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1// SPDX-License-Identifier: GPL-2.0
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
13static sector_t bio_discard_limit(struct block_device *bdev, sector_t sector)
14{
15 unsigned int discard_granularity = bdev_discard_granularity(bdev);
16 sector_t granularity_aligned_sector;
17
18 if (bdev_is_partition(bdev))
19 sector += bdev->bd_start_sect;
20
21 granularity_aligned_sector =
22 round_up(sector, discard_granularity >> SECTOR_SHIFT);
23
24 /*
25 * Make sure subsequent bios start aligned to the discard granularity if
26 * it needs to be split.
27 */
28 if (granularity_aligned_sector != sector)
29 return granularity_aligned_sector - sector;
30
31 /*
32 * Align the bio size to the discard granularity to make splitting the bio
33 * at discard granularity boundaries easier in the driver if needed.
34 */
35 return round_down(UINT_MAX, discard_granularity) >> SECTOR_SHIFT;
36}
37
38int __blkdev_issue_discard(struct block_device *bdev, sector_t sector,
39 sector_t nr_sects, gfp_t gfp_mask, struct bio **biop)
40{
41 struct bio *bio = *biop;
42 sector_t bs_mask;
43
44 if (bdev_read_only(bdev))
45 return -EPERM;
46 if (!bdev_max_discard_sectors(bdev))
47 return -EOPNOTSUPP;
48
49 /* In case the discard granularity isn't set by buggy device driver */
50 if (WARN_ON_ONCE(!bdev_discard_granularity(bdev))) {
51 pr_err_ratelimited("%pg: Error: discard_granularity is 0.\n",
52 bdev);
53 return -EOPNOTSUPP;
54 }
55
56 bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
57 if ((sector | nr_sects) & bs_mask)
58 return -EINVAL;
59
60 if (!nr_sects)
61 return -EINVAL;
62
63 while (nr_sects) {
64 sector_t req_sects =
65 min(nr_sects, bio_discard_limit(bdev, sector));
66
67 bio = blk_next_bio(bio, bdev, 0, REQ_OP_DISCARD, gfp_mask);
68 bio->bi_iter.bi_sector = sector;
69 bio->bi_iter.bi_size = req_sects << 9;
70 sector += req_sects;
71 nr_sects -= req_sects;
72
73 /*
74 * We can loop for a long time in here, if someone does
75 * full device discards (like mkfs). Be nice and allow
76 * us to schedule out to avoid softlocking if preempt
77 * is disabled.
78 */
79 cond_resched();
80 }
81
82 *biop = bio;
83 return 0;
84}
85EXPORT_SYMBOL(__blkdev_issue_discard);
86
87/**
88 * blkdev_issue_discard - queue a discard
89 * @bdev: blockdev to issue discard for
90 * @sector: start sector
91 * @nr_sects: number of sectors to discard
92 * @gfp_mask: memory allocation flags (for bio_alloc)
93 *
94 * Description:
95 * Issue a discard request for the sectors in question.
96 */
97int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
98 sector_t nr_sects, gfp_t gfp_mask)
99{
100 struct bio *bio = NULL;
101 struct blk_plug plug;
102 int ret;
103
104 blk_start_plug(&plug);
105 ret = __blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask, &bio);
106 if (!ret && bio) {
107 ret = submit_bio_wait(bio);
108 if (ret == -EOPNOTSUPP)
109 ret = 0;
110 bio_put(bio);
111 }
112 blk_finish_plug(&plug);
113
114 return ret;
115}
116EXPORT_SYMBOL(blkdev_issue_discard);
117
118static int __blkdev_issue_write_zeroes(struct block_device *bdev,
119 sector_t sector, sector_t nr_sects, gfp_t gfp_mask,
120 struct bio **biop, unsigned flags)
121{
122 struct bio *bio = *biop;
123 unsigned int max_write_zeroes_sectors;
124
125 if (bdev_read_only(bdev))
126 return -EPERM;
127
128 /* Ensure that max_write_zeroes_sectors doesn't overflow bi_size */
129 max_write_zeroes_sectors = bdev_write_zeroes_sectors(bdev);
130
131 if (max_write_zeroes_sectors == 0)
132 return -EOPNOTSUPP;
133
134 while (nr_sects) {
135 bio = blk_next_bio(bio, bdev, 0, REQ_OP_WRITE_ZEROES, gfp_mask);
136 bio->bi_iter.bi_sector = sector;
137 if (flags & BLKDEV_ZERO_NOUNMAP)
138 bio->bi_opf |= REQ_NOUNMAP;
139
140 if (nr_sects > max_write_zeroes_sectors) {
141 bio->bi_iter.bi_size = max_write_zeroes_sectors << 9;
142 nr_sects -= max_write_zeroes_sectors;
143 sector += max_write_zeroes_sectors;
144 } else {
145 bio->bi_iter.bi_size = nr_sects << 9;
146 nr_sects = 0;
147 }
148 cond_resched();
149 }
150
151 *biop = bio;
152 return 0;
153}
154
155/*
156 * Convert a number of 512B sectors to a number of pages.
157 * The result is limited to a number of pages that can fit into a BIO.
158 * Also make sure that the result is always at least 1 (page) for the cases
159 * where nr_sects is lower than the number of sectors in a page.
160 */
161static unsigned int __blkdev_sectors_to_bio_pages(sector_t nr_sects)
162{
163 sector_t pages = DIV_ROUND_UP_SECTOR_T(nr_sects, PAGE_SIZE / 512);
164
165 return min(pages, (sector_t)BIO_MAX_VECS);
166}
167
168static int __blkdev_issue_zero_pages(struct block_device *bdev,
169 sector_t sector, sector_t nr_sects, gfp_t gfp_mask,
170 struct bio **biop)
171{
172 struct bio *bio = *biop;
173 int bi_size = 0;
174 unsigned int sz;
175
176 if (bdev_read_only(bdev))
177 return -EPERM;
178
179 while (nr_sects != 0) {
180 bio = blk_next_bio(bio, bdev, __blkdev_sectors_to_bio_pages(nr_sects),
181 REQ_OP_WRITE, gfp_mask);
182 bio->bi_iter.bi_sector = sector;
183
184 while (nr_sects != 0) {
185 sz = min((sector_t) PAGE_SIZE, nr_sects << 9);
186 bi_size = bio_add_page(bio, ZERO_PAGE(0), sz, 0);
187 nr_sects -= bi_size >> 9;
188 sector += bi_size >> 9;
189 if (bi_size < sz)
190 break;
191 }
192 cond_resched();
193 }
194
195 *biop = bio;
196 return 0;
197}
198
199/**
200 * __blkdev_issue_zeroout - generate number of zero filed write bios
201 * @bdev: blockdev to issue
202 * @sector: start sector
203 * @nr_sects: number of sectors to write
204 * @gfp_mask: memory allocation flags (for bio_alloc)
205 * @biop: pointer to anchor bio
206 * @flags: controls detailed behavior
207 *
208 * Description:
209 * Zero-fill a block range, either using hardware offload or by explicitly
210 * writing zeroes to the device.
211 *
212 * If a device is using logical block provisioning, the underlying space will
213 * not be released if %flags contains BLKDEV_ZERO_NOUNMAP.
214 *
215 * If %flags contains BLKDEV_ZERO_NOFALLBACK, the function will return
216 * -EOPNOTSUPP if no explicit hardware offload for zeroing is provided.
217 */
218int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
219 sector_t nr_sects, gfp_t gfp_mask, struct bio **biop,
220 unsigned flags)
221{
222 int ret;
223 sector_t bs_mask;
224
225 bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
226 if ((sector | nr_sects) & bs_mask)
227 return -EINVAL;
228
229 ret = __blkdev_issue_write_zeroes(bdev, sector, nr_sects, gfp_mask,
230 biop, flags);
231 if (ret != -EOPNOTSUPP || (flags & BLKDEV_ZERO_NOFALLBACK))
232 return ret;
233
234 return __blkdev_issue_zero_pages(bdev, sector, nr_sects, gfp_mask,
235 biop);
236}
237EXPORT_SYMBOL(__blkdev_issue_zeroout);
238
239/**
240 * blkdev_issue_zeroout - zero-fill a block range
241 * @bdev: blockdev to write
242 * @sector: start sector
243 * @nr_sects: number of sectors to write
244 * @gfp_mask: memory allocation flags (for bio_alloc)
245 * @flags: controls detailed behavior
246 *
247 * Description:
248 * Zero-fill a block range, either using hardware offload or by explicitly
249 * writing zeroes to the device. See __blkdev_issue_zeroout() for the
250 * valid values for %flags.
251 */
252int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
253 sector_t nr_sects, gfp_t gfp_mask, unsigned flags)
254{
255 int ret = 0;
256 sector_t bs_mask;
257 struct bio *bio;
258 struct blk_plug plug;
259 bool try_write_zeroes = !!bdev_write_zeroes_sectors(bdev);
260
261 bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
262 if ((sector | nr_sects) & bs_mask)
263 return -EINVAL;
264
265retry:
266 bio = NULL;
267 blk_start_plug(&plug);
268 if (try_write_zeroes) {
269 ret = __blkdev_issue_write_zeroes(bdev, sector, nr_sects,
270 gfp_mask, &bio, flags);
271 } else if (!(flags & BLKDEV_ZERO_NOFALLBACK)) {
272 ret = __blkdev_issue_zero_pages(bdev, sector, nr_sects,
273 gfp_mask, &bio);
274 } else {
275 /* No zeroing offload support */
276 ret = -EOPNOTSUPP;
277 }
278 if (ret == 0 && bio) {
279 ret = submit_bio_wait(bio);
280 bio_put(bio);
281 }
282 blk_finish_plug(&plug);
283 if (ret && try_write_zeroes) {
284 if (!(flags & BLKDEV_ZERO_NOFALLBACK)) {
285 try_write_zeroes = false;
286 goto retry;
287 }
288 if (!bdev_write_zeroes_sectors(bdev)) {
289 /*
290 * Zeroing offload support was indicated, but the
291 * device reported ILLEGAL REQUEST (for some devices
292 * there is no non-destructive way to verify whether
293 * WRITE ZEROES is actually supported).
294 */
295 ret = -EOPNOTSUPP;
296 }
297 }
298
299 return ret;
300}
301EXPORT_SYMBOL(blkdev_issue_zeroout);
302
303int blkdev_issue_secure_erase(struct block_device *bdev, sector_t sector,
304 sector_t nr_sects, gfp_t gfp)
305{
306 sector_t bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
307 unsigned int max_sectors = bdev_max_secure_erase_sectors(bdev);
308 struct bio *bio = NULL;
309 struct blk_plug plug;
310 int ret = 0;
311
312 /* make sure that "len << SECTOR_SHIFT" doesn't overflow */
313 if (max_sectors > UINT_MAX >> SECTOR_SHIFT)
314 max_sectors = UINT_MAX >> SECTOR_SHIFT;
315 max_sectors &= ~bs_mask;
316
317 if (max_sectors == 0)
318 return -EOPNOTSUPP;
319 if ((sector | nr_sects) & bs_mask)
320 return -EINVAL;
321 if (bdev_read_only(bdev))
322 return -EPERM;
323
324 blk_start_plug(&plug);
325 for (;;) {
326 unsigned int len = min_t(sector_t, nr_sects, max_sectors);
327
328 bio = blk_next_bio(bio, bdev, 0, REQ_OP_SECURE_ERASE, gfp);
329 bio->bi_iter.bi_sector = sector;
330 bio->bi_iter.bi_size = len << SECTOR_SHIFT;
331
332 sector += len;
333 nr_sects -= len;
334 if (!nr_sects) {
335 ret = submit_bio_wait(bio);
336 bio_put(bio);
337 break;
338 }
339 cond_resched();
340 }
341 blk_finish_plug(&plug);
342
343 return ret;
344}
345EXPORT_SYMBOL(blkdev_issue_secure_erase);
1/*
2 * Functions related to generic helpers functions
3 */
4#include <linux/kernel.h>
5#include <linux/module.h>
6#include <linux/bio.h>
7#include <linux/blkdev.h>
8#include <linux/scatterlist.h>
9
10#include "blk.h"
11
12static struct bio *next_bio(struct bio *bio, unsigned int nr_pages,
13 gfp_t gfp)
14{
15 struct bio *new = bio_alloc(gfp, nr_pages);
16
17 if (bio) {
18 bio_chain(bio, new);
19 submit_bio(bio);
20 }
21
22 return new;
23}
24
25int __blkdev_issue_discard(struct block_device *bdev, sector_t sector,
26 sector_t nr_sects, gfp_t gfp_mask, int flags,
27 struct bio **biop)
28{
29 struct request_queue *q = bdev_get_queue(bdev);
30 struct bio *bio = *biop;
31 unsigned int granularity;
32 unsigned int op;
33 int alignment;
34 sector_t bs_mask;
35
36 if (!q)
37 return -ENXIO;
38
39 if (flags & BLKDEV_DISCARD_SECURE) {
40 if (flags & BLKDEV_DISCARD_ZERO)
41 return -EOPNOTSUPP;
42 if (!blk_queue_secure_erase(q))
43 return -EOPNOTSUPP;
44 op = REQ_OP_SECURE_ERASE;
45 } else {
46 if (!blk_queue_discard(q))
47 return -EOPNOTSUPP;
48 if ((flags & BLKDEV_DISCARD_ZERO) &&
49 !q->limits.discard_zeroes_data)
50 return -EOPNOTSUPP;
51 op = REQ_OP_DISCARD;
52 }
53
54 bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
55 if ((sector | nr_sects) & bs_mask)
56 return -EINVAL;
57
58 /* Zero-sector (unknown) and one-sector granularities are the same. */
59 granularity = max(q->limits.discard_granularity >> 9, 1U);
60 alignment = (bdev_discard_alignment(bdev) >> 9) % granularity;
61
62 while (nr_sects) {
63 unsigned int req_sects;
64 sector_t end_sect, tmp;
65
66 /* Make sure bi_size doesn't overflow */
67 req_sects = min_t(sector_t, nr_sects, UINT_MAX >> 9);
68
69 /**
70 * If splitting a request, and the next starting sector would be
71 * misaligned, stop the discard at the previous aligned sector.
72 */
73 end_sect = sector + req_sects;
74 tmp = end_sect;
75 if (req_sects < nr_sects &&
76 sector_div(tmp, granularity) != alignment) {
77 end_sect = end_sect - alignment;
78 sector_div(end_sect, granularity);
79 end_sect = end_sect * granularity + alignment;
80 req_sects = end_sect - sector;
81 }
82
83 bio = next_bio(bio, 0, gfp_mask);
84 bio->bi_iter.bi_sector = sector;
85 bio->bi_bdev = bdev;
86 bio_set_op_attrs(bio, op, 0);
87
88 bio->bi_iter.bi_size = req_sects << 9;
89 nr_sects -= req_sects;
90 sector = end_sect;
91
92 /*
93 * We can loop for a long time in here, if someone does
94 * full device discards (like mkfs). Be nice and allow
95 * us to schedule out to avoid softlocking if preempt
96 * is disabled.
97 */
98 cond_resched();
99 }
100
101 *biop = bio;
102 return 0;
103}
104EXPORT_SYMBOL(__blkdev_issue_discard);
105
106/**
107 * blkdev_issue_discard - queue a discard
108 * @bdev: blockdev to issue discard for
109 * @sector: start sector
110 * @nr_sects: number of sectors to discard
111 * @gfp_mask: memory allocation flags (for bio_alloc)
112 * @flags: BLKDEV_IFL_* flags to control behaviour
113 *
114 * Description:
115 * Issue a discard request for the sectors in question.
116 */
117int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
118 sector_t nr_sects, gfp_t gfp_mask, unsigned long flags)
119{
120 struct bio *bio = NULL;
121 struct blk_plug plug;
122 int ret;
123
124 blk_start_plug(&plug);
125 ret = __blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask, flags,
126 &bio);
127 if (!ret && bio) {
128 ret = submit_bio_wait(bio);
129 if (ret == -EOPNOTSUPP && !(flags & BLKDEV_DISCARD_ZERO))
130 ret = 0;
131 bio_put(bio);
132 }
133 blk_finish_plug(&plug);
134
135 return ret;
136}
137EXPORT_SYMBOL(blkdev_issue_discard);
138
139/**
140 * __blkdev_issue_write_same - generate number of bios with same page
141 * @bdev: target blockdev
142 * @sector: start sector
143 * @nr_sects: number of sectors to write
144 * @gfp_mask: memory allocation flags (for bio_alloc)
145 * @page: page containing data to write
146 * @biop: pointer to anchor bio
147 *
148 * Description:
149 * Generate and issue number of bios(REQ_OP_WRITE_SAME) with same page.
150 */
151static int __blkdev_issue_write_same(struct block_device *bdev, sector_t sector,
152 sector_t nr_sects, gfp_t gfp_mask, struct page *page,
153 struct bio **biop)
154{
155 struct request_queue *q = bdev_get_queue(bdev);
156 unsigned int max_write_same_sectors;
157 struct bio *bio = *biop;
158 sector_t bs_mask;
159
160 if (!q)
161 return -ENXIO;
162
163 bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
164 if ((sector | nr_sects) & bs_mask)
165 return -EINVAL;
166
167 if (!bdev_write_same(bdev))
168 return -EOPNOTSUPP;
169
170 /* Ensure that max_write_same_sectors doesn't overflow bi_size */
171 max_write_same_sectors = UINT_MAX >> 9;
172
173 while (nr_sects) {
174 bio = next_bio(bio, 1, gfp_mask);
175 bio->bi_iter.bi_sector = sector;
176 bio->bi_bdev = bdev;
177 bio->bi_vcnt = 1;
178 bio->bi_io_vec->bv_page = page;
179 bio->bi_io_vec->bv_offset = 0;
180 bio->bi_io_vec->bv_len = bdev_logical_block_size(bdev);
181 bio_set_op_attrs(bio, REQ_OP_WRITE_SAME, 0);
182
183 if (nr_sects > max_write_same_sectors) {
184 bio->bi_iter.bi_size = max_write_same_sectors << 9;
185 nr_sects -= max_write_same_sectors;
186 sector += max_write_same_sectors;
187 } else {
188 bio->bi_iter.bi_size = nr_sects << 9;
189 nr_sects = 0;
190 }
191 cond_resched();
192 }
193
194 *biop = bio;
195 return 0;
196}
197
198/**
199 * blkdev_issue_write_same - queue a write same operation
200 * @bdev: target blockdev
201 * @sector: start sector
202 * @nr_sects: number of sectors to write
203 * @gfp_mask: memory allocation flags (for bio_alloc)
204 * @page: page containing data
205 *
206 * Description:
207 * Issue a write same request for the sectors in question.
208 */
209int blkdev_issue_write_same(struct block_device *bdev, sector_t sector,
210 sector_t nr_sects, gfp_t gfp_mask,
211 struct page *page)
212{
213 struct bio *bio = NULL;
214 struct blk_plug plug;
215 int ret;
216
217 blk_start_plug(&plug);
218 ret = __blkdev_issue_write_same(bdev, sector, nr_sects, gfp_mask, page,
219 &bio);
220 if (ret == 0 && bio) {
221 ret = submit_bio_wait(bio);
222 bio_put(bio);
223 }
224 blk_finish_plug(&plug);
225 return ret;
226}
227EXPORT_SYMBOL(blkdev_issue_write_same);
228
229/**
230 * __blkdev_issue_write_zeroes - generate number of bios with WRITE ZEROES
231 * @bdev: blockdev to issue
232 * @sector: start sector
233 * @nr_sects: number of sectors to write
234 * @gfp_mask: memory allocation flags (for bio_alloc)
235 * @biop: pointer to anchor bio
236 *
237 * Description:
238 * Generate and issue number of bios(REQ_OP_WRITE_ZEROES) with zerofiled pages.
239 */
240static int __blkdev_issue_write_zeroes(struct block_device *bdev,
241 sector_t sector, sector_t nr_sects, gfp_t gfp_mask,
242 struct bio **biop)
243{
244 struct bio *bio = *biop;
245 unsigned int max_write_zeroes_sectors;
246 struct request_queue *q = bdev_get_queue(bdev);
247
248 if (!q)
249 return -ENXIO;
250
251 /* Ensure that max_write_zeroes_sectors doesn't overflow bi_size */
252 max_write_zeroes_sectors = bdev_write_zeroes_sectors(bdev);
253
254 if (max_write_zeroes_sectors == 0)
255 return -EOPNOTSUPP;
256
257 while (nr_sects) {
258 bio = next_bio(bio, 0, gfp_mask);
259 bio->bi_iter.bi_sector = sector;
260 bio->bi_bdev = bdev;
261 bio_set_op_attrs(bio, REQ_OP_WRITE_ZEROES, 0);
262
263 if (nr_sects > max_write_zeroes_sectors) {
264 bio->bi_iter.bi_size = max_write_zeroes_sectors << 9;
265 nr_sects -= max_write_zeroes_sectors;
266 sector += max_write_zeroes_sectors;
267 } else {
268 bio->bi_iter.bi_size = nr_sects << 9;
269 nr_sects = 0;
270 }
271 cond_resched();
272 }
273
274 *biop = bio;
275 return 0;
276}
277
278/**
279 * __blkdev_issue_zeroout - generate number of zero filed write bios
280 * @bdev: blockdev to issue
281 * @sector: start sector
282 * @nr_sects: number of sectors to write
283 * @gfp_mask: memory allocation flags (for bio_alloc)
284 * @biop: pointer to anchor bio
285 * @discard: discard flag
286 *
287 * Description:
288 * Generate and issue number of bios with zerofiled pages.
289 */
290int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
291 sector_t nr_sects, gfp_t gfp_mask, struct bio **biop,
292 bool discard)
293{
294 int ret;
295 int bi_size = 0;
296 struct bio *bio = *biop;
297 unsigned int sz;
298 sector_t bs_mask;
299
300 bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
301 if ((sector | nr_sects) & bs_mask)
302 return -EINVAL;
303
304 ret = __blkdev_issue_write_zeroes(bdev, sector, nr_sects, gfp_mask,
305 biop);
306 if (ret == 0 || (ret && ret != -EOPNOTSUPP))
307 goto out;
308
309 ret = 0;
310 while (nr_sects != 0) {
311 bio = next_bio(bio, min(nr_sects, (sector_t)BIO_MAX_PAGES),
312 gfp_mask);
313 bio->bi_iter.bi_sector = sector;
314 bio->bi_bdev = bdev;
315 bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
316
317 while (nr_sects != 0) {
318 sz = min((sector_t) PAGE_SIZE >> 9 , nr_sects);
319 bi_size = bio_add_page(bio, ZERO_PAGE(0), sz << 9, 0);
320 nr_sects -= bi_size >> 9;
321 sector += bi_size >> 9;
322 if (bi_size < (sz << 9))
323 break;
324 }
325 cond_resched();
326 }
327
328 *biop = bio;
329out:
330 return ret;
331}
332EXPORT_SYMBOL(__blkdev_issue_zeroout);
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)
340 * @discard: whether to discard the block range
341 *
342 * Description:
343 * Zero-fill a block range. If the discard flag is set and the block
344 * device guarantees that subsequent READ operations to the block range
345 * in question will return zeroes, the blocks will be discarded. Should
346 * the discard request fail, if the discard flag is not set, or if
347 * discard_zeroes_data is not supported, this function will resort to
348 * zeroing the blocks manually, thus provisioning (allocating,
349 * anchoring) them. If the block device supports WRITE ZEROES or WRITE SAME
350 * command(s), blkdev_issue_zeroout() will use it to optimize the process of
351 * clearing the block range. Otherwise the zeroing will be performed
352 * using regular WRITE calls.
353 */
354int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
355 sector_t nr_sects, gfp_t gfp_mask, bool discard)
356{
357 int ret;
358 struct bio *bio = NULL;
359 struct blk_plug plug;
360
361 if (discard) {
362 if (!blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask,
363 BLKDEV_DISCARD_ZERO))
364 return 0;
365 }
366
367 if (!blkdev_issue_write_same(bdev, sector, nr_sects, gfp_mask,
368 ZERO_PAGE(0)))
369 return 0;
370
371 blk_start_plug(&plug);
372 ret = __blkdev_issue_zeroout(bdev, sector, nr_sects, gfp_mask,
373 &bio, discard);
374 if (ret == 0 && bio) {
375 ret = submit_bio_wait(bio);
376 bio_put(bio);
377 }
378 blk_finish_plug(&plug);
379
380 return ret;
381}
382EXPORT_SYMBOL(blkdev_issue_zeroout);