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
13 static 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
38 struct 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, 0, 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
63 int __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, §or, &nr_sects,
69 gfp_mask)))
70 *biop = bio_chain_and_submit(*biop, bio);
71 return 0;
72 }
73 EXPORT_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 */
85 int 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;
91
92 blk_start_plug(&plug);
93 ret = __blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask, &bio);
94 if (!ret && 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 }
104 EXPORT_SYMBOL(blkdev_issue_discard);
105
106 static 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 */
121 static 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, 0, 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(*biop, bio);
141
142 nr_sects -= len;
143 sector += len;
144 cond_resched();
145 }
146 }
147
148 static 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, &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 */
188 static 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
195 static 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 while (nr_sects) {
200 unsigned int nr_vecs = __blkdev_sectors_to_bio_pages(nr_sects);
201 struct bio *bio;
202
203 bio = bio_alloc(bdev, nr_vecs, REQ_OP_WRITE, gfp_mask);
204 bio->bi_iter.bi_sector = sector;
205
206 if ((flags & BLKDEV_ZERO_KILLABLE) &&
207 fatal_signal_pending(current))
208 break;
209
210 do {
211 unsigned int len, added;
212
213 len = min_t(sector_t,
214 PAGE_SIZE, nr_sects << SECTOR_SHIFT);
215 added = bio_add_page(bio, ZERO_PAGE(0), len, 0);
216 if (added < len)
217 break;
218 nr_sects -= added >> SECTOR_SHIFT;
219 sector += added >> SECTOR_SHIFT;
220 } while (nr_sects);
221
222 *biop = bio_chain_and_submit(*biop, bio);
223 cond_resched();
224 }
225 }
226
227 static int blkdev_issue_zero_pages(struct block_device *bdev, sector_t sector,
228 sector_t nr_sects, gfp_t gfp, unsigned flags)
229 {
230 struct bio *bio = NULL;
231 struct blk_plug plug;
232 int ret = 0;
233
234 if (flags & BLKDEV_ZERO_NOFALLBACK)
235 return -EOPNOTSUPP;
236
237 blk_start_plug(&plug);
238 __blkdev_issue_zero_pages(bdev, sector, nr_sects, gfp, &bio, flags);
239 if (bio) {
240 if ((flags & BLKDEV_ZERO_KILLABLE) &&
241 fatal_signal_pending(current)) {
242 bio_await_chain(bio);
243 blk_finish_plug(&plug);
244 return -EINTR;
245 }
246 ret = submit_bio_wait(bio);
247 bio_put(bio);
248 }
249 blk_finish_plug(&plug);
250
251 return ret;
252 }
253
254 /**
255 * __blkdev_issue_zeroout - generate number of zero filed write bios
256 * @bdev: blockdev to issue
257 * @sector: start sector
258 * @nr_sects: number of sectors to write
259 * @gfp_mask: memory allocation flags (for bio_alloc)
260 * @biop: pointer to anchor bio
261 * @flags: controls detailed behavior
262 *
263 * Description:
264 * Zero-fill a block range, either using hardware offload or by explicitly
265 * writing zeroes to the device.
266 *
267 * If a device is using logical block provisioning, the underlying space will
268 * not be released if %flags contains BLKDEV_ZERO_NOUNMAP.
269 *
270 * If %flags contains BLKDEV_ZERO_NOFALLBACK, the function will return
271 * -EOPNOTSUPP if no explicit hardware offload for zeroing is provided.
272 */
273 int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
274 sector_t nr_sects, gfp_t gfp_mask, struct bio **biop,
275 unsigned flags)
276 {
277 sector_t limit = bio_write_zeroes_limit(bdev);
278
279 if (bdev_read_only(bdev))
280 return -EPERM;
281
282 if (limit) {
283 __blkdev_issue_write_zeroes(bdev, sector, nr_sects,
284 gfp_mask, biop, flags, limit);
285 } else {
286 if (flags & BLKDEV_ZERO_NOFALLBACK)
287 return -EOPNOTSUPP;
288 __blkdev_issue_zero_pages(bdev, sector, nr_sects, gfp_mask,
289 biop, flags);
290 }
291 return 0;
292 }
293 EXPORT_SYMBOL(__blkdev_issue_zeroout);
294
295 /**
296 * blkdev_issue_zeroout - zero-fill a block range
297 * @bdev: blockdev to write
298 * @sector: start sector
299 * @nr_sects: number of sectors to write
300 * @gfp_mask: memory allocation flags (for bio_alloc)
301 * @flags: controls detailed behavior
302 *
303 * Description:
304 * Zero-fill a block range, either using hardware offload or by explicitly
305 * writing zeroes to the device. See __blkdev_issue_zeroout() for the
306 * valid values for %flags.
307 */
308 int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
309 sector_t nr_sects, gfp_t gfp_mask, unsigned flags)
310 {
311 int ret;
312
313 if ((sector | nr_sects) & ((bdev_logical_block_size(bdev) >> 9) - 1))
314 return -EINVAL;
315 if (bdev_read_only(bdev))
316 return -EPERM;
317
318 if (bdev_write_zeroes_sectors(bdev)) {
319 ret = blkdev_issue_write_zeroes(bdev, sector, nr_sects,
320 gfp_mask, flags);
321 if (ret != -EOPNOTSUPP)
322 return ret;
323 }
324
325 return blkdev_issue_zero_pages(bdev, sector, nr_sects, gfp_mask, flags);
326 }
327 EXPORT_SYMBOL(blkdev_issue_zeroout);
328
329 int blkdev_issue_secure_erase(struct block_device *bdev, sector_t sector,
330 sector_t nr_sects, gfp_t gfp)
331 {
332 sector_t bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
333 unsigned int max_sectors = bdev_max_secure_erase_sectors(bdev);
334 struct bio *bio = NULL;
335 struct blk_plug plug;
336 int ret = 0;
337
338 /* make sure that "len << SECTOR_SHIFT" doesn't overflow */
339 if (max_sectors > UINT_MAX >> SECTOR_SHIFT)
340 max_sectors = UINT_MAX >> SECTOR_SHIFT;
341 max_sectors &= ~bs_mask;
342
343 if (max_sectors == 0)
344 return -EOPNOTSUPP;
345 if ((sector | nr_sects) & bs_mask)
346 return -EINVAL;
347 if (bdev_read_only(bdev))
348 return -EPERM;
349
350 blk_start_plug(&plug);
351 while (nr_sects) {
352 unsigned int len = min_t(sector_t, nr_sects, max_sectors);
353
354 bio = blk_next_bio(bio, bdev, 0, REQ_OP_SECURE_ERASE, gfp);
355 bio->bi_iter.bi_sector = sector;
356 bio->bi_iter.bi_size = len << SECTOR_SHIFT;
357
358 sector += len;
359 nr_sects -= len;
360 cond_resched();
361 }
362 if (bio) {
363 ret = submit_bio_wait(bio);
364 bio_put(bio);
365 }
366 blk_finish_plug(&plug);
367
368 return ret;
369 }
370 EXPORT_SYMBOL(blkdev_issue_secure_erase);
371
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