[mirror_ubuntu-bionic-kernel.git] / block / blk-lib.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Functions related to generic helpers functions
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/bio.h>
#include <linux/blkdev.h>
#include <linux/scatterlist.h>

#include "blk.h"

static struct bio *next_bio(struct bio *bio, unsigned int nr_pages,
		gfp_t gfp)
{
	struct bio *new = bio_alloc(gfp, nr_pages);

	if (bio) {
		bio_chain(bio, new);
		submit_bio(bio);
	}

	return new;
}

int __blkdev_issue_discard(struct block_device *bdev, sector_t sector,
		sector_t nr_sects, gfp_t gfp_mask, int flags,
		struct bio **biop)
{
	struct request_queue *q = bdev_get_queue(bdev);
	struct bio *bio = *biop;
	unsigned int op;
	sector_t bs_mask;

	if (!q)
		return -ENXIO;

	if (flags & BLKDEV_DISCARD_SECURE) {
		if (!blk_queue_secure_erase(q))
			return -EOPNOTSUPP;
		op = REQ_OP_SECURE_ERASE;
	} else {
		if (!blk_queue_discard(q))
			return -EOPNOTSUPP;
		op = REQ_OP_DISCARD;
	}

	bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
	if ((sector | nr_sects) & bs_mask)
		return -EINVAL;

	while (nr_sects) {
		unsigned int req_sects = nr_sects;
		sector_t end_sect;

		req_sects = min(req_sects, bio_allowed_max_sectors(q));

		end_sect = sector + req_sects;

		bio = next_bio(bio, 0, gfp_mask);
		bio->bi_iter.bi_sector = sector;
		bio_set_dev(bio, bdev);
		bio_set_op_attrs(bio, op, 0);

		bio->bi_iter.bi_size = req_sects << 9;
		nr_sects -= req_sects;
		sector = end_sect;

		/*
		 * We can loop for a long time in here, if someone does
		 * full device discards (like mkfs). Be nice and allow
		 * us to schedule out to avoid softlocking if preempt
		 * is disabled.
		 */
		cond_resched();
	}

	*biop = bio;
	return 0;
}
EXPORT_SYMBOL(__blkdev_issue_discard);

/**
 * blkdev_issue_discard - queue a discard
 * @bdev:	blockdev to issue discard for
 * @sector:	start sector
 * @nr_sects:	number of sectors to discard
 * @gfp_mask:	memory allocation flags (for bio_alloc)
 * @flags:	BLKDEV_DISCARD_* flags to control behaviour
 *
 * Description:
 *    Issue a discard request for the sectors in question.
 */
int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
		sector_t nr_sects, gfp_t gfp_mask, unsigned long flags)
{
	struct bio *bio = NULL;
	struct blk_plug plug;
	int ret;

	blk_start_plug(&plug);
	ret = __blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask, flags,
			&bio);
	if (!ret && bio) {
		ret = submit_bio_wait(bio);
		if (ret == -EOPNOTSUPP)
			ret = 0;
		bio_put(bio);
	}
	blk_finish_plug(&plug);

	return ret;
}
EXPORT_SYMBOL(blkdev_issue_discard);

/**
 * __blkdev_issue_write_same - generate number of bios with same page
 * @bdev:	target blockdev
 * @sector:	start sector
 * @nr_sects:	number of sectors to write
 * @gfp_mask:	memory allocation flags (for bio_alloc)
 * @page:	page containing data to write
 * @biop:	pointer to anchor bio
 *
 * Description:
 *  Generate and issue number of bios(REQ_OP_WRITE_SAME) with same page.
 */
static int __blkdev_issue_write_same(struct block_device *bdev, sector_t sector,
		sector_t nr_sects, gfp_t gfp_mask, struct page *page,
		struct bio **biop)
{
	struct request_queue *q = bdev_get_queue(bdev);
	unsigned int max_write_same_sectors;
	struct bio *bio = *biop;
	sector_t bs_mask;

	if (!q)
		return -ENXIO;

	bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
	if ((sector | nr_sects) & bs_mask)
		return -EINVAL;

	if (!bdev_write_same(bdev))
		return -EOPNOTSUPP;

	/* Ensure that max_write_same_sectors doesn't overflow bi_size */
	max_write_same_sectors = bio_allowed_max_sectors(q);

	while (nr_sects) {
		bio = next_bio(bio, 1, gfp_mask);
		bio->bi_iter.bi_sector = sector;
		bio_set_dev(bio, bdev);
		bio->bi_vcnt = 1;
		bio->bi_io_vec->bv_page = page;
		bio->bi_io_vec->bv_offset = 0;
		bio->bi_io_vec->bv_len = bdev_logical_block_size(bdev);
		bio_set_op_attrs(bio, REQ_OP_WRITE_SAME, 0);

		if (nr_sects > max_write_same_sectors) {
			bio->bi_iter.bi_size = max_write_same_sectors << 9;
			nr_sects -= max_write_same_sectors;
			sector += max_write_same_sectors;
		} else {
			bio->bi_iter.bi_size = nr_sects << 9;
			nr_sects = 0;
		}
		cond_resched();
	}

	*biop = bio;
	return 0;
}

/**
 * blkdev_issue_write_same - queue a write same operation
 * @bdev:	target blockdev
 * @sector:	start sector
 * @nr_sects:	number of sectors to write
 * @gfp_mask:	memory allocation flags (for bio_alloc)
 * @page:	page containing data
 *
 * Description:
 *    Issue a write same request for the sectors in question.
 */
int blkdev_issue_write_same(struct block_device *bdev, sector_t sector,
				sector_t nr_sects, gfp_t gfp_mask,
				struct page *page)
{
	struct bio *bio = NULL;
	struct blk_plug plug;
	int ret;

	blk_start_plug(&plug);
	ret = __blkdev_issue_write_same(bdev, sector, nr_sects, gfp_mask, page,
			&bio);
	if (ret == 0 && bio) {
		ret = submit_bio_wait(bio);
		bio_put(bio);
	}
	blk_finish_plug(&plug);
	return ret;
}
EXPORT_SYMBOL(blkdev_issue_write_same);

static int __blkdev_issue_write_zeroes(struct block_device *bdev,
		sector_t sector, sector_t nr_sects, gfp_t gfp_mask,
		struct bio **biop, unsigned flags)
{
	struct bio *bio = *biop;
	unsigned int max_write_zeroes_sectors;
	struct request_queue *q = bdev_get_queue(bdev);

	if (!q)
		return -ENXIO;

	/* Ensure that max_write_zeroes_sectors doesn't overflow bi_size */
	max_write_zeroes_sectors = bdev_write_zeroes_sectors(bdev);

	if (max_write_zeroes_sectors == 0)
		return -EOPNOTSUPP;

	while (nr_sects) {
		bio = next_bio(bio, 0, gfp_mask);
		bio->bi_iter.bi_sector = sector;
		bio_set_dev(bio, bdev);
		bio->bi_opf = REQ_OP_WRITE_ZEROES;
		if (flags & BLKDEV_ZERO_NOUNMAP)
			bio->bi_opf |= REQ_NOUNMAP;

		if (nr_sects > max_write_zeroes_sectors) {
			bio->bi_iter.bi_size = max_write_zeroes_sectors << 9;
			nr_sects -= max_write_zeroes_sectors;
			sector += max_write_zeroes_sectors;
		} else {
			bio->bi_iter.bi_size = nr_sects << 9;
			nr_sects = 0;
		}
		cond_resched();
	}

	*biop = bio;
	return 0;
}

/*
 * Convert a number of 512B sectors to a number of pages.
 * The result is limited to a number of pages that can fit into a BIO.
 * Also make sure that the result is always at least 1 (page) for the cases
 * where nr_sects is lower than the number of sectors in a page.
 */
static unsigned int __blkdev_sectors_to_bio_pages(sector_t nr_sects)
{
	sector_t pages = DIV_ROUND_UP_SECTOR_T(nr_sects, PAGE_SIZE / 512);

	return min(pages, (sector_t)BIO_MAX_PAGES);
}

static int __blkdev_issue_zero_pages(struct block_device *bdev,
		sector_t sector, sector_t nr_sects, gfp_t gfp_mask,
		struct bio **biop)
{
	struct request_queue *q = bdev_get_queue(bdev);
	struct bio *bio = *biop;
	int bi_size = 0;
	unsigned int sz;

	if (!q)
		return -ENXIO;

	while (nr_sects != 0) {
		bio = next_bio(bio, __blkdev_sectors_to_bio_pages(nr_sects),
			       gfp_mask);
		bio->bi_iter.bi_sector = sector;
		bio_set_dev(bio, bdev);
		bio_set_op_attrs(bio, REQ_OP_WRITE, 0);

		while (nr_sects != 0) {
			sz = min((sector_t) PAGE_SIZE, nr_sects << 9);
			bi_size = bio_add_page(bio, ZERO_PAGE(0), sz, 0);
			nr_sects -= bi_size >> 9;
			sector += bi_size >> 9;
			if (bi_size < sz)
				break;
		}
		cond_resched();
	}

	*biop = bio;
	return 0;
}

/**
 * __blkdev_issue_zeroout - generate number of zero filed write bios
 * @bdev:	blockdev to issue
 * @sector:	start sector
 * @nr_sects:	number of sectors to write
 * @gfp_mask:	memory allocation flags (for bio_alloc)
 * @biop:	pointer to anchor bio
 * @flags:	controls detailed behavior
 *
 * Description:
 *  Zero-fill a block range, either using hardware offload or by explicitly
 *  writing zeroes to the device.
 *
 *  If a device is using logical block provisioning, the underlying space will
 *  not be released if %flags contains BLKDEV_ZERO_NOUNMAP.
 *
 *  If %flags contains BLKDEV_ZERO_NOFALLBACK, the function will return
 *  -EOPNOTSUPP if no explicit hardware offload for zeroing is provided.
 */
int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
		sector_t nr_sects, gfp_t gfp_mask, struct bio **biop,
		unsigned flags)
{
	int ret;
	sector_t bs_mask;

	bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
	if ((sector | nr_sects) & bs_mask)
		return -EINVAL;

	ret = __blkdev_issue_write_zeroes(bdev, sector, nr_sects, gfp_mask,
			biop, flags);
	if (ret != -EOPNOTSUPP || (flags & BLKDEV_ZERO_NOFALLBACK))
		return ret;

	return __blkdev_issue_zero_pages(bdev, sector, nr_sects, gfp_mask,
					 biop);
}
EXPORT_SYMBOL(__blkdev_issue_zeroout);

/**
 * blkdev_issue_zeroout - zero-fill a block range
 * @bdev:	blockdev to write
 * @sector:	start sector
 * @nr_sects:	number of sectors to write
 * @gfp_mask:	memory allocation flags (for bio_alloc)
 * @flags:	controls detailed behavior
 *
 * Description:
 *  Zero-fill a block range, either using hardware offload or by explicitly
 *  writing zeroes to the device.  See __blkdev_issue_zeroout() for the
 *  valid values for %flags.
 */
int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
		sector_t nr_sects, gfp_t gfp_mask, unsigned flags)
{
	int ret = 0;
	sector_t bs_mask;
	struct bio *bio;
	struct blk_plug plug;
	bool try_write_zeroes = !!bdev_write_zeroes_sectors(bdev);

	bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
	if ((sector | nr_sects) & bs_mask)
		return -EINVAL;

retry:
	bio = NULL;
	blk_start_plug(&plug);
	if (try_write_zeroes) {
		ret = __blkdev_issue_write_zeroes(bdev, sector, nr_sects,
						  gfp_mask, &bio, flags);
	} else if (!(flags & BLKDEV_ZERO_NOFALLBACK)) {
		ret = __blkdev_issue_zero_pages(bdev, sector, nr_sects,
						gfp_mask, &bio);
	} else {
		/* No zeroing offload support */
		ret = -EOPNOTSUPP;
	}
	if (ret == 0 && bio) {
		ret = submit_bio_wait(bio);
		bio_put(bio);
	}
	blk_finish_plug(&plug);
	if (ret && try_write_zeroes) {
		if (!(flags & BLKDEV_ZERO_NOFALLBACK)) {
			try_write_zeroes = false;
			goto retry;
		}
		if (!bdev_write_zeroes_sectors(bdev)) {
			/*
			 * Zeroing offload support was indicated, but the
			 * device reported ILLEGAL REQUEST (for some devices
			 * there is no non-destructive way to verify whether
			 * WRITE ZEROES is actually supported).
			 */
			ret = -EOPNOTSUPP;
		}
	}

	return ret;
}
EXPORT_SYMBOL(blkdev_issue_zeroout);
Commit	Line	Data
b2441318	1	// SPDX-License-Identifier: GPL-2.0
f31e7e40 DM	2	/*
	3	* Functions related to generic helpers functions
	4	*/
	5	#include <linux/kernel.h>
	6	#include <linux/module.h>
	7	#include <linux/bio.h>
	8	#include <linux/blkdev.h>
	9	#include <linux/scatterlist.h>
	10
	11	#include "blk.h"
	12
4e49ea4a	13	static struct bio next_bio(struct bio bio, unsigned int nr_pages,
9082e87b	14	gfp_t gfp)
f31e7e40	15	{
9082e87b CH	16	struct bio *new = bio_alloc(gfp, nr_pages);
	17
	18	if (bio) {
	19	bio_chain(bio, new);
4e49ea4a	20	submit_bio(bio);
9082e87b	21	}
5dba3089	22
9082e87b	23	return new;
f31e7e40 DM	24	}
f31e7e40 DM	25
38f25255	26	int __blkdev_issue_discard(struct block_device *bdev, sector_t sector,
288dab8a	27	sector_t nr_sects, gfp_t gfp_mask, int flags,
469e3216	28	struct bio **biop)
f31e7e40	29	{
f31e7e40	30	struct request_queue *q = bdev_get_queue(bdev);
38f25255	31	struct bio bio = biop;
ef295ecf	32	unsigned int op;
28b2be20	33	sector_t bs_mask;
f31e7e40 DM	34
	35	if (!q)
	36	return -ENXIO;
288dab8a CH	37
	38	if (flags & BLKDEV_DISCARD_SECURE) {
	39	if (!blk_queue_secure_erase(q))
	40	return -EOPNOTSUPP;
	41	op = REQ_OP_SECURE_ERASE;
	42	} else {
	43	if (!blk_queue_discard(q))
	44	return -EOPNOTSUPP;
	45	op = REQ_OP_DISCARD;
	46	}
f31e7e40	47
28b2be20 DW	48	bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
	49	if ((sector \| nr_sects) & bs_mask)
	50	return -EINVAL;
	51
5dba3089	52	while (nr_sects) {
3c2f83d8 ML	53	unsigned int req_sects = nr_sects;
3c2f83d8 ML	54	sector_t end_sect;
a22c4d7e	55
b515257f ML	56	req_sects = min(req_sects, bio_allowed_max_sectors(q));
b515257f ML	57
c6e66634	58	end_sect = sector + req_sects;
c6e66634	59
f9d03f96	60	bio = next_bio(bio, 0, gfp_mask);
4f024f37	61	bio->bi_iter.bi_sector = sector;
74d46992	62	bio_set_dev(bio, bdev);
288dab8a	63	bio_set_op_attrs(bio, op, 0);
f31e7e40	64
4f024f37	65	bio->bi_iter.bi_size = req_sects << 9;
c6e66634 PB	66	nr_sects -= req_sects;
c6e66634 PB	67	sector = end_sect;
f31e7e40	68
c8123f8c JA	69	/*
	70	* We can loop for a long time in here, if someone does
	71	* full device discards (like mkfs). Be nice and allow
	72	* us to schedule out to avoid softlocking if preempt
	73	* is disabled.
	74	*/
	75	cond_resched();
5dba3089	76	}
38f25255 CH	77
	78	*biop = bio;
	79	return 0;
	80	}
	81	EXPORT_SYMBOL(__blkdev_issue_discard);
	82
	83	/**
	84	* blkdev_issue_discard - queue a discard
	85	* @bdev: blockdev to issue discard for
	86	* @sector: start sector
	87	* @nr_sects: number of sectors to discard
	88	* @gfp_mask: memory allocation flags (for bio_alloc)
e554911c	89	* @flags: BLKDEV_DISCARD_* flags to control behaviour
38f25255 CH	90	*
	91	* Description:
	92	* Issue a discard request for the sectors in question.
	93	*/
	94	int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
	95	sector_t nr_sects, gfp_t gfp_mask, unsigned long flags)
	96	{
38f25255 CH	97	struct bio *bio = NULL;
	98	struct blk_plug plug;
	99	int ret;
	100
38f25255	101	blk_start_plug(&plug);
288dab8a	102	ret = __blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask, flags,
38f25255	103	&bio);
bbd848e0	104	if (!ret && bio) {
4e49ea4a	105	ret = submit_bio_wait(bio);
48920ff2	106	if (ret == -EOPNOTSUPP)
bbd848e0	107	ret = 0;
05bd92dd	108	bio_put(bio);
bbd848e0	109	}
0cfbcafc	110	blk_finish_plug(&plug);
f31e7e40	111
bbd848e0	112	return ret;
f31e7e40 DM	113	}
f31e7e40 DM	114	EXPORT_SYMBOL(blkdev_issue_discard);
3f14d792	115
4363ac7c	116	/**
e73c23ff	117	* __blkdev_issue_write_same - generate number of bios with same page
4363ac7c MP	118	* @bdev: target blockdev
	119	* @sector: start sector
	120	* @nr_sects: number of sectors to write
	121	* @gfp_mask: memory allocation flags (for bio_alloc)
	122	* @page: page containing data to write
e73c23ff	123	* @biop: pointer to anchor bio
4363ac7c MP	124	*
4363ac7c MP	125	* Description:
e73c23ff	126	* Generate and issue number of bios(REQ_OP_WRITE_SAME) with same page.
4363ac7c	127	*/
e73c23ff CK	128	static int __blkdev_issue_write_same(struct block_device *bdev, sector_t sector,
	129	sector_t nr_sects, gfp_t gfp_mask, struct page *page,
	130	struct bio **biop)
4363ac7c	131	{
4363ac7c MP	132	struct request_queue *q = bdev_get_queue(bdev);
4363ac7c MP	133	unsigned int max_write_same_sectors;
e73c23ff	134	struct bio bio = biop;
28b2be20	135	sector_t bs_mask;
4363ac7c MP	136
	137	if (!q)
	138	return -ENXIO;
	139
28b2be20 DW	140	bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
	141	if ((sector \| nr_sects) & bs_mask)
	142	return -EINVAL;
	143
e73c23ff CK	144	if (!bdev_write_same(bdev))
	145	return -EOPNOTSUPP;
	146
b49a0871	147	/* Ensure that max_write_same_sectors doesn't overflow bi_size */
425bc216	148	max_write_same_sectors = bio_allowed_max_sectors(q);
4363ac7c	149
4363ac7c	150	while (nr_sects) {
4e49ea4a	151	bio = next_bio(bio, 1, gfp_mask);
4f024f37	152	bio->bi_iter.bi_sector = sector;
74d46992	153	bio_set_dev(bio, bdev);
4363ac7c MP	154	bio->bi_vcnt = 1;
	155	bio->bi_io_vec->bv_page = page;
	156	bio->bi_io_vec->bv_offset = 0;
	157	bio->bi_io_vec->bv_len = bdev_logical_block_size(bdev);
95fe6c1a	158	bio_set_op_attrs(bio, REQ_OP_WRITE_SAME, 0);
4363ac7c MP	159
4363ac7c MP	160	if (nr_sects > max_write_same_sectors) {
4f024f37	161	bio->bi_iter.bi_size = max_write_same_sectors << 9;
4363ac7c MP	162	nr_sects -= max_write_same_sectors;
	163	sector += max_write_same_sectors;
	164	} else {
4f024f37	165	bio->bi_iter.bi_size = nr_sects << 9;
4363ac7c MP	166	nr_sects = 0;
4363ac7c MP	167	}
e73c23ff	168	cond_resched();
4363ac7c MP	169	}
4363ac7c MP	170
e73c23ff CK	171	*biop = bio;
	172	return 0;
	173	}
	174
	175	/**
	176	* blkdev_issue_write_same - queue a write same operation
	177	* @bdev: target blockdev
	178	* @sector: start sector
	179	* @nr_sects: number of sectors to write
	180	* @gfp_mask: memory allocation flags (for bio_alloc)
	181	* @page: page containing data
	182	*
	183	* Description:
	184	* Issue a write same request for the sectors in question.
	185	*/
	186	int blkdev_issue_write_same(struct block_device *bdev, sector_t sector,
	187	sector_t nr_sects, gfp_t gfp_mask,
	188	struct page *page)
	189	{
	190	struct bio *bio = NULL;
	191	struct blk_plug plug;
	192	int ret;
	193
	194	blk_start_plug(&plug);
	195	ret = __blkdev_issue_write_same(bdev, sector, nr_sects, gfp_mask, page,
	196	&bio);
	197	if (ret == 0 && bio) {
4e49ea4a	198	ret = submit_bio_wait(bio);
05bd92dd ST	199	bio_put(bio);
05bd92dd ST	200	}
e73c23ff	201	blk_finish_plug(&plug);
3f40bf2c	202	return ret;
4363ac7c MP	203	}
	204	EXPORT_SYMBOL(blkdev_issue_write_same);
	205
a6f0788e CK	206	static int __blkdev_issue_write_zeroes(struct block_device *bdev,
a6f0788e CK	207	sector_t sector, sector_t nr_sects, gfp_t gfp_mask,
d928be9f	208	struct bio **biop, unsigned flags)
a6f0788e CK	209	{
	210	struct bio bio = biop;
	211	unsigned int max_write_zeroes_sectors;
	212	struct request_queue *q = bdev_get_queue(bdev);
	213
	214	if (!q)
	215	return -ENXIO;
	216
	217	/* Ensure that max_write_zeroes_sectors doesn't overflow bi_size */
	218	max_write_zeroes_sectors = bdev_write_zeroes_sectors(bdev);
	219
	220	if (max_write_zeroes_sectors == 0)
	221	return -EOPNOTSUPP;
	222
	223	while (nr_sects) {
	224	bio = next_bio(bio, 0, gfp_mask);
	225	bio->bi_iter.bi_sector = sector;
74d46992	226	bio_set_dev(bio, bdev);
d928be9f CH	227	bio->bi_opf = REQ_OP_WRITE_ZEROES;
	228	if (flags & BLKDEV_ZERO_NOUNMAP)
	229	bio->bi_opf \|= REQ_NOUNMAP;
a6f0788e CK	230
	231	if (nr_sects > max_write_zeroes_sectors) {
	232	bio->bi_iter.bi_size = max_write_zeroes_sectors << 9;
	233	nr_sects -= max_write_zeroes_sectors;
	234	sector += max_write_zeroes_sectors;
	235	} else {
	236	bio->bi_iter.bi_size = nr_sects << 9;
	237	nr_sects = 0;
	238	}
	239	cond_resched();
	240	}
	241
	242	*biop = bio;
	243	return 0;
	244	}
	245
615d22a5 DLM	246	/*
	247	* Convert a number of 512B sectors to a number of pages.
	248	* The result is limited to a number of pages that can fit into a BIO.
	249	* Also make sure that the result is always at least 1 (page) for the cases
	250	* where nr_sects is lower than the number of sectors in a page.
	251	*/
	252	static unsigned int __blkdev_sectors_to_bio_pages(sector_t nr_sects)
	253	{
09c2c359	254	sector_t pages = DIV_ROUND_UP_SECTOR_T(nr_sects, PAGE_SIZE / 512);
615d22a5	255
09c2c359	256	return min(pages, (sector_t)BIO_MAX_PAGES);
615d22a5 DLM	257	}
615d22a5 DLM	258
425a4dba ID	259	static int __blkdev_issue_zero_pages(struct block_device *bdev,
	260	sector_t sector, sector_t nr_sects, gfp_t gfp_mask,
	261	struct bio **biop)
	262	{
	263	struct request_queue *q = bdev_get_queue(bdev);
	264	struct bio bio = biop;
	265	int bi_size = 0;
	266	unsigned int sz;
	267
	268	if (!q)
	269	return -ENXIO;
	270
	271	while (nr_sects != 0) {
	272	bio = next_bio(bio, __blkdev_sectors_to_bio_pages(nr_sects),
	273	gfp_mask);
	274	bio->bi_iter.bi_sector = sector;
	275	bio_set_dev(bio, bdev);
	276	bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
	277
	278	while (nr_sects != 0) {
	279	sz = min((sector_t) PAGE_SIZE, nr_sects << 9);
	280	bi_size = bio_add_page(bio, ZERO_PAGE(0), sz, 0);
	281	nr_sects -= bi_size >> 9;
	282	sector += bi_size >> 9;
	283	if (bi_size < sz)
	284	break;
	285	}
	286	cond_resched();
	287	}
	288
	289	*biop = bio;
	290	return 0;
	291	}
	292
3f14d792	293	/**
e73c23ff	294	* __blkdev_issue_zeroout - generate number of zero filed write bios
3f14d792 DM	295	* @bdev: blockdev to issue
	296	* @sector: start sector
	297	* @nr_sects: number of sectors to write
	298	* @gfp_mask: memory allocation flags (for bio_alloc)
e73c23ff	299	* @biop: pointer to anchor bio
ee472d83	300	* @flags: controls detailed behavior
3f14d792 DM	301	*
3f14d792 DM	302	* Description:
ee472d83 CH	303	* Zero-fill a block range, either using hardware offload or by explicitly
	304	* writing zeroes to the device.
	305	*
	306	* If a device is using logical block provisioning, the underlying space will
	307	* not be released if %flags contains BLKDEV_ZERO_NOUNMAP.
cb365b96 CH	308	*
	309	* If %flags contains BLKDEV_ZERO_NOFALLBACK, the function will return
	310	* -EOPNOTSUPP if no explicit hardware offload for zeroing is provided.
3f14d792	311	*/
e73c23ff CK	312	int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
e73c23ff CK	313	sector_t nr_sects, gfp_t gfp_mask, struct bio **biop,
ee472d83	314	unsigned flags)
3f14d792	315	{
18edc8ea	316	int ret;
28b2be20 DW	317	sector_t bs_mask;
	318
	319	bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
	320	if ((sector \| nr_sects) & bs_mask)
	321	return -EINVAL;
3f14d792	322
a6f0788e	323	ret = __blkdev_issue_write_zeroes(bdev, sector, nr_sects, gfp_mask,
d928be9f	324	biop, flags);
cb365b96	325	if (ret != -EOPNOTSUPP \|\| (flags & BLKDEV_ZERO_NOFALLBACK))
425a4dba	326	return ret;
3f14d792	327
425a4dba ID	328	return __blkdev_issue_zero_pages(bdev, sector, nr_sects, gfp_mask,
425a4dba ID	329	biop);
3f14d792	330	}
e73c23ff	331	EXPORT_SYMBOL(__blkdev_issue_zeroout);
579e8f3c MP	332
	333	/**
	334	* blkdev_issue_zeroout - zero-fill a block range
	335	* @bdev: blockdev to write
	336	* @sector: start sector
	337	* @nr_sects: number of sectors to write
	338	* @gfp_mask: memory allocation flags (for bio_alloc)
ee472d83	339	* @flags: controls detailed behavior
579e8f3c MP	340	*
579e8f3c MP	341	* Description:
ee472d83 CH	342	* Zero-fill a block range, either using hardware offload or by explicitly
	343	* writing zeroes to the device. See __blkdev_issue_zeroout() for the
	344	* valid values for %flags.
579e8f3c	345	*/
579e8f3c	346	int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
ee472d83	347	sector_t nr_sects, gfp_t gfp_mask, unsigned flags)
579e8f3c	348	{
d5ce4c31 ID	349	int ret = 0;
	350	sector_t bs_mask;
	351	struct bio *bio;
e73c23ff	352	struct blk_plug plug;
d5ce4c31	353	bool try_write_zeroes = !!bdev_write_zeroes_sectors(bdev);
d93ba7a5	354
d5ce4c31 ID	355	bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
	356	if ((sector \| nr_sects) & bs_mask)
	357	return -EINVAL;
	358
	359	retry:
	360	bio = NULL;
e73c23ff	361	blk_start_plug(&plug);
d5ce4c31 ID	362	if (try_write_zeroes) {
	363	ret = __blkdev_issue_write_zeroes(bdev, sector, nr_sects,
	364	gfp_mask, &bio, flags);
	365	} else if (!(flags & BLKDEV_ZERO_NOFALLBACK)) {
	366	ret = __blkdev_issue_zero_pages(bdev, sector, nr_sects,
	367	gfp_mask, &bio);
	368	} else {
	369	/* No zeroing offload support */
	370	ret = -EOPNOTSUPP;
	371	}
e73c23ff CK	372	if (ret == 0 && bio) {
	373	ret = submit_bio_wait(bio);
	374	bio_put(bio);
	375	}
	376	blk_finish_plug(&plug);
d5ce4c31 ID	377	if (ret && try_write_zeroes) {
	378	if (!(flags & BLKDEV_ZERO_NOFALLBACK)) {
	379	try_write_zeroes = false;
	380	goto retry;
	381	}
	382	if (!bdev_write_zeroes_sectors(bdev)) {
	383	/*
	384	* Zeroing offload support was indicated, but the
	385	* device reported ILLEGAL REQUEST (for some devices
	386	* there is no non-destructive way to verify whether
	387	* WRITE ZEROES is actually supported).
	388	*/
	389	ret = -EOPNOTSUPP;
	390	}
	391	}
579e8f3c	392
e73c23ff	393	return ret;
579e8f3c	394	}
3f14d792	395	EXPORT_SYMBOL(blkdev_issue_zeroout);