bio.c 28.2 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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#define BIO_POOL_SIZE 2
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static struct kmem_cache *bio_slab __read_mostly;
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#define BIOVEC_NR_POOLS 6

/*
 * a small number of entries is fine, not going to be performance critical.
 * basically we just need to survive
 */
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#define BIO_SPLIT_ENTRIES 2
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mempool_t *bio_split_pool __read_mostly;
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struct biovec_slab {
	int nr_vecs;
	char *name; 
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	struct kmem_cache *slab;
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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

/*
 * bio_set is used to allow other portions of the IO system to
 * allocate their own private memory pools for bio and iovec structures.
 * These memory pools in turn all allocate from the bio_slab
 * and the bvec_slabs[].
 */
struct bio_set {
	mempool_t *bio_pool;
	mempool_t *bvec_pools[BIOVEC_NR_POOLS];
};

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

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static inline 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) {
		struct biovec_slab *bp = bvec_slabs + *idx;

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		memset(bvl, 0, bp->nr_vecs * sizeof(struct bio_vec));
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	}
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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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	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;
	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 idx = 0; /* shut up gcc */
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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;
			bio->bi_max_vecs = bvec_slabs[idx].nr_vecs;
		}
		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;
}

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inline int bio_hw_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_hw_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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	struct request_queue *q = bdev_get_queue(bio_src->bi_bdev);
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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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	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_phys_segments(q, bio);
	bio_hw_segments(q, bio);
}

/**
 *	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) {
		b->bi_destructor = bio_fs_destructor;
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		__bio_clone(b, bio);
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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;
			if (q->merge_bvec_fn &&
			    q->merge_bvec_fn(q, bio, prev) < len) {
				prev->bv_len -= len;
				return 0;
			}

			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
	       || bio->bi_hw_segments >= q->max_hw_segments
	       || BIOVEC_VIRT_OVERSIZE(bio->bi_size)) {

		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) {
		/*
		 * merge_bvec_fn() returns number of bytes it can accept
		 * at this offset
		 */
		if (q->merge_bvec_fn(q, bio, bvec) < len) {
			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 */
	if (bio->bi_vcnt && (BIOVEC_PHYS_MERGEABLE(bvec-1, bvec) ||
	    BIOVEC_VIRT_MERGEABLE(bvec-1, bvec)))
		bio->bi_flags &= ~(1 << BIO_SEG_VALID);

	bio->bi_vcnt++;
	bio->bi_phys_segments++;
	bio->bi_hw_segments++;
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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;
	void __user *userptr;
};

static void bio_set_map_data(struct bio_map_data *bmd, struct bio *bio)
{
	memcpy(bmd->iovecs, bio->bi_io_vec, sizeof(struct bio_vec) * bio->bi_vcnt);
	bio->bi_private = bmd;
}

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

static struct bio_map_data *bio_alloc_map_data(int nr_segs)
{
	struct bio_map_data *bmd = kmalloc(sizeof(*bmd), GFP_KERNEL);

	if (!bmd)
		return NULL;

	bmd->iovecs = kmalloc(sizeof(struct bio_vec) * nr_segs, GFP_KERNEL);
	if (bmd->iovecs)
		return bmd;

	kfree(bmd);
	return NULL;
}

/**
 *	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;
	const int read = bio_data_dir(bio) == READ;
	struct bio_vec *bvec;
	int i, ret = 0;

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

		if (read && !ret && copy_to_user(bmd->userptr, addr, len))
			ret = -EFAULT;

		__free_page(bvec->bv_page);
		bmd->userptr += len;
	}
	bio_free_map_data(bmd);
	bio_put(bio);
	return ret;
}

/**
 *	bio_copy_user	-	copy user data to bio
 *	@q: destination block queue
 *	@uaddr: start of user address
 *	@len: length in bytes
 *	@write_to_vm: bool indicating writing to pages or not
 *
 *	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(struct request_queue *q, unsigned long uaddr,
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			  unsigned int len, int write_to_vm)
{
	unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
	unsigned long start = uaddr >> PAGE_SHIFT;
	struct bio_map_data *bmd;
	struct bio_vec *bvec;
	struct page *page;
	struct bio *bio;
	int i, ret;

	bmd = bio_alloc_map_data(end - start);
	if (!bmd)
		return ERR_PTR(-ENOMEM);

	bmd->userptr = (void __user *) uaddr;

	ret = -ENOMEM;
	bio = bio_alloc(GFP_KERNEL, end - start);
	if (!bio)
		goto out_bmd;

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

	ret = 0;
	while (len) {
		unsigned int bytes = PAGE_SIZE;

		if (bytes > len)
			bytes = len;

		page = alloc_page(q->bounce_gfp | GFP_KERNEL);
		if (!page) {
			ret = -ENOMEM;
			break;
		}

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		if (bio_add_pc_page(q, bio, page, bytes, 0) < bytes)
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			break;

		len -= bytes;
	}

	if (ret)
		goto cleanup;

	/*
	 * success
	 */
	if (!write_to_vm) {
		char __user *p = (char __user *) uaddr;

		/*
		 * for a write, copy in data to kernel pages
		 */
		ret = -EFAULT;
		bio_for_each_segment(bvec, bio, i) {
			char *addr = page_address(bvec->bv_page);

			if (copy_from_user(addr, p, bvec->bv_len))
				goto cleanup;
			p += bvec->bv_len;
		}
	}

	bio_set_map_data(bmd, bio);
	return bio;
cleanup:
	bio_for_each_segment(bvec, bio, i)
		__free_page(bvec->bv_page);

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

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static struct bio *__bio_map_user_iov(struct request_queue *q,
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				      struct block_device *bdev,
				      struct sg_iovec *iov, int iov_count,
				      int write_to_vm)
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{
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	int i, j;
	int nr_pages = 0;
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	struct page **pages;
	struct bio *bio;
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	int cur_page = 0;
	int ret, offset;
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	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;
		/*
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		 * buffer must be aligned to at least hardsector size for now
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		 */
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		if (uaddr & queue_dma_alignment(q))
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			return ERR_PTR(-EINVAL);
	}

	if (!nr_pages)
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		return ERR_PTR(-EINVAL);

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

	ret = -ENOMEM;
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	pages = kcalloc(nr_pages, sizeof(struct page *), GFP_KERNEL);
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	if (!pages)
		goto out;

632 633 634 635 636 637 638 639 640 641 642 643 644 645
	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;
		
		down_read(&current->mm->mmap_sem);
		ret = get_user_pages(current, current->mm, uaddr,
				     local_nr_pages,
				     write_to_vm, 0, &pages[cur_page], NULL);
		up_read(&current->mm->mmap_sem);

646 647
		if (ret < local_nr_pages) {
			ret = -EFAULT;
648
			goto out_unmap;
649
		}
650 651 652 653 654 655 656 657 658 659 660 661 662 663

		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...
			 */
664 665
			if (bio_add_pc_page(q, bio, pages[j], bytes, offset) <
					    bytes)
666 667 668 669 670
				break;

			len -= bytes;
			offset = 0;
		}
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Linus Torvalds 已提交
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672
		cur_page = j;
L
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		/*
674
		 * release the pages we didn't map into the bio, if any
L
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		 */
676 677
		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);

688
	bio->bi_bdev = bdev;
L
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	bio->bi_flags |= (1 << BIO_USER_MAPPED);
	return bio;
691 692 693 694 695 696 697 698

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

/**
 *	bio_map_user	-	map user address into bio
706
 *	@q: the struct request_queue for the bio
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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
 *
 *	Map the user space address into a bio suitable for io to a block
 *	device. Returns an error pointer in case of error.
 */
715
struct bio *bio_map_user(struct request_queue *q, struct block_device *bdev,
L
Linus Torvalds 已提交
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			 unsigned long uaddr, unsigned int len, int write_to_vm)
717 718 719
{
	struct sg_iovec iov;

720
	iov.iov_base = (void __user *)uaddr;
721 722 723 724 725 726 727
	iov.iov_len = len;

	return bio_map_user_iov(q, bdev, &iov, 1, write_to_vm);
}

/**
 *	bio_map_user_iov - map user sg_iovec table into bio
728
 *	@q: the struct request_queue for the bio
729 730 731 732 733 734 735 736
 *	@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
 *
 *	Map the user space address into a bio suitable for io to a block
 *	device. Returns an error pointer in case of error.
 */
737
struct bio *bio_map_user_iov(struct request_queue *q, struct block_device *bdev,
738 739
			     struct sg_iovec *iov, int iov_count,
			     int write_to_vm)
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{
	struct bio *bio;

743
	bio = __bio_map_user_iov(q, bdev, iov, iov_count, write_to_vm);
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	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);

756
	return bio;
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}

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);
}

792
static void bio_map_kern_endio(struct bio *bio, int err)
793 794 795 796 797
{
	bio_put(bio);
}


798
static struct bio *__bio_map_kern(struct request_queue *q, void *data,
A
Al Viro 已提交
799
				  unsigned int len, gfp_t gfp_mask)
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{
	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;

822 823
		if (bio_add_pc_page(q, bio, virt_to_page(data), bytes,
				    offset) < bytes)
M
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			break;

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

831
	bio->bi_end_io = bio_map_kern_endio;
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	return bio;
}

/**
 *	bio_map_kern	-	map kernel address into bio
837
 *	@q: the struct request_queue for the bio
M
Mike Christie 已提交
838 839 840 841 842 843 844
 *	@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.
 */
845
struct bio *bio_map_kern(struct request_queue *q, void *data, unsigned int len,
A
Al Viro 已提交
846
			 gfp_t gfp_mask)
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847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863
{
	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);
}

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864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905
/*
 * 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);
	}
}

906
void bio_release_pages(struct bio *bio)
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907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929
{
	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.
 */

930
static void bio_dirty_fn(struct work_struct *work);
L
Linus Torvalds 已提交
931

932
static DECLARE_WORK(bio_dirty_work, bio_dirty_fn);
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933 934 935 936 937 938
static DEFINE_SPINLOCK(bio_dirty_lock);
static struct bio *bio_dirty_list;

/*
 * This runs in process context
 */
939
static void bio_dirty_fn(struct work_struct *work)
L
Linus Torvalds 已提交
940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994
{
	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:
995
 *   bio_endio() will end I/O on the whole bio. bio_endio() is the
N
NeilBrown 已提交
996 997 998 999 1000 1001
 *   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
1002
 **/
1003
void bio_endio(struct bio *bio, int error)
L
Linus Torvalds 已提交
1004 1005 1006
{
	if (error)
		clear_bit(BIO_UPTODATE, &bio->bi_flags);
N
NeilBrown 已提交
1007 1008
	else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
		error = -EIO;
L
Linus Torvalds 已提交
1009

N
NeilBrown 已提交
1010
	if (bio->bi_end_io)
1011
		bio->bi_end_io(bio, error);
L
Linus Torvalds 已提交
1012 1013 1014 1015 1016 1017 1018
}

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

1019
		bio_endio(master, bp->error);
L
Linus Torvalds 已提交
1020 1021 1022 1023
		mempool_free(bp, bp->bio2.bi_private);
	}
}

1024
static void bio_pair_end_1(struct bio *bi, int err)
L
Linus Torvalds 已提交
1025 1026 1027 1028 1029 1030 1031 1032 1033
{
	struct bio_pair *bp = container_of(bi, struct bio_pair, bio1);

	if (err)
		bp->error = err;

	bio_pair_release(bp);
}

1034
static void bio_pair_end_2(struct bio *bi, int err)
L
Linus Torvalds 已提交
1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054
{
	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;

1055 1056 1057
	blk_add_trace_pdu_int(bdev_get_queue(bi->bi_bdev), BLK_TA_SPLIT, bi,
				bi->bi_sector + first_sectors);

L
Linus Torvalds 已提交
1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076
	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;

1077 1078 1079
	bp->bio1.bi_max_vecs = 1;
	bp->bio2.bi_max_vecs = 1;

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1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093
	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;

	return bp;
}


/*
 * create memory pools for biovec's in a bio_set.
 * use the global biovec slabs created for general use.
 */
1094
static int biovec_create_pools(struct bio_set *bs, int pool_entries)
L
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1095 1096 1097 1098 1099 1100 1101
{
	int i;

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

1102
		*bvp = mempool_create_slab_pool(pool_entries, bp->slab);
L
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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
		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);

	biovec_free_pools(bs);

	kfree(bs);
}

1132
struct bio_set *bioset_create(int bio_pool_size, int bvec_pool_size)
L
Linus Torvalds 已提交
1133
{
1134
	struct bio_set *bs = kzalloc(sizeof(*bs), GFP_KERNEL);
L
Linus Torvalds 已提交
1135 1136 1137 1138

	if (!bs)
		return NULL;

1139
	bs->bio_pool = mempool_create_slab_pool(bio_pool_size, bio_slab);
L
Linus Torvalds 已提交
1140 1141 1142
	if (!bs->bio_pool)
		goto bad;

1143
	if (!biovec_create_pools(bs, bvec_pool_size))
L
Linus Torvalds 已提交
1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160
		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,
1161
                                SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
L
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1162 1163 1164 1165 1166
	}
}

static int __init init_bio(void)
{
1167
	bio_slab = KMEM_CACHE(bio, SLAB_HWCACHE_ALIGN|SLAB_PANIC);
L
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	biovec_init_slabs();

1171
	fs_bio_set = bioset_create(BIO_POOL_SIZE, 2);
L
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1172 1173 1174
	if (!fs_bio_set)
		panic("bio: can't allocate bios\n");

1175 1176
	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);
P
Peter Osterlund 已提交
1187
EXPORT_SYMBOL(bio_free);
L
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1188 1189 1190 1191 1192 1193 1194
EXPORT_SYMBOL(bio_endio);
EXPORT_SYMBOL(bio_init);
EXPORT_SYMBOL(__bio_clone);
EXPORT_SYMBOL(bio_clone);
EXPORT_SYMBOL(bio_phys_segments);
EXPORT_SYMBOL(bio_hw_segments);
EXPORT_SYMBOL(bio_add_page);
1195
EXPORT_SYMBOL(bio_add_pc_page);
L
Linus Torvalds 已提交
1196
EXPORT_SYMBOL(bio_get_nr_vecs);
M
Mike Christie 已提交
1197
EXPORT_SYMBOL(bio_map_kern);
L
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1198 1199 1200 1201 1202 1203 1204 1205
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);