bio.c 32.1 KB
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/*
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 * Copyright (C) 2001 Jens Axboe <axboe@kernel.dk>
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 *
 * 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/slab.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mempool.h>
#include <linux/workqueue.h>
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#include <linux/blktrace_api.h>
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#include <scsi/sg.h>		/* for struct sg_iovec */
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static struct kmem_cache *bio_slab __read_mostly;
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mempool_t *bio_split_pool __read_mostly;
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/*
 * 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) { .nr_vecs = x, .name = "biovec-"__stringify(x) }
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static struct biovec_slab bvec_slabs[BIOVEC_NR_POOLS] __read_mostly = {
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	BV(1), BV(4), BV(16), BV(64), BV(128), BV(BIO_MAX_PAGES),
};
#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.
 */
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struct bio_set *fs_bio_set;
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unsigned int bvec_nr_vecs(unsigned short idx)
{
	return bvec_slabs[idx].nr_vecs;
}

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struct bio_vec *bvec_alloc_bs(gfp_t gfp_mask, int nr, unsigned long *idx, struct bio_set *bs)
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{
	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
	 */

	bvl = mempool_alloc(bs->bvec_pools[*idx], gfp_mask);
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	if (bvl)
		memset(bvl, 0, bvec_nr_vecs(*idx) * sizeof(struct bio_vec));
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	return bvl;
}

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void bio_free(struct bio *bio, struct bio_set *bio_set)
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{
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	if (bio->bi_io_vec) {
		const int pool_idx = BIO_POOL_IDX(bio);
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		BIO_BUG_ON(pool_idx >= BIOVEC_NR_POOLS);

		mempool_free(bio->bi_io_vec, bio_set->bvec_pools[pool_idx]);
	}
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	if (bio_integrity(bio))
		bio_integrity_free(bio, bio_set);

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	mempool_free(bio, bio_set->bio_pool);
}

/*
 * default destructor for a bio allocated with bio_alloc_bioset()
 */
static void bio_fs_destructor(struct bio *bio)
{
	bio_free(bio, fs_bio_set);
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}

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void bio_init(struct bio *bio)
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{
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	memset(bio, 0, sizeof(*bio));
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	bio->bi_flags = 1 << BIO_UPTODATE;
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	bio->bi_comp_cpu = -1;
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	atomic_set(&bio->bi_cnt, 1);
}

/**
 * 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
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 * @bs:		the bio_set to allocate from
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 *
 * Description:
 *   bio_alloc_bioset will first try it's on mempool to satisfy the allocation.
 *   If %__GFP_WAIT is set then we will block on the internal pool waiting
 *   for a &struct bio to become free.
 *
 *   allocate bio and iovecs from the memory pools specified by the
 *   bio_set structure.
 **/
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struct bio *bio_alloc_bioset(gfp_t gfp_mask, int nr_iovecs, struct bio_set *bs)
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{
	struct bio *bio = mempool_alloc(bs->bio_pool, gfp_mask);

	if (likely(bio)) {
		struct bio_vec *bvl = NULL;

		bio_init(bio);
		if (likely(nr_iovecs)) {
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			unsigned long uninitialized_var(idx);
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			bvl = bvec_alloc_bs(gfp_mask, nr_iovecs, &idx, bs);
			if (unlikely(!bvl)) {
				mempool_free(bio, bs->bio_pool);
				bio = NULL;
				goto out;
			}
			bio->bi_flags |= idx << BIO_POOL_OFFSET;
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			bio->bi_max_vecs = bvec_nr_vecs(idx);
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		}
		bio->bi_io_vec = bvl;
	}
out:
	return bio;
}

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struct bio *bio_alloc(gfp_t gfp_mask, int nr_iovecs)
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{
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	struct bio *bio = bio_alloc_bioset(gfp_mask, nr_iovecs, fs_bio_set);

	if (bio)
		bio->bi_destructor = bio_fs_destructor;

	return bio;
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}

void zero_fill_bio(struct bio *bio)
{
	unsigned long flags;
	struct bio_vec *bv;
	int i;

	bio_for_each_segment(bv, bio, i) {
		char *data = bvec_kmap_irq(bv, &flags);
		memset(data, 0, bv->bv_len);
		flush_dcache_page(bv->bv_page);
		bvec_kunmap_irq(data, &flags);
	}
}
EXPORT_SYMBOL(zero_fill_bio);

/**
 * 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 or bio_get. The last put of a bio will free it.
 **/
void bio_put(struct bio *bio)
{
	BIO_BUG_ON(!atomic_read(&bio->bi_cnt));

	/*
	 * last put frees it
	 */
	if (atomic_dec_and_test(&bio->bi_cnt)) {
		bio->bi_next = NULL;
		bio->bi_destructor(bio);
	}
}

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

	return bio->bi_phys_segments;
}

/**
 * 	__bio_clone	-	clone a bio
 * 	@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.
 */
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void __bio_clone(struct bio *bio, struct bio *bio_src)
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{
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	memcpy(bio->bi_io_vec, bio_src->bi_io_vec,
		bio_src->bi_max_vecs * sizeof(struct bio_vec));
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	/*
	 * most users will be overriding ->bi_bdev with a new target,
	 * so we don't set nor calculate new physical/hw segment counts here
	 */
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	bio->bi_sector = bio_src->bi_sector;
	bio->bi_bdev = bio_src->bi_bdev;
	bio->bi_flags |= 1 << BIO_CLONED;
	bio->bi_rw = bio_src->bi_rw;
	bio->bi_vcnt = bio_src->bi_vcnt;
	bio->bi_size = bio_src->bi_size;
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	bio->bi_idx = bio_src->bi_idx;
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}

/**
 *	bio_clone	-	clone a bio
 *	@bio: bio to clone
 *	@gfp_mask: allocation priority
 *
 * 	Like __bio_clone, only also allocates the returned bio
 */
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struct bio *bio_clone(struct bio *bio, gfp_t gfp_mask)
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{
	struct bio *b = bio_alloc_bioset(gfp_mask, bio->bi_max_vecs, fs_bio_set);

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	if (!b)
		return NULL;

	b->bi_destructor = bio_fs_destructor;
	__bio_clone(b, bio);

	if (bio_integrity(bio)) {
		int ret;

		ret = bio_integrity_clone(b, bio, fs_bio_set);

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

/**
 *	bio_get_nr_vecs		- return approx number of vecs
 *	@bdev:  I/O target
 *
 *	Return the approximate number of pages we can send to this target.
 *	There's no guarantee that you will be able to fit this number of pages
 *	into a bio, it does not account for dynamic restrictions that vary
 *	on offset.
 */
int bio_get_nr_vecs(struct block_device *bdev)
{
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	struct request_queue *q = bdev_get_queue(bdev);
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	int nr_pages;

	nr_pages = ((q->max_sectors << 9) + PAGE_SIZE - 1) >> PAGE_SHIFT;
	if (nr_pages > q->max_phys_segments)
		nr_pages = q->max_phys_segments;
	if (nr_pages > q->max_hw_segments)
		nr_pages = q->max_hw_segments;

	return nr_pages;
}

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

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

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	if (((bio->bi_size + len) >> 9) > max_sectors)
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		return 0;

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	/*
	 * 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;
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			if (q->merge_bvec_fn) {
				struct bvec_merge_data bvm = {
					.bi_bdev = bio->bi_bdev,
					.bi_sector = bio->bi_sector,
					.bi_size = bio->bi_size,
					.bi_rw = bio->bi_rw,
				};

				if (q->merge_bvec_fn(q, &bvm, prev) < len) {
					prev->bv_len -= len;
					return 0;
				}
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			}

			goto done;
		}
	}

	if (bio->bi_vcnt >= bio->bi_max_vecs)
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		return 0;

	/*
	 * we might lose a segment or two here, but rather that than
	 * make this too complex.
	 */

	while (bio->bi_phys_segments >= q->max_phys_segments
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	       || bio->bi_phys_segments >= q->max_hw_segments) {
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		if (retried_segments)
			return 0;

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

	/*
	 * 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;

	/*
	 * if queue has other restrictions (eg varying max sector size
	 * depending on offset), it can specify a merge_bvec_fn in the
	 * queue to get further control
	 */
	if (q->merge_bvec_fn) {
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		struct bvec_merge_data bvm = {
			.bi_bdev = bio->bi_bdev,
			.bi_sector = bio->bi_sector,
			.bi_size = bio->bi_size,
			.bi_rw = bio->bi_rw,
		};

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		/*
		 * merge_bvec_fn() returns number of bytes it can accept
		 * at this offset
		 */
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		if (q->merge_bvec_fn(q, &bvm, bvec) < len) {
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			bvec->bv_page = NULL;
			bvec->bv_len = 0;
			bvec->bv_offset = 0;
			return 0;
		}
	}

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

	bio->bi_vcnt++;
	bio->bi_phys_segments++;
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 done:
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	bio->bi_size += len;
	return len;
}

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/**
 *	bio_add_pc_page	-	attempt to add page to bio
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 *	@q: the target queue
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 *	@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
 *      smaller than 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.
 */
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int bio_add_pc_page(struct request_queue *q, struct bio *bio, struct page *page,
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		    unsigned int len, unsigned int offset)
{
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	return __bio_add_page(q, bio, page, len, offset, q->max_hw_sectors);
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}

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/**
 *	bio_add_page	-	attempt to add page to bio
 *	@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
 *      smaller than PAGE_SIZE, so it is always possible to add a single
 *      page to an empty bio.
 */
int bio_add_page(struct bio *bio, struct page *page, unsigned int len,
		 unsigned int offset)
{
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	struct request_queue *q = bdev_get_queue(bio->bi_bdev);
	return __bio_add_page(q, bio, page, len, offset, q->max_sectors);
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}

struct bio_map_data {
	struct bio_vec *iovecs;
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	struct sg_iovec *sgvecs;
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	int nr_sgvecs;
	int is_our_pages;
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};

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static void bio_set_map_data(struct bio_map_data *bmd, struct bio *bio,
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			     struct sg_iovec *iov, int iov_count,
			     int is_our_pages)
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{
	memcpy(bmd->iovecs, bio->bi_io_vec, sizeof(struct bio_vec) * bio->bi_vcnt);
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	memcpy(bmd->sgvecs, iov, sizeof(struct sg_iovec) * iov_count);
	bmd->nr_sgvecs = iov_count;
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	bmd->is_our_pages = is_our_pages;
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	bio->bi_private = bmd;
}

static void bio_free_map_data(struct bio_map_data *bmd)
{
	kfree(bmd->iovecs);
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	kfree(bmd->sgvecs);
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	kfree(bmd);
}

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static struct bio_map_data *bio_alloc_map_data(int nr_segs, int iov_count,
					       gfp_t gfp_mask)
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{
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	struct bio_map_data *bmd = kmalloc(sizeof(*bmd), gfp_mask);
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	if (!bmd)
		return NULL;

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	bmd->iovecs = kmalloc(sizeof(struct bio_vec) * nr_segs, gfp_mask);
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	if (!bmd->iovecs) {
		kfree(bmd);
		return NULL;
	}

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	bmd->sgvecs = kmalloc(sizeof(struct sg_iovec) * iov_count, gfp_mask);
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	if (bmd->sgvecs)
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		return bmd;

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	kfree(bmd->iovecs);
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	kfree(bmd);
	return NULL;
}

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static int __bio_copy_iov(struct bio *bio, struct bio_vec *iovecs,
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			  struct sg_iovec *iov, int iov_count, int uncopy,
			  int do_free_page)
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{
	int ret = 0, i;
	struct bio_vec *bvec;
	int iov_idx = 0;
	unsigned int iov_off = 0;
	int read = bio_data_dir(bio) == READ;

	__bio_for_each_segment(bvec, bio, i, 0) {
		char *bv_addr = page_address(bvec->bv_page);
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		unsigned int bv_len = iovecs[i].bv_len;
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		while (bv_len && iov_idx < iov_count) {
			unsigned int bytes;
			char *iov_addr;

			bytes = min_t(unsigned int,
				      iov[iov_idx].iov_len - iov_off, bv_len);
			iov_addr = iov[iov_idx].iov_base + iov_off;

			if (!ret) {
				if (!read && !uncopy)
					ret = copy_from_user(bv_addr, iov_addr,
							     bytes);
				if (read && uncopy)
					ret = copy_to_user(iov_addr, bv_addr,
							   bytes);

				if (ret)
					ret = -EFAULT;
			}

			bv_len -= bytes;
			bv_addr += bytes;
			iov_addr += bytes;
			iov_off += bytes;

			if (iov[iov_idx].iov_len == iov_off) {
				iov_idx++;
				iov_off = 0;
			}
		}

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		if (do_free_page)
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			__free_page(bvec->bv_page);
	}

	return ret;
}

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/**
 *	bio_uncopy_user	-	finish previously mapped bio
 *	@bio: bio being terminated
 *
 *	Free pages allocated from bio_copy_user() and write back data
 *	to user space in case of a read.
 */
int bio_uncopy_user(struct bio *bio)
{
	struct bio_map_data *bmd = bio->bi_private;
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	int ret = 0;
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	if (!bio_flagged(bio, BIO_NULL_MAPPED))
		ret = __bio_copy_iov(bio, bmd->iovecs, bmd->sgvecs,
				     bmd->nr_sgvecs, 1, bmd->is_our_pages);
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	bio_free_map_data(bmd);
	bio_put(bio);
	return ret;
}

/**
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 *	bio_copy_user_iov	-	copy user data to bio
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 *	@q: destination block queue
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 *	@map_data: pointer to the rq_map_data holding pages (if necessary)
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 *	@iov:	the iovec.
 *	@iov_count: number of elements in the iovec
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 *	@write_to_vm: bool indicating writing to pages or not
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 *	@gfp_mask: memory allocation flags
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 *
 *	Prepares and returns a bio for indirect user io, bouncing data
 *	to/from kernel pages as necessary. Must be paired with
 *	call bio_uncopy_user() on io completion.
 */
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struct bio *bio_copy_user_iov(struct request_queue *q,
			      struct rq_map_data *map_data,
			      struct sg_iovec *iov, int iov_count,
			      int write_to_vm, gfp_t gfp_mask)
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{
	struct bio_map_data *bmd;
	struct bio_vec *bvec;
	struct page *page;
	struct bio *bio;
	int i, ret;
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	int nr_pages = 0;
	unsigned int len = 0;
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	for (i = 0; i < iov_count; i++) {
		unsigned long uaddr;
		unsigned long end;
		unsigned long start;

		uaddr = (unsigned long)iov[i].iov_base;
		end = (uaddr + iov[i].iov_len + PAGE_SIZE - 1) >> PAGE_SHIFT;
		start = uaddr >> PAGE_SHIFT;

		nr_pages += end - start;
		len += iov[i].iov_len;
	}

599
	bmd = bio_alloc_map_data(nr_pages, iov_count, gfp_mask);
L
Linus Torvalds 已提交
600 601 602 603
	if (!bmd)
		return ERR_PTR(-ENOMEM);

	ret = -ENOMEM;
604
	bio = bio_alloc(gfp_mask, nr_pages);
L
Linus Torvalds 已提交
605 606 607 608 609 610
	if (!bio)
		goto out_bmd;

	bio->bi_rw |= (!write_to_vm << BIO_RW);

	ret = 0;
611
	i = 0;
L
Linus Torvalds 已提交
612
	while (len) {
613 614 615 616 617 618
		unsigned int bytes;

		if (map_data)
			bytes = 1U << (PAGE_SHIFT + map_data->page_order);
		else
			bytes = PAGE_SIZE;
L
Linus Torvalds 已提交
619 620 621 622

		if (bytes > len)
			bytes = len;

623 624 625 626 627 628 629 630
		if (map_data) {
			if (i == map_data->nr_entries) {
				ret = -ENOMEM;
				break;
			}
			page = map_data->pages[i++];
		} else
			page = alloc_page(q->bounce_gfp | gfp_mask);
L
Linus Torvalds 已提交
631 632 633 634 635
		if (!page) {
			ret = -ENOMEM;
			break;
		}

636
		if (bio_add_pc_page(q, bio, page, bytes, 0) < bytes)
L
Linus Torvalds 已提交
637 638 639 640 641 642 643 644 645 646 647 648
			break;

		len -= bytes;
	}

	if (ret)
		goto cleanup;

	/*
	 * success
	 */
	if (!write_to_vm) {
649
		ret = __bio_copy_iov(bio, bio->bi_io_vec, iov, iov_count, 0, 0);
650 651
		if (ret)
			goto cleanup;
L
Linus Torvalds 已提交
652 653
	}

654
	bio_set_map_data(bmd, bio, iov, iov_count, map_data ? 0 : 1);
L
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	return bio;
cleanup:
657 658 659
	if (!map_data)
		bio_for_each_segment(bvec, bio, i)
			__free_page(bvec->bv_page);
L
Linus Torvalds 已提交
660 661 662 663 664 665 666

	bio_put(bio);
out_bmd:
	bio_free_map_data(bmd);
	return ERR_PTR(ret);
}

667 668 669
/**
 *	bio_copy_user	-	copy user data to bio
 *	@q: destination block queue
670
 *	@map_data: pointer to the rq_map_data holding pages (if necessary)
671 672 673
 *	@uaddr: start of user address
 *	@len: length in bytes
 *	@write_to_vm: bool indicating writing to pages or not
674
 *	@gfp_mask: memory allocation flags
675 676 677 678 679
 *
 *	Prepares and returns a bio for indirect user io, bouncing data
 *	to/from kernel pages as necessary. Must be paired with
 *	call bio_uncopy_user() on io completion.
 */
680 681 682
struct bio *bio_copy_user(struct request_queue *q, struct rq_map_data *map_data,
			  unsigned long uaddr, unsigned int len,
			  int write_to_vm, gfp_t gfp_mask)
683 684 685 686 687 688
{
	struct sg_iovec iov;

	iov.iov_base = (void __user *)uaddr;
	iov.iov_len = len;

689
	return bio_copy_user_iov(q, map_data, &iov, 1, write_to_vm, gfp_mask);
690 691
}

692
static struct bio *__bio_map_user_iov(struct request_queue *q,
693 694
				      struct block_device *bdev,
				      struct sg_iovec *iov, int iov_count,
695
				      int write_to_vm, gfp_t gfp_mask)
L
Linus Torvalds 已提交
696
{
697 698
	int i, j;
	int nr_pages = 0;
L
Linus Torvalds 已提交
699 700
	struct page **pages;
	struct bio *bio;
701 702
	int cur_page = 0;
	int ret, offset;
L
Linus Torvalds 已提交
703

704 705 706 707 708 709 710 711
	for (i = 0; i < iov_count; i++) {
		unsigned long uaddr = (unsigned long)iov[i].iov_base;
		unsigned long len = iov[i].iov_len;
		unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
		unsigned long start = uaddr >> PAGE_SHIFT;

		nr_pages += end - start;
		/*
712
		 * buffer must be aligned to at least hardsector size for now
713
		 */
714
		if (uaddr & queue_dma_alignment(q))
715 716 717 718
			return ERR_PTR(-EINVAL);
	}

	if (!nr_pages)
L
Linus Torvalds 已提交
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		return ERR_PTR(-EINVAL);

721
	bio = bio_alloc(gfp_mask, nr_pages);
L
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	if (!bio)
		return ERR_PTR(-ENOMEM);

	ret = -ENOMEM;
726
	pages = kcalloc(nr_pages, sizeof(struct page *), gfp_mask);
L
Linus Torvalds 已提交
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	if (!pages)
		goto out;

730 731 732 733 734 735 736 737
	for (i = 0; i < iov_count; i++) {
		unsigned long uaddr = (unsigned long)iov[i].iov_base;
		unsigned long len = iov[i].iov_len;
		unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
		unsigned long start = uaddr >> PAGE_SHIFT;
		const int local_nr_pages = end - start;
		const int page_limit = cur_page + local_nr_pages;
		
N
Nick Piggin 已提交
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		ret = get_user_pages_fast(uaddr, local_nr_pages,
				write_to_vm, &pages[cur_page]);
740 741
		if (ret < local_nr_pages) {
			ret = -EFAULT;
742
			goto out_unmap;
743
		}
744 745 746 747 748 749 750 751 752 753 754 755 756 757

		offset = uaddr & ~PAGE_MASK;
		for (j = cur_page; j < page_limit; j++) {
			unsigned int bytes = PAGE_SIZE - offset;

			if (len <= 0)
				break;
			
			if (bytes > len)
				bytes = len;

			/*
			 * sorry...
			 */
758 759
			if (bio_add_pc_page(q, bio, pages[j], bytes, offset) <
					    bytes)
760 761 762 763 764
				break;

			len -= bytes;
			offset = 0;
		}
L
Linus Torvalds 已提交
765

766
		cur_page = j;
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767
		/*
768
		 * release the pages we didn't map into the bio, if any
L
Linus Torvalds 已提交
769
		 */
770 771
		while (j < page_limit)
			page_cache_release(pages[j++]);
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	}

	kfree(pages);

	/*
	 * set data direction, and check if mapped pages need bouncing
	 */
	if (!write_to_vm)
		bio->bi_rw |= (1 << BIO_RW);

782
	bio->bi_bdev = bdev;
L
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	bio->bi_flags |= (1 << BIO_USER_MAPPED);
	return bio;
785 786 787 788 789 790 791 792

 out_unmap:
	for (i = 0; i < nr_pages; i++) {
		if(!pages[i])
			break;
		page_cache_release(pages[i]);
	}
 out:
L
Linus Torvalds 已提交
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	kfree(pages);
	bio_put(bio);
	return ERR_PTR(ret);
}

/**
 *	bio_map_user	-	map user address into bio
800
 *	@q: the struct request_queue for the bio
L
Linus Torvalds 已提交
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 *	@bdev: destination block device
 *	@uaddr: start of user address
 *	@len: length in bytes
 *	@write_to_vm: bool indicating writing to pages or not
805
 *	@gfp_mask: memory allocation flags
L
Linus Torvalds 已提交
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 *
 *	Map the user space address into a bio suitable for io to a block
 *	device. Returns an error pointer in case of error.
 */
810
struct bio *bio_map_user(struct request_queue *q, struct block_device *bdev,
811 812
			 unsigned long uaddr, unsigned int len, int write_to_vm,
			 gfp_t gfp_mask)
813 814 815
{
	struct sg_iovec iov;

816
	iov.iov_base = (void __user *)uaddr;
817 818
	iov.iov_len = len;

819
	return bio_map_user_iov(q, bdev, &iov, 1, write_to_vm, gfp_mask);
820 821 822 823
}

/**
 *	bio_map_user_iov - map user sg_iovec table into bio
824
 *	@q: the struct request_queue for the bio
825 826 827 828
 *	@bdev: destination block device
 *	@iov:	the iovec.
 *	@iov_count: number of elements in the iovec
 *	@write_to_vm: bool indicating writing to pages or not
829
 *	@gfp_mask: memory allocation flags
830 831 832 833
 *
 *	Map the user space address into a bio suitable for io to a block
 *	device. Returns an error pointer in case of error.
 */
834
struct bio *bio_map_user_iov(struct request_queue *q, struct block_device *bdev,
835
			     struct sg_iovec *iov, int iov_count,
836
			     int write_to_vm, gfp_t gfp_mask)
L
Linus Torvalds 已提交
837 838 839
{
	struct bio *bio;

840 841
	bio = __bio_map_user_iov(q, bdev, iov, iov_count, write_to_vm,
				 gfp_mask);
L
Linus Torvalds 已提交
842 843 844 845 846 847 848 849 850 851 852
	if (IS_ERR(bio))
		return bio;

	/*
	 * subtle -- if __bio_map_user() ended up bouncing a bio,
	 * it would normally disappear when its bi_end_io is run.
	 * however, we need it for the unmap, so grab an extra
	 * reference to it
	 */
	bio_get(bio);

853
	return bio;
L
Linus Torvalds 已提交
854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888
}

static void __bio_unmap_user(struct bio *bio)
{
	struct bio_vec *bvec;
	int i;

	/*
	 * make sure we dirty pages we wrote to
	 */
	__bio_for_each_segment(bvec, bio, i, 0) {
		if (bio_data_dir(bio) == READ)
			set_page_dirty_lock(bvec->bv_page);

		page_cache_release(bvec->bv_page);
	}

	bio_put(bio);
}

/**
 *	bio_unmap_user	-	unmap a bio
 *	@bio:		the bio being unmapped
 *
 *	Unmap a bio previously mapped by bio_map_user(). Must be called with
 *	a process context.
 *
 *	bio_unmap_user() may sleep.
 */
void bio_unmap_user(struct bio *bio)
{
	__bio_unmap_user(bio);
	bio_put(bio);
}

889
static void bio_map_kern_endio(struct bio *bio, int err)
890 891 892 893 894
{
	bio_put(bio);
}


895
static struct bio *__bio_map_kern(struct request_queue *q, void *data,
A
Al Viro 已提交
896
				  unsigned int len, gfp_t gfp_mask)
M
Mike Christie 已提交
897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918
{
	unsigned long kaddr = (unsigned long)data;
	unsigned long end = (kaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
	unsigned long start = kaddr >> PAGE_SHIFT;
	const int nr_pages = end - start;
	int offset, i;
	struct bio *bio;

	bio = bio_alloc(gfp_mask, nr_pages);
	if (!bio)
		return ERR_PTR(-ENOMEM);

	offset = offset_in_page(kaddr);
	for (i = 0; i < nr_pages; i++) {
		unsigned int bytes = PAGE_SIZE - offset;

		if (len <= 0)
			break;

		if (bytes > len)
			bytes = len;

919 920
		if (bio_add_pc_page(q, bio, virt_to_page(data), bytes,
				    offset) < bytes)
M
Mike Christie 已提交
921 922 923 924 925 926 927
			break;

		data += bytes;
		len -= bytes;
		offset = 0;
	}

928
	bio->bi_end_io = bio_map_kern_endio;
M
Mike Christie 已提交
929 930 931 932 933
	return bio;
}

/**
 *	bio_map_kern	-	map kernel address into bio
934
 *	@q: the struct request_queue for the bio
M
Mike Christie 已提交
935 936 937 938 939 940 941
 *	@data: pointer to buffer to map
 *	@len: length in bytes
 *	@gfp_mask: allocation flags for bio allocation
 *
 *	Map the kernel address into a bio suitable for io to a block
 *	device. Returns an error pointer in case of error.
 */
942
struct bio *bio_map_kern(struct request_queue *q, void *data, unsigned int len,
A
Al Viro 已提交
943
			 gfp_t gfp_mask)
M
Mike Christie 已提交
944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960
{
	struct bio *bio;

	bio = __bio_map_kern(q, data, len, gfp_mask);
	if (IS_ERR(bio))
		return bio;

	if (bio->bi_size == len)
		return bio;

	/*
	 * Don't support partial mappings.
	 */
	bio_put(bio);
	return ERR_PTR(-EINVAL);
}

961 962 963 964
static void bio_copy_kern_endio(struct bio *bio, int err)
{
	struct bio_vec *bvec;
	const int read = bio_data_dir(bio) == READ;
965
	struct bio_map_data *bmd = bio->bi_private;
966
	int i;
967
	char *p = bmd->sgvecs[0].iov_base;
968 969 970

	__bio_for_each_segment(bvec, bio, i, 0) {
		char *addr = page_address(bvec->bv_page);
971
		int len = bmd->iovecs[i].bv_len;
972 973

		if (read && !err)
974
			memcpy(p, addr, len);
975 976

		__free_page(bvec->bv_page);
977
		p += len;
978 979
	}

980
	bio_free_map_data(bmd);
981 982 983 984 985 986 987 988 989
	bio_put(bio);
}

/**
 *	bio_copy_kern	-	copy kernel address into bio
 *	@q: the struct request_queue for the bio
 *	@data: pointer to buffer to copy
 *	@len: length in bytes
 *	@gfp_mask: allocation flags for bio and page allocation
990
 *	@reading: data direction is READ
991 992 993 994 995 996 997 998 999
 *
 *	copy the kernel address into a bio suitable for io to a block
 *	device. Returns an error pointer in case of error.
 */
struct bio *bio_copy_kern(struct request_queue *q, void *data, unsigned int len,
			  gfp_t gfp_mask, int reading)
{
	struct bio *bio;
	struct bio_vec *bvec;
1000
	int i;
1001

1002 1003 1004
	bio = bio_copy_user(q, NULL, (unsigned long)data, len, 1, gfp_mask);
	if (IS_ERR(bio))
		return bio;
1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017

	if (!reading) {
		void *p = data;

		bio_for_each_segment(bvec, bio, i) {
			char *addr = page_address(bvec->bv_page);

			memcpy(addr, p, bvec->bv_len);
			p += bvec->bv_len;
		}
	}

	bio->bi_end_io = bio_copy_kern_endio;
1018

1019 1020 1021
	return bio;
}

L
Linus Torvalds 已提交
1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063
/*
 * bio_set_pages_dirty() and bio_check_pages_dirty() are support functions
 * for performing direct-IO in BIOs.
 *
 * The problem is that we cannot run set_page_dirty() from interrupt context
 * because the required locks are not interrupt-safe.  So what we can do is to
 * mark the pages dirty _before_ performing IO.  And in interrupt context,
 * check that the pages are still dirty.   If so, fine.  If not, redirty them
 * in process context.
 *
 * We special-case compound pages here: normally this means reads into hugetlb
 * pages.  The logic in here doesn't really work right for compound pages
 * because the VM does not uniformly chase down the head page in all cases.
 * But dirtiness of compound pages is pretty meaningless anyway: the VM doesn't
 * handle them at all.  So we skip compound pages here at an early stage.
 *
 * Note that this code is very hard to test under normal circumstances because
 * direct-io pins the pages with get_user_pages().  This makes
 * is_page_cache_freeable return false, and the VM will not clean the pages.
 * But other code (eg, pdflush) could clean the pages if they are mapped
 * pagecache.
 *
 * Simply disabling the call to bio_set_pages_dirty() is a good way to test the
 * deferred bio dirtying paths.
 */

/*
 * bio_set_pages_dirty() will mark all the bio's pages as dirty.
 */
void bio_set_pages_dirty(struct bio *bio)
{
	struct bio_vec *bvec = bio->bi_io_vec;
	int i;

	for (i = 0; i < bio->bi_vcnt; i++) {
		struct page *page = bvec[i].bv_page;

		if (page && !PageCompound(page))
			set_page_dirty_lock(page);
	}
}

1064
static void bio_release_pages(struct bio *bio)
L
Linus Torvalds 已提交
1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087
{
	struct bio_vec *bvec = bio->bi_io_vec;
	int i;

	for (i = 0; i < bio->bi_vcnt; i++) {
		struct page *page = bvec[i].bv_page;

		if (page)
			put_page(page);
	}
}

/*
 * bio_check_pages_dirty() will check that all the BIO's pages are still dirty.
 * If they are, then fine.  If, however, some pages are clean then they must
 * have been written out during the direct-IO read.  So we take another ref on
 * the BIO and the offending pages and re-dirty the pages in process context.
 *
 * It is expected that bio_check_pages_dirty() will wholly own the BIO from
 * here on.  It will run one page_cache_release() against each page and will
 * run one bio_put() against the BIO.
 */

1088
static void bio_dirty_fn(struct work_struct *work);
L
Linus Torvalds 已提交
1089

1090
static DECLARE_WORK(bio_dirty_work, bio_dirty_fn);
L
Linus Torvalds 已提交
1091 1092 1093 1094 1095 1096
static DEFINE_SPINLOCK(bio_dirty_lock);
static struct bio *bio_dirty_list;

/*
 * This runs in process context
 */
1097
static void bio_dirty_fn(struct work_struct *work)
L
Linus Torvalds 已提交
1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152
{
	unsigned long flags;
	struct bio *bio;

	spin_lock_irqsave(&bio_dirty_lock, flags);
	bio = bio_dirty_list;
	bio_dirty_list = NULL;
	spin_unlock_irqrestore(&bio_dirty_lock, flags);

	while (bio) {
		struct bio *next = bio->bi_private;

		bio_set_pages_dirty(bio);
		bio_release_pages(bio);
		bio_put(bio);
		bio = next;
	}
}

void bio_check_pages_dirty(struct bio *bio)
{
	struct bio_vec *bvec = bio->bi_io_vec;
	int nr_clean_pages = 0;
	int i;

	for (i = 0; i < bio->bi_vcnt; i++) {
		struct page *page = bvec[i].bv_page;

		if (PageDirty(page) || PageCompound(page)) {
			page_cache_release(page);
			bvec[i].bv_page = NULL;
		} else {
			nr_clean_pages++;
		}
	}

	if (nr_clean_pages) {
		unsigned long flags;

		spin_lock_irqsave(&bio_dirty_lock, flags);
		bio->bi_private = bio_dirty_list;
		bio_dirty_list = bio;
		spin_unlock_irqrestore(&bio_dirty_lock, flags);
		schedule_work(&bio_dirty_work);
	} else {
		bio_put(bio);
	}
}

/**
 * bio_endio - end I/O on a bio
 * @bio:	bio
 * @error:	error, if any
 *
 * Description:
1153
 *   bio_endio() will end I/O on the whole bio. bio_endio() is the
N
NeilBrown 已提交
1154 1155 1156 1157 1158 1159
 *   preferred way to end I/O on a bio, it takes care of clearing
 *   BIO_UPTODATE on error. @error is 0 on success, and and one of the
 *   established -Exxxx (-EIO, for instance) error values in case
 *   something went wrong. Noone should call bi_end_io() directly on a
 *   bio unless they own it and thus know that it has an end_io
 *   function.
L
Linus Torvalds 已提交
1160
 **/
1161
void bio_endio(struct bio *bio, int error)
L
Linus Torvalds 已提交
1162 1163 1164
{
	if (error)
		clear_bit(BIO_UPTODATE, &bio->bi_flags);
N
NeilBrown 已提交
1165 1166
	else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
		error = -EIO;
L
Linus Torvalds 已提交
1167

N
NeilBrown 已提交
1168
	if (bio->bi_end_io)
1169
		bio->bi_end_io(bio, error);
L
Linus Torvalds 已提交
1170 1171 1172 1173 1174 1175 1176
}

void bio_pair_release(struct bio_pair *bp)
{
	if (atomic_dec_and_test(&bp->cnt)) {
		struct bio *master = bp->bio1.bi_private;

1177
		bio_endio(master, bp->error);
L
Linus Torvalds 已提交
1178 1179 1180 1181
		mempool_free(bp, bp->bio2.bi_private);
	}
}

1182
static void bio_pair_end_1(struct bio *bi, int err)
L
Linus Torvalds 已提交
1183 1184 1185 1186 1187 1188 1189 1190 1191
{
	struct bio_pair *bp = container_of(bi, struct bio_pair, bio1);

	if (err)
		bp->error = err;

	bio_pair_release(bp);
}

1192
static void bio_pair_end_2(struct bio *bi, int err)
L
Linus Torvalds 已提交
1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212
{
	struct bio_pair *bp = container_of(bi, struct bio_pair, bio2);

	if (err)
		bp->error = err;

	bio_pair_release(bp);
}

/*
 * split a bio - only worry about a bio with a single page
 * in it's iovec
 */
struct bio_pair *bio_split(struct bio *bi, mempool_t *pool, int first_sectors)
{
	struct bio_pair *bp = mempool_alloc(pool, GFP_NOIO);

	if (!bp)
		return bp;

1213 1214 1215
	blk_add_trace_pdu_int(bdev_get_queue(bi->bi_bdev), BLK_TA_SPLIT, bi,
				bi->bi_sector + first_sectors);

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	BUG_ON(bi->bi_vcnt != 1);
	BUG_ON(bi->bi_idx != 0);
	atomic_set(&bp->cnt, 3);
	bp->error = 0;
	bp->bio1 = *bi;
	bp->bio2 = *bi;
	bp->bio2.bi_sector += first_sectors;
	bp->bio2.bi_size -= first_sectors << 9;
	bp->bio1.bi_size = first_sectors << 9;

	bp->bv1 = bi->bi_io_vec[0];
	bp->bv2 = bi->bi_io_vec[0];
	bp->bv2.bv_offset += first_sectors << 9;
	bp->bv2.bv_len -= first_sectors << 9;
	bp->bv1.bv_len = first_sectors << 9;

	bp->bio1.bi_io_vec = &bp->bv1;
	bp->bio2.bi_io_vec = &bp->bv2;

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	bp->bio1.bi_max_vecs = 1;
	bp->bio2.bi_max_vecs = 1;

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	bp->bio1.bi_end_io = bio_pair_end_1;
	bp->bio2.bi_end_io = bio_pair_end_2;

	bp->bio1.bi_private = bi;
	bp->bio2.bi_private = pool;

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	if (bio_integrity(bi))
		bio_integrity_split(bi, bp, first_sectors);

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	return bp;
}


/*
 * create memory pools for biovec's in a bio_set.
 * use the global biovec slabs created for general use.
 */
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static int biovec_create_pools(struct bio_set *bs, int pool_entries)
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{
	int i;

	for (i = 0; i < BIOVEC_NR_POOLS; i++) {
		struct biovec_slab *bp = bvec_slabs + i;
		mempool_t **bvp = bs->bvec_pools + i;

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		*bvp = mempool_create_slab_pool(pool_entries, bp->slab);
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		if (!*bvp)
			return -ENOMEM;
	}
	return 0;
}

static void biovec_free_pools(struct bio_set *bs)
{
	int i;

	for (i = 0; i < BIOVEC_NR_POOLS; i++) {
		mempool_t *bvp = bs->bvec_pools[i];

		if (bvp)
			mempool_destroy(bvp);
	}

}

void bioset_free(struct bio_set *bs)
{
	if (bs->bio_pool)
		mempool_destroy(bs->bio_pool);

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	bioset_integrity_free(bs);
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	biovec_free_pools(bs);

	kfree(bs);
}

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struct bio_set *bioset_create(int bio_pool_size, int bvec_pool_size)
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{
1296
	struct bio_set *bs = kzalloc(sizeof(*bs), GFP_KERNEL);
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	if (!bs)
		return NULL;

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	bs->bio_pool = mempool_create_slab_pool(bio_pool_size, bio_slab);
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	if (!bs->bio_pool)
		goto bad;

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	if (bioset_integrity_create(bs, bio_pool_size))
		goto bad;

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	if (!biovec_create_pools(bs, bvec_pool_size))
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		return bs;

bad:
	bioset_free(bs);
	return NULL;
}

static void __init biovec_init_slabs(void)
{
	int i;

	for (i = 0; i < BIOVEC_NR_POOLS; i++) {
		int size;
		struct biovec_slab *bvs = bvec_slabs + i;

		size = bvs->nr_vecs * sizeof(struct bio_vec);
		bvs->slab = kmem_cache_create(bvs->name, size, 0,
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                                SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
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	}
}

static int __init init_bio(void)
{
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	bio_slab = KMEM_CACHE(bio, SLAB_HWCACHE_ALIGN|SLAB_PANIC);
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	bio_integrity_init_slab();
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	biovec_init_slabs();

1337
	fs_bio_set = bioset_create(BIO_POOL_SIZE, 2);
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	if (!fs_bio_set)
		panic("bio: can't allocate bios\n");

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	bio_split_pool = mempool_create_kmalloc_pool(BIO_SPLIT_ENTRIES,
						     sizeof(struct bio_pair));
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	if (!bio_split_pool)
		panic("bio: can't create split pool\n");

	return 0;
}

subsys_initcall(init_bio);

EXPORT_SYMBOL(bio_alloc);
EXPORT_SYMBOL(bio_put);
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EXPORT_SYMBOL(bio_free);
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EXPORT_SYMBOL(bio_endio);
EXPORT_SYMBOL(bio_init);
EXPORT_SYMBOL(__bio_clone);
EXPORT_SYMBOL(bio_clone);
EXPORT_SYMBOL(bio_phys_segments);
EXPORT_SYMBOL(bio_add_page);
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EXPORT_SYMBOL(bio_add_pc_page);
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EXPORT_SYMBOL(bio_get_nr_vecs);
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EXPORT_SYMBOL(bio_map_user);
EXPORT_SYMBOL(bio_unmap_user);
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EXPORT_SYMBOL(bio_map_kern);
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EXPORT_SYMBOL(bio_copy_kern);
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EXPORT_SYMBOL(bio_pair_release);
EXPORT_SYMBOL(bio_split);
EXPORT_SYMBOL(bio_split_pool);
EXPORT_SYMBOL(bio_copy_user);
EXPORT_SYMBOL(bio_uncopy_user);
EXPORT_SYMBOL(bioset_create);
EXPORT_SYMBOL(bioset_free);
EXPORT_SYMBOL(bio_alloc_bioset);