[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) {
		unsigned int req_sects = min_t(unsigned int, nr_sects,
				bio_allowed_max_sectors(q));

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