[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;

	if (!nr_sects)
		return -EINVAL;

	while (nr_sects) {
		sector_t req_sects = min_t(sector_t, nr_sects,
				bio_allowed_max_sectors(q));

		WARN_ON_ONCE((req_sects << 9) > UINT_MAX);

		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;
		sector += req_sects;
		nr_sects -= req_sects;

		/*
		 * 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
3a343bb3 ML	52	if (!nr_sects)
3a343bb3 ML	53	return -EINVAL;
b515257f	54
3a343bb3	55	while (nr_sects) {
4718e888	56	sector_t req_sects = min_t(sector_t, nr_sects,
3a343bb3	57	bio_allowed_max_sectors(q));
c6e66634	58
4718e888 DC	59	WARN_ON_ONCE((req_sects << 9) > UINT_MAX);
4718e888 DC	60
f9d03f96	61	bio = next_bio(bio, 0, gfp_mask);
4f024f37	62	bio->bi_iter.bi_sector = sector;
74d46992	63	bio_set_dev(bio, bdev);
288dab8a	64	bio_set_op_attrs(bio, op, 0);
f31e7e40	65
4f024f37	66	bio->bi_iter.bi_size = req_sects << 9;
3a343bb3	67	sector += req_sects;
c6e66634	68	nr_sects -= req_sects;
f31e7e40	69
c8123f8c JA	70	/*
	71	* We can loop for a long time in here, if someone does
	72	* full device discards (like mkfs). Be nice and allow
	73	* us to schedule out to avoid softlocking if preempt
	74	* is disabled.
	75	*/
	76	cond_resched();
5dba3089	77	}
38f25255 CH	78
	79	*biop = bio;
	80	return 0;
	81	}
	82	EXPORT_SYMBOL(__blkdev_issue_discard);
	83
	84	/**
	85	* blkdev_issue_discard - queue a discard
	86	* @bdev: blockdev to issue discard for
	87	* @sector: start sector
	88	* @nr_sects: number of sectors to discard
	89	* @gfp_mask: memory allocation flags (for bio_alloc)
e554911c	90	* @flags: BLKDEV_DISCARD_* flags to control behaviour
38f25255 CH	91	*
	92	* Description:
	93	* Issue a discard request for the sectors in question.
	94	*/
	95	int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
	96	sector_t nr_sects, gfp_t gfp_mask, unsigned long flags)
	97	{
38f25255 CH	98	struct bio *bio = NULL;
	99	struct blk_plug plug;
	100	int ret;
	101
38f25255	102	blk_start_plug(&plug);
288dab8a	103	ret = __blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask, flags,
38f25255	104	&bio);
bbd848e0	105	if (!ret && bio) {
4e49ea4a	106	ret = submit_bio_wait(bio);
48920ff2	107	if (ret == -EOPNOTSUPP)
bbd848e0	108	ret = 0;
05bd92dd	109	bio_put(bio);
bbd848e0	110	}
0cfbcafc	111	blk_finish_plug(&plug);
f31e7e40	112
bbd848e0	113	return ret;
f31e7e40 DM	114	}
f31e7e40 DM	115	EXPORT_SYMBOL(blkdev_issue_discard);
3f14d792	116
4363ac7c	117	/**
e73c23ff	118	* __blkdev_issue_write_same - generate number of bios with same page
4363ac7c MP	119	* @bdev: target blockdev
	120	* @sector: start sector
	121	* @nr_sects: number of sectors to write
	122	* @gfp_mask: memory allocation flags (for bio_alloc)
	123	* @page: page containing data to write
e73c23ff	124	* @biop: pointer to anchor bio
4363ac7c MP	125	*
4363ac7c MP	126	* Description:
e73c23ff	127	* Generate and issue number of bios(REQ_OP_WRITE_SAME) with same page.
4363ac7c	128	*/
e73c23ff CK	129	static int __blkdev_issue_write_same(struct block_device *bdev, sector_t sector,
	130	sector_t nr_sects, gfp_t gfp_mask, struct page *page,
	131	struct bio **biop)
4363ac7c	132	{
4363ac7c MP	133	struct request_queue *q = bdev_get_queue(bdev);
4363ac7c MP	134	unsigned int max_write_same_sectors;
e73c23ff	135	struct bio bio = biop;
28b2be20	136	sector_t bs_mask;
4363ac7c MP	137
	138	if (!q)
	139	return -ENXIO;
	140
28b2be20 DW	141	bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
	142	if ((sector \| nr_sects) & bs_mask)
	143	return -EINVAL;
	144
e73c23ff CK	145	if (!bdev_write_same(bdev))
	146	return -EOPNOTSUPP;
	147
b49a0871	148	/* Ensure that max_write_same_sectors doesn't overflow bi_size */
425bc216	149	max_write_same_sectors = bio_allowed_max_sectors(q);
4363ac7c	150
4363ac7c	151	while (nr_sects) {
4e49ea4a	152	bio = next_bio(bio, 1, gfp_mask);
4f024f37	153	bio->bi_iter.bi_sector = sector;
74d46992	154	bio_set_dev(bio, bdev);
4363ac7c MP	155	bio->bi_vcnt = 1;
	156	bio->bi_io_vec->bv_page = page;
	157	bio->bi_io_vec->bv_offset = 0;
	158	bio->bi_io_vec->bv_len = bdev_logical_block_size(bdev);
95fe6c1a	159	bio_set_op_attrs(bio, REQ_OP_WRITE_SAME, 0);
4363ac7c MP	160
4363ac7c MP	161	if (nr_sects > max_write_same_sectors) {
4f024f37	162	bio->bi_iter.bi_size = max_write_same_sectors << 9;
4363ac7c MP	163	nr_sects -= max_write_same_sectors;
	164	sector += max_write_same_sectors;
	165	} else {
4f024f37	166	bio->bi_iter.bi_size = nr_sects << 9;
4363ac7c MP	167	nr_sects = 0;
4363ac7c MP	168	}
e73c23ff	169	cond_resched();
4363ac7c MP	170	}
4363ac7c MP	171
e73c23ff CK	172	*biop = bio;
	173	return 0;
	174	}
	175
	176	/**
	177	* blkdev_issue_write_same - queue a write same operation
	178	* @bdev: target blockdev
	179	* @sector: start sector
	180	* @nr_sects: number of sectors to write
	181	* @gfp_mask: memory allocation flags (for bio_alloc)
	182	* @page: page containing data
	183	*
	184	* Description:
	185	* Issue a write same request for the sectors in question.
	186	*/
	187	int blkdev_issue_write_same(struct block_device *bdev, sector_t sector,
	188	sector_t nr_sects, gfp_t gfp_mask,
	189	struct page *page)
	190	{
	191	struct bio *bio = NULL;
	192	struct blk_plug plug;
	193	int ret;
	194
	195	blk_start_plug(&plug);
	196	ret = __blkdev_issue_write_same(bdev, sector, nr_sects, gfp_mask, page,
	197	&bio);
	198	if (ret == 0 && bio) {
4e49ea4a	199	ret = submit_bio_wait(bio);
05bd92dd ST	200	bio_put(bio);
05bd92dd ST	201	}
e73c23ff	202	blk_finish_plug(&plug);
3f40bf2c	203	return ret;
4363ac7c MP	204	}
	205	EXPORT_SYMBOL(blkdev_issue_write_same);
	206
a6f0788e CK	207	static int __blkdev_issue_write_zeroes(struct block_device *bdev,
a6f0788e CK	208	sector_t sector, sector_t nr_sects, gfp_t gfp_mask,
d928be9f	209	struct bio **biop, unsigned flags)
a6f0788e CK	210	{
	211	struct bio bio = biop;
	212	unsigned int max_write_zeroes_sectors;
	213	struct request_queue *q = bdev_get_queue(bdev);
	214
	215	if (!q)
	216	return -ENXIO;
	217
	218	/* Ensure that max_write_zeroes_sectors doesn't overflow bi_size */
	219	max_write_zeroes_sectors = bdev_write_zeroes_sectors(bdev);
	220
	221	if (max_write_zeroes_sectors == 0)
	222	return -EOPNOTSUPP;
	223
	224	while (nr_sects) {
	225	bio = next_bio(bio, 0, gfp_mask);
	226	bio->bi_iter.bi_sector = sector;
74d46992	227	bio_set_dev(bio, bdev);
d928be9f CH	228	bio->bi_opf = REQ_OP_WRITE_ZEROES;
	229	if (flags & BLKDEV_ZERO_NOUNMAP)
	230	bio->bi_opf \|= REQ_NOUNMAP;
a6f0788e CK	231
	232	if (nr_sects > max_write_zeroes_sectors) {
	233	bio->bi_iter.bi_size = max_write_zeroes_sectors << 9;
	234	nr_sects -= max_write_zeroes_sectors;
	235	sector += max_write_zeroes_sectors;
	236	} else {
	237	bio->bi_iter.bi_size = nr_sects << 9;
	238	nr_sects = 0;
	239	}
	240	cond_resched();
	241	}
	242
	243	*biop = bio;
	244	return 0;
	245	}
	246
615d22a5 DLM	247	/*
	248	* Convert a number of 512B sectors to a number of pages.
	249	* The result is limited to a number of pages that can fit into a BIO.
	250	* Also make sure that the result is always at least 1 (page) for the cases
	251	* where nr_sects is lower than the number of sectors in a page.
	252	*/
	253	static unsigned int __blkdev_sectors_to_bio_pages(sector_t nr_sects)
	254	{
09c2c359	255	sector_t pages = DIV_ROUND_UP_SECTOR_T(nr_sects, PAGE_SIZE / 512);
615d22a5	256
09c2c359	257	return min(pages, (sector_t)BIO_MAX_PAGES);
615d22a5 DLM	258	}
615d22a5 DLM	259
425a4dba ID	260	static int __blkdev_issue_zero_pages(struct block_device *bdev,
	261	sector_t sector, sector_t nr_sects, gfp_t gfp_mask,
	262	struct bio **biop)
	263	{
	264	struct request_queue *q = bdev_get_queue(bdev);
	265	struct bio bio = biop;
	266	int bi_size = 0;
	267	unsigned int sz;
	268
	269	if (!q)
	270	return -ENXIO;
	271
	272	while (nr_sects != 0) {
	273	bio = next_bio(bio, __blkdev_sectors_to_bio_pages(nr_sects),
	274	gfp_mask);
	275	bio->bi_iter.bi_sector = sector;
	276	bio_set_dev(bio, bdev);
	277	bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
	278
	279	while (nr_sects != 0) {
	280	sz = min((sector_t) PAGE_SIZE, nr_sects << 9);
	281	bi_size = bio_add_page(bio, ZERO_PAGE(0), sz, 0);
	282	nr_sects -= bi_size >> 9;
	283	sector += bi_size >> 9;
	284	if (bi_size < sz)
	285	break;
	286	}
	287	cond_resched();
	288	}
	289
	290	*biop = bio;
	291	return 0;
	292	}
	293
3f14d792	294	/**
e73c23ff	295	* __blkdev_issue_zeroout - generate number of zero filed write bios
3f14d792 DM	296	* @bdev: blockdev to issue
	297	* @sector: start sector
	298	* @nr_sects: number of sectors to write
	299	* @gfp_mask: memory allocation flags (for bio_alloc)
e73c23ff	300	* @biop: pointer to anchor bio
ee472d83	301	* @flags: controls detailed behavior
3f14d792 DM	302	*
3f14d792 DM	303	* Description:
ee472d83 CH	304	* Zero-fill a block range, either using hardware offload or by explicitly
	305	* writing zeroes to the device.
	306	*
	307	* If a device is using logical block provisioning, the underlying space will
	308	* not be released if %flags contains BLKDEV_ZERO_NOUNMAP.
cb365b96 CH	309	*
	310	* If %flags contains BLKDEV_ZERO_NOFALLBACK, the function will return
	311	* -EOPNOTSUPP if no explicit hardware offload for zeroing is provided.
3f14d792	312	*/
e73c23ff CK	313	int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
e73c23ff CK	314	sector_t nr_sects, gfp_t gfp_mask, struct bio **biop,
ee472d83	315	unsigned flags)
3f14d792	316	{
18edc8ea	317	int ret;
28b2be20 DW	318	sector_t bs_mask;
	319
	320	bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
	321	if ((sector \| nr_sects) & bs_mask)
	322	return -EINVAL;
3f14d792	323
a6f0788e	324	ret = __blkdev_issue_write_zeroes(bdev, sector, nr_sects, gfp_mask,
d928be9f	325	biop, flags);
cb365b96	326	if (ret != -EOPNOTSUPP \|\| (flags & BLKDEV_ZERO_NOFALLBACK))
425a4dba	327	return ret;
3f14d792	328
425a4dba ID	329	return __blkdev_issue_zero_pages(bdev, sector, nr_sects, gfp_mask,
425a4dba ID	330	biop);
3f14d792	331	}
e73c23ff	332	EXPORT_SYMBOL(__blkdev_issue_zeroout);
579e8f3c MP	333
	334	/**
	335	* blkdev_issue_zeroout - zero-fill a block range
	336	* @bdev: blockdev to write
	337	* @sector: start sector
	338	* @nr_sects: number of sectors to write
	339	* @gfp_mask: memory allocation flags (for bio_alloc)
ee472d83	340	* @flags: controls detailed behavior
579e8f3c MP	341	*
579e8f3c MP	342	* Description:
ee472d83 CH	343	* Zero-fill a block range, either using hardware offload or by explicitly
	344	* writing zeroes to the device. See __blkdev_issue_zeroout() for the
	345	* valid values for %flags.
579e8f3c	346	*/
579e8f3c	347	int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
ee472d83	348	sector_t nr_sects, gfp_t gfp_mask, unsigned flags)
579e8f3c	349	{
d5ce4c31 ID	350	int ret = 0;
	351	sector_t bs_mask;
	352	struct bio *bio;
e73c23ff	353	struct blk_plug plug;
d5ce4c31	354	bool try_write_zeroes = !!bdev_write_zeroes_sectors(bdev);
d93ba7a5	355
d5ce4c31 ID	356	bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
	357	if ((sector \| nr_sects) & bs_mask)
	358	return -EINVAL;
	359
	360	retry:
	361	bio = NULL;
e73c23ff	362	blk_start_plug(&plug);
d5ce4c31 ID	363	if (try_write_zeroes) {
	364	ret = __blkdev_issue_write_zeroes(bdev, sector, nr_sects,
	365	gfp_mask, &bio, flags);
	366	} else if (!(flags & BLKDEV_ZERO_NOFALLBACK)) {
	367	ret = __blkdev_issue_zero_pages(bdev, sector, nr_sects,
	368	gfp_mask, &bio);
	369	} else {
	370	/* No zeroing offload support */
	371	ret = -EOPNOTSUPP;
	372	}
e73c23ff CK	373	if (ret == 0 && bio) {
	374	ret = submit_bio_wait(bio);
	375	bio_put(bio);
	376	}
	377	blk_finish_plug(&plug);
d5ce4c31 ID	378	if (ret && try_write_zeroes) {
	379	if (!(flags & BLKDEV_ZERO_NOFALLBACK)) {
	380	try_write_zeroes = false;
	381	goto retry;
	382	}
	383	if (!bdev_write_zeroes_sectors(bdev)) {
	384	/*
	385	* Zeroing offload support was indicated, but the
	386	* device reported ILLEGAL REQUEST (for some devices
	387	* there is no non-destructive way to verify whether
	388	* WRITE ZEROES is actually supported).
	389	*/
	390	ret = -EOPNOTSUPP;
	391	}
	392	}
579e8f3c	393
e73c23ff	394	return ret;
579e8f3c	395	}
3f14d792	396	EXPORT_SYMBOL(blkdev_issue_zeroout);