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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
12 struct bio_batch {
13         atomic_t                done;
14         int                     error;
15         struct completion       *wait;
16 };
17
18 static void bio_batch_end_io(struct bio *bio)
19 {
20         struct bio_batch *bb = bio->bi_private;
21
22         if (bio->bi_error && bio->bi_error != -EOPNOTSUPP)
23                 bb->error = bio->bi_error;
24         if (atomic_dec_and_test(&bb->done))
25                 complete(bb->wait);
26         bio_put(bio);
27 }
28
29 /**
30  * blkdev_issue_discard - queue a discard
31  * @bdev:       blockdev to issue discard for
32  * @sector:     start sector
33  * @nr_sects:   number of sectors to discard
34  * @gfp_mask:   memory allocation flags (for bio_alloc)
35  * @flags:      BLKDEV_IFL_* flags to control behaviour
36  *
37  * Description:
38  *    Issue a discard request for the sectors in question.
39  */
40 int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
41                 sector_t nr_sects, gfp_t gfp_mask, unsigned long flags)
42 {
43         DECLARE_COMPLETION_ONSTACK(wait);
44         struct request_queue *q = bdev_get_queue(bdev);
45         int type = REQ_WRITE | REQ_DISCARD;
46         unsigned int granularity;
47         int alignment;
48         struct bio_batch bb;
49         struct bio *bio;
50         int ret = 0;
51         struct blk_plug plug;
52
53         if (!q)
54                 return -ENXIO;
55
56         if (!blk_queue_discard(q))
57                 return -EOPNOTSUPP;
58
59         /* Zero-sector (unknown) and one-sector granularities are the same.  */
60         granularity = max(q->limits.discard_granularity >> 9, 1U);
61         alignment = (bdev_discard_alignment(bdev) >> 9) % granularity;
62
63         if (flags & BLKDEV_DISCARD_SECURE) {
64                 if (!blk_queue_secdiscard(q))
65                         return -EOPNOTSUPP;
66                 type |= REQ_SECURE;
67         }
68
69         atomic_set(&bb.done, 1);
70         bb.error = 0;
71         bb.wait = &wait;
72
73         blk_start_plug(&plug);
74         while (nr_sects) {
75                 unsigned int req_sects;
76                 sector_t end_sect, tmp;
77
78                 bio = bio_alloc(gfp_mask, 1);
79                 if (!bio) {
80                         ret = -ENOMEM;
81                         break;
82                 }
83
84                 /* Make sure bi_size doesn't overflow */
85                 req_sects = min_t(sector_t, nr_sects, UINT_MAX >> 9);
86
87                 /*
88                  * If splitting a request, and the next starting sector would be
89                  * misaligned, stop the discard at the previous aligned sector.
90                  */
91                 end_sect = sector + req_sects;
92                 tmp = end_sect;
93                 if (req_sects < nr_sects &&
94                     sector_div(tmp, granularity) != alignment) {
95                         end_sect = end_sect - alignment;
96                         sector_div(end_sect, granularity);
97                         end_sect = end_sect * granularity + alignment;
98                         req_sects = end_sect - sector;
99                 }
100
101                 bio->bi_iter.bi_sector = sector;
102                 bio->bi_end_io = bio_batch_end_io;
103                 bio->bi_bdev = bdev;
104                 bio->bi_private = &bb;
105
106                 bio->bi_iter.bi_size = req_sects << 9;
107                 nr_sects -= req_sects;
108                 sector = end_sect;
109
110                 atomic_inc(&bb.done);
111                 submit_bio(type, bio);
112
113                 /*
114                  * We can loop for a long time in here, if someone does
115                  * full device discards (like mkfs). Be nice and allow
116                  * us to schedule out to avoid softlocking if preempt
117                  * is disabled.
118                  */
119                 cond_resched();
120         }
121         blk_finish_plug(&plug);
122
123         /* Wait for bios in-flight */
124         if (!atomic_dec_and_test(&bb.done))
125                 wait_for_completion_io(&wait);
126
127         if (bb.error)
128                 return bb.error;
129         return ret;
130 }
131 EXPORT_SYMBOL(blkdev_issue_discard);
132
133 /**
134  * blkdev_issue_write_same - queue a write same operation
135  * @bdev:       target blockdev
136  * @sector:     start sector
137  * @nr_sects:   number of sectors to write
138  * @gfp_mask:   memory allocation flags (for bio_alloc)
139  * @page:       page containing data to write
140  *
141  * Description:
142  *    Issue a write same request for the sectors in question.
143  */
144 int blkdev_issue_write_same(struct block_device *bdev, sector_t sector,
145                             sector_t nr_sects, gfp_t gfp_mask,
146                             struct page *page)
147 {
148         DECLARE_COMPLETION_ONSTACK(wait);
149         struct request_queue *q = bdev_get_queue(bdev);
150         unsigned int max_write_same_sectors;
151         struct bio_batch bb;
152         struct bio *bio;
153         int ret = 0;
154
155         if (!q)
156                 return -ENXIO;
157
158         /* Ensure that max_write_same_sectors doesn't overflow bi_size */
159         max_write_same_sectors = UINT_MAX >> 9;
160
161         atomic_set(&bb.done, 1);
162         bb.error = 0;
163         bb.wait = &wait;
164
165         while (nr_sects) {
166                 bio = bio_alloc(gfp_mask, 1);
167                 if (!bio) {
168                         ret = -ENOMEM;
169                         break;
170                 }
171
172                 bio->bi_iter.bi_sector = sector;
173                 bio->bi_end_io = bio_batch_end_io;
174                 bio->bi_bdev = bdev;
175                 bio->bi_private = &bb;
176                 bio->bi_vcnt = 1;
177                 bio->bi_io_vec->bv_page = page;
178                 bio->bi_io_vec->bv_offset = 0;
179                 bio->bi_io_vec->bv_len = bdev_logical_block_size(bdev);
180
181                 if (nr_sects > max_write_same_sectors) {
182                         bio->bi_iter.bi_size = max_write_same_sectors << 9;
183                         nr_sects -= max_write_same_sectors;
184                         sector += max_write_same_sectors;
185                 } else {
186                         bio->bi_iter.bi_size = nr_sects << 9;
187                         nr_sects = 0;
188                 }
189
190                 atomic_inc(&bb.done);
191                 submit_bio(REQ_WRITE | REQ_WRITE_SAME, bio);
192         }
193
194         /* Wait for bios in-flight */
195         if (!atomic_dec_and_test(&bb.done))
196                 wait_for_completion_io(&wait);
197
198         if (bb.error)
199                 return bb.error;
200         return ret;
201 }
202 EXPORT_SYMBOL(blkdev_issue_write_same);
203
204 /**
205  * blkdev_issue_zeroout - generate number of zero filed write bios
206  * @bdev:       blockdev to issue
207  * @sector:     start sector
208  * @nr_sects:   number of sectors to write
209  * @gfp_mask:   memory allocation flags (for bio_alloc)
210  *
211  * Description:
212  *  Generate and issue number of bios with zerofiled pages.
213  */
214
215 static int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
216                                   sector_t nr_sects, gfp_t gfp_mask)
217 {
218         int ret;
219         struct bio *bio;
220         struct bio_batch bb;
221         unsigned int sz;
222         DECLARE_COMPLETION_ONSTACK(wait);
223
224         atomic_set(&bb.done, 1);
225         bb.error = 0;
226         bb.wait = &wait;
227
228         ret = 0;
229         while (nr_sects != 0) {
230                 bio = bio_alloc(gfp_mask,
231                                 min(nr_sects, (sector_t)BIO_MAX_PAGES));
232                 if (!bio) {
233                         ret = -ENOMEM;
234                         break;
235                 }
236
237                 bio->bi_iter.bi_sector = sector;
238                 bio->bi_bdev   = bdev;
239                 bio->bi_end_io = bio_batch_end_io;
240                 bio->bi_private = &bb;
241
242                 while (nr_sects != 0) {
243                         sz = min((sector_t) PAGE_SIZE >> 9 , nr_sects);
244                         ret = bio_add_page(bio, ZERO_PAGE(0), sz << 9, 0);
245                         nr_sects -= ret >> 9;
246                         sector += ret >> 9;
247                         if (ret < (sz << 9))
248                                 break;
249                 }
250                 ret = 0;
251                 atomic_inc(&bb.done);
252                 submit_bio(WRITE, bio);
253         }
254
255         /* Wait for bios in-flight */
256         if (!atomic_dec_and_test(&bb.done))
257                 wait_for_completion_io(&wait);
258
259         if (bb.error)
260                 return bb.error;
261         return ret;
262 }
263
264 /**
265  * blkdev_issue_zeroout - zero-fill a block range
266  * @bdev:       blockdev to write
267  * @sector:     start sector
268  * @nr_sects:   number of sectors to write
269  * @gfp_mask:   memory allocation flags (for bio_alloc)
270  * @discard:    whether to discard the block range
271  *
272  * Description:
273  *  Zero-fill a block range.  If the discard flag is set and the block
274  *  device guarantees that subsequent READ operations to the block range
275  *  in question will return zeroes, the blocks will be discarded. Should
276  *  the discard request fail, if the discard flag is not set, or if
277  *  discard_zeroes_data is not supported, this function will resort to
278  *  zeroing the blocks manually, thus provisioning (allocating,
279  *  anchoring) them. If the block device supports the WRITE SAME command
280  *  blkdev_issue_zeroout() will use it to optimize the process of
281  *  clearing the block range. Otherwise the zeroing will be performed
282  *  using regular WRITE calls.
283  */
284
285 int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
286                          sector_t nr_sects, gfp_t gfp_mask, bool discard)
287 {
288         struct request_queue *q = bdev_get_queue(bdev);
289
290         if (discard && blk_queue_discard(q) && q->limits.discard_zeroes_data &&
291             blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask, 0) == 0)
292                 return 0;
293
294         if (bdev_write_same(bdev) &&
295             blkdev_issue_write_same(bdev, sector, nr_sects, gfp_mask,
296                                     ZERO_PAGE(0)) == 0)
297                 return 0;
298
299         return __blkdev_issue_zeroout(bdev, sector, nr_sects, gfp_mask);
300 }
301 EXPORT_SYMBOL(blkdev_issue_zeroout);