block: move bio.c and bio-integrity.c from fs/ to block/

They really belong in block/, especially now since it's not in
drivers/block/ anymore. Additionally, the get_maintainer script
gets it wrong when in fs/.

Suggested-by: Christoph Hellwig <hch@infradead.org>
Acked-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Jens Axboe <axboe@fb.com>

3 files changed, 1 insertions, 2697 deletions

diff --git a/fs/Makefile b/fs/Makefile
index f9cb9876e466..1ed9eab5e0a9 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -14,14 +14,13 @@ obj-y :=	open.o read_write.o file_table.o super.o \
 		stack.o fs_struct.o statfs.o
 
 ifeq ($(CONFIG_BLOCK),y)
-obj-y +=	buffer.o bio.o block_dev.o direct-io.o mpage.o ioprio.o
+obj-y +=	buffer.o block_dev.o direct-io.o mpage.o ioprio.o
 else
 obj-y +=	no-block.o
 endif
 
 obj-$(CONFIG_PROC_FS) += proc_namespace.o
 
-obj-$(CONFIG_BLK_DEV_INTEGRITY) += bio-integrity.o
 obj-y				+= notify/
 obj-$(CONFIG_EPOLL)		+= eventpoll.o
 obj-$(CONFIG_ANON_INODES)	+= anon_inodes.o
diff --git a/fs/bio-integrity.c b/fs/bio-integrity.c
deleted file mode 100644
index 9e241063a616..000000000000
--- a/fs/bio-integrity.c
+++ /dev/null
@@ -1,657 +0,0 @@
-/*
- * bio-integrity.c - bio data integrity extensions
- *
- * Copyright (C) 2007, 2008, 2009 Oracle Corporation
- * Written by: Martin K. Petersen <martin.petersen@oracle.com>
- *
- * 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 License
- * along with this program; see the file COPYING.  If not, write to
- * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139,
- * USA.
- *
- */
-
-#include <linux/blkdev.h>
-#include <linux/mempool.h>
-#include <linux/export.h>
-#include <linux/bio.h>
-#include <linux/workqueue.h>
-#include <linux/slab.h>
-
-#define BIP_INLINE_VECS	4
-
-static struct kmem_cache *bip_slab;
-static struct workqueue_struct *kintegrityd_wq;
-
-/**
- * bio_integrity_alloc - Allocate integrity payload and attach it to bio
- * @bio:	bio to attach integrity metadata to
- * @gfp_mask:	Memory allocation mask
- * @nr_vecs:	Number of integrity metadata scatter-gather elements
- *
- * Description: This function prepares a bio for attaching integrity
- * metadata.  nr_vecs specifies the maximum number of pages containing
- * integrity metadata that can be attached.
- */
-struct bio_integrity_payload *bio_integrity_alloc(struct bio *bio,
-						  gfp_t gfp_mask,
-						  unsigned int nr_vecs)
-{
-	struct bio_integrity_payload *bip;
-	struct bio_set *bs = bio->bi_pool;
-	unsigned long idx = BIO_POOL_NONE;
-	unsigned inline_vecs;
-
-	if (!bs) {
-		bip = kmalloc(sizeof(struct bio_integrity_payload) +
-			      sizeof(struct bio_vec) * nr_vecs, gfp_mask);
-		inline_vecs = nr_vecs;
-	} else {
-		bip = mempool_alloc(bs->bio_integrity_pool, gfp_mask);
-		inline_vecs = BIP_INLINE_VECS;
-	}
-
-	if (unlikely(!bip))
-		return NULL;
-
-	memset(bip, 0, sizeof(*bip));
-
-	if (nr_vecs > inline_vecs) {
-		bip->bip_vec = bvec_alloc(gfp_mask, nr_vecs, &idx,
-					  bs->bvec_integrity_pool);
-		if (!bip->bip_vec)
-			goto err;
-	} else {
-		bip->bip_vec = bip->bip_inline_vecs;
-	}
-
-	bip->bip_slab = idx;
-	bip->bip_bio = bio;
-	bio->bi_integrity = bip;
-
-	return bip;
-err:
-	mempool_free(bip, bs->bio_integrity_pool);
-	return NULL;
-}
-EXPORT_SYMBOL(bio_integrity_alloc);
-
-/**
- * bio_integrity_free - Free bio integrity payload
- * @bio:	bio containing bip to be freed
- *
- * Description: Used to free the integrity portion of a bio. Usually
- * called from bio_free().
- */
-void bio_integrity_free(struct bio *bio)
-{
-	struct bio_integrity_payload *bip = bio->bi_integrity;
-	struct bio_set *bs = bio->bi_pool;
-
-	if (bip->bip_owns_buf)
-		kfree(bip->bip_buf);
-
-	if (bs) {
-		if (bip->bip_slab != BIO_POOL_NONE)
-			bvec_free(bs->bvec_integrity_pool, bip->bip_vec,
-				  bip->bip_slab);
-
-		mempool_free(bip, bs->bio_integrity_pool);
-	} else {
-		kfree(bip);
-	}
-
-	bio->bi_integrity = NULL;
-}
-EXPORT_SYMBOL(bio_integrity_free);
-
-static inline unsigned int bip_integrity_vecs(struct bio_integrity_payload *bip)
-{
-	if (bip->bip_slab == BIO_POOL_NONE)
-		return BIP_INLINE_VECS;
-
-	return bvec_nr_vecs(bip->bip_slab);
-}
-
-/**
- * bio_integrity_add_page - Attach integrity metadata
- * @bio:	bio to update
- * @page:	page containing integrity metadata
- * @len:	number of bytes of integrity metadata in page
- * @offset:	start offset within page
- *
- * Description: Attach a page containing integrity metadata to bio.
- */
-int bio_integrity_add_page(struct bio *bio, struct page *page,
-			   unsigned int len, unsigned int offset)
-{
-	struct bio_integrity_payload *bip = bio->bi_integrity;
-	struct bio_vec *iv;
-
-	if (bip->bip_vcnt >= bip_integrity_vecs(bip)) {
-		printk(KERN_ERR "%s: bip_vec full\n", __func__);
-		return 0;
-	}
-
-	iv = bip->bip_vec + bip->bip_vcnt;
-
-	iv->bv_page = page;
-	iv->bv_len = len;
-	iv->bv_offset = offset;
-	bip->bip_vcnt++;
-
-	return len;
-}
-EXPORT_SYMBOL(bio_integrity_add_page);
-
-static int bdev_integrity_enabled(struct block_device *bdev, int rw)
-{
-	struct blk_integrity *bi = bdev_get_integrity(bdev);
-
-	if (bi == NULL)
-		return 0;
-
-	if (rw == READ && bi->verify_fn != NULL &&
-	    (bi->flags & INTEGRITY_FLAG_READ))
-		return 1;
-
-	if (rw == WRITE && bi->generate_fn != NULL &&
-	    (bi->flags & INTEGRITY_FLAG_WRITE))
-		return 1;
-
-	return 0;
-}
-
-/**
- * bio_integrity_enabled - Check whether integrity can be passed
- * @bio:	bio to check
- *
- * Description: Determines whether bio_integrity_prep() can be called
- * on this bio or not.	bio data direction and target device must be
- * set prior to calling.  The functions honors the write_generate and
- * read_verify flags in sysfs.
- */
-int bio_integrity_enabled(struct bio *bio)
-{
-	if (!bio_is_rw(bio))
-		return 0;
-
-	/* Already protected? */
-	if (bio_integrity(bio))
-		return 0;
-
-	return bdev_integrity_enabled(bio->bi_bdev, bio_data_dir(bio));
-}
-EXPORT_SYMBOL(bio_integrity_enabled);
-
-/**
- * bio_integrity_hw_sectors - Convert 512b sectors to hardware ditto
- * @bi:		blk_integrity profile for device
- * @sectors:	Number of 512 sectors to convert
- *
- * Description: The block layer calculates everything in 512 byte
- * sectors but integrity metadata is done in terms of the hardware
- * sector size of the storage device.  Convert the block layer sectors
- * to physical sectors.
- */
-static inline unsigned int bio_integrity_hw_sectors(struct blk_integrity *bi,
-						    unsigned int sectors)
-{
-	/* At this point there are only 512b or 4096b DIF/EPP devices */
-	if (bi->sector_size == 4096)
-		return sectors >>= 3;
-
-	return sectors;
-}
-
-static inline unsigned int bio_integrity_bytes(struct blk_integrity *bi,
-					       unsigned int sectors)
-{
-	return bio_integrity_hw_sectors(bi, sectors) * bi->tuple_size;
-}
-
-/**
- * bio_integrity_tag_size - Retrieve integrity tag space
- * @bio:	bio to inspect
- *
- * Description: Returns the maximum number of tag bytes that can be
- * attached to this bio. Filesystems can use this to determine how
- * much metadata to attach to an I/O.
- */
-unsigned int bio_integrity_tag_size(struct bio *bio)
-{
-	struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);
-
-	BUG_ON(bio->bi_iter.bi_size == 0);
-
-	return bi->tag_size * (bio->bi_iter.bi_size / bi->sector_size);
-}
-EXPORT_SYMBOL(bio_integrity_tag_size);
-
-static int bio_integrity_tag(struct bio *bio, void *tag_buf, unsigned int len,
-			     int set)
-{
-	struct bio_integrity_payload *bip = bio->bi_integrity;
-	struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);
-	unsigned int nr_sectors;
-
-	BUG_ON(bip->bip_buf == NULL);
-
-	if (bi->tag_size == 0)
-		return -1;
-
-	nr_sectors = bio_integrity_hw_sectors(bi,
-					DIV_ROUND_UP(len, bi->tag_size));
-
-	if (nr_sectors * bi->tuple_size > bip->bip_iter.bi_size) {
-		printk(KERN_ERR "%s: tag too big for bio: %u > %u\n", __func__,
-		       nr_sectors * bi->tuple_size, bip->bip_iter.bi_size);
-		return -1;
-	}
-
-	if (set)
-		bi->set_tag_fn(bip->bip_buf, tag_buf, nr_sectors);
-	else
-		bi->get_tag_fn(bip->bip_buf, tag_buf, nr_sectors);
-
-	return 0;
-}
-
-/**
- * bio_integrity_set_tag - Attach a tag buffer to a bio
- * @bio:	bio to attach buffer to
- * @tag_buf:	Pointer to a buffer containing tag data
- * @len:	Length of the included buffer
- *
- * Description: Use this function to tag a bio by leveraging the extra
- * space provided by devices formatted with integrity protection.  The
- * size of the integrity buffer must be <= to the size reported by
- * bio_integrity_tag_size().
- */
-int bio_integrity_set_tag(struct bio *bio, void *tag_buf, unsigned int len)
-{
-	BUG_ON(bio_data_dir(bio) != WRITE);
-
-	return bio_integrity_tag(bio, tag_buf, len, 1);
-}
-EXPORT_SYMBOL(bio_integrity_set_tag);
-
-/**
- * bio_integrity_get_tag - Retrieve a tag buffer from a bio
- * @bio:	bio to retrieve buffer from
- * @tag_buf:	Pointer to a buffer for the tag data
- * @len:	Length of the target buffer
- *
- * Description: Use this function to retrieve the tag buffer from a
- * completed I/O. The size of the integrity buffer must be <= to the
- * size reported by bio_integrity_tag_size().
- */
-int bio_integrity_get_tag(struct bio *bio, void *tag_buf, unsigned int len)
-{
-	BUG_ON(bio_data_dir(bio) != READ);
-
-	return bio_integrity_tag(bio, tag_buf, len, 0);
-}
-EXPORT_SYMBOL(bio_integrity_get_tag);
-
-/**
- * bio_integrity_generate_verify - Generate/verify integrity metadata for a bio
- * @bio:	bio to generate/verify integrity metadata for
- * @operate:	operate number, 1 for generate, 0 for verify
- */
-static int bio_integrity_generate_verify(struct bio *bio, int operate)
-{
-	struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);
-	struct blk_integrity_exchg bix;
-	struct bio_vec *bv;
-	sector_t sector;
-	unsigned int sectors, ret = 0, i;
-	void *prot_buf = bio->bi_integrity->bip_buf;
-
-	if (operate)
-		sector = bio->bi_iter.bi_sector;
-	else
-		sector = bio->bi_integrity->bip_iter.bi_sector;
-
-	bix.disk_name = bio->bi_bdev->bd_disk->disk_name;
-	bix.sector_size = bi->sector_size;
-
-	bio_for_each_segment_all(bv, bio, i) {
-		void *kaddr = kmap_atomic(bv->bv_page);
-		bix.data_buf = kaddr + bv->bv_offset;
-		bix.data_size = bv->bv_len;
-		bix.prot_buf = prot_buf;
-		bix.sector = sector;
-
-		if (operate)
-			bi->generate_fn(&bix);
-		else {
-			ret = bi->verify_fn(&bix);
-			if (ret) {
-				kunmap_atomic(kaddr);
-				return ret;
-			}
-		}
-
-		sectors = bv->bv_len / bi->sector_size;
-		sector += sectors;
-		prot_buf += sectors * bi->tuple_size;
-
-		kunmap_atomic(kaddr);
-	}
-	return ret;
-}
-
-/**
- * bio_integrity_generate - Generate integrity metadata for a bio
- * @bio:	bio to generate integrity metadata for
- *
- * Description: Generates integrity metadata for a bio by calling the
- * block device's generation callback function.  The bio must have a
- * bip attached with enough room to accommodate the generated
- * integrity metadata.
- */
-static void bio_integrity_generate(struct bio *bio)
-{
-	bio_integrity_generate_verify(bio, 1);
-}
-
-static inline unsigned short blk_integrity_tuple_size(struct blk_integrity *bi)
-{
-	if (bi)
-		return bi->tuple_size;
-
-	return 0;
-}
-
-/**
- * bio_integrity_prep - Prepare bio for integrity I/O
- * @bio:	bio to prepare
- *
- * Description: Allocates a buffer for integrity metadata, maps the
- * pages and attaches them to a bio.  The bio must have data
- * direction, target device and start sector set priot to calling.  In
- * the WRITE case, integrity metadata will be generated using the
- * block device's integrity function.  In the READ case, the buffer
- * will be prepared for DMA and a suitable end_io handler set up.
- */
-int bio_integrity_prep(struct bio *bio)
-{
-	struct bio_integrity_payload *bip;
-	struct blk_integrity *bi;
-	struct request_queue *q;
-	void *buf;
-	unsigned long start, end;
-	unsigned int len, nr_pages;
-	unsigned int bytes, offset, i;
-	unsigned int sectors;
-
-	bi = bdev_get_integrity(bio->bi_bdev);
-	q = bdev_get_queue(bio->bi_bdev);
-	BUG_ON(bi == NULL);
-	BUG_ON(bio_integrity(bio));
-
-	sectors = bio_integrity_hw_sectors(bi, bio_sectors(bio));
-
-	/* Allocate kernel buffer for protection data */
-	len = sectors * blk_integrity_tuple_size(bi);
-	buf = kmalloc(len, GFP_NOIO | q->bounce_gfp);
-	if (unlikely(buf == NULL)) {
-		printk(KERN_ERR "could not allocate integrity buffer\n");
-		return -ENOMEM;
-	}
-
-	end = (((unsigned long) buf) + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
-	start = ((unsigned long) buf) >> PAGE_SHIFT;
-	nr_pages = end - start;
-
-	/* Allocate bio integrity payload and integrity vectors */
-	bip = bio_integrity_alloc(bio, GFP_NOIO, nr_pages);
-	if (unlikely(bip == NULL)) {
-		printk(KERN_ERR "could not allocate data integrity bioset\n");
-		kfree(buf);
-		return -EIO;
-	}
-
-	bip->bip_owns_buf = 1;
-	bip->bip_buf = buf;
-	bip->bip_iter.bi_size = len;
-	bip->bip_iter.bi_sector = bio->bi_iter.bi_sector;
-
-	/* Map it */
-	offset = offset_in_page(buf);
-	for (i = 0 ; i < nr_pages ; i++) {
-		int ret;
-		bytes = PAGE_SIZE - offset;
-
-		if (len <= 0)
-			break;
-
-		if (bytes > len)
-			bytes = len;
-
-		ret = bio_integrity_add_page(bio, virt_to_page(buf),
-					     bytes, offset);
-
-		if (ret == 0)
-			return 0;
-
-		if (ret < bytes)
-			break;
-
-		buf += bytes;
-		len -= bytes;
-		offset = 0;
-	}
-
-	/* Install custom I/O completion handler if read verify is enabled */
-	if (bio_data_dir(bio) == READ) {
-		bip->bip_end_io = bio->bi_end_io;
-		bio->bi_end_io = bio_integrity_endio;
-	}
-
-	/* Auto-generate integrity metadata if this is a write */
-	if (bio_data_dir(bio) == WRITE)
-		bio_integrity_generate(bio);
-
-	return 0;
-}
-EXPORT_SYMBOL(bio_integrity_prep);
-
-/**
- * bio_integrity_verify - Verify integrity metadata for a bio
- * @bio:	bio to verify
- *
- * Description: This function is called to verify the integrity of a
- * bio.	 The data in the bio io_vec is compared to the integrity
- * metadata returned by the HBA.
- */
-static int bio_integrity_verify(struct bio *bio)
-{
-	return bio_integrity_generate_verify(bio, 0);
-}
-
-/**
- * bio_integrity_verify_fn - Integrity I/O completion worker
- * @work:	Work struct stored in bio to be verified
- *
- * Description: This workqueue function is called to complete a READ
- * request.  The function verifies the transferred integrity metadata
- * and then calls the original bio end_io function.
- */
-static void bio_integrity_verify_fn(struct work_struct *work)
-{
-	struct bio_integrity_payload *bip =
-		container_of(work, struct bio_integrity_payload, bip_work);
-	struct bio *bio = bip->bip_bio;
-	int error;
-
-	error = bio_integrity_verify(bio);
-
-	/* Restore original bio completion handler */
-	bio->bi_end_io = bip->bip_end_io;
-	bio_endio_nodec(bio, error);
-}
-
-/**
- * bio_integrity_endio - Integrity I/O completion function
- * @bio:	Protected bio
- * @error:	Pointer to errno
- *
- * Description: Completion for integrity I/O
- *
- * Normally I/O completion is done in interrupt context.  However,
- * verifying I/O integrity is a time-consuming task which must be run
- * in process context.	This function postpones completion
- * accordingly.
- */
-void bio_integrity_endio(struct bio *bio, int error)
-{
-	struct bio_integrity_payload *bip = bio->bi_integrity;
-
-	BUG_ON(bip->bip_bio != bio);
-
-	/* In case of an I/O error there is no point in verifying the
-	 * integrity metadata.  Restore original bio end_io handler
-	 * and run it.
-	 */
-	if (error) {
-		bio->bi_end_io = bip->bip_end_io;
-		bio_endio(bio, error);
-
-		return;
-	}
-
-	INIT_WORK(&bip->bip_work, bio_integrity_verify_fn);
-	queue_work(kintegrityd_wq, &bip->bip_work);
-}
-EXPORT_SYMBOL(bio_integrity_endio);
-
-/**
- * bio_integrity_advance - Advance integrity vector
- * @bio:	bio whose integrity vector to update
- * @bytes_done:	number of data bytes that have been completed
- *
- * Description: This function calculates how many integrity bytes the
- * number of completed data bytes correspond to and advances the
- * integrity vector accordingly.
- */
-void bio_integrity_advance(struct bio *bio, unsigned int bytes_done)
-{
-	struct bio_integrity_payload *bip = bio->bi_integrity;
-	struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);
-	unsigned bytes = bio_integrity_bytes(bi, bytes_done >> 9);
-
-	bvec_iter_advance(bip->bip_vec, &bip->bip_iter, bytes);
-}
-EXPORT_SYMBOL(bio_integrity_advance);
-
-/**
- * bio_integrity_trim - Trim integrity vector
- * @bio:	bio whose integrity vector to update
- * @offset:	offset to first data sector
- * @sectors:	number of data sectors
- *
- * Description: Used to trim the integrity vector in a cloned bio.
- * The ivec will be advanced corresponding to 'offset' data sectors
- * and the length will be truncated corresponding to 'len' data
- * sectors.
- */
-void bio_integrity_trim(struct bio *bio, unsigned int offset,
-			unsigned int sectors)
-{
-	struct bio_integrity_payload *bip = bio->bi_integrity;
-	struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);
-
-	bio_integrity_advance(bio, offset << 9);
-	bip->bip_iter.bi_size = bio_integrity_bytes(bi, sectors);
-}
-EXPORT_SYMBOL(bio_integrity_trim);
-
-/**
- * bio_integrity_clone - Callback for cloning bios with integrity metadata
- * @bio:	New bio
- * @bio_src:	Original bio
- * @gfp_mask:	Memory allocation mask
- *
- * Description:	Called to allocate a bip when cloning a bio
- */
-int bio_integrity_clone(struct bio *bio, struct bio *bio_src,
-			gfp_t gfp_mask)
-{
-	struct bio_integrity_payload *bip_src = bio_src->bi_integrity;
-	struct bio_integrity_payload *bip;
-
-	BUG_ON(bip_src == NULL);
-
-	bip = bio_integrity_alloc(bio, gfp_mask, bip_src->bip_vcnt);
-
-	if (bip == NULL)
-		return -EIO;
-
-	memcpy(bip->bip_vec, bip_src->bip_vec,
-	       bip_src->bip_vcnt * sizeof(struct bio_vec));
-
-	bip->bip_vcnt = bip_src->bip_vcnt;
-	bip->bip_iter = bip_src->bip_iter;
-
-	return 0;
-}
-EXPORT_SYMBOL(bio_integrity_clone);
-
-int bioset_integrity_create(struct bio_set *bs, int pool_size)
-{
-	if (bs->bio_integrity_pool)
-		return 0;
-
-	bs->bio_integrity_pool = mempool_create_slab_pool(pool_size, bip_slab);
-	if (!bs->bio_integrity_pool)
-		return -1;
-
-	bs->bvec_integrity_pool = biovec_create_pool(pool_size);
-	if (!bs->bvec_integrity_pool) {
-		mempool_destroy(bs->bio_integrity_pool);
-		return -1;
-	}
-
-	return 0;
-}
-EXPORT_SYMBOL(bioset_integrity_create);
-
-void bioset_integrity_free(struct bio_set *bs)
-{
-	if (bs->bio_integrity_pool)
-		mempool_destroy(bs->bio_integrity_pool);
-
-	if (bs->bvec_integrity_pool)
-		mempool_destroy(bs->bvec_integrity_pool);
-}
-EXPORT_SYMBOL(bioset_integrity_free);
-
-void __init bio_integrity_init(void)
-{
-	/*
-	 * kintegrityd won't block much but may burn a lot of CPU cycles.
-	 * Make it highpri CPU intensive wq with max concurrency of 1.
-	 */
-	kintegrityd_wq = alloc_workqueue("kintegrityd", WQ_MEM_RECLAIM |
-					 WQ_HIGHPRI | WQ_CPU_INTENSIVE, 1);
-	if (!kintegrityd_wq)
-		panic("Failed to create kintegrityd\n");
-
-	bip_slab = kmem_cache_create("bio_integrity_payload",
-				     sizeof(struct bio_integrity_payload) +
-				     sizeof(struct bio_vec) * BIP_INLINE_VECS,
-				     0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
-	if (!bip_slab)
-		panic("Failed to create slab\n");
-}
diff --git a/fs/bio.c b/fs/bio.c
deleted file mode 100644
index 96d28eee8a1e..000000000000
--- a/fs/bio.c
+++ /dev/null
@@ -1,2038 +0,0 @@
-/*
- * 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 <scsi/sg.h>		/* for struct sg_iovec */
-
-#include <trace/events/block.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) { .nr_vecs = x, .name = "biovec-"__stringify(x) }
-static struct biovec_slab bvec_slabs[BIOVEC_NR_POOLS] __read_mostly = {
-	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.
- */
-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, 0, 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;
-}
-
-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);
-}
-
-unsigned int bvec_nr_vecs(unsigned short idx)
-{
-	return bvec_slabs[idx].nr_vecs;
-}
-
-void bvec_free(mempool_t *pool, struct bio_vec *bv, unsigned int idx)
-{
-	BIO_BUG_ON(idx >= BIOVEC_NR_POOLS);
-
-	if (idx == BIOVEC_MAX_IDX)
-		mempool_free(bv, pool);
-	else {
-		struct biovec_slab *bvs = bvec_slabs + idx;
-
-		kmem_cache_free(bvs->slab, bv);
-	}
-}
-
-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 == BIOVEC_MAX_IDX) {
-fallback:
-		bvl = mempool_alloc(pool, gfp_mask);
-	} else {
-		struct biovec_slab *bvs = bvec_slabs + *idx;
-		gfp_t __gfp_mask = gfp_mask & ~(__GFP_WAIT | __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_WAIT
-		 * is set, retry with the 1-entry mempool
-		 */
-		bvl = kmem_cache_alloc(bvs->slab, __gfp_mask);
-		if (unlikely(!bvl && (gfp_mask & __GFP_WAIT))) {
-			*idx = BIOVEC_MAX_IDX;
-			goto fallback;
-		}
-	}
-
-	return bvl;
-}
-
-static void __bio_free(struct bio *bio)
-{
-	bio_disassociate_task(bio);
-
-	if (bio_integrity(bio))
-		bio_integrity_free(bio);
-}
-
-static void bio_free(struct bio *bio)
-{
-	struct bio_set *bs = bio->bi_pool;
-	void *p;
-
-	__bio_free(bio);
-
-	if (bs) {
-		if (bio_flagged(bio, BIO_OWNS_VEC))
-			bvec_free(bs->bvec_pool, bio->bi_io_vec, BIO_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);
-	}
-}
-
-void bio_init(struct bio *bio)
-{
-	memset(bio, 0, sizeof(*bio));
-	bio->bi_flags = 1 << BIO_UPTODATE;
-	atomic_set(&bio->bi_remaining, 1);
-	atomic_set(&bio->bi_cnt, 1);
-}
-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_free(bio);
-
-	memset(bio, 0, BIO_RESET_BYTES);
-	bio->bi_flags = flags|(1 << BIO_UPTODATE);
-	atomic_set(&bio->bi_remaining, 1);
-}
-EXPORT_SYMBOL(bio_reset);
-
-static void bio_chain_endio(struct bio *bio, int error)
-{
-	bio_endio(bio->bi_private, error);
-	bio_put(bio);
-}
-
-/**
- * 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;
-	atomic_inc(&parent->bi_remaining);
-}
-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);
-	}
-}
-
-static void punt_bios_to_rescuer(struct bio_set *bs)
-{
-	struct bio_list punt, nopunt;
-	struct bio *bio;
-
-	/*
-	 * 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)))
-		bio_list_add(bio->bi_pool == bs ? &punt : &nopunt, bio);
-
-	*current->bio_list = 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);
-}
-
-/**
- * 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_WAIT 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, int nr_iovecs, struct bio_set *bs)
-{
-	gfp_t saved_gfp = gfp_mask;
-	unsigned front_pad;
-	unsigned inline_vecs;
-	unsigned long idx = BIO_POOL_NONE;
-	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 {
-		/*
-		 * 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_WAIT; 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))
-			gfp_mask &= ~__GFP_WAIT;
-
-		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);
-
-	if (nr_iovecs > inline_vecs) {
-		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 |= 1 << BIO_OWNS_VEC;
-	} else if (nr_iovecs) {
-		bvl = bio->bi_inline_vecs;
-	}
-
-	bio->bi_pool = bs;
-	bio->bi_flags |= idx << BIO_POOL_OFFSET;
-	bio->bi_max_vecs = nr_iovecs;
-	bio->bi_io_vec = bvl;
-	return bio;
-
-err_free:
-	mempool_free(p, bs->bio_pool);
-	return NULL;
-}
-EXPORT_SYMBOL(bio_alloc_bioset);
-
-void zero_fill_bio(struct bio *bio)
-{
-	unsigned long flags;
-	struct bio_vec bv;
-	struct bvec_iter iter;
-
-	bio_for_each_segment(bv, bio, iter) {
-		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, bio_get or bio_clone. 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_free(bio);
-}
-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;
-}
-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 && BIO_POOL_IDX(bio) != BIO_POOL_NONE);
-
-	/*
-	 * most users will be overriding ->bi_bdev with a new target,
-	 * so we don't set nor calculate new physical/hw segment counts here
-	 */
-	bio->bi_bdev = bio_src->bi_bdev;
-	bio->bi_flags |= 1 << BIO_CLONED;
-	bio->bi_rw = bio_src->bi_rw;
-	bio->bi_iter = bio_src->bi_iter;
-	bio->bi_io_vec = bio_src->bi_io_vec;
-}
-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;
-}
-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_bdev		= bio_src->bi_bdev;
-	bio->bi_rw		= bio_src->bi_rw;
-	bio->bi_iter.bi_sector	= bio_src->bi_iter.bi_sector;
-	bio->bi_iter.bi_size	= bio_src->bi_iter.bi_size;
-
-	if (bio->bi_rw & REQ_DISCARD)
-		goto integrity_clone;
-
-	if (bio->bi_rw & REQ_WRITE_SAME) {
-		bio->bi_io_vec[bio->bi_vcnt++] = bio_src->bi_io_vec[0];
-		goto integrity_clone;
-	}
-
-	bio_for_each_segment(bv, bio_src, iter)
-		bio->bi_io_vec[bio->bi_vcnt++] = bv;
-
-integrity_clone:
-	if (bio_integrity(bio_src)) {
-		int ret;
-
-		ret = bio_integrity_clone(bio, bio_src, gfp_mask);
-		if (ret < 0) {
-			bio_put(bio);
-			return NULL;
-		}
-	}
-
-	return bio;
-}
-EXPORT_SYMBOL(bio_clone_bioset);
-
-/**
- *	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)
-{
-	struct request_queue *q = bdev_get_queue(bdev);
-	int nr_pages;
-
-	nr_pages = min_t(unsigned,
-		     queue_max_segments(q),
-		     queue_max_sectors(q) / (PAGE_SIZE >> 9) + 1);
-
-	return min_t(unsigned, nr_pages, BIO_MAX_PAGES);
-
-}
-EXPORT_SYMBOL(bio_get_nr_vecs);
-
-static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page
-			  *page, unsigned int len, unsigned int offset,
-			  unsigned int max_sectors)
-{
-	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) > max_sectors)
-		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) {
-			unsigned int prev_bv_len = prev->bv_len;
-			prev->bv_len += len;
-
-			if (q->merge_bvec_fn) {
-				struct bvec_merge_data bvm = {
-					/* prev_bvec is already charged in
-					   bi_size, discharge it in order to
-					   simulate merging updated prev_bvec
-					   as new bvec. */
-					.bi_bdev = bio->bi_bdev,
-					.bi_sector = bio->bi_iter.bi_sector,
-					.bi_size = bio->bi_iter.bi_size -
-						prev_bv_len,
-					.bi_rw = bio->bi_rw,
-				};
-
-				if (q->merge_bvec_fn(q, &bvm, prev) < prev->bv_len) {
-					prev->bv_len -= len;
-					return 0;
-				}
-			}
-
-			goto done;
-		}
-	}
-
-	if (bio->bi_vcnt >= bio->bi_max_vecs)
-		return 0;
-
-	/*
-	 * we might lose a segment or two here, but rather that than
-	 * make this too complex.
-	 */
-
-	while (bio->bi_phys_segments >= queue_max_segments(q)) {
-
-		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) {
-		struct bvec_merge_data bvm = {
-			.bi_bdev = bio->bi_bdev,
-			.bi_sector = bio->bi_iter.bi_sector,
-			.bi_size = bio->bi_iter.bi_size,
-			.bi_rw = bio->bi_rw,
-		};
-
-		/*
-		 * merge_bvec_fn() returns number of bytes it can accept
-		 * at this offset
-		 */
-		if (q->merge_bvec_fn(q, &bvm, bvec) < bvec->bv_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)))
-		bio->bi_flags &= ~(1 << BIO_SEG_VALID);
-
-	bio->bi_vcnt++;
-	bio->bi_phys_segments++;
- done:
-	bio->bi_iter.bi_size += len;
-	return len;
-}
-
-/**
- *	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)
-{
-	return __bio_add_page(q, bio, page, len, offset,
-			      queue_max_hw_sectors(q));
-}
-EXPORT_SYMBOL(bio_add_pc_page);
-
-/**
- *	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 up to 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)
-{
-	struct request_queue *q = bdev_get_queue(bio->bi_bdev);
-	return __bio_add_page(q, bio, page, len, offset, queue_max_sectors(q));
-}
-EXPORT_SYMBOL(bio_add_page);
-
-struct submit_bio_ret {
-	struct completion event;
-	int error;
-};
-
-static void submit_bio_wait_endio(struct bio *bio, int error)
-{
-	struct submit_bio_ret *ret = bio->bi_private;
-
-	ret->error = error;
-	complete(&ret->event);
-}
-
-/**
- * submit_bio_wait - submit a bio, and wait until it completes
- * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead)
- * @bio: The &struct bio which describes the I/O
- *
- * Simple wrapper around submit_bio(). Returns 0 on success, or the error from
- * bio_endio() on failure.
- */
-int submit_bio_wait(int rw, struct bio *bio)
-{
-	struct submit_bio_ret ret;
-
-	rw |= REQ_SYNC;
-	init_completion(&ret.event);
-	bio->bi_private = &ret;
-	bio->bi_end_io = submit_bio_wait_endio;
-	submit_bio(rw, bio);
-	wait_for_completion(&ret.event);
-
-	return ret.error;
-}
-EXPORT_SYMBOL(submit_bio_wait);
-
-/**
- * bio_advance - increment/complete a bio by some number of bytes
- * @bio:	bio to advance
- * @bytes:	number of bytes to complete
- *
- * This updates bi_sector, bi_size and bi_idx; if the number of bytes to
- * complete doesn't align with a bvec boundary, then bv_len and bv_offset will
- * be updated on the last bvec as well.
- *
- * @bio will then represent the remaining, uncompleted portion of the io.
- */
-void bio_advance(struct bio *bio, unsigned bytes)
-{
-	if (bio_integrity(bio))
-		bio_integrity_advance(bio, bytes);
-
-	bio_advance_iter(bio, &bio->bi_iter, bytes);
-}
-EXPORT_SYMBOL(bio_advance);
-
-/**
- * bio_alloc_pages - allocates a single page for each bvec in a bio
- * @bio: bio to allocate pages for
- * @gfp_mask: flags for allocation
- *
- * Allocates pages up to @bio->bi_vcnt.
- *
- * Returns 0 on success, -ENOMEM on failure. On failure, any allocated pages are
- * freed.
- */
-int bio_alloc_pages(struct bio *bio, gfp_t gfp_mask)
-{
-	int i;
-	struct bio_vec *bv;
-
-	bio_for_each_segment_all(bv, bio, i) {
-		bv->bv_page = alloc_page(gfp_mask);
-		if (!bv->bv_page) {
-			while (--bv >= bio->bi_io_vec)
-				__free_page(bv->bv_page);
-			return -ENOMEM;
-		}
-	}
-
-	return 0;
-}
-EXPORT_SYMBOL(bio_alloc_pages);
-
-/**
- * bio_copy_data - copy contents of data buffers from one chain of bios to
- * another
- * @src: source bio list
- * @dst: destination bio list
- *
- * If @src and @dst are single bios, bi_next must be NULL - otherwise, treats
- * @src and @dst as linked lists of bios.
- *
- * Stops when it reaches the end of either @src or @dst - that is, copies
- * min(src->bi_size, dst->bi_size) bytes (or the equivalent for lists of bios).
- */
-void bio_copy_data(struct bio *dst, struct bio *src)
-{
-	struct bvec_iter src_iter, dst_iter;
-	struct bio_vec src_bv, dst_bv;
-	void *src_p, *dst_p;
-	unsigned bytes;
-
-	src_iter = src->bi_iter;
-	dst_iter = dst->bi_iter;
-
-	while (1) {
-		if (!src_iter.bi_size) {
-			src = src->bi_next;
-			if (!src)
-				break;
-
-			src_iter = src->bi_iter;
-		}
-
-		if (!dst_iter.bi_size) {
-			dst = dst->bi_next;
-			if (!dst)
-				break;
-
-			dst_iter = dst->bi_iter;
-		}
-
-		src_bv = bio_iter_iovec(src, src_iter);
-		dst_bv = bio_iter_iovec(dst, dst_iter);
-
-		bytes = min(src_bv.bv_len, dst_bv.bv_len);
-
-		src_p = kmap_atomic(src_bv.bv_page);
-		dst_p = kmap_atomic(dst_bv.bv_page);
-
-		memcpy(dst_p + dst_bv.bv_offset,
-		       src_p + src_bv.bv_offset,
-		       bytes);
-
-		kunmap_atomic(dst_p);
-		kunmap_atomic(src_p);
-
-		bio_advance_iter(src, &src_iter, bytes);
-		bio_advance_iter(dst, &dst_iter, bytes);
-	}
-}
-EXPORT_SYMBOL(bio_copy_data);
-
-struct bio_map_data {
-	int nr_sgvecs;
-	int is_our_pages;
-	struct sg_iovec sgvecs[];
-};
-
-static void bio_set_map_data(struct bio_map_data *bmd, struct bio *bio,
-			     const struct sg_iovec *iov, int iov_count,
-			     int is_our_pages)
-{
-	memcpy(bmd->sgvecs, iov, sizeof(struct sg_iovec) * iov_count);
-	bmd->nr_sgvecs = iov_count;
-	bmd->is_our_pages = is_our_pages;
-	bio->bi_private = bmd;
-}
-
-static struct bio_map_data *bio_alloc_map_data(unsigned int iov_count,
-					       gfp_t gfp_mask)
-{
-	if (iov_count > UIO_MAXIOV)
-		return NULL;
-
-	return kmalloc(sizeof(struct bio_map_data) +
-		       sizeof(struct sg_iovec) * iov_count, gfp_mask);
-}
-
-static int __bio_copy_iov(struct bio *bio, const struct sg_iovec *iov, int iov_count,
-			  int to_user, int from_user, int do_free_page)
-{
-	int ret = 0, i;
-	struct bio_vec *bvec;
-	int iov_idx = 0;
-	unsigned int iov_off = 0;
-
-	bio_for_each_segment_all(bvec, bio, i) {
-		char *bv_addr = page_address(bvec->bv_page);
-		unsigned int bv_len = bvec->bv_len;
-
-		while (bv_len && iov_idx < iov_count) {
-			unsigned int bytes;
-			char __user *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 (to_user)
-					ret = copy_to_user(iov_addr, bv_addr,
-							   bytes);
-
-				if (from_user)
-					ret = copy_from_user(bv_addr, iov_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;
-			}
-		}
-
-		if (do_free_page)
-			__free_page(bvec->bv_page);
-	}
-
-	return ret;
-}
-
-/**
- *	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;
-	struct bio_vec *bvec;
-	int ret = 0, i;
-
-	if (!bio_flagged(bio, BIO_NULL_MAPPED)) {
-		/*
-		 * if we're in a workqueue, the request is orphaned, so
-		 * don't copy into a random user address space, just free.
-		 */
-		if (current->mm)
-			ret = __bio_copy_iov(bio, bmd->sgvecs, bmd->nr_sgvecs,
-					     bio_data_dir(bio) == READ,
-					     0, bmd->is_our_pages);
-		else if (bmd->is_our_pages)
-			bio_for_each_segment_all(bvec, bio, i)
-				__free_page(bvec->bv_page);
-	}
-	kfree(bmd);
-	bio_put(bio);
-	return ret;
-}
-EXPORT_SYMBOL(bio_uncopy_user);
-
-/**
- *	bio_copy_user_iov	-	copy user data to bio
- *	@q: destination block queue
- *	@map_data: pointer to the rq_map_data holding pages (if necessary)
- *	@iov:	the iovec.
- *	@iov_count: number of elements in the iovec
- *	@write_to_vm: bool indicating writing to pages or not
- *	@gfp_mask: memory allocation flags
- *
- *	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.
- */
-struct bio *bio_copy_user_iov(struct request_queue *q,
-			      struct rq_map_data *map_data,
-			      const struct sg_iovec *iov, int iov_count,
-			      int write_to_vm, gfp_t gfp_mask)
-{
-	struct bio_map_data *bmd;
-	struct bio_vec *bvec;
-	struct page *page;
-	struct bio *bio;
-	int i, ret;
-	int nr_pages = 0;
-	unsigned int len = 0;
-	unsigned int offset = map_data ? map_data->offset & ~PAGE_MASK : 0;
-
-	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;
-
-		/*
-		 * Overflow, abort
-		 */
-		if (end < start)
-			return ERR_PTR(-EINVAL);
-
-		nr_pages += end - start;
-		len += iov[i].iov_len;
-	}
-
-	if (offset)
-		nr_pages++;
-
-	bmd = bio_alloc_map_data(iov_count, gfp_mask);
-	if (!bmd)
-		return ERR_PTR(-ENOMEM);
-
-	ret = -ENOMEM;
-	bio = bio_kmalloc(gfp_mask, nr_pages);
-	if (!bio)
-		goto out_bmd;
-
-	if (!write_to_vm)
-		bio->bi_rw |= REQ_WRITE;
-
-	ret = 0;
-
-	if (map_data) {
-		nr_pages = 1 << map_data->page_order;
-		i = map_data->offset / PAGE_SIZE;
-	}
-	while (len) {
-		unsigned int bytes = PAGE_SIZE;
-
-		bytes -= offset;
-
-		if (bytes > len)
-			bytes = len;
-
-		if (map_data) {
-			if (i == map_data->nr_entries * nr_pages) {
-				ret = -ENOMEM;
-				break;
-			}
-
-			page = map_data->pages[i / nr_pages];
-			page += (i % nr_pages);
-
-			i++;
-		} else {
-			page = alloc_page(q->bounce_gfp | gfp_mask);
-			if (!page) {
-				ret = -ENOMEM;
-				break;
-			}
-		}
-
-		if (bio_add_pc_page(q, bio, page, bytes, offset) < bytes)
-			break;
-
-		len -= bytes;
-		offset = 0;
-	}
-
-	if (ret)
-		goto cleanup;
-
-	/*
-	 * success
-	 */
-	if ((!write_to_vm && (!map_data || !map_data->null_mapped)) ||
-	    (map_data && map_data->from_user)) {
-		ret = __bio_copy_iov(bio, iov, iov_count, 0, 1, 0);
-		if (ret)
-			goto cleanup;
-	}
-
-	bio_set_map_data(bmd, bio, iov, iov_count, map_data ? 0 : 1);
-	return bio;
-cleanup:
-	if (!map_data)
-		bio_for_each_segment_all(bvec, bio, i)
-			__free_page(bvec->bv_page);
-
-	bio_put(bio);
-out_bmd:
-	kfree(bmd);
-	return ERR_PTR(ret);
-}
-
-/**
- *	bio_copy_user	-	copy user data to bio
- *	@q: destination block queue
- *	@map_data: pointer to the rq_map_data holding pages (if necessary)
- *	@uaddr: start of user address
- *	@len: length in bytes
- *	@write_to_vm: bool indicating writing to pages or not
- *	@gfp_mask: memory allocation flags
- *
- *	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.
- */
-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)
-{
-	struct sg_iovec iov;
-
-	iov.iov_base = (void __user *)uaddr;
-	iov.iov_len = len;
-
-	return bio_copy_user_iov(q, map_data, &iov, 1, write_to_vm, gfp_mask);
-}
-EXPORT_SYMBOL(bio_copy_user);
-
-static struct bio *__bio_map_user_iov(struct request_queue *q,
-				      struct block_device *bdev,
-				      const struct sg_iovec *iov, int iov_count,
-				      int write_to_vm, gfp_t gfp_mask)
-{
-	int i, j;
-	int nr_pages = 0;
-	struct page **pages;
-	struct bio *bio;
-	int cur_page = 0;
-	int ret, offset;
-
-	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;
-
-		/*
-		 * Overflow, abort
-		 */
-		if (end < start)
-			return ERR_PTR(-EINVAL);
-
-		nr_pages += end - start;
-		/*
-		 * buffer must be aligned to at least hardsector size for now
-		 */
-		if (uaddr & queue_dma_alignment(q))
-			return ERR_PTR(-EINVAL);
-	}
-
-	if (!nr_pages)
-		return ERR_PTR(-EINVAL);
-
-	bio = bio_kmalloc(gfp_mask, nr_pages);
-	if (!bio)
-		return ERR_PTR(-ENOMEM);
-
-	ret = -ENOMEM;
-	pages = kcalloc(nr_pages, sizeof(struct page *), gfp_mask);
-	if (!pages)
-		goto out;
-
-	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;
-
-		ret = get_user_pages_fast(uaddr, local_nr_pages,
-				write_to_vm, &pages[cur_page]);
-		if (ret < local_nr_pages) {
-			ret = -EFAULT;
-			goto out_unmap;
-		}
-
-		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...
-			 */
-			if (bio_add_pc_page(q, bio, pages[j], bytes, offset) <
-					    bytes)
-				break;
-
-			len -= bytes;
-			offset = 0;
-		}
-
-		cur_page = j;
-		/*
-		 * release the pages we didn't map into the bio, if any
-		 */
-		while (j < page_limit)
-			page_cache_release(pages[j++]);
-	}
-
-	kfree(pages);
-
-	/*
-	 * set data direction, and check if mapped pages need bouncing
-	 */
-	if (!write_to_vm)
-		bio->bi_rw |= REQ_WRITE;
-
-	bio->bi_bdev = bdev;
-	bio->bi_flags |= (1 << BIO_USER_MAPPED);
-	return bio;
-
- out_unmap:
-	for (i = 0; i < nr_pages; i++) {
-		if(!pages[i])
-			break;
-		page_cache_release(pages[i]);
-	}
- out:
-	kfree(pages);
-	bio_put(bio);
-	return ERR_PTR(ret);
-}
-
-/**
- *	bio_map_user	-	map user address into bio
- *	@q: the struct request_queue for the bio
- *	@bdev: destination block device
- *	@uaddr: start of user address
- *	@len: length in bytes
- *	@write_to_vm: bool indicating writing to pages or not
- *	@gfp_mask: memory allocation flags
- *
- *	Map the user space address into a bio suitable for io to a block
- *	device. Returns an error pointer in case of error.
- */
-struct bio *bio_map_user(struct request_queue *q, struct block_device *bdev,
-			 unsigned long uaddr, unsigned int len, int write_to_vm,
-			 gfp_t gfp_mask)
-{
-	struct sg_iovec iov;
-
-	iov.iov_base = (void __user *)uaddr;
-	iov.iov_len = len;
-
-	return bio_map_user_iov(q, bdev, &iov, 1, write_to_vm, gfp_mask);
-}
-EXPORT_SYMBOL(bio_map_user);
-
-/**
- *	bio_map_user_iov - map user sg_iovec table into bio
- *	@q: the struct request_queue for the bio
- *	@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
- *	@gfp_mask: memory allocation flags
- *
- *	Map the user space address into a bio suitable for io to a block
- *	device. Returns an error pointer in case of error.
- */
-struct bio *bio_map_user_iov(struct request_queue *q, struct block_device *bdev,
-			     const struct sg_iovec *iov, int iov_count,
-			     int write_to_vm, gfp_t gfp_mask)
-{
-	struct bio *bio;
-
-	bio = __bio_map_user_iov(q, bdev, iov, iov_count, write_to_vm,
-				 gfp_mask);
-	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);
-
-	return bio;
-}
-
-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_all(bvec, bio, i) {
-		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);
-}
-EXPORT_SYMBOL(bio_unmap_user);
-
-static void bio_map_kern_endio(struct bio *bio, int err)
-{
-	bio_put(bio);
-}
-
-static struct bio *__bio_map_kern(struct request_queue *q, void *data,
-				  unsigned int len, gfp_t gfp_mask)
-{
-	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_kmalloc(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;
-
-		if (bio_add_pc_page(q, bio, virt_to_page(data), bytes,
-				    offset) < bytes)
-			break;
-
-		data += bytes;
-		len -= bytes;
-		offset = 0;
-	}
-
-	bio->bi_end_io = bio_map_kern_endio;
-	return bio;
-}
-
-/**
- *	bio_map_kern	-	map kernel address into bio
- *	@q: the struct request_queue for the bio
- *	@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.
- */
-struct bio *bio_map_kern(struct request_queue *q, void *data, unsigned int len,
-			 gfp_t gfp_mask)
-{
-	struct bio *bio;
-
-	bio = __bio_map_kern(q, data, len, gfp_mask);
-	if (IS_ERR(bio))
-		return bio;
-
-	if (bio->bi_iter.bi_size == len)
-		return bio;
-
-	/*
-	 * Don't support partial mappings.
-	 */
-	bio_put(bio);
-	return ERR_PTR(-EINVAL);
-}
-EXPORT_SYMBOL(bio_map_kern);
-
-static void bio_copy_kern_endio(struct bio *bio, int err)
-{
-	struct bio_vec *bvec;
-	const int read = bio_data_dir(bio) == READ;
-	struct bio_map_data *bmd = bio->bi_private;
-	int i;
-	char *p = bmd->sgvecs[0].iov_base;
-
-	bio_for_each_segment_all(bvec, bio, i) {
-		char *addr = page_address(bvec->bv_page);
-
-		if (read)
-			memcpy(p, addr, bvec->bv_len);
-
-		__free_page(bvec->bv_page);
-		p += bvec->bv_len;
-	}
-
-	kfree(bmd);
-	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
- *	@reading: data direction is READ
- *
- *	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;
-	int i;
-
-	bio = bio_copy_user(q, NULL, (unsigned long)data, len, 1, gfp_mask);
-	if (IS_ERR(bio))
-		return bio;
-
-	if (!reading) {
-		void *p = data;
-
-		bio_for_each_segment_all(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;
-
-	return bio;
-}
-EXPORT_SYMBOL(bio_copy_kern);
-
-/*
- * 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, flusher threads) 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;
-	int i;
-
-	bio_for_each_segment_all(bvec, bio, i) {
-		struct page *page = bvec->bv_page;
-
-		if (page && !PageCompound(page))
-			set_page_dirty_lock(page);
-	}
-}
-
-static void bio_release_pages(struct bio *bio)
-{
-	struct bio_vec *bvec;
-	int i;
-
-	bio_for_each_segment_all(bvec, bio, i) {
-		struct page *page = bvec->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.
- */
-
-static void bio_dirty_fn(struct work_struct *work);
-
-static DECLARE_WORK(bio_dirty_work, bio_dirty_fn);
-static DEFINE_SPINLOCK(bio_dirty_lock);
-static struct bio *bio_dirty_list;
-
-/*
- * This runs in process context
- */
-static void bio_dirty_fn(struct work_struct *work)
-{
-	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;
-	int nr_clean_pages = 0;
-	int i;
-
-	bio_for_each_segment_all(bvec, bio, i) {
-		struct page *page = bvec->bv_page;
-
-		if (PageDirty(page) || PageCompound(page)) {
-			page_cache_release(page);
-			bvec->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);
-	}
-}
-
-#if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
-void bio_flush_dcache_pages(struct bio *bi)
-{
-	struct bio_vec bvec;
-	struct bvec_iter iter;
-
-	bio_for_each_segment(bvec, bi, iter)
-		flush_dcache_page(bvec.bv_page);
-}
-EXPORT_SYMBOL(bio_flush_dcache_pages);
-#endif
-
-/**
- * bio_endio - end I/O on a bio
- * @bio:	bio
- * @error:	error, if any
- *
- * Description:
- *   bio_endio() will end I/O on the whole bio. bio_endio() is the
- *   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. No one should call bi_end_io() directly on a
- *   bio unless they own it and thus know that it has an end_io
- *   function.
- **/
-void bio_endio(struct bio *bio, int error)
-{
-	while (bio) {
-		BUG_ON(atomic_read(&bio->bi_remaining) <= 0);
-
-		if (error)
-			clear_bit(BIO_UPTODATE, &bio->bi_flags);
-		else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
-			error = -EIO;
-
-		if (!atomic_dec_and_test(&bio->bi_remaining))
-			return;
-
-		/*
-		 * Need to have a real endio function for chained bios,
-		 * otherwise various corner cases will break (like stacking
-		 * block devices that save/restore bi_end_io) - however, we want
-		 * to avoid unbounded recursion and blowing the stack. Tail call
-		 * optimization would handle this, but compiling with frame
-		 * pointers also disables gcc's sibling call optimization.
-		 */
-		if (bio->bi_end_io == bio_chain_endio) {
-			struct bio *parent = bio->bi_private;
-			bio_put(bio);
-			bio = parent;
-		} else {
-			if (bio->bi_end_io)
-				bio->bi_end_io(bio, error);
-			bio = NULL;
-		}
-	}
-}
-EXPORT_SYMBOL(bio_endio);
-
-/**
- * bio_endio_nodec - end I/O on a bio, without decrementing bi_remaining
- * @bio:	bio
- * @error:	error, if any
- *
- * For code that has saved and restored bi_end_io; thing hard before using this
- * function, probably you should've cloned the entire bio.
- **/
-void bio_endio_nodec(struct bio *bio, int error)
-{
-	atomic_inc(&bio->bi_remaining);
-	bio_endio(bio, error);
-}
-EXPORT_SYMBOL(bio_endio_nodec);
-
-/**
- * bio_split - split a bio
- * @bio:	bio to split
- * @sectors:	number of sectors to split from the front of @bio
- * @gfp:	gfp mask
- * @bs:		bio set to allocate from
- *
- * Allocates and returns a new bio which represents @sectors from the start of
- * @bio, and updates @bio to represent the remaining sectors.
- *
- * The newly allocated bio will point to @bio's bi_io_vec; it is the caller's
- * responsibility to ensure that @bio is not freed before the split.
- */
-struct bio *bio_split(struct bio *bio, int sectors,
-		      gfp_t gfp, struct bio_set *bs)
-{
-	struct bio *split = NULL;
-
-	BUG_ON(sectors <= 0);
-	BUG_ON(sectors >= bio_sectors(bio));
-
-	split = bio_clone_fast(bio, gfp, bs);
-	if (!split)
-		return NULL;
-
-	split->bi_iter.bi_size = sectors << 9;
-
-	if (bio_integrity(split))
-		bio_integrity_trim(split, 0, sectors);
-
-	bio_advance(bio, split->bi_iter.bi_size);
-
-	return split;
-}
-EXPORT_SYMBOL(bio_split);
-
-/**
- * bio_trim - trim a bio
- * @bio:	bio to trim
- * @offset:	number of sectors to trim from the front of @bio
- * @size:	size we want to trim @bio to, in sectors
- */
-void bio_trim(struct bio *bio, int offset, int size)
-{
-	/* 'bio' is a cloned bio which we need to trim to match
-	 * the given offset and size.
-	 */
-
-	size <<= 9;
-	if (offset == 0 && size == bio->bi_iter.bi_size)
-		return;
-
-	clear_bit(BIO_SEG_VALID, &bio->bi_flags);
-
-	bio_advance(bio, offset << 9);
-
-	bio->bi_iter.bi_size = size;
-}
-EXPORT_SYMBOL_GPL(bio_trim);
-
-/*
- * create memory pools for biovec's in a bio_set.
- * use the global biovec slabs created for general use.
- */
-mempool_t *biovec_create_pool(int pool_entries)
-{
-	struct biovec_slab *bp = bvec_slabs + BIOVEC_MAX_IDX;
-
-	return mempool_create_slab_pool(pool_entries, bp->slab);
-}
-
-void bioset_free(struct bio_set *bs)
-{
-	if (bs->rescue_workqueue)
-		destroy_workqueue(bs->rescue_workqueue);
-
-	if (bs->bio_pool)
-		mempool_destroy(bs->bio_pool);
-
-	if (bs->bvec_pool)
-		mempool_destroy(bs->bvec_pool);
-
-	bioset_integrity_free(bs);
-	bio_put_slab(bs);
-
-	kfree(bs);
-}
-EXPORT_SYMBOL(bioset_free);
-
-/**
- * bioset_create  - Create a bio_set
- * @pool_size:	Number of bio and bio_vecs to cache in the mempool
- * @front_pad:	Number of bytes to allocate in front of the returned bio
- *
- * Description:
- *    Set up a bio_set to be used with @bio_alloc_bioset. Allows the caller
- *    to ask for a number of bytes to be allocated in front of the bio.
- *    Front pad allocation is useful for embedding the bio inside
- *    another structure, to avoid allocating extra data to go with the bio.
- *    Note that the bio must be embedded at the END of that structure always,
- *    or things will break badly.
- */
-struct bio_set *bioset_create(unsigned int pool_size, unsigned int front_pad)
-{
-	unsigned int back_pad = BIO_INLINE_VECS * sizeof(struct bio_vec);
-	struct bio_set *bs;
-
-	bs = kzalloc(sizeof(*bs), GFP_KERNEL);
-	if (!bs)
-		return NULL;
-
-	bs->front_pad = front_pad;
-
-	spin_lock_init(&bs->rescue_lock);
-	bio_list_init(&bs->rescue_list);
-	INIT_WORK(&bs->rescue_work, bio_alloc_rescue);
-
-	bs->bio_slab = bio_find_or_create_slab(front_pad + back_pad);
-	if (!bs->bio_slab) {
-		kfree(bs);
-		return NULL;
-	}
-
-	bs->bio_pool = mempool_create_slab_pool(pool_size, bs->bio_slab);
-	if (!bs->bio_pool)
-		goto bad;
-
-	bs->bvec_pool = biovec_create_pool(pool_size);
-	if (!bs->bvec_pool)
-		goto bad;
-
-	bs->rescue_workqueue = alloc_workqueue("bioset", WQ_MEM_RECLAIM, 0);
-	if (!bs->rescue_workqueue)
-		goto bad;
-
-	return bs;
-bad:
-	bioset_free(bs);
-	return NULL;
-}
-EXPORT_SYMBOL(bioset_create);
-
-#ifdef CONFIG_BLK_CGROUP
-/**
- * bio_associate_current - associate a bio with %current
- * @bio: target bio
- *
- * Associate @bio with %current if it hasn't been associated yet.  Block
- * layer will treat @bio as if it were issued by %current no matter which
- * task actually issues it.
- *
- * This function takes an extra reference of @task's io_context and blkcg
- * which will be put when @bio is released.  The caller must own @bio,
- * ensure %current->io_context exists, and is responsible for synchronizing
- * calls to this function.
- */
-int bio_associate_current(struct bio *bio)
-{
-	struct io_context *ioc;
-	struct cgroup_subsys_state *css;
-
-	if (bio->bi_ioc)
-		return -EBUSY;
-
-	ioc = current->io_context;
-	if (!ioc)
-		return -ENOENT;
-
-	/* acquire active ref on @ioc and associate */
-	get_io_context_active(ioc);
-	bio->bi_ioc = ioc;
-
-	/* associate blkcg if exists */
-	rcu_read_lock();
-	css = task_css(current, blkio_cgrp_id);
-	if (css && css_tryget(css))
-		bio->bi_css = css;
-	rcu_read_unlock();
-
-	return 0;
-}
-
-/**
- * bio_disassociate_task - undo bio_associate_current()
- * @bio: target bio
- */
-void bio_disassociate_task(struct bio *bio)
-{
-	if (bio->bi_ioc) {
-		put_io_context(bio->bi_ioc);
-		bio->bi_ioc = NULL;
-	}
-	if (bio->bi_css) {
-		css_put(bio->bi_css);
-		bio->bi_css = NULL;
-	}
-}
-
-#endif /* CONFIG_BLK_CGROUP */
-
-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;
-
-		if (bvs->nr_vecs <= BIO_INLINE_VECS) {
-			bvs->slab = NULL;
-			continue;
-		}
-
-		size = bvs->nr_vecs * sizeof(struct bio_vec);
-		bvs->slab = kmem_cache_create(bvs->name, size, 0,
-                                SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
-	}
-}
-
-static int __init init_bio(void)
-{
-	bio_slab_max = 2;
-	bio_slab_nr = 0;
-	bio_slabs = kzalloc(bio_slab_max * sizeof(struct bio_slab), GFP_KERNEL);
-	if (!bio_slabs)
-		panic("bio: can't allocate bios\n");
-
-	bio_integrity_init();
-	biovec_init_slabs();
-
-	fs_bio_set = bioset_create(BIO_POOL_SIZE, 0);
-	if (!fs_bio_set)
-		panic("bio: can't allocate bios\n");
-
-	if (bioset_integrity_create(fs_bio_set, BIO_POOL_SIZE))
-		panic("bio: can't create integrity pool\n");
-
-	return 0;
-}
-subsys_initcall(init_bio);