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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
38struct bio *blk_alloc_discard_bio(struct block_device *bdev,
39 sector_t *sector, sector_t *nr_sects, gfp_t gfp_mask)
40{
41 sector_t bio_sects = min(*nr_sects, bio_discard_limit(bdev, *sector));
42 struct bio *bio;
43
44 if (!bio_sects)
45 return NULL;
46
47 bio = bio_alloc(bdev, nr_vecs: 0, opf: REQ_OP_DISCARD, gfp_mask);
48 if (!bio)
49 return NULL;
50 bio->bi_iter.bi_sector = *sector;
51 bio->bi_iter.bi_size = bio_sects << SECTOR_SHIFT;
52 *sector += bio_sects;
53 *nr_sects -= bio_sects;
54 /*
55 * We can loop for a long time in here if someone does full device
56 * discards (like mkfs). Be nice and allow us to schedule out to avoid
57 * softlocking if preempt is disabled.
58 */
59 cond_resched();
60 return bio;
61}
62
63int __blkdev_issue_discard(struct block_device *bdev, sector_t sector,
64 sector_t nr_sects, gfp_t gfp_mask, struct bio **biop)
65{
66 struct bio *bio;
67
68 while ((bio = blk_alloc_discard_bio(bdev, sector: &sector, nr_sects: &nr_sects,
69 gfp_mask)))
70 *biop = bio_chain_and_submit(prev: *biop, new: bio);
71 return 0;
72}
73EXPORT_SYMBOL(__blkdev_issue_discard);
74
75/**
76 * blkdev_issue_discard - queue a discard
77 * @bdev: blockdev to issue discard for
78 * @sector: start sector
79 * @nr_sects: number of sectors to discard
80 * @gfp_mask: memory allocation flags (for bio_alloc)
81 *
82 * Description:
83 * Issue a discard request for the sectors in question.
84 */
85int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
86 sector_t nr_sects, gfp_t gfp_mask)
87{
88 struct bio *bio = NULL;
89 struct blk_plug plug;
90 int ret = 0;
91
92 blk_start_plug(&plug);
93 __blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask, &bio);
94 if (bio) {
95 ret = submit_bio_wait(bio);
96 if (ret == -EOPNOTSUPP)
97 ret = 0;
98 bio_put(bio);
99 }
100 blk_finish_plug(&plug);
101
102 return ret;
103}
104EXPORT_SYMBOL(blkdev_issue_discard);
105
106static sector_t bio_write_zeroes_limit(struct block_device *bdev)
107{
108 sector_t bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
109
110 return min(bdev_write_zeroes_sectors(bdev),
111 (UINT_MAX >> SECTOR_SHIFT) & ~bs_mask);
112}
113
114/*
115 * There is no reliable way for the SCSI subsystem to determine whether a
116 * device supports a WRITE SAME operation without actually performing a write
117 * to media. As a result, write_zeroes is enabled by default and will be
118 * disabled if a zeroing operation subsequently fails. This means that this
119 * queue limit is likely to change at runtime.
120 */
121static void __blkdev_issue_write_zeroes(struct block_device *bdev,
122 sector_t sector, sector_t nr_sects, gfp_t gfp_mask,
123 struct bio **biop, unsigned flags, sector_t limit)
124{
125
126 while (nr_sects) {
127 unsigned int len = min(nr_sects, limit);
128 struct bio *bio;
129
130 if ((flags & BLKDEV_ZERO_KILLABLE) &&
131 fatal_signal_pending(current))
132 break;
133
134 bio = bio_alloc(bdev, nr_vecs: 0, opf: REQ_OP_WRITE_ZEROES, gfp_mask);
135 bio->bi_iter.bi_sector = sector;
136 if (flags & BLKDEV_ZERO_NOUNMAP)
137 bio->bi_opf |= REQ_NOUNMAP;
138
139 bio->bi_iter.bi_size = len << SECTOR_SHIFT;
140 *biop = bio_chain_and_submit(prev: *biop, new: bio);
141
142 nr_sects -= len;
143 sector += len;
144 cond_resched();
145 }
146}
147
148static int blkdev_issue_write_zeroes(struct block_device *bdev, sector_t sector,
149 sector_t nr_sects, gfp_t gfp, unsigned flags)
150{
151 sector_t limit = bio_write_zeroes_limit(bdev);
152 struct bio *bio = NULL;
153 struct blk_plug plug;
154 int ret = 0;
155
156 blk_start_plug(&plug);
157 __blkdev_issue_write_zeroes(bdev, sector, nr_sects, gfp_mask: gfp, biop: &bio,
158 flags, limit);
159 if (bio) {
160 if ((flags & BLKDEV_ZERO_KILLABLE) &&
161 fatal_signal_pending(current)) {
162 bio_await_chain(bio);
163 blk_finish_plug(&plug);
164 return -EINTR;
165 }
166 ret = submit_bio_wait(bio);
167 bio_put(bio);
168 }
169 blk_finish_plug(&plug);
170
171 /*
172 * For some devices there is no non-destructive way to verify whether
173 * WRITE ZEROES is actually supported. These will clear the capability
174 * on an I/O error, in which case we'll turn any error into
175 * "not supported" here.
176 */
177 if (ret && !bdev_write_zeroes_sectors(bdev))
178 return -EOPNOTSUPP;
179 return ret;
180}
181
182/*
183 * Convert a number of 512B sectors to a number of pages.
184 * The result is limited to a number of pages that can fit into a BIO.
185 * Also make sure that the result is always at least 1 (page) for the cases
186 * where nr_sects is lower than the number of sectors in a page.
187 */
188static unsigned int __blkdev_sectors_to_bio_pages(sector_t nr_sects)
189{
190 sector_t pages = DIV_ROUND_UP_SECTOR_T(nr_sects, PAGE_SIZE / 512);
191
192 return min(pages, (sector_t)BIO_MAX_VECS);
193}
194
195static void __blkdev_issue_zero_pages(struct block_device *bdev,
196 sector_t sector, sector_t nr_sects, gfp_t gfp_mask,
197 struct bio **biop, unsigned int flags)
198{
199 struct folio *zero_folio = largest_zero_folio();
200
201 while (nr_sects) {
202 unsigned int nr_vecs = __blkdev_sectors_to_bio_pages(nr_sects);
203 struct bio *bio;
204
205 if ((flags & BLKDEV_ZERO_KILLABLE) &&
206 fatal_signal_pending(current))
207 break;
208
209 bio = bio_alloc(bdev, nr_vecs, opf: REQ_OP_WRITE, gfp_mask);
210 bio->bi_iter.bi_sector = sector;
211
212 do {
213 unsigned int len;
214
215 len = min_t(sector_t, folio_size(zero_folio),
216 nr_sects << SECTOR_SHIFT);
217 if (!bio_add_folio(bio, folio: zero_folio, len, off: 0))
218 break;
219 nr_sects -= len >> SECTOR_SHIFT;
220 sector += len >> SECTOR_SHIFT;
221 } while (nr_sects);
222
223 *biop = bio_chain_and_submit(prev: *biop, new: bio);
224 cond_resched();
225 }
226}
227
228static int blkdev_issue_zero_pages(struct block_device *bdev, sector_t sector,
229 sector_t nr_sects, gfp_t gfp, unsigned flags)
230{
231 struct bio *bio = NULL;
232 struct blk_plug plug;
233 int ret = 0;
234
235 if (flags & BLKDEV_ZERO_NOFALLBACK)
236 return -EOPNOTSUPP;
237
238 blk_start_plug(&plug);
239 __blkdev_issue_zero_pages(bdev, sector, nr_sects, gfp_mask: gfp, biop: &bio, flags);
240 if (bio) {
241 if ((flags & BLKDEV_ZERO_KILLABLE) &&
242 fatal_signal_pending(current)) {
243 bio_await_chain(bio);
244 blk_finish_plug(&plug);
245 return -EINTR;
246 }
247 ret = submit_bio_wait(bio);
248 bio_put(bio);
249 }
250 blk_finish_plug(&plug);
251
252 return ret;
253}
254
255/**
256 * __blkdev_issue_zeroout - generate number of zero filed write bios
257 * @bdev: blockdev to issue
258 * @sector: start sector
259 * @nr_sects: number of sectors to write
260 * @gfp_mask: memory allocation flags (for bio_alloc)
261 * @biop: pointer to anchor bio
262 * @flags: controls detailed behavior
263 *
264 * Description:
265 * Zero-fill a block range, either using hardware offload or by explicitly
266 * writing zeroes to the device.
267 *
268 * If a device is using logical block provisioning, the underlying space will
269 * not be released if %flags contains BLKDEV_ZERO_NOUNMAP.
270 *
271 * If %flags contains BLKDEV_ZERO_NOFALLBACK, the function will return
272 * -EOPNOTSUPP if no explicit hardware offload for zeroing is provided.
273 */
274int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
275 sector_t nr_sects, gfp_t gfp_mask, struct bio **biop,
276 unsigned flags)
277{
278 sector_t limit = bio_write_zeroes_limit(bdev);
279
280 if (bdev_read_only(bdev))
281 return -EPERM;
282
283 if (limit) {
284 __blkdev_issue_write_zeroes(bdev, sector, nr_sects,
285 gfp_mask, biop, flags, limit);
286 } else {
287 if (flags & BLKDEV_ZERO_NOFALLBACK)
288 return -EOPNOTSUPP;
289 __blkdev_issue_zero_pages(bdev, sector, nr_sects, gfp_mask,
290 biop, flags);
291 }
292 return 0;
293}
294EXPORT_SYMBOL(__blkdev_issue_zeroout);
295
296/**
297 * blkdev_issue_zeroout - zero-fill a block range
298 * @bdev: blockdev to write
299 * @sector: start sector
300 * @nr_sects: number of sectors to write
301 * @gfp_mask: memory allocation flags (for bio_alloc)
302 * @flags: controls detailed behavior
303 *
304 * Description:
305 * Zero-fill a block range, either using hardware offload or by explicitly
306 * writing zeroes to the device. See __blkdev_issue_zeroout() for the
307 * valid values for %flags.
308 */
309int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
310 sector_t nr_sects, gfp_t gfp_mask, unsigned flags)
311{
312 int ret;
313
314 if ((sector | nr_sects) & ((bdev_logical_block_size(bdev) >> 9) - 1))
315 return -EINVAL;
316 if (bdev_read_only(bdev))
317 return -EPERM;
318
319 if (bdev_write_zeroes_sectors(bdev)) {
320 ret = blkdev_issue_write_zeroes(bdev, sector, nr_sects,
321 gfp: gfp_mask, flags);
322 if (ret != -EOPNOTSUPP)
323 return ret;
324 }
325
326 return blkdev_issue_zero_pages(bdev, sector, nr_sects, gfp: gfp_mask, flags);
327}
328EXPORT_SYMBOL(blkdev_issue_zeroout);
329
330int blkdev_issue_secure_erase(struct block_device *bdev, sector_t sector,
331 sector_t nr_sects, gfp_t gfp)
332{
333 sector_t bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
334 unsigned int max_sectors = bdev_max_secure_erase_sectors(bdev);
335 struct bio *bio = NULL;
336 struct blk_plug plug;
337 int ret = 0;
338
339 /* make sure that "len << SECTOR_SHIFT" doesn't overflow */
340 if (max_sectors > UINT_MAX >> SECTOR_SHIFT)
341 max_sectors = UINT_MAX >> SECTOR_SHIFT;
342 max_sectors &= ~bs_mask;
343
344 if (max_sectors == 0)
345 return -EOPNOTSUPP;
346 if ((sector | nr_sects) & bs_mask)
347 return -EINVAL;
348 if (bdev_read_only(bdev))
349 return -EPERM;
350
351 blk_start_plug(&plug);
352 while (nr_sects) {
353 unsigned int len = min_t(sector_t, nr_sects, max_sectors);
354
355 bio = blk_next_bio(bio, bdev, nr_pages: 0, opf: REQ_OP_SECURE_ERASE, gfp);
356 bio->bi_iter.bi_sector = sector;
357 bio->bi_iter.bi_size = len << SECTOR_SHIFT;
358
359 sector += len;
360 nr_sects -= len;
361 cond_resched();
362 }
363 if (bio) {
364 ret = submit_bio_wait(bio);
365 bio_put(bio);
366 }
367 blk_finish_plug(&plug);
368
369 return ret;
370}
371EXPORT_SYMBOL(blkdev_issue_secure_erase);
372

source code of linux/block/blk-lib.c