allocation. Subsequently,
  243  * they must remember to pair any call to bio_init() with bio_uninit()
  244  * when IO has completed, or when the bio is released.
  245  */
  246 void bio_init(struct bio *bio, struct block_device *bdev, struct bio_vec *table,
  247 	      unsigned short max_vecs, blk_opf_t opf)
  248 {
  249 	bio->bi_next = NULL;
  250 	bio->bi_bdev = bdev;
  251 	bio->bi_opf = opf;
  252 	bio->bi_flags = 0;
  253 	bio->bi_ioprio = 0;
  254 	bio->bi_status = 0;
  255 	bio->bi_iter.bi_sector = 0;
  256 	bio->bi_iter.bi_size = 0;
  257 	bio->bi_iter.bi_idx = 0;
  258 	bio->bi_iter.bi_bvec_done = 0;
  259 	bio->bi_end_io = NULL;
  260 	bio->bi_private = NULL;
  261 #ifdef CONFIG_BLK_CGROUP
  262 	bio->bi_blkg = NULL;
  263 	bio->bi_issue.value = 0;
  264 	if (bdev)
  265 		bio_associate_blkg(bio);
  266 #ifdef CONFIG_BLK_CGROUP_IOCOST
  267 	bio->bi_iocost_cost = 0;
  268 #endif
  269 #endif
  270 #ifdef CONFIG_BLK_INLINE_ENCRYPTION
  271 	bio->bi_crypt_context = NULL;
  272 #endif
  273 #ifdef CONFIG_BLK_DEV_INTEGRITY
  274 	bio->bi_integrity = NULL;
  275 #endif
  276 	bio->bi_vcnt = 0;
  277 
  278 	atomic_set(&bio->__bi_remaining, 1);
  279 	atomic_set(&bio->__bi_cnt, 1);
  280 	bio->bi_cookie = BLK_QC_T_NONE;
  281 
  282 	bio->bi_max_vecs = max_vecs;
  283 	bio->bi_io_vec = table;
  284 	bio->bi_pool = NULL;
  285 }
  286 EXPORT_SYMBOL(bio_init);
  287 
  288 /**
  289  * bio_reset - reinitialize a bio
  290  * @bio:	bio to reset
  291  * @bdev:	block device to use the bio for
  292  * @opf:	operation and flags for bio
  293  *
  294  * Description:
  295  *   After calling bio_reset(), @bio will be in the same state as a freshly
  296  *   allocated bio returned bio bio_alloc_bioset() - the only fields that are
  297  *   preserved are the ones that are initialized by bio_alloc_bioset(). See
  298  *   comment in struct bio.
  299  */
  300 void bio_reset(struct bio *bio, struct block_device *bdev, blk_opf_t opf)
  301 {
  302 	bio_uninit(bio);
  303 	memset(bio, 0, BIO_RESET_BYTES);
  304 	atomic_set(&bio->__bi_remaining, 1);
  305 	bio->bi_bdev = bdev;
  306 	if (bio->bi_bdev)
  307 		bio_associate_blkg(bio);
  308 	bio->bi_opf = opf;
  309 }
  310 EXPORT_SYMBOL(bio_reset);
  311 
  312 static struct bio *__bio_chain_endio(struct bio *bio)
  313 {
  314 	struct bio *parent = bio->bi_private;
  315 
  316 	if (bio->bi_status && !parent->bi_status)
  317 		parent->bi_status = bio->bi_status;
  318 	bio_put(bio);
  319 	return parent;
  320 }
  321 
  322 static void bio_chain_endio(struct bio *bio)
  323 {
  324 	bio_endio(__bio_chain_endio(bio));
  325 }
  326 
  327 /**
  328  * bio_chain - chain bio completions
  329  * @bio: the target bio
  330  * @parent: the parent bio of @bio
  331  *
  332  * The caller won't have a bi_end_io called when @bio completes - instead,
  333  * @parent's bi_end_io won't be called until both @parent and @bio have
  334  * completed; the chained bio will also be freed when it completes.
  335  *
  336  * The caller must not set bi_private or bi_end_io in @bio.
  337  */
  338 void bio_chain(struct bio *bio, struct bio *parent)
  339 {
  340 	BUG_ON(bio->bi_private || bio->bi_end_io);
  341 
  342 	bio->bi_private = parent;
  343 	bio->bi_end_io	= bio_chain_endio;
  344 	bio_inc_remaining(parent);
  345 }
  346 EXPORT_SYMBOL(bio_chain);
  347 
  348 struct bio *blk_next_bio(struct bio *bio, struct block_device *bdev,
  349 		unsigned int nr_pages, blk_opf_t opf, gfp_t gfp)
  350 {
  351 	struct bio *new = bio_alloc(bdev, nr_pages, opf, gfp);
  352 
  353 	if (bio) {
  354 		bio_chain(bio, new);
  355 		submit_bio(bio);
  356 	}
  357 
  358 	return new;
  359 }
  360 EXPORT_SYMBOL_GPL(blk_next_bio);
  361 
  362 static void bio_alloc_rescue(struct work_struct *work)
  363 {
  364 	struct bio_set *bs = container_of(work, struct bio_set, rescue_work);
  365 	struct bio *bio;
  366 
  367 	while (1) {
  368 		spin_lock(&bs->rescue_lock);
  369 		bio = bio_list_pop(&bs->rescue_list);
  370 		spin_unlock(&bs->rescue_lock);
  371 
  372 		if (!bio)
  373 			break;
  374 
  375 		submit_bio_noacct(bio);
  376 	}
  377 }
  378 
  379 static void punt_bios_to_rescuer(struct bio_set *bs)
  380 {
  381 	struct bio_list punt, nopunt;
  382 	struct bio *bio;
  383 
  384 	if (WARN_ON_ONCE(!bs->rescue_workqueue))
  385 		return;
  386 	/*
  387 	 * In order to guarantee forward progress we must punt only bios that
  388 	 * were allocated from this bio_set; otherwise, if there was a bio on
  389 	 * there for a stacking driver higher up in the stack, processing it
  390 	 * could require allocating bios from this bio_set, and doing that from
  391 	 * our own rescuer would be bad.
  392 	 *
  393 	 * Since bio lists are singly linked, pop them all instead of trying to
  394 	 * remove from the middle of the list:
  395 	 */
  396 
  397 	bio_list_init(&punt);
  398 	bio_list_init(&nopunt);
  399 
  400 	while ((bio = bio_list_pop(&current->bio_list[0])))
  401 		bio_list_add(bio->bi_pool == bs ? &punt : &nopunt, bio);
  402 	current->bio_list[0] = nopunt;
  403 
  404 	bio_list_init(&nopunt);
  405 	while ((bio = bio_list_pop(&current->bio_list[1])))
  406 		bio_list_add(bio->bi_pool == bs ? &punt : &nopunt, bio);
  407 	current->bio_list[1] = nopunt;
  408 
  409 	spin_lock(&bs->rescue_lock);
  410 	bio_list_merge(&bs->rescue_list, &punt);
  411 	spin_unlock(&bs->rescue_lock);
  412 
  413 	queue_work(bs->rescue_workqueue, &bs->rescue_work);
  414 }
  415 
  416 static void bio_alloc_irq_cache_splice(struct bio_alloc_cache *cache)
  417 {
  418 	unsigned long flags;
  419 
  420 	/* cache->free_list must be empty */
  421 	if (WARN_ON_ONCE(cache->free_list))
  422 		return;
  423 
  424 	local_irq_save(flags);
  425 	cache->free_list = cache->free_list_irq;
  426 	cache->free_list_irq = NULL;
  427 	cache->nr += cache->nr_irq;
  428 	cache->nr_irq = 0;
  429 	local_irq_restore(flags);
  430 }
  431 
  432 static struct bio *bio_alloc_percpu_cache(struct block_device *bdev,
  433 		unsigned short nr_vecs, blk_opf_t opf, gfp_t gfp,
  434 		struct bio_set *bs)
  435 {
  436 	struct bio_alloc_cache *cache;
  437 	struct bio *bio;
  438 
  439 	cache = per_cpu_ptr(bs->cache, get_cpu());
  440 	if (!cache->free_list) {
  441 		if (READ_ONCE(cache->nr_irq) >= ALLOC_CACHE_THRESHOLD)
  442 			bio_alloc_irq_cache_splice(cache);
  443 		if (!cache->free_list) {
  444 			put_cpu();
  445 			return NULL;
  446 		}
  447 	}
  448 	bio = cache->free_list;
  449 	cache->free_list = bio->bi_next;
  450 	cache->nr--;
  451 	put_cpu();
  452 
  453 	bio_init(bio, bdev, nr_vecs ? bio->bi_inline_vecs : NULL, nr_vecs, opf);
  454 	bio->bi_pool = bs;
  455 	return bio;
  456 }
  457 
  458 /**
  459  * bio_alloc_bioset - allocate a bio for I/O
  460  * @bdev:	block device to allocate the bio for (can be %NULL)
  461  * @nr_vecs:	number of bvecs to pre-allocate
  462  * @opf:	operation and flags for bio
  463  * @gfp_mask:   the GFP_* mask given to the slab allocator
  464  * @bs:		the bio_set to allocate from.
  465  *
  466  * Allocate a bio from the mempools in @bs.
  467  *
  468  * If %__GFP_DIRECT_RECLAIM is set then bio_alloc will always be able to
  469  * allocate a bio.  This is due to the mempool guarantees.  To make this work,
  470  * callers must never allocate more than 1 bio at a time from the general pool.
  471  * Callers that need to allocate more than 1 bio must always submit the
  472  * previously allocated bio for IO before attempting to allocate a new one.
  473  * Failure to do so can cause deadlocks under memory pressure.
  474  *
  475  * Note that when running under submit_bio_noacct() (i.e. any block driver),
  476  * bios are not submitted until after you return - see the code in
  477  * submit_bio_noacct() that converts recursion into iteration, to prevent
  478  * stack overflows.
  479  *
  480  * This would normally mean allocating multiple bios under submit_bio_noacct()
  481  * would be susceptible to deadlocks, but we have
  482  * deadlock avoidance code that resubmits any blocked bios from a rescuer
  483  * thread.
  484  *
  485  * However, we do not guarantee forward progress for allocations from other
  486  * mempools. Doing multiple allocations from the same mempool under
  487  * submit_bio_noacct() should be avoided - instead, use bio_set's front_pad
  488  * for per bio allocations.
  489  *
  490  * Returns: Pointer to new bio on success, NULL on failure.
  491  */
  492 struct bio *bio_alloc_bioset(struct block_device *bdev, unsigned short nr_vecs,
  493 			     blk_opf_t opf, gfp_t gfp_mask,
  494 			     struct bio_set *bs)
  495 {
  496 	gfp_t saved_gfp = gfp_mask;
  497 	struct bio *bio;
  498 	void *p;
  499 
  500 	/* should not use nobvec bioset for nr_vecs > 0 */
  501 	if (WARN_ON_ONCE(!mempool_initialized(&bs->bvec_pool) && nr_vecs > 0))
  502 		return NULL;
  503 
  504 	if (opf & REQ_ALLOC_CACHE) {
  505 		if (bs->cache && nr_vecs <= BIO_INLINE_VECS) {
  506 			bio = bio_alloc_percpu_cache(bdev, nr_vecs, opf,
  507 						     gfp_mask, bs);
  508 			if (bio)
  509 				return bio;
  510 			/*
  511 			 * No cached bio available, bio returned below marked with
  512 			 * REQ_ALLOC_CACHE to particpate in per-cpu alloc cache.
  513 			 */
  514 		} else {
  515 			opf &= ~REQ_ALLOC_CACHE;
  516 		}
  517 	}
  518 
  519 	/*
  520 	 * submit_bio_noacct() converts recursion to iteration; this means if
  521 	 * we're running beneath it, any bios we allocate and submit will not be
  522 	 * submitted (and thus freed) until after we return.
  523 	 *
  524 	 * This exposes us to a potential deadlock if we allocate multiple bios
  525 	 * from the same bio_set() while running underneath submit_bio_noacct().
  526 	 * If we were to allocate multiple bios (say a stacking block driver
  527 	 * that was splitting bios), we would deadlock if we exhausted the
  528 	 * mempool's reserve.
  529 	 *
  530 	 * We solve this, and guarantee forward progress, with a rescuer
  531 	 * workqueue per bio_set. If we go to allocate and there are bios on
  532 	 * current->bio_list, we first try the allocation without
  533 	 * __GFP_DIRECT_RECLAIM; if that fails, we punt those bios we would be
  534 	 * blocking to the rescuer workqueue before we retry with the original
  535 	 * gfp_flags.
  536 	 */
  537 	if (current->bio_list &&
  538 	    (!bio_list_empty(&current->bio_list[0]) ||
  539 	     !bio_list_empty(&current->bio_list[1])) &&
  540 	    bs->rescue_workqueue)
  541 		gfp_mask &= ~__GFP_DIRECT_RECLAIM;
  542 
  543 	p = mempool_alloc(&bs->bio_pool, gfp_mask);
  544 	if (!p && gfp_mask != saved_gfp) {
  545 		punt_bios_to_rescuer(bs);
  546 		gfp_mask = saved_gfp;
  547 		p = mempool_alloc(&bs->bio_pool, gfp_mask);
  548 	}
  549 	if (unlikely(!p))
  550 		return NULL;
  551 	if (!mempool_is_saturated(&bs->bio_pool))
  552 		opf &= ~REQ_ALLOC_CACHE;
  553 
  554 	bio = p + bs->front_pad;
  555 	if (nr_vecs > BIO_INLINE_VECS) {
  556 		struct bio_vec *bvl = NULL;
  557 
  558 		bvl = bvec_alloc(&bs->bvec_pool, &nr_vecs, gfp_mask);
  559 		if (!bvl && gfp_mask != saved_gfp) {
  560 			punt_bios_to_rescuer(bs);
  561 			gfp_mask = saved_gfp;
  562 			bvl = bvec_alloc(&bs->bvec_pool, &nr_vecs, gfp_mask);
  563 		}
  564 		if (unlikely(!bvl))
  565 			goto err_free;
  566 
  567 		bio_init(bio, bdev, bvl, nr_vecs, opf);
  568 	} else if (nr_vecs) {
  569 		bio_init(bio, bdev, bio->bi_inline_vecs, BIO_INLINE_VECS, opf);
  570 	} else {
  571 		bio_init(bio, bdev, NULL, 0, opf);
  572 	}
  573 
  574 	bio->bi_pool = bs;
  575 	return bio;
  576 
  577 err_free:
  578 	mempool_free(p, &bs->bio_pool);
  579 	return NULL;
  580 }
  581 EXPORT_SYMBOL(bio_alloc_bioset);
  582 
  583 /**
  584  * bio_kmalloc - kmalloc a bio
  585  * @nr_vecs:	number of bio_vecs to allocate
  586  * @gfp_mask:   the GFP_* mask given to the slab allocator
  587  *
  588  * Use kmalloc to allocate a bio (including bvecs).  The bio must be initialized
  589  * using bio_init() before use.  To free a bio returned from this function use
  590  * kfree() after calling bio_uninit().  A bio returned from this function can
  591  * be reused by calling bio_uninit() before calling bio_init() again.
  592  *
  593  * Note that unlike bio_alloc() or bio_alloc_bioset() allocations from this
  594  * function are not backed by a mempool can fail.  Do not use this function
  595  * for allocations in the file system I/O path.
  596  *
  597  * Returns: Pointer to new bio on success, NULL on failure.
  598  */
  599 struct bio *bio_kmalloc(unsigned short nr_vecs, gfp_t gfp_mask)
  600 {
  601 	struct bio *bio;
  602 
  603 	if (nr_vecs > UIO_MAXIOV)
  604 		return NULL;
  605 	return kmalloc(struct_size(bio, bi_inline_vecs, nr_vecs), gfp_mask);
  606 }
  607 EXPORT_SYMBOL(bio_kmalloc);
  608 
  609 void zero_fill_bio_iter(struct bio *bio, struct bvec_iter start)
  610 {
  611 	struct bio_vec bv;
  612 	struct bvec_iter iter;
  613 
  614 	__bio_for_each_segment(bv, bio, iter, start)
  615 		memzero_bvec(&bv);
  616 }
  617 EXPORT_SYMBOL(zero_fill_bio_iter);
  618 
  619 /**
  620  * bio_truncate - truncate the bio to small size of @new_size
  621  * @bio:	the bio to be truncated
  622  * @new_size:	new size for truncating the bio
  623  *
  624  * Description:
  625  *   Truncate the bio to new size of @new_size. If bio_op(bio) is
  626  *   REQ_OP_READ, zero the truncated part. This function should only
  627  *   be used for handling corner cases, such as bio eod.
  628  */
  629 static void bio_truncate(struct bio *bio, unsigned new_size)
  630 {
  631 	struct bio_vec bv;
  632 	struct bvec_iter iter;
  633 	unsigned int done = 0;
  634 	bool truncated = false;
  635 
  636 	if (new_size >= bio->bi_iter.bi_size)
  637 		return;
  638 
  639 	if (bio_op(bio) != REQ_OP_READ)
  640 		goto exit;
  641 
  642 	bio_for_each_segment(bv, bio, iter) {
  643 		if (done + bv.bv_len > new_size) {
  644 			unsigned offset;
  645 
  646 			if (!truncated)
  647 				offset = new_size - done;
  648 			else
  649 				offset = 0;
  650 			zero_user(bv.bv_page, bv.bv_offset + offset,
  651 				  bv.bv_len - offset);
  652 			truncated = true;
  653 		}
  654 		done += bv.bv_len;
  655 	}
  656 
  657  exit:
  658 	/*
  659 	 * Don't touch bvec table here and make it really immutable, since
  660 	 * fs bio user has to retrieve all pages via bio_for_each_segment_all
  661 	 * in its .end_bio() callback.
  662 	 *
  663 	 * It is enough to truncate bio by updating .bi_size since we can make
  664 	 * correct bvec with the updated .bi_size for drivers.
  665 	 */
  666 	bio->bi_iter.bi_size = new_size;
  667 }
  668 
  669 /**
  670  * guard_bio_eod - truncate a BIO to fit the block device
  671  * @bio:	bio to truncate
  672  *
  673  * This allows us to do IO even on the odd last sectors of a device, even if the
  674  * block size is some multiple of the physical sector size.
  675  *
  676  * We'll just truncate the bio to the size of the device, and clear the end of
  677  * the buffer head manually.  Truly out-of-range accesses will turn into actual
  678  * I/O errors, this only handles the "we need to be able to do I/O at the final
  679  * sector" case.
  680  */
  681 void guard_bio_eod(struct bio *bio)
  682 {
  683 	sector_t maxsector = bdev_nr_sectors(bio->bi_bdev);
  684 
  685 	if (!maxsector)
  686 		return;
  687 
  688 	/*
  689 	 * If the *whole* IO is past the end of the device,
  690 	 * let it through, and the IO layer will turn it into
  691 	 * an EIO.
  692 	 */
  693 	if (unlikely(bio->bi_iter.bi_sector >= maxsector))
  694 		return;
  695 
  696 	maxsector -= bio->bi_iter.bi_sector;
  697 	if (likely((bio->bi_iter.bi_size >> 9) <= maxsector))
  698 		return;
  699 
  700 	bio_truncate(bio, maxsector << 9);
  701 }
  702 
  703 static int __bio_alloc_cache_prune(struct bio_alloc_cache *cache,
  704 				   unsigned int nr)
  705 {
  706 	unsigned int i = 0;
  707 	struct bio *bio;
  708 
  709 	while ((bio = cache->free_list) != NULL) {
  710 		cache->free_list = bio->bi_next;
  711 		cache->nr--;
  712 		bio_free(bio);
  713 		if (++i == nr)
  714 			break;
  715 	}
  716 	return i;
  717 }
  718 
  719 static void bio_alloc_cache_prune(struct bio_alloc_cache *cache,
  720 				  unsigned int nr)
  721 {
  722 	nr -= __bio_alloc_cache_prune(cache, nr);
  723 	if (!READ_ONCE(cache->free_list)) {
  724 		bio_alloc_irq_cache_splice(cache);
  725 		__bio_alloc_cache_prune(cache, nr);
  726 	}
  727 }
  728 
  729 static int bio_cpu_dead(unsigned int cpu, struct hlist_node *node)
  730 {
  731 	struct bio_set *bs;
  732 
  733 	bs = hlist_entry_safe(node, struct bio_set, cpuhp_dead);
  734 	if (bs->cache) {
  735 		struct bio_alloc_cache *cache = per_cpu_ptr(bs->cache, cpu);
  736 
  737 		bio_alloc_cache_prune(cache, -1U);
  738 	}
  739 	return 0;
  740 }
  741 
  742 static void bio_alloc_cache_destroy(struct bio_set *bs)
  743 {
  744 	int cpu;
  745 
  746 	if (!bs->cache)
  747 		return;
  748 
  749 	cpuhp_state_remove_instance_nocalls(CPUHP_BIO_DEAD, &bs->cpuhp_dead);
  750 	for_each_possible_cpu(cpu) {
  751 		struct bio_alloc_cache *cache;
  752 
  753 		cache = per_cpu_ptr(bs->cache, cpu);
  754 		bio_alloc_cache_prune(cache, -1U);
  755 	}
  756 	free_percpu(bs->cache);
  757 	bs->cache = NULL;
  758 }
  759 
  760 static inline void bio_put_percpu_cache(struct bio *bio)
  761 {
  762 	struct bio_alloc_cache *cache;
  763 
  764 	cache = per_cpu_ptr(bio->bi_pool->cache, get_cpu());
  765 	if (READ_ONCE(cache->nr_irq) + cache->nr > ALLOC_CACHE_MAX) {
  766 		put_cpu();
  767 		bio_free(bio);
  768 		return;
  769 	}
  770 
  771 	bio_uninit(bio);
  772 
  773 	if ((bio->bi_opf & REQ_POLLED) && !WARN_ON_ONCE(in_interrupt())) {
  774 		bio->bi_next = cache->free_list;
  775 		bio->bi_bdev = NULL;
  776 		cache->free_list = bio;
  777 		cache->nr++;
  778 	} else {
  779 		unsigned long flags;
  780 
  781 		local_irq_save(flags);
  782 		bio->bi_next = cache->free_list_irq;
  783 		cache->free_list_irq = bio;
  784 		cache->nr_irq++;
  785 		local_irq_restore(flags);
  786 	}
  787 	put_cpu();
  788 }
  789 
  790 /**
  791  * bio_put - release a reference to a bio
  792  * @bio:   bio to release reference to
  793  *
  794  * Description:
  795  *   Put a reference to a &struct bio, either one you have gotten with
  796  *   bio_alloc, bio_get or bio_clone_*. The last put of a bio will free it.
  797  **/
  798 void bio_put(struct bio *bio)
  799 {
  800 	if (unlikely(bio_flagged(bio, BIO_REFFED))) {
  801 		BUG_ON(!atomic_read(&bio->__bi_cnt));
  802 		if (!atomic_dec_and_test(&bio->__bi_cnt))
  803 			return;
  804 	}
  805 	if (bio->bi_opf & REQ_ALLOC_CACHE)
  806 		bio_put_percpu_cache(bio);
  807 	else
  808 		bio_free(bio);
  809 }
  810 EXPORT_SYMBOL(bio_put);
  811 
  812 static int __bio_clone(struct bio *bio, struct bio *bio_src, gfp_t gfp)
  813 {
  814 	bio_set_flag(bio, BIO_CLONED);
  815 	bio->bi_ioprio = bio_src->bi_ioprio;
  816 	bio->bi_iter = bio_src->bi_iter;
  817 
  818 	if (bio->bi_bdev) {
  819 		if (bio->bi_bdev == bio_src->bi_bdev &&
  820 		    bio_flagged(bio_src, BIO_REMAPPED))
  821 			bio_set_flag(bio, BIO_REMAPPED);
  822 		bio_clone_blkg_association(bio, bio_src);
  823 	}
  824 
  825 	if (bio_crypt_clone(bio, bio_src, gfp) < 0)
  826 		return -ENOMEM;
  827 	if (bio_integrity(bio_src) &&
  828 	    bio_integrity_clone(bio, bio_src, gfp) < 0)
  829 		return -ENOMEM;
  830 	return 0;
  831 }
  832 
  833 /**
  834  * bio_alloc_clone - clone a bio that shares the original bio's biovec
  835  * @bdev: block_device to clone onto
  836  * @bio_src: bio to clone from
  837  * @gfp: allocation priority
  838  * @bs: bio_set to allocate from
  839  *
  840  * Allocate a new bio that is a clone of @bio_src. The caller owns the returned
  841  * bio, but not the actual data it points to.
  842  *
  843  * The caller must ensure that the return bio is not freed before @bio_src.
  844  */
  845 struct bio *bio_alloc_clone(struct block_device *bdev, struct bio *bio_src,
  846 		gfp_t gfp, struct bio_set *bs)
  847 {
  848 	struct bio *bio;
  849 
  850 	bio = bio_alloc_bioset(bdev, 0, bio_src->bi_opf, gfp, bs);
  851 	if (!bio)
  852 		return NULL;
  853 
  854 	if (__bio_clone(bio, bio_src, gfp) < 0) {
  855 		bio_put(bio);
  856 		return NULL;
  857 	}
  858 	bio->bi_io_vec = bio_src->bi_io_vec;
  859 
  860 	return bio;
  861 }
  862 EXPORT_SYMBOL(bio_alloc_clone);
  863 
  864 /**
  865  * bio_init_clone - clone a bio that shares the original bio's biovec
  866  * @bdev: block_device to clone onto
  867  * @bio: bio to clone into
  868  * @bio_src: bio to clone from
  869  * @gfp: allocation priority
  870  *
  871  * Initialize a new bio in caller provided memory that is a clone of @bio_src.
  872  * The caller owns the returned bio, but not the actual data it points to.
  873  *
  874  * The caller must ensure that @bio_src is not freed before @bio.
  875  */
  876 int bio_init_clone(struct block_device *bdev, struct bio *bio,
  877 		struct bio *bio_src, gfp_t gfp)
  878 {
  879 	int ret;
  880 
  881 	bio_init(bio, bdev, bio_src->bi_io_vec, 0, bio_src->bi_opf);
  882 	ret = __bio_clone(bio, bio_src, gfp);
  883 	if (ret)
  884 		bio_uninit(bio);
  885 	return ret;
  886 }
  887 EXPORT_SYMBOL(bio_init_clone);
  888 
  889 /**
  890  * bio_full - check if the bio is full
  891  * @bio:	bio to check
  892  * @len:	length of one segment to be added
  893  *
  894  * Return true if @bio is full and one segment with @len bytes can't be
  895  * added to the bio, otherwise return false
  896  */
  897 static inline bool bio_full(struct bio *bio, unsigned len)
  898 {
  899 	if (bio->bi_vcnt >= bio->bi_max_vecs)
  900 		return true;
  901 	if (bio->bi_iter.bi_size > UINT_MAX - len)
  902 		return true;
  903 	return false;
  904 }
  905 
  906 static bool bvec_try_merge_page(struct bio_vec *bv, struct page *page,
  907 		unsigned int len, unsigned int off, bool *same_page)
  908 {
  909 	size_t bv_end = bv->bv_offset + bv->bv_len;
  910 	phys_addr_t vec_end_addr = page_to_phys(bv->bv_page) + bv_end - 1;
  911 	phys_addr_t page_addr = page_to_phys(page);
  912 
  913 	if (vec_end_addr + 1 != page_addr + off)
  914 		return false;
  915 	if (xen_domain() && !xen_biovec_phys_mergeable(bv, page))
  916 		return false;
  917 	if (!zone_device_pages_have_same_pgmap(bv->bv_page, page))
  918 		return false;
  919 
  920 	*same_page = ((vec_end_addr & PAGE_MASK) == page_addr);
  921 	if (!*same_page) {
  922 		if (IS_ENABLED(CONFIG_KMSAN))
  923 			return false;
  924 		if (bv->bv_page + bv_end / PAGE_SIZE != page + off / PAGE_SIZE)
  925 			return false;
  926 	}
  927 
  928 	bv->bv_len += len;
  929 	return true;
  930 }
  931 
  932 /*
  933  * Try to merge a page into a segment, while obeying the hardware segment
  934  * size limit.  This is not for normal read/write bios, but for passthrough
  935  * or Zone Append operations that we can't split.
  936  */
  937 bool bvec_try_merge_hw_page(struct request_queue *q, struct bio_vec *bv,
  938 		struct page *page, unsigned len, unsigned offset,
  939 		bool *same_page)
  940 {
  941 	unsigned long mask = queue_segment_boundary(q);
  942 	phys_addr_t addr1 = page_to_phys(bv->bv_page) + bv->bv_offset;
  943 	phys_addr_t addr2 = page_to_phys(page) + offset + len - 1;
  944 
  945 	if ((addr1 | mask) != (addr2 | mask))
  946 		return false;
  947 	if (bv->bv_len + len > queue_max_segment_size(q))
  948 		return false;
  949 	return bvec_try_merge_page(bv, page, len, offset, same_page);
  950 }
  951 
  952 /**
  953  * bio_add_hw_page - attempt to add a page to a bio with hw constraints
  954  * @q: the target queue
  955  * @bio: destination bio
  956  * @page: page to add
  957  * @len: vec entry length
  958  * @offset: vec entry offset
  959  * @max_sectors: maximum number of sectors that can be added
  960  * @same_page: return if the segment has been merged inside the same page
  961  *
  962  * Add a page to a bio while respecting the hardware max_sectors, max_segment
  963  * and gap limitations.
  964  */
  965 int bio_add_hw_page(struct request_queue *q, struct bio *bio,
  966 		struct page *page, unsigned int len, unsigned int offset,
  967 		unsigned int max_sectors, bool *same_page)
  968 {
  969 	if (WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED)))
  970 		return 0;
  971 
  972 	if (((bio->bi_iter.bi_size + len) >> SECTOR_SHIFT) > max_sectors)
  973 		return 0;
  974 
  975 	if (bio->bi_vcnt > 0) {
  976 		struct bio_vec *bv = &bio->bi_io_vec[bio->bi_vcnt - 1];
  977 
  978 		if (bvec_try_merge_hw_page(q, bv, page, len, offset,
  979 				same_page)) {
  980 			bio->bi_iter.bi_size += len;
  981 			return len;
  982 		}
  983 
  984 		if (bio->bi_vcnt >=
  985 		    min(bio->bi_max_vecs, queue_max_segments(q)))
  986 			return 0;
  987 
  988 		/*
  989 		 * If the queue doesn't support SG gaps and adding this segment
  990 		 * would create a gap, disallow it.
  991 		 */
  992 		if (bvec_gap_to_prev(&q->limits, bv, offset))
  993 			return 0;
  994 	}
  995 
  996 	bvec_set_page(&bio->bi_io_vec[bio->bi_vcnt], page, len, offset);
  997 	bio->bi_vcnt++;
  998 	bio->bi_iter.bi_size += len;
  999 	return len;
 1000 }
 1001 
 1002 /**
 1003  * bio_add_pc_page	- attempt to add page to passthrough bio
 1004  * @q: the target queue
 1005  * @bio: destination bio
 1006  * @page: page to add
 1007  * @len: vec entry length
 1008  * @offset: vec entry offset
 1009  *
 1010  * Attempt to add a page to the bio_vec maplist. This can fail for a
 1011  * number of reasons, such as the bio being full or target block device
 1012  * limitations. The target block device must allow bio's up to PAGE_SIZE,
 1013  * so it is always possible to add a single page to an empty bio.
 1014  *
 1015  * This should only be used by passthrough bios.
 1016  */
 1017 int bio_add_pc_page(struct request_queue *q, struct bio *bio,
 1018 		struct page *page, unsigned int len, unsigned int offset)
 1019 {
 1020 	bool same_page = false;
 1021 	return bio_add_hw_page(q, bio, page, len, offset,
 1022 			queue_max_hw_sectors(q), &same_page);
 1023 }
 1024 EXPORT_SYMBOL(bio_add_pc_page);
 1025 
 1026 /**
 1027  * bio_add_zone_append_page - attempt to add page to zone-append bio
 1028  * @bio: destination bio
 1029  * @page: page to add
 1030  * @len: vec entry length
 1031  * @offset: vec entry offset
 1032  *
 1033  * Attempt to add a page to the bio_vec maplist of a bio that will be submitted
 1034  * for a zone-append request. This can fail for a number of reasons, such as the
 1035  * bio being full or the target block device is not a zoned block device or
 1036  * other limitations of the target block device. The target block device must
 1037  * allow bio's up to PAGE_SIZE, so it is always possible to add a single page
 1038  * to an empty bio.
 1039  *
 1040  * Returns: number of bytes added to the bio, or 0 in case of a failure.
 1041  */
 1042 int bio_add_zone_append_page(struct bio *bio, struct page *page,
 1043 			     unsigned int len, unsigned int offset)
 1044 {
 1045 	struct request_queue *q = bdev_get_queue(bio->bi_bdev);
 1046 	bool same_page = false;
 1047 
 1048 	if (WARN_ON_ONCE(bio_op(bio) != REQ_OP_ZONE_APPEND))
 1049 		return 0;
 1050 
 1051 	if (WARN_ON_ONCE(!bdev_is_zoned(bio->bi_bdev)))
 1052 		return 0;
 1053 
 1054 	return bio_add_hw_page(q, bio, page, len, offset,
 1055 			       queue_max_zone_append_sectors(q), &same_page);
 1056 }
 1057 EXPORT_SYMBOL_GPL(bio_add_zone_append_page);
 1058 
 1059 /**
 1060  * __bio_add_page - add page(s) to a bio in a new segment
 1061  * @bio: destination bio
 1062  * @page: start page to add
 1063  * @len: length of the data to add, may cross pages
 1064  * @off: offset of the data relative to @page, may cross pages
 1065  *
 1066  * Add the data at @page + @off to @bio as a new bvec.  The caller must ensure
 1067  * that @bio has space for another bvec.
 1068  */
 1069 void __bio_add_page(struct bio *bio, struct page *page,
 1070 		unsigned int len, unsigned int off)
 1071 {
 1072 	WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED));
 1073 	WARN_ON_ONCE(bio_full(bio, len));
 1074 
 1075 	bvec_set_page(&bio->bi_io_vec[bio->bi_vcnt], page, len, off);
 1076 	bio->bi_iter.bi_size += len;
 1077 	bio->bi_vcnt++;
 1078 }
 1079 EXPORT_SYMBOL_GPL(__bio_add_page);
 1080 
 1081 /**
 1082  *	bio_add_page	-	attempt to add page(s) to bio
 1083  *	@bio: destination bio
 1084  *	@page: start page to add
 1085  *	@len: vec entry length, may cross pages
 1086  *	@offset: vec entry offset relative to @page, may cross pages
 1087  *
 1088  *	Attempt to add page(s) to the bio_vec maplist. This will only fail
 1089  *	if either bio->bi_vcnt == bio->bi_max_vecs or it's a cloned bio.
 1090  */
 1091 int bio_add_page(struct bio *bio, struct page *page,
 1092 		 unsigned int len, unsigned int offset)
 1093 {
 1094 	bool same_page = false;
 1095 
 1096 	if (WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED)))
 1097 		return 0;
 1098 	if (bio->bi_iter.bi_size > UINT_MAX - len)
 1099 		return 0;
 1100 
 1101 	if (bio->bi_vcnt > 0 &&
 1102 	    bvec_try_merge_page(&bio->bi_io_vec[bio->bi_vcnt - 1],
 1103 				page, len, offset, &same_page)) {
 1104 		bio->bi_iter.bi_size += len;
 1105 		return len;
 1106 	}
 1107 
 1108 	if (bio->bi_vcnt >= bio->bi_max_vecs)
 1109 		return 0;
 1110 	__bio_add_page(bio, page, len, offset);
 1111 	return len;
 1112 }
 1113 EXPORT_SYMBOL(bio_add_page);
 1114 
 1115 void bio_add_folio_nofail(struct bio *bio, struct folio *folio, size_t len,
 1116 			  size_t off)
 1117 {
 1118 	WARN_ON_ONCE(len > UINT_MAX);
 1119 	WARN_ON_ONCE(off > UINT_MAX);
 1120 	__bio_add_page(bio, &folio->page, len, off);
 1121 }
 1122 
 1123 /**
 1124  * bio_add_folio - Attempt to add part of a folio to a bio.
 1125  * @bio: BIO to add to.
 1126  * @folio: Folio to add.
 1127  * @len: How many bytes from the folio to add.
 1128  * @off: First byte in this folio to add.
 1129  *
 1130  * Filesystems that use folios can call this function instead of calling
 1131  * bio_add_page() for each page in the folio.  If @off is bigger than
 1132  * PAGE_SIZE, this function can create a bio_vec that starts in a page
 1133  * after the bv_page.  BIOs do not support folios that are 4GiB or larger.
 1134  *
 1135  * Return: Whether the addition was successful.
 1136  */
 1137 bool bio_add_folio(struct bio *bio, struct folio *folio, size_t len,
 1138 		   size_t off)
 1139 {
 1140 	if (len > UINT_MAX || off > UINT_MAX)
 1141 		return false;
 1142 	return bio_add_page(bio, &folio->page, len, off) > 0;
 1143 }
 1144 EXPORT_SYMBOL(bio_add_folio);
 1145 
 1146 void __bio_release_pages(struct bio *bio, bool mark_dirty)
 1147 {
 1148 	struct bvec_iter_all iter_all;
 1149 	struct bio_vec *bvec;
 1150 
 1151 	bio_for_each_segment_all(bvec, bio, iter_all) {
 1152 		if (mark_dirty && !PageCompound(bvec->bv_page))
 1153 			set_page_dirty_lock(bvec->bv_page);
 1154 		bio_release_page(bio, bvec->bv_page);
 1155 	}
 1156 }
 1157 EXPORT_SYMBOL_GPL(__bio_release_pages);
 1158 
 1159 void bio_iov_bvec_set(struct bio *bio, struct iov_iter *iter)
 1160 {
 1161 	size_t size = iov_iter_count(iter);
 1162 
 1163 	WARN_ON_ONCE(bio->bi_max_vecs);
 1164 
 1165 	if (bio_op(bio) == REQ_OP_ZONE_APPEND) {
 1166 		struct request_queue *q = bdev_get_queue(bio->bi_bdev);
 1167 		size_t max_sectors = queue_max_zone_append_sectors(q);
 1168 
 1169 		size = min(size, max_sectors << SECTOR_SHIFT);
 1170 	}
 1171 
 1172 	bio->bi_vcnt = iter->nr_segs;
 1173 	bio->bi_io_vec = (struct bio_vec *)iter->bvec;
 1174 	bio->bi_iter.bi_bvec_done = iter->iov_offset;
 1175 	bio->bi_iter.bi_size = size;
 1176 	bio_set_flag(bio, BIO_CLONED);
 1177 }
 1178 
 1179 static int bio_iov_add_page(struct bio *bio, struct page *page,
 1180 		unsigned int len, unsigned int offset)
 1181 {
 1182 	bool same_page = false;
 1183 
 1184 	if (WARN_ON_ONCE(bio->bi_iter.bi_size > UINT_MAX - len))
 1185 		return -EIO;
 1186 
 1187 	if (bio->bi_vcnt > 0 &&
 1188 	    bvec_try_merge_page(&bio->bi_io_vec[bio->bi_vcnt - 1],
 1189 				page, len, offset, &same_page)) {
 1190 		bio->bi_iter.bi_size += len;
 1191 		if (same_page)
 1192 			bio_release_page(bio, page);
 1193 		return 0;
 1194 	}
 1195 	__bio_add_page(bio, page, len, offset);
 1196 	return 0;
 1197 }
 1198 
 1199 static int bio_iov_add_zone_append_page(struct bio *bio, struct page *page,
 1200 		unsigned int len, unsigned int offset)
 1201 {
 1202 	struct request_queue *q = bdev_get_queue(bio->bi_bdev);
 1203 	bool same_page = false;
 1204 
 1205 	if (bio_add_hw_page(q, bio, page, len, offset,
 1206 			queue_max_zone_append_sectors(q), &same_page) != len)
 1207 		return -EINVAL;
 1208 	if (same_page)
 1209 		bio_release_page(bio, page);
 1210 	return 0;
 1211 }
 1212 
 1213 #define PAGE_PTRS_PER_BVEC     (sizeof(struct bio_vec) / sizeof(struct page *))
 1214 
 1215 /**
 1216  * __bio_iov_iter_get_pages - pin user or kernel pages and add them to a bio
 1217  * @bio: bio to add pages to
 1218  * @iter: iov iterator describing the region to be mapped
 1219  *
 1220  * Extracts pages from *iter and appends them to @bio's bvec array.  The pages
 1221  * will have to be cleaned up in the way indicated by the BIO_PAGE_PINNED flag.
 1222  * For a multi-segment *iter, this function only adds pages from the next
 1223  * non-empty segment of the iov iterator.
 1224  */
 1225 static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
 1226 {
 1227 	iov_iter_extraction_t extraction_flags = 0;
 1228 	unsigned short nr_pages = bio->bi_max_vecs - bio->bi_vcnt;
 1229 	unsigned short entries_left = bio->bi_max_vecs - bio->bi_vcnt;
 1230 	struct bio_vec *bv = bio->bi_io_vec + bio->bi_vcnt;
 1231 	struct page **pages = (struct page **)bv;
 1232 	ssize_t size, left;
 1233 	unsigned len, i = 0;
 1234 	size_t offset;
 1235 	int ret = 0;
 1236 
 1237 	/*
 1238 	 * Move page array up in the allocated memory for the bio vecs as far as
 1239 	 * possible so that we can start filling biovecs from the beginning
 1240 	 * without overwriting the temporary page array.
 1241 	 */
 1242 	BUILD_BUG_ON(PAGE_PTRS_PER_BVEC < 2);
 1243 	pages += entries_left * (PAGE_PTRS_PER_BVEC - 1);
 1244 
 1245 	if (bio->bi_bdev && blk_queue_pci_p2pdma(bio->bi_bdev->bd_disk->queue))
 1246 		extraction_flags |= ITER_ALLOW_P2PDMA;
 1247 
 1248 	/*
 1249 	 * Each segment in the iov is required to be a block size multiple.
 1250 	 * However, we may not be able to get the entire segment if it spans
 1251 	 * more pages than bi_max_vecs allows, so we have to ALIGN_DOWN the
 1252 	 * result to ensure the bio's total size is correct. The remainder of
 1253 	 * the iov data will be picked up in the next bio iteration.
 1254 	 */
 1255 	size = iov_iter_extract_pages(iter, &pages,
 1256 				      UINT_MAX - bio->bi_iter.bi_size,
 1257 				      nr_pages, extraction_flags, &offset);
 1258 	if (unlikely(size <= 0))
 1259 		return size ? size : -EFAULT;
 1260 
 1261 	nr_pages = DIV_ROUND_UP(offset + size, PAGE_SIZE);
 1262 
 1263 	if (bio->bi_bdev) {
 1264 		size_t trim = size & (bdev_logical_block_size(bio->bi_bdev) - 1);
 1265 		iov_iter_revert(iter, trim);
 1266 		size -= trim;
 1267 	}
 1268 
 1269 	if (unlikely(!size)) {
 1270 		ret = -EFAULT;
 1271 		goto out;
 1272 	}
 1273 
 1274 	for (left = size, i = 0; left > 0; left -= len, i++) {
 1275 		struct page *page = pages[i];
 1276 
 1277 		len = min_t(size_t, PAGE_SIZE - offset, left);
 1278 		if (bio_op(bio) == REQ_OP_ZONE_APPEND) {
 1279 			ret = bio_iov_add_zone_append_page(bio, page, len,
 1280 					offset);
 1281 			if (ret)
 1282 				break;
 1283 		} else
 1284 			bio_iov_add_page(bio, page, len, offset);
 1285 
 1286 		offset = 0;
 1287 	}
 1288 
 1289 	iov_iter_revert(iter, left);
 1290 out:
 1291 	while (i < nr_pages)
 1292 		bio_release_page(bio, pages[i++]);
 1293 
 1294 	return ret;
 1295 }
 1296 
 1297 /**
 1298  * bio_iov_iter_get_pages - add user or kernel pages to a bio
 1299  * @bio: bio to add pages to
 1300  * @iter: iov iterator describing the region to be added
 1301  *
 1302  * This takes either an iterator pointing to user memory, or one pointing to
 1303  * kernel pages (BVEC iterator). If we're adding user pages, we pin them and
 1304  * map them into the kernel. On IO completion, the caller should put those
 1305  * pages. For bvec based iterators bio_iov_iter_get_pages() uses the provided
 1306  * bvecs rather than copying them. Hence anyone issuing kiocb based IO needs
 1307  * to ensure the bvecs and pages stay referenced until the submitted I/O is
 1308  * completed by a call to ->ki_complete() or returns with an error other than
 1309  * -EIOCBQUEUED. The caller needs to check if the bio is flagged BIO_NO_PAGE_REF
 1310  * on IO completion. If it isn't, then pages should be released.
 1311  *
 1312  * The function tries, but does not guarantee, to pin as many pages as
 1313  * fit into the bio, or are requested in @iter, whatever is smaller. If
 1314  * MM encounters an error pinning the requested pages, it stops. Error
 1315  * is returned only if 0 pages could be pinned.
 1316  */
 1317 int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
 1318 {
 1319 	int ret = 0;
 1320 
 1321 	if (WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED)))
 1322 		return -EIO;
 1323 
 1324 	if (iov_iter_is_bvec(iter)) {
 1325 		bio_iov_bvec_set(bio, iter);
 1326 		iov_iter_advance(iter, bio->bi_iter.bi_size);
 1327 		return 0;
 1328 	}
 1329 
 1330 	if (iov_iter_extract_will_pin(iter))
 1331 		bio_set_flag(bio, BIO_PAGE_PINNED);
 1332 	do {
 1333 		ret = __bio_iov_iter_get_pages(bio, iter);
 1334 	} while (!ret && iov_iter_count(iter) && !bio_full(bio, 0));
 1335 
 1336 	return bio->bi_vcnt ? 0 : ret;
 1337 }
 1338 EXPORT_SYMBOL_GPL(bio_iov_iter_get_pages);
 1339 
 1340 static void submit_bio_wait_endio(struct bio *bio)
 1341 {
 1342 	complete(bio->bi_private);
 1343 }
 1344 
 1345 /**
 1346  * submit_bio_wait - submit a bio, and wait until it completes
 1347  * @bio: The &struct bio which describes the I/O
 1348  *
 1349  * Simple wrapper around submit_bio(). Returns 0 on success, or the error from
 1350  * bio_endio() on failure.
 1351  *
 1352  * WARNING: Unlike to how submit_bio() is usually used, this function does not
 1353  * result in bio reference to be consumed. The caller must drop the reference
 1354  * on his own.
 1355  */
 1356 int submit_bio_wait(struct bio *bio)
 1357 {
 1358 	DECLARE_COMPLETION_ONSTACK_MAP(done,
 1359 			bio->bi_bdev->bd_disk->lockdep_map);
 1360 	unsigned long hang_check;
 1361 
 1362 	bio->bi_private = &done;
 1363 	bio->bi_end_io = submit_bio_wait_endio;
 1364 	bio->bi_opf |= REQ_SYNC;
 1365 	submit_bio(bio);
 1366 
 1367 	/* Prevent hang_check timer from firing at us during very long I/O */
 1368 	hang_check = sysctl_hung_task_timeout_secs;
 1369 	if (hang_check)
 1370 		while (!wait_for_completion_io_timeout(&done,
 1371 					hang_check * (HZ/2)))
 1372 			;
 1373 	else
 1374 		wait_for_completion_io(&done);
 1375 
 1376 	return blk_status_to_errno(bio->bi_status);
 1377 }
 1378 EXPORT_SYMBOL(submit_bio_wait);
 1379 
 1380 void __bio_advance(struct bio *bio, unsigned bytes)
 1381 {
 1382 	if (bio_integrity(bio))
 1383 		bio_integrity_advance(bio, bytes);
 1384 
 1385 	bio_crypt_advance(bio, bytes);
 1386 	bio_advance_iter(bio, &bio->bi_iter, bytes);
 1387 }
 1388 EXPORT_SYMBOL(__bio_advance);
 1389 
 1390 void bio_copy_data_iter(struct bio *dst, struct bvec_iter *dst_iter,
 1391 			struct bio *src, struct bvec_iter *src_iter)
 1392 {
 1393 	while (src_iter->bi_size && dst_iter->bi_size) {
 1394 		struct bio_vec src_bv = bio_iter_iovec(src, *src_iter);
 1395 		struct bio_vec dst_bv = bio_iter_iovec(dst, *dst_iter);
 1396 		unsigned int bytes = min(src_bv.bv_len, dst_bv.bv_len);
 1397 		void *src_buf = bvec_kmap_local(&src_bv);
 1398 		void *dst_buf = bvec_kmap_local(&dst_bv);
 1399 
 1400 		memcpy(dst_buf, src_buf, bytes);
 1401 
 1402 		kunmap_local(dst_buf);
 1403 		kunmap_local(src_buf);
 1404 
 1405 		bio_advance_iter_single(src, src_iter, bytes);
 1406 		bio_advance_iter_single(dst, dst_iter, bytes);
 1407 	}
 1408 }
 1409 EXPORT_SYMBOL(bio_copy_data_iter);
 1410 
 1411 /**
 1412  * bio_copy_data - copy contents of data buffers from one bio to another
 1413  * @src: source bio
 1414  * @dst: destination bio
 1415  *
 1416  * Stops when it reaches the end of either @src or @dst - that is, copies
 1417  * min(src->bi_size, dst->bi_size) bytes (or the equivalent for lists of bios).
 1418  */
 1419 void bio_copy_data(struct bio *dst, struct bio *src)
 1420 {
 1421 	struct bvec_iter src_iter = src->bi_iter;
 1422 	struct bvec_iter dst_iter = dst->bi_iter;
 1423 
 1424 	bio_copy_data_iter(dst, &dst_iter, src, &src_iter);
 1425 }
 1426 EXPORT_SYMBOL(bio_copy_data);
 1427 
 1428 void bio_free_pages(struct bio *bio)
 1429 {
 1430 	struct bio_vec *bvec;
 1431 	struct bvec_iter_all iter_all;
 1432 
 1433 	bio_for_each_segment_all(bvec, bio, iter_all)
 1434 		__free_page(bvec->bv_page);
 1435 }
 1436 EXPORT_SYMBOL(bio_free_pages);
 1437 
 1438 /*
 1439  * bio_set_pages_dirty() and bio_check_pages_dirty() are support functions
 1440  * for performing direct-IO in BIOs.
 1441  *
 1442  * The problem is that we cannot run set_page_dirty() from interrupt context
 1443  * because the required locks are not interrupt-safe.  So what we can do is to
 1444  * mark the pages dirty _before_ performing IO.  And in interrupt context,
 1445  * check that the pages are still dirty.   If so, fine.  If not, redirty them
 1446  * in process context.
 1447  *
 1448  * We special-case compound pages here: normally this means reads into hugetlb
 1449  * pages.  The logic in here doesn't really work right for compound pages
 1450  * because the VM does not uniformly chase down the head page in all cases.
 1451  * But dirtiness of compound pages is pretty meaningless anyway: the VM doesn't
 1452  * handle them at all.  So we skip compound pages here at an early stage.
 1453  *
 1454  * Note that this code is very hard to test under normal circumstances because
 1455  * direct-io pins the pages with get_user_pages().  This makes
 1456  * is_page_cache_freeable return false, and the VM will not clean the pages.
 1457  * But other code (eg, flusher threads) could clean the pages if they are mapped
 1458  * pagecache.
 1459  *
 1460  * Simply disabling the call to bio_set_pages_dirty() is a good way to test the
 1461  * deferred bio dirtying paths.
 1462  */
 1463 
 1464 /*
 1465  * bio_set_pages_dirty() will mark all the bio's pages as dirty.
 1466  */
 1467 void bio_set_pages_dirty(struct bio *bio)
 1468 {
 1469 	struct bio_vec *bvec;
 1470 	struct bvec_iter_all iter_all;
 1471 
 1472 	bio_for_each_segment_all(bvec, bio, iter_all) {
 1473 		if (!PageCompound(bvec->bv_page))
 1474 			set_page_dirty_lock(bvec->bv_page);
 1475 	}
 1476 }
 1477 EXPORT_SYMBOL_GPL(bio_set_pages_dirty);
 1478 
 1479 /*
 1480  * bio_check_pages_dirty() will check that all the BIO's pages are still dirty.
 1481  * If they are, then fine.  If, however, some pages are clean then they must
 1482  * have been written out during the direct-IO read.  So we take another ref on
 1483  * the BIO and re-dirty the pages in process context.
 1484  *
 1485  * It is expected that bio_check_pages_dirty() will wholly own the BIO from
 1486  * here on.  It will unpin each page and will run one bio_put() against the
 1487  * BIO.
 1488  */
 1489 
 1490 static void bio_dirty_fn(struct work_struct *work);
 1491 
 1492 static DECLARE_WORK(bio_dirty_work, bio_dirty_fn);
 1493 static DEFINE_SPINLOCK(bio_dirty_lock);
 1494 static struct bio *bio_dirty_list;
 1495 
 1496 /*
 1497  * This runs in process context
 1498  */
 1499 static void bio_dirty_fn(struct work_struct *work)
 1500 {
 1501 	struct bio *bio, *next;
 1502 
 1503 	spin_lock_irq(&bio_dirty_lock);
 1504 	next = bio_dirty_list;
 1505 	bio_dirty_list = NULL;
 1506 	spin_unlock_irq(&bio_dirty_lock);
 1507 
 1508 	while ((bio = next) != NULL) {
 1509 		next = bio->bi_private;
 1510 
 1511 		bio_release_pages(bio, true);
 1512 		bio_put(bio);
 1513 	}
 1514 }
 1515 
 1516 void bio_check_pages_dirty(struct bio *bio)
 1517 {
 1518 	struct bio_vec *bvec;
 1519 	unsigned long flags;
 1520 	struct bvec_iter_all iter_all;
 1521 
 1522 	bio_for_each_segment_all(bvec, bio, iter_all) {
 1523 		if (!PageDirty(bvec->bv_page) && !PageCompound(bvec->bv_page))
 1524 			goto defer;
 1525 	}
 1526 
 1527 	bio_release_pages(bio, false);
 1528 	bio_put(bio);
 1529 	return;
 1530 defer:
 1531 	spin_lock_irqsave(&bio_dirty_lock, flags);
 1532 	bio->bi_private = bio_dirty_list;
 1533 	bio_dirty_list = bio;
 1534 	spin_unlock_irqrestore(&bio_dirty_lock, flags);
 1535 	schedule_work(&bio_dirty_work);
 1536 }
 1537 EXPORT_SYMBOL_GPL(bio_check_pages_dirty);
 1538 
 1539 static inline bool bio_remaining_done(struct bio *bio)
 1540 {
 1541 	/*
 1542 	 * If we're not chaining, then ->__bi_remaining is always 1 and
 1543 	 * we always end io on the first invocation.
 1544 	 */
 1545 	if (!bio_flagged(bio, BIO_CHAIN))
 1546 		return true;
 1547 
 1548 	BUG_ON(atomic_read(&bio->__bi_remaining) <= 0);
 1549 
 1550 	if (atomic_dec_and_test(&bio->__bi_remaining)) {
 1551 		bio_clear_flag(bio, BIO_CHAIN);
 1552 		return true;
 1553 	}
 1554 
 1555 	return false;
 1556 }
 1557 
 1558 /**
 1559  * bio_endio - end I/O on a bio
 1560  * @bio:	bio
 1561  *
 1562  * Description:
 1563  *   bio_endio() will end I/O on the whole bio. bio_endio() is the preferred
 1564  *   way to end I/O on a bio. No one should call bi_end_io() directly on a
 1565  *   bio unless they own it and thus know that it has an end_io function.
 1566  *
 1567  *   bio_endio() can be called several times on a bio that has been chained
 1568  *   using bio_chain().  The ->bi_end_io() function will only be called the
 1569  *   last time.
 1570  **/
 1571 void bio_endio(struct bio *bio)
 1572 {
 1573 again:
 1574 	if (!bio_remaining_done(bio))
 1575 		return;
 1576 	if (!bio_integrity_endio(bio))
 1577 		return;
 1578 
 1579 	rq_qos_done_bio(bio);
 1580 
 1581 	if (bio->bi_bdev && bio_flagged(bio, BIO_TRACE_COMPLETION)) {
 1582 		trace_block_bio_complete(bdev_get_queue(bio->bi_bdev), bio);
 1583 		bio_clear_flag(bio, BIO_TRACE_COMPLETION);
 1584 	}
 1585 
 1586 	/*
 1587 	 * Need to have a real endio function for chained bios, otherwise
 1588 	 * various corner cases will break (like stacking block devices that
 1589 	 * save/restore bi_end_io) - however, we want to avoid unbounded
 1590 	 * recursion and blowing the stack. Tail call optimization would
 1591 	 * handle this, but compiling with frame pointers also disables
 1592 	 * gcc's sibling call optimization.
 1593 	 */
 1594 	if (bio->bi_end_io == bio_chain_endio) {
 1595 		bio = __bio_chain_endio(bio);
 1596 		goto again;
 1597 	}
 1598 
 1599 	blk_throtl_bio_endio(bio);
 1600 	/* release cgroup info */
 1601 	bio_uninit(bio);
 1602 	if (bio->bi_end_io)
 1603 		bio->bi_end_io(bio);
 1604 }
 1605 EXPORT_SYMBOL(bio_endio);
 1606 
 1607 /**
 1608  * bio_split - split a bio
 1609  * @bio:	bio to split
 1610  * @sectors:	number of sectors to split from the front of @bio
 1611  * @gfp:	gfp mask
 1612  * @bs:		bio set to allocate from
 1613  *
 1614  * Allocates and returns a new bio which represents @sectors from the start of
 1615  * @bio, and updates @bio to represent the remaining sectors.
 1616  *
 1617  * Unless this is a discard request the newly allocated bio will point
 1618  * to @bio's bi_io_vec. It is the caller's responsibility to ensure that
 1619  * neither @bio nor @bs are freed before the split bio.
 1620  */
 1621 struct bio *bio_split(struct bio *bio, int sectors,
 1622 		      gfp_t gfp, struct bio_set *bs)
 1623 {
 1624 	struct bio *split;
 1625 
 1626 	BUG_ON(sectors <= 0);
 1627 	BUG_ON(sectors >= bio_sectors(bio));
 1628 
 1629 	/* Zone append commands cannot be split */
 1630 	if (WARN_ON_ONCE(bio_op(bio) == REQ_OP_ZONE_APPEND))
 1631 		return NULL;
 1632 
 1633 	split = bio_alloc_clone(bio->bi_bdev, bio, gfp, bs);
 1634 	if (!split)
 1635 		return NULL;
 1636 
 1637 	split->bi_iter.bi_size = sectors << 9;
 1638 
 1639 	if (bio_integrity(split))
 1640 		bio_integrity_trim(split);
 1641 
 1642 	bio_advance(bio, split->bi_iter.bi_size);
 1643 
 1644 	if (bio_flagged(bio, BIO_TRACE_COMPLETION))
 1645 		bio_set_flag(split, BIO_TRACE_COMPLETION);
 1646 
 1647 	return split;
 1648 }
 1649 EXPORT_SYMBOL(bio_split);
 1650 
 1651 /**
 1652  * bio_trim - trim a bio
 1653  * @bio:	bio to trim
 1654  * @offset:	number of sectors to trim from the front of @bio
 1655  * @size:	size we want to trim @bio to, in sectors
 1656  *
 1657  * This function is typically used for bios that are cloned and submitted
 1658  * to the underlying device in parts.
 1659  */
 1660 void bio_trim(struct bio *bio, sector_t offset, sector_t size)
 1661 {
 1662 	if (WARN_ON_ONCE(offset > BIO_MAX_SECTORS || size > BIO_MAX_SECTORS ||
 1663 			 offset + size > bio_sectors(bio)))
 1664 		return;
 1665 
 1666 	size <<= 9;
 1667 	if (offset == 0 && size == bio->bi_iter.bi_size)
 1668 		return;
 1669 
 1670 	bio_advance(bio, offset << 9);
 1671 	bio->bi_iter.bi_size = size;
 1672 
 1673 	if (bio_integrity(bio))
 1674 		bio_integrity_trim(bio);
 1675 }
 1676 EXPORT_SYMBOL_GPL(bio_trim);
 1677 
 1678 /*
 1679  * create memory pools for biovec's in a bio_set.
 1680  * use the global biovec slabs created for general use.
 1681  */
 1682 int biovec_init_pool(mempool_t *pool, int pool_entries)
 1683 {
 1684 	struct biovec_slab *bp = bvec_slabs + ARRAY_SIZE(bvec_slabs) - 1;
 1685 
 1686 	return mempool_init_slab_pool(pool, pool_entries, bp->slab);
 1687 }
 1688 
 1689 /*
 1690  * bioset_exit - exit a bioset initialized with bioset_init()
 1691  *
 1692  * May be called on a zeroed but uninitialized bioset (i.e. allocated with
 1693  * kzalloc()).
 1694  */
 1695 void bioset_exit(struct bio_set *bs)
 1696 {
 1697 	bio_alloc_cache_destroy(bs);
 1698 	if (bs->rescue_workqueue)
 1699 		destroy_workqueue(bs->rescue_workqueue);
 1700 	bs->rescue_workqueue = NULL;
 1701 
 1702 	mempool_exit(&bs->bio_pool);
 1703 	mempool_exit(&bs->bvec_pool);
 1704 
 1705 	bioset_integrity_free(bs);
 1706 	if (bs->bio_slab)
 1707 		bio_put_slab(bs);
 1708 	bs->bio_slab = NULL;
 1709 }
 1710 EXPORT_SYMBOL(bioset_exit);
 1711 
 1712 /**
 1713  * bioset_init - Initialize a bio_set
 1714  * @bs:		pool to initialize
 1715  * @pool_size:	Number of bio and bio_vecs to cache in the mempool
 1716  * @front_pad:	Number of bytes to allocate in front of the returned bio
 1717  * @flags:	Flags to modify behavior, currently %BIOSET_NEED_BVECS
 1718  *              and %BIOSET_NEED_RESCUER
 1719  *
 1720  * Description:
 1721  *    Set up a bio_set to be used with @bio_alloc_bioset. Allows the caller
 1722  *    to ask for a number of bytes to be allocated in front of the bio.
 1723  *    Front pad allocation is useful for embedding the bio inside
 1724  *    another structure, to avoid allocating extra data to go with the bio.
 1725  *    Note that the bio must be embedded at the END of that structure always,
 1726  *    or things will break badly.
 1727  *    If %BIOSET_NEED_BVECS is set in @flags, a separate pool will be allocated
 1728  *    for allocating iovecs.  This pool is not needed e.g. for bio_init_clone().
 1729  *    If %BIOSET_NEED_RESCUER is set, a workqueue is created which can be used
 1730  *    to dispatch queued requests when the mempool runs out of space.
 1731  *
 1732  */
 1733 int bioset_init(struct bio_set *bs,
 1734 		unsigned int pool_size,
 1735 		unsigned int front_pad,
 1736 		int flags)
 1737 {
 1738 	bs->front_pad = front_pad;
 1739 	if (flags & BIOSET_NEED_BVECS)
 1740 		bs->back_pad = BIO_INLINE_VECS * sizeof(struct bio_vec);
 1741 	else
 1742 		bs->back_pad = 0;
 1743 
 1744 	spin_lock_init(&bs->rescue_lock);
 1745 	bio_list_init(&bs->rescue_list);
 1746 	INIT_WORK(&bs->rescue_work, bio_alloc_rescue);
 1747 
 1748 	bs->bio_slab = bio_find_or_create_slab(bs);
 1749 	if (!bs->bio_slab)
 1750 		return -ENOMEM;
 1751 
 1752 	if (mempool_init_slab_pool(&bs->bio_pool, pool_size, bs->bio_slab))
 1753 		goto bad;
 1754 
 1755 	if ((flags & BIOSET_NEED_BVECS) &&
 1756 	    biovec_init_pool(&bs->bvec_pool, pool_size))
 1757 		goto bad;
 1758 
 1759 	if (flags & BIOSET_NEED_RESCUER) {
 1760 		bs->rescue_workqueue = alloc_workqueue("bioset",
 1761 							WQ_MEM_RECLAIM, 0);
 1762 		if (!bs->rescue_workqueue)
 1763 			goto bad;
 1764 	}
 1765 	if (flags & BIOSET_PERCPU_CACHE) {
 1766 		bs->cache = alloc_percpu(struct bio_alloc_cache);
 1767 		if (!bs->cache)
 1768 			goto bad;
 1769 		cpuhp_state_add_instance_nocalls(CPUHP_BIO_DEAD, &bs->cpuhp_dead);
 1770 	}
 1771 
 1772 	return 0;
 1773 bad:
 1774 	bioset_exit(bs);
 1775 	return -ENOMEM;
 1776 }
 1777 EXPORT_SYMBOL(bioset_init);
 1778 
 1779 static int __init init_bio(void)
 1780 {
 1781 	int i;
 1782 
 1783 	BUILD_BUG_ON(BIO_FLAG_LAST > 8 * sizeof_field(struct bio, bi_flags));
 1784 
 1785 	bio_integrity_init();
 1786 
 1787 	for (i = 0; i < ARRAY_SIZE(bvec_slabs); i++) {
 1788 		struct biovec_slab *bvs = bvec_slabs + i;
 1789 
 1790 		bvs->slab = kmem_cache_create(bvs->name,
 1791 				bvs->nr_vecs * sizeof(struct bio_vec), 0,
 1792 				SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL);
 1793 	}
 1794 
 1795 	cpuhp_setup_state_multi(CPUHP_BIO_DEAD, "block/bio:dead", NULL,
 1796 					bio_cpu_dead);
 1797 
 1798 	if (bioset_init(&fs_bio_set, BIO_POOL_SIZE, 0,
 1799 			BIOSET_NEED_BVECS | BIOSET_PERCPU_CACHE))
 1800 		panic("bio: can't allocate bios\n");
 1801 
 1802 	if (bioset_integrity_create(&fs_bio_set, BIO_POOL_SIZE))
 1803 		panic("bio: can't create integrity pool\n");
 1804 
 1805 	return 0;
 1806 }
 1807 subsys_initcall(init_bio);