cregit-Linux how code gets into the kernel

Release 4.18 block/bio.c

Directory: block
/*
 * Copyright (C) 2001 Jens Axboe <axboe@kernel.dk>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public Licens
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-
 *
 */
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/bio.h>
#include <linux/blkdev.h>
#include <linux/uio.h>
#include <linux/iocontext.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/mempool.h>
#include <linux/workqueue.h>
#include <linux/cgroup.h>

#include <trace/events/block.h>
#include "blk.h"

/*
 * Test patch to inline a certain number of bi_io_vec's inside the bio
 * itself, to shrink a bio data allocation from two mempool calls to one
 */

#define BIO_INLINE_VECS		4

/*
 * if you change this list, also change bvec_alloc or things will
 * break badly! cannot be bigger than what you can fit into an
 * unsigned short
 */

#define BV(x, n) { .nr_vecs = x, .name = "biovec-"#n }

static struct biovec_slab bvec_slabs[BVEC_POOL_NR] __read_mostly = {
	BV(1, 1), BV(4, 4), BV(16, 16), BV(64, 64), BV(128, 128), BV(BIO_MAX_PAGES, max),
};
#undef BV

/*
 * fs_bio_set is the bio_set containing bio and iovec memory pools used by
 * IO code that does not need private memory pools.
 */

struct bio_set fs_bio_set;
EXPORT_SYMBOL(fs_bio_set);

/*
 * Our slab pool management
 */

struct bio_slab {
	
struct kmem_cache *slab;
	
unsigned int slab_ref;
	
unsigned int slab_size;
	
char name[8];
};
static DEFINE_MUTEX(bio_slab_lock);

static struct bio_slab *bio_slabs;


static unsigned int bio_slab_nr, bio_slab_max;




static struct kmem_cache *bio_find_or_create_slab(unsigned int extra_size)
{
	unsigned int sz = sizeof(struct bio) + extra_size;
	struct kmem_cache *slab = NULL;
	struct bio_slab *bslab, *new_bio_slabs;
	unsigned int new_bio_slab_max;
	unsigned int i, entry = -1;

	mutex_lock(&bio_slab_lock);

	i = 0;
	while (i < bio_slab_nr) {
		bslab = &bio_slabs[i];

		if (!bslab->slab && entry == -1)
			entry = i;
		else if (bslab->slab_size == sz) {
			slab = bslab->slab;
			bslab->slab_ref++;
			break;
		}
		i++;
	}

	if (slab)
		goto out_unlock;

	if (bio_slab_nr == bio_slab_max && entry == -1) {
		new_bio_slab_max = bio_slab_max << 1;
		new_bio_slabs = krealloc(bio_slabs,
					 new_bio_slab_max * sizeof(struct bio_slab),
					 GFP_KERNEL);
		if (!new_bio_slabs)
			goto out_unlock;
		bio_slab_max = new_bio_slab_max;
		bio_slabs = new_bio_slabs;
	}
	if (entry == -1)
		entry = bio_slab_nr++;

	bslab = &bio_slabs[entry];

	snprintf(bslab->name, sizeof(bslab->name), "bio-%d", entry);
	slab = kmem_cache_create(bslab->name, sz, ARCH_KMALLOC_MINALIGN,
				 SLAB_HWCACHE_ALIGN, NULL);
	if (!slab)
		goto out_unlock;

	bslab->slab = slab;
	bslab->slab_ref = 1;
	bslab->slab_size = sz;
out_unlock:
	mutex_unlock(&bio_slab_lock);
	return slab;
}


Contributors
PersonTokensPropCommitsCommitProp
Jens Axboe24791.14%120.00%


Anna Leuschner124.43%120.00%


Alexey Khoroshilov93.32%120.00%


Thiago Farina20.74%120.00%


Mikulas Patocka10.37%120.00%


Total271100.00%5100.00%






static void bio_put_slab(struct bio_set *bs)
{
	struct bio_slab *bslab = NULL;
	unsigned int i;

	mutex_lock(&bio_slab_lock);

	for (i = 0; i < bio_slab_nr; i++) {
		if (bs->bio_slab == bio_slabs[i].slab) {
			bslab = &bio_slabs[i];
			break;
		}
	}

	if (WARN(!bslab, KERN_ERR "bio: unable to find slab!\n"))
		goto out;

	WARN_ON(!bslab->slab_ref);

	if (--bslab->slab_ref)
		goto out;

	kmem_cache_destroy(bslab->slab);
	bslab->slab = NULL;

out:
	mutex_unlock(&bio_slab_lock);
}


Contributors
PersonTokensPropCommitsCommitProp
Jens Axboe11797.50%150.00%


Andi Kleen32.50%150.00%


Total120100.00%2100.00%






unsigned int bvec_nr_vecs(unsigned short idx)
{
	return bvec_slabs[idx].nr_vecs;
}


Contributors
PersonTokensPropCommitsCommitProp
Martin K. Petersen18100.00%1100.00%


Total18100.00%1100.00%






void bvec_free(mempool_t *pool, struct bio_vec *bv, unsigned int idx)
{
	if (!idx)
		return;
	idx--;

	BIO_BUG_ON(idx >= BVEC_POOL_NR);

	if (idx == BVEC_POOL_MAX) {
		mempool_free(bv, pool);
	} else {
		struct biovec_slab *bvs = bvec_slabs + idx;

		kmem_cache_free(bvs->slab, bv);
	}
}


Contributors
PersonTokensPropCommitsCommitProp
Jens Axboe5375.71%133.33%


Christoph Hellwig1318.57%133.33%


Kent Overstreet45.71%133.33%


Total70100.00%3100.00%






struct bio_vec *bvec_alloc(gfp_t gfp_mask, int nr, unsigned long *idx,
			   mempool_t *pool)
{
	struct bio_vec *bvl;

	/*
         * see comment near bvec_array define!
         */
	switch (nr) {
	case 1:
		*idx = 0;
		break;
	case 2 ... 4:
		*idx = 1;
		break;
	case 5 ... 16:
		*idx = 2;
		break;
	case 17 ... 64:
		*idx = 3;
		break;
	case 65 ... 128:
		*idx = 4;
		break;
	case 129 ... BIO_MAX_PAGES:
		*idx = 5;
		break;
	default:
		return NULL;
	}

	/*
         * idx now points to the pool we want to allocate from. only the
         * 1-vec entry pool is mempool backed.
         */
	if (*idx == BVEC_POOL_MAX) {
fallback:
		bvl = mempool_alloc(pool, gfp_mask);
	} else {
		struct biovec_slab *bvs = bvec_slabs + *idx;
		gfp_t __gfp_mask = gfp_mask & ~(__GFP_DIRECT_RECLAIM | __GFP_IO);

		/*
                 * Make this allocation restricted and don't dump info on
                 * allocation failures, since we'll fallback to the mempool
                 * in case of failure.
                 */
		__gfp_mask |= __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN;

		/*
                 * Try a slab allocation. If this fails and __GFP_DIRECT_RECLAIM
                 * is set, retry with the 1-entry mempool
                 */
		bvl = kmem_cache_alloc(bvs->slab, __gfp_mask);
		if (unlikely(!bvl && (gfp_mask & __GFP_DIRECT_RECLAIM))) {
			*idx = BVEC_POOL_MAX;
			goto fallback;
		}
	}

	(*idx)++;
	return bvl;
}


Contributors
PersonTokensPropCommitsCommitProp
Linus Torvalds10150.00%327.27%


Jens Axboe7939.11%327.27%


Christoph Hellwig83.96%19.09%


Dave Olien62.97%19.09%


Kent Overstreet41.98%19.09%


Mel Gorman31.49%19.09%


Al Viro10.50%19.09%


Total202100.00%11100.00%






void bio_uninit(struct bio *bio)
{
	bio_disassociate_task(bio);
}

Contributors
PersonTokensPropCommitsCommitProp
Kent Overstreet1493.33%150.00%


Jens Axboe16.67%150.00%


Total15100.00%2100.00%



EXPORT_SYMBOL(bio_uninit);




static void bio_free(struct bio *bio)
{
	struct bio_set *bs = bio->bi_pool;
	void *p;

	bio_uninit(bio);

	if (bs) {
		bvec_free(&bs->bvec_pool, bio->bi_io_vec, BVEC_POOL_IDX(bio));

		/*
                 * If we have front padding, adjust the bio pointer before freeing
                 */
		p = bio;
		p -= bs->front_pad;

		mempool_free(p, &bs->bio_pool);
	} else {
		/* Bio was allocated by bio_kmalloc() */
		kfree(bio);
	}
}


Contributors
PersonTokensPropCommitsCommitProp
Kent Overstreet3036.59%323.08%


Jens Axboe2328.05%323.08%


Linus Torvalds2024.39%323.08%


Peter Osterlund44.88%17.69%


H Hartley Sweeten33.66%17.69%


Dave Olien11.22%17.69%


Christoph Hellwig11.22%17.69%


Total82100.00%13100.00%



/*
 * Users of this function have their own bio allocation. Subsequently,
 * they must remember to pair any call to bio_init() with bio_uninit()
 * when IO has completed, or when the bio is released.
 */



void bio_init(struct bio *bio, struct bio_vec *table,
	      unsigned short max_vecs)
{
	memset(bio, 0, sizeof(*bio));
	atomic_set(&bio->__bi_remaining, 1);
	atomic_set(&bio->__bi_cnt, 1);

	bio->bi_io_vec = table;
	bio->bi_max_vecs = max_vecs;
}

Contributors
PersonTokensPropCommitsCommitProp
Linus Torvalds2132.81%225.00%


Lei Ming2132.81%112.50%


Jens Axboe1320.31%450.00%


Kent Overstreet914.06%112.50%


Total64100.00%8100.00%



EXPORT_SYMBOL(bio_init);

/**
 * bio_reset - reinitialize a bio
 * @bio:        bio to reset
 *
 * Description:
 *   After calling bio_reset(), @bio will be in the same state as a freshly
 *   allocated bio returned bio bio_alloc_bioset() - the only fields that are
 *   preserved are the ones that are initialized by bio_alloc_bioset(). See
 *   comment in struct bio.
 */



void bio_reset(struct bio *bio)
{
	unsigned long flags = bio->bi_flags & (~0UL << BIO_RESET_BITS);

	bio_uninit(bio);

	memset(bio, 0, BIO_RESET_BYTES);
	bio->bi_flags = flags;
	atomic_set(&bio->__bi_remaining, 1);
}

Contributors
PersonTokensPropCommitsCommitProp
Kent Overstreet5396.36%250.00%


Jens Axboe23.64%250.00%


Total55100.00%4100.00%



EXPORT_SYMBOL(bio_reset);




static struct bio *__bio_chain_endio(struct bio *bio)
{
	struct bio *parent = bio->bi_private;

	if (!parent->bi_status)
		parent->bi_status = bio->bi_status;
	bio_put(bio);
	return parent;
}


Contributors
PersonTokensPropCommitsCommitProp
Christoph Hellwig3271.11%480.00%


Kent Overstreet1328.89%120.00%


Total45100.00%5100.00%






static void bio_chain_endio(struct bio *bio)
{
	bio_endio(__bio_chain_endio(bio));
}


Contributors
PersonTokensPropCommitsCommitProp
Christoph Hellwig1473.68%150.00%


Kent Overstreet526.32%150.00%


Total19100.00%2100.00%



/**
 * bio_chain - chain bio completions
 * @bio: the target bio
 * @parent: the @bio's parent bio
 *
 * The caller won't have a bi_end_io called when @bio completes - instead,
 * @parent's bi_end_io won't be called until both @parent and @bio have
 * completed; the chained bio will also be freed when it completes.
 *
 * The caller must not set bi_private or bi_end_io in @bio.
 */



void bio_chain(struct bio *bio, struct bio *parent)
{
	BUG_ON(bio->bi_private || bio->bi_end_io);

	bio->bi_private = parent;
	bio->bi_end_io	= bio_chain_endio;
	bio_inc_remaining(parent);
}

Contributors
PersonTokensPropCommitsCommitProp
Kent Overstreet4297.67%150.00%


Jens Axboe12.33%150.00%


Total43100.00%2100.00%



EXPORT_SYMBOL(bio_chain);




static void bio_alloc_rescue(struct work_struct *work)
{
	struct bio_set *bs = container_of(work, struct bio_set, rescue_work);
	struct bio *bio;

	while (1) {
		spin_lock(&bs->rescue_lock);
		bio = bio_list_pop(&bs->rescue_list);
		spin_unlock(&bs->rescue_lock);

		if (!bio)
			break;

		generic_make_request(bio);
	}
}


Contributors
PersonTokensPropCommitsCommitProp
Kent Overstreet74100.00%1100.00%


Total74100.00%1100.00%






static void punt_bios_to_rescuer(struct bio_set *bs)
{
	struct bio_list punt, nopunt;
	struct bio *bio;

	if (WARN_ON_ONCE(!bs->rescue_workqueue))
		return;
	/*
         * In order to guarantee forward progress we must punt only bios that
         * were allocated from this bio_set; otherwise, if there was a bio on
         * there for a stacking driver higher up in the stack, processing it
         * could require allocating bios from this bio_set, and doing that from
         * our own rescuer would be bad.
         *
         * Since bio lists are singly linked, pop them all instead of trying to
         * remove from the middle of the list:
         */

	bio_list_init(&punt);
	bio_list_init(&nopunt);

	while ((bio = bio_list_pop(&current->bio_list[0])))
		bio_list_add(bio->bi_pool == bs ? &punt : &nopunt, bio);
	current->bio_list[0] = nopunt;

	bio_list_init(&nopunt);
	while ((bio = bio_list_pop(&current->bio_list[1])))
		bio_list_add(bio->bi_pool == bs ? &punt : &nopunt, bio);
	current->bio_list[1] = nopunt;

	spin_lock(&bs->rescue_lock);
	bio_list_merge(&bs->rescue_list, &punt);
	spin_unlock(&bs->rescue_lock);

	queue_work(bs->rescue_workqueue, &bs->rescue_work);
}


Contributors
PersonTokensPropCommitsCommitProp
Kent Overstreet11062.15%133.33%


Neil Brown6737.85%266.67%


Total177100.00%3100.00%



/**
 * bio_alloc_bioset - allocate a bio for I/O
 * @gfp_mask:   the GFP_* mask given to the slab allocator
 * @nr_iovecs:  number of iovecs to pre-allocate
 * @bs:         the bio_set to allocate from.
 *
 * Description:
 *   If @bs is NULL, uses kmalloc() to allocate the bio; else the allocation is
 *   backed by the @bs's mempool.
 *
 *   When @bs is not NULL, if %__GFP_DIRECT_RECLAIM is set then bio_alloc will
 *   always be able to allocate a bio. This is due to the mempool guarantees.
 *   To make this work, callers must never allocate more than 1 bio at a time
 *   from this pool. Callers that need to allocate more than 1 bio must always
 *   submit the previously allocated bio for IO before attempting to allocate
 *   a new one. Failure to do so can cause deadlocks under memory pressure.
 *
 *   Note that when running under generic_make_request() (i.e. any block
 *   driver), bios are not submitted until after you return - see the code in
 *   generic_make_request() that converts recursion into iteration, to prevent
 *   stack overflows.
 *
 *   This would normally mean allocating multiple bios under
 *   generic_make_request() would be susceptible to deadlocks, but we have
 *   deadlock avoidance code that resubmits any blocked bios from a rescuer
 *   thread.
 *
 *   However, we do not guarantee forward progress for allocations from other
 *   mempools. Doing multiple allocations from the same mempool under
 *   generic_make_request() should be avoided - instead, use bio_set's front_pad
 *   for per bio allocations.
 *
 *   RETURNS:
 *   Pointer to new bio on success, NULL on failure.
 */



struct bio *bio_alloc_bioset(gfp_t gfp_mask, unsigned int nr_iovecs,
			     struct bio_set *bs)
{
	gfp_t saved_gfp = gfp_mask;
	unsigned front_pad;
	unsigned inline_vecs;
	struct bio_vec *bvl = NULL;
	struct bio *bio;
	void *p;

	if (!bs) {
		if (nr_iovecs > UIO_MAXIOV)
			return NULL;

		p = kmalloc(sizeof(struct bio) +
			    nr_iovecs * sizeof(struct bio_vec),
			    gfp_mask);
		front_pad = 0;
		inline_vecs = nr_iovecs;
	} else {
		/* should not use nobvec bioset for nr_iovecs > 0 */
		if (WARN_ON_ONCE(!mempool_initialized(&bs->bvec_pool) &&
				 nr_iovecs > 0))
			return NULL;
		/*
                 * generic_make_request() converts recursion to iteration; this
                 * means if we're running beneath it, any bios we allocate and
                 * submit will not be submitted (and thus freed) until after we
                 * return.
                 *
                 * This exposes us to a potential deadlock if we allocate
                 * multiple bios from the same bio_set() while running
                 * underneath generic_make_request(). If we were to allocate
                 * multiple bios (say a stacking block driver that was splitting
                 * bios), we would deadlock if we exhausted the mempool's
                 * reserve.
                 *
                 * We solve this, and guarantee forward progress, with a rescuer
                 * workqueue per bio_set. If we go to allocate and there are
                 * bios on current->bio_list, we first try the allocation
                 * without __GFP_DIRECT_RECLAIM; if that fails, we punt those
                 * bios we would be blocking to the rescuer workqueue before
                 * we retry with the original gfp_flags.
                 */

		if (current->bio_list &&
		    (!bio_list_empty(&current->bio_list[0]) ||
		     !bio_list_empty(&current->bio_list[1])) &&
		    bs->rescue_workqueue)
			gfp_mask &= ~__GFP_DIRECT_RECLAIM;

		p = mempool_alloc(&bs->bio_pool, gfp_mask);
		if (!p && gfp_mask != saved_gfp) {
			punt_bios_to_rescuer(bs);
			gfp_mask = saved_gfp;
			p = mempool_alloc(&bs->bio_pool, gfp_mask);
		}

		front_pad = bs->front_pad;
		inline_vecs = BIO_INLINE_VECS;
	}

	if (unlikely(!p))
		return NULL;

	bio = p + front_pad;
	bio_init(bio, NULL, 0);

	if (nr_iovecs > inline_vecs) {
		unsigned long idx = 0;

		bvl = bvec_alloc(gfp_mask, nr_iovecs, &idx, &bs->bvec_pool);
		if (!bvl && gfp_mask != saved_gfp) {
			punt_bios_to_rescuer(bs);
			gfp_mask = saved_gfp;
			bvl = bvec_alloc(gfp_mask, nr_iovecs, &idx, &bs->bvec_pool);
		}

		if (unlikely(!bvl))
			goto err_free;

		bio->bi_flags |= idx << BVEC_POOL_OFFSET;
	} else if (nr_iovecs) {
		bvl = bio->bi_inline_vecs;
	}

	bio->bi_pool = bs;
	bio->bi_max_vecs = nr_iovecs;
	bio->bi_io_vec = bvl;
	return bio;

err_free:
	mempool_free(p, &bs->bio_pool);
	return NULL;
}

Contributors
PersonTokensPropCommitsCommitProp
Kent Overstreet16945.19%519.23%


Jens Axboe359.36%415.38%


Linus Torvalds328.56%311.54%


Ingo Molnar266.95%13.85%


Neil Brown225.88%27.69%


Andrew Morton215.61%27.69%


Jun'ichi Nomura184.81%13.85%


Christoph Hellwig123.21%13.85%


Dave Olien123.21%13.85%


Tejun Heo112.94%13.85%


Subhash Peddamallu82.14%13.85%


Lei Ming41.07%13.85%


Mel Gorman20.53%13.85%


Al Viro10.27%13.85%


Dan Carpenter10.27%13.85%


Total374100.00%26100.00%



EXPORT_SYMBOL(bio_alloc_bioset);




void zero_fill_bio_iter(struct bio *bio, struct bvec_iter start)
{
	unsigned long flags;
	struct bio_vec bv;
	struct bvec_iter iter;

	__bio_for_each_segment(bv, bio, iter, start) {
		char *data = bvec_kmap_irq(&bv, &flags);
		memset(data, 0, bv.bv_len);
		flush_dcache_page(bv.bv_page);
		bvec_kunmap_irq(data, &flags);
	}
}

Contributors
PersonTokensPropCommitsCommitProp
Dave Olien6280.52%133.33%


Kent Overstreet1519.48%266.67%


Total77100.00%3100.00%



EXPORT_SYMBOL(zero_fill_bio_iter);

/**
 * bio_put - release a reference to a bio
 * @bio:   bio to release reference to
 *
 * Description:
 *   Put a reference to a &struct bio, either one you have gotten with
 *   bio_alloc, bio_get or bio_clone_*. The last put of a bio will free it.
 **/



void bio_put(struct bio *bio)
{
	if (!bio_flagged(bio, BIO_REFFED))
		bio_free(bio);
	else {
		BIO_BUG_ON(!atomic_read(&bio->__bi_cnt));

		/*
                 * last put frees it
                 */
		if (atomic_dec_and_test(&bio->__bi_cnt))
			bio_free(bio);
	}
}

Contributors
PersonTokensPropCommitsCommitProp
Linus Torvalds3053.57%360.00%


Jens Axboe2137.50%120.00%


Kent Overstreet58.93%120.00%


Total56100.00%5100.00%



EXPORT_SYMBOL(bio_put);




inline int bio_phys_segments(struct request_queue *q, struct bio *bio)
{
	if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
		blk_recount_segments(q, bio);

	return bio->bi_phys_segments;
}

Contributors
PersonTokensPropCommitsCommitProp
Linus Torvalds3585.37%133.33%


Jens Axboe614.63%266.67%


Total41100.00%3100.00%



EXPORT_SYMBOL(bio_phys_segments);

/**
 *      __bio_clone_fast - clone a bio that shares the original bio's biovec
 *      @bio: destination bio
 *      @bio_src: bio to clone
 *
 *      Clone a &bio. Caller will own the returned bio, but not
 *      the actual data it points to. Reference count of returned
 *      bio will be one.
 *
 *      Caller must ensure that @bio_src is not freed before @bio.
 */



void __bio_clone_fast(struct bio *bio, struct bio *bio_src)
{
	BUG_ON(bio->bi_pool && BVEC_POOL_IDX(bio));

	/*
         * most users will be overriding ->bi_disk with a new target,
         * so we don't set nor calculate new physical/hw segment counts here
         */
	bio->bi_disk = bio_src->bi_disk;
	bio->bi_partno = bio_src->bi_partno;
	bio_set_flag(bio, BIO_CLONED);
	if (bio_flagged(bio_src, BIO_THROTTLED))
		bio_set_flag(bio, BIO_THROTTLED);
	bio->bi_opf = bio_src->bi_opf;
	bio->bi_write_hint = bio_src->bi_write_hint;
	bio->bi_iter = bio_src->bi_iter;
	bio->bi_io_vec = bio_src->bi_io_vec;

	bio_clone_blkcg_association(bio, bio_src);
}

Contributors
PersonTokensPropCommitsCommitProp
Kent Overstreet5753.77%111.11%


Shaohua Li1615.09%111.11%


Jens Axboe1413.21%333.33%


Michael Lyle87.55%111.11%


Paolo Valente76.60%111.11%


Christoph Hellwig43.77%222.22%


Total106100.00%9100.00%



EXPORT_SYMBOL(__bio_clone_fast);

/**
 *      bio_clone_fast - clone a bio that shares the original bio's biovec
 *      @bio: bio to clone
 *      @gfp_mask: allocation priority
 *      @bs: bio_set to allocate from
 *
 *      Like __bio_clone_fast, only also allocates the returned bio
 */



struct bio *bio_clone_fast(struct bio *bio, gfp_t gfp_mask, struct bio_set *bs)
{
	struct bio *b;

	b = bio_alloc_bioset(gfp_mask, 0, bs);
	if (!b)
		return NULL;

	__bio_clone_fast(b, bio);

	if (bio_integrity(bio)) {
		int ret;

		ret = bio_integrity_clone(b, bio, gfp_mask);

		if (ret < 0) {
			bio_put(b);
			return NULL;
		}
	}

	return b;
}

Contributors
PersonTokensPropCommitsCommitProp
Kent Overstreet93100.00%1100.00%


Total93100.00%1100.00%



EXPORT_SYMBOL(bio_clone_fast);

/**
 *      bio_clone_bioset - clone a bio
 *      @bio_src: bio to clone
 *      @gfp_mask: allocation priority
 *      @bs: bio_set to allocate from
 *
 *      Clone bio. Caller will own the returned bio, but not the actual data it
 *      points to. Reference count of returned bio will be one.
 */



struct bio *bio_clone_bioset(struct bio *bio_src, gfp_t gfp_mask,
			     struct bio_set *bs)
{
	struct bvec_iter iter;
	struct bio_vec bv;
	struct bio *bio;

	/*
         * Pre immutable biovecs, __bio_clone() used to just do a memcpy from
         * bio_src->bi_io_vec to bio->bi_io_vec.
         *
         * We can't do that anymore, because:
         *
         *  - The point of cloning the biovec is to produce a bio with a biovec
         *    the caller can modify: bi_idx and bi_bvec_done should be 0.
         *
         *  - The original bio could've had more than BIO_MAX_PAGES biovecs; if
         *    we tried to clone the whole thing bio_alloc_bioset() would fail.
         *    But the clone should succeed as long as the number of biovecs we
         *    actually need to allocate is fewer than BIO_MAX_PAGES.
         *
         *  - Lastly, bi_vcnt should not be looked at or relied upon by code
         *    that does not own the bio - reason being drivers don't use it for
         *    iterating over the biovec anymore, so expecting it to be kept up
         *    to date (i.e. for clones that share the parent biovec) is just
         *    asking for trouble and would force extra work on
         *    __bio_clone_fast() anyways.
         */

	bio = bio_alloc_bioset(gfp_mask, bio_segments(bio_src), bs);
	if (!bio)
		return NULL;
	bio->bi_disk		= bio_src->bi_disk;
	bio->bi_opf		= bio_src->bi_opf;
	bio->bi_write_hint	= bio_src->bi_write_hint;
	bio->bi_iter.bi_sector	= bio_src->bi_iter.bi_sector;
	bio->bi_iter.bi_size	= bio_src->bi_iter.bi_size;

	switch (bio_op(bio)) {
	case REQ_OP_DISCARD:
	case REQ_OP_SECURE_ERASE:
	case REQ_OP_WRITE_ZEROES:
		break;
	case REQ_OP_WRITE_SAME:
		bio->bi_io_vec[bio->bi_vcnt++] = bio_src->bi_io_vec[0];
		break;
	default:
		bio_for_each_segment(bv, bio_src, iter)
			bio->bi_io_vec[bio->bi_vcnt++] = bv;
		break;
	}

	if (bio_integrity(bio_src)) {
		int ret;

		ret = bio_integrity_clone(bio, bio_src, gfp_mask);
		if (ret < 0) {
			bio_put(bio);
			return NULL;
		}
	}

	bio_clone_blkcg_association(bio, bio_src);

	return bio;
}

Contributors
PersonTokensPropCommitsCommitProp
Kent Overstreet10448.37%316.67%


Martin K. Petersen3114.42%15.56%


Linus Torvalds2813.02%211.11%


Adrian Hunter156.98%15.56%


Jens Axboe104.65%211.11%


Paolo Valente73.26%15.56%


Li Zefan62.79%15.56%


Shaohua Li31.40%15.56%


Michael Christie31.40%15.56%


Chaitanya Kulkarni31.40%15.56%


Christoph Hellwig20.93%15.56%


Jun'ichi Nomura10.47%15.56%


Al Viro10.47%15.56%


Peter Osterlund10.47%15.56%


Total215100.00%18100.00%



EXPORT_SYMBOL(bio_clone_bioset);

/**
 *      bio_add_pc_page -       attempt to add page to bio
 *      @q: the target queue
 *      @bio: destination bio
 *      @page: page to add
 *      @len: vec entry length
 *      @offset: vec entry offset
 *
 *      Attempt to add a page to the bio_vec maplist. This can fail for a
 *      number of reasons, such as the bio being full or target block device
 *      limitations. The target block device must allow bio's up to PAGE_SIZE,
 *      so it is always possible to add a single page to an empty bio.
 *
 *      This should only be used by REQ_PC bios.
 */



int bio_add_pc_page(struct request_queue *q, struct bio *bio, struct page
		    *page, unsigned int len, unsigned int offset)
{
	int retried_segments = 0;
	struct bio_vec *bvec;

	/*
         * cloned bio must not modify vec list
         */
	if (unlikely(bio_flagged(bio, BIO_CLONED)))
		return 0;

	if (((bio->bi_iter.bi_size + len) >> 9) > queue_max_hw_sectors(q))
		return 0;

	/*
         * For filesystems with a blocksize smaller than the pagesize
         * we will often be called with the same page as last time and
         * a consecutive offset.  Optimize this special case.
         */
	if (bio->bi_vcnt > 0) {
		struct bio_vec *prev = &bio->bi_io_vec[bio->bi_vcnt - 1];

		if (page == prev->bv_page &&
		    offset == prev->bv_offset + prev->bv_len) {
			prev->bv_len += len;
			bio->bi_iter.bi_size += len;
			goto done;
		}

		/*
                 * If the queue doesn't support SG gaps and adding this
                 * offset would create a gap, disallow it.
                 */
		if (bvec_gap_to_prev(q, prev, offset))
			return 0;
	}

	if (bio_full(bio))
		return 0;

	/*
         * setup the new entry, we might clear it again later if we
         * cannot add the page
         */
	bvec = &bio->bi_io_vec[bio->bi_vcnt];
	bvec->bv_page = page;
	bvec->bv_len = len;
	bvec->bv_offset = offset;
	bio->bi_vcnt++;
	bio->bi_phys_segments++;
	bio->bi_iter.bi_size += len;

	/*
         * Perform a recount if the number of segments is greater
         * than queue_max_segments(q).
         */

	while (bio->bi_phys_segments > queue_max_segments(q)) {

		if (retried_segments)
			goto failed;

		retried_segments = 1;
		blk_recount_segments(q, bio);
	}

	/* If we may be able to merge these biovecs, force a recount */
	if (bio->bi_vcnt > 1 && (BIOVEC_PHYS_MERGEABLE(bvec-1, bvec)))
		bio_clear_flag(bio, BIO_SEG_VALID);

 done:
	return len;

 failed:
	bvec->bv_page = NULL;
	bvec->bv_len = 0;
	bvec->bv_offset = 0;
	bio->bi_vcnt--;
	bio->bi_iter.bi_size -= len;
	blk_recount_segments(q, bio);
	return 0;
}

Contributors
PersonTokensPropCommitsCommitProp
Jens Axboe21064.81%750.00%


Maurizio Lombardi8927.47%17.14%


Kent Overstreet92.78%214.29%


Mike Christie82.47%17.14%


Christoph Hellwig30.93%17.14%


Patrick Mansfield30.93%17.14%


Keith Busch20.62%17.14%


Total324100.00%14100.00%



EXPORT_SYMBOL(bio_add_pc_page)