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1 /*
2 * blk-integrity.c - Block layer data integrity extensions
3 *
4 * Copyright (C) 2007, 2008 Oracle Corporation
5 * Written by: Martin K. Petersen <martin.petersen@oracle.com>
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License version
9 * 2 as published by the Free Software Foundation.
10 *
11 * This program is distributed in the hope that it will be useful, but
12 * WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; see the file COPYING. If not, write to
18 * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139,
19 * USA.
20 *
21 */
22
23 #include <linux/blkdev.h>
24 #include <linux/backing-dev.h>
25 #include <linux/mempool.h>
26 #include <linux/bio.h>
27 #include <linux/scatterlist.h>
28 #include <linux/export.h>
29 #include <linux/slab.h>
30
31 #include "blk.h"
32
33 static struct kmem_cache *integrity_cachep;
34
35 static const char *bi_unsupported_name = "unsupported";
36
37 /**
38 * blk_rq_count_integrity_sg - Count number of integrity scatterlist elements
39 * @q: request queue
40 * @bio: bio with integrity metadata attached
41 *
42 * Description: Returns the number of elements required in a
43 * scatterlist corresponding to the integrity metadata in a bio.
44 */
45 int blk_rq_count_integrity_sg(struct request_queue *q, struct bio *bio)
46 {
47 struct bio_vec iv, ivprv = { NULL };
48 unsigned int segments = 0;
49 unsigned int seg_size = 0;
50 struct bvec_iter iter;
51 int prev = 0;
52
53 bio_for_each_integrity_vec(iv, bio, iter) {
54
55 if (prev) {
56 if (!BIOVEC_PHYS_MERGEABLE(&ivprv, &iv))
57 goto new_segment;
58
59 if (!BIOVEC_SEG_BOUNDARY(q, &ivprv, &iv))
60 goto new_segment;
61
62 if (seg_size + iv.bv_len > queue_max_segment_size(q))
63 goto new_segment;
64
65 seg_size += iv.bv_len;
66 } else {
67 new_segment:
68 segments++;
69 seg_size = iv.bv_len;
70 }
71
72 prev = 1;
73 ivprv = iv;
74 }
75
76 return segments;
77 }
78 EXPORT_SYMBOL(blk_rq_count_integrity_sg);
79
80 /**
81 * blk_rq_map_integrity_sg - Map integrity metadata into a scatterlist
82 * @q: request queue
83 * @bio: bio with integrity metadata attached
84 * @sglist: target scatterlist
85 *
86 * Description: Map the integrity vectors in request into a
87 * scatterlist. The scatterlist must be big enough to hold all
88 * elements. I.e. sized using blk_rq_count_integrity_sg().
89 */
90 int blk_rq_map_integrity_sg(struct request_queue *q, struct bio *bio,
91 struct scatterlist *sglist)
92 {
93 struct bio_vec iv, ivprv = { NULL };
94 struct scatterlist *sg = NULL;
95 unsigned int segments = 0;
96 struct bvec_iter iter;
97 int prev = 0;
98
99 bio_for_each_integrity_vec(iv, bio, iter) {
100
101 if (prev) {
102 if (!BIOVEC_PHYS_MERGEABLE(&ivprv, &iv))
103 goto new_segment;
104
105 if (!BIOVEC_SEG_BOUNDARY(q, &ivprv, &iv))
106 goto new_segment;
107
108 if (sg->length + iv.bv_len > queue_max_segment_size(q))
109 goto new_segment;
110
111 sg->length += iv.bv_len;
112 } else {
113 new_segment:
114 if (!sg)
115 sg = sglist;
116 else {
117 sg_unmark_end(sg);
118 sg = sg_next(sg);
119 }
120
121 sg_set_page(sg, iv.bv_page, iv.bv_len, iv.bv_offset);
122 segments++;
123 }
124
125 prev = 1;
126 ivprv = iv;
127 }
128
129 if (sg)
130 sg_mark_end(sg);
131
132 return segments;
133 }
134 EXPORT_SYMBOL(blk_rq_map_integrity_sg);
135
136 /**
137 * blk_integrity_compare - Compare integrity profile of two disks
138 * @gd1: Disk to compare
139 * @gd2: Disk to compare
140 *
141 * Description: Meta-devices like DM and MD need to verify that all
142 * sub-devices use the same integrity format before advertising to
143 * upper layers that they can send/receive integrity metadata. This
144 * function can be used to check whether two gendisk devices have
145 * compatible integrity formats.
146 */
147 int blk_integrity_compare(struct gendisk *gd1, struct gendisk *gd2)
148 {
149 struct blk_integrity *b1 = gd1->integrity;
150 struct blk_integrity *b2 = gd2->integrity;
151
152 if (!b1 && !b2)
153 return 0;
154
155 if (!b1 || !b2)
156 return -1;
157
158 if (b1->interval != b2->interval) {
159 pr_err("%s: %s/%s protection interval %u != %u\n",
160 __func__, gd1->disk_name, gd2->disk_name,
161 b1->interval, b2->interval);
162 return -1;
163 }
164
165 if (b1->tuple_size != b2->tuple_size) {
166 printk(KERN_ERR "%s: %s/%s tuple sz %u != %u\n", __func__,
167 gd1->disk_name, gd2->disk_name,
168 b1->tuple_size, b2->tuple_size);
169 return -1;
170 }
171
172 if (b1->tag_size && b2->tag_size && (b1->tag_size != b2->tag_size)) {
173 printk(KERN_ERR "%s: %s/%s tag sz %u != %u\n", __func__,
174 gd1->disk_name, gd2->disk_name,
175 b1->tag_size, b2->tag_size);
176 return -1;
177 }
178
179 if (strcmp(b1->name, b2->name)) {
180 printk(KERN_ERR "%s: %s/%s type %s != %s\n", __func__,
181 gd1->disk_name, gd2->disk_name,
182 b1->name, b2->name);
183 return -1;
184 }
185
186 return 0;
187 }
188 EXPORT_SYMBOL(blk_integrity_compare);
189
190 bool blk_integrity_merge_rq(struct request_queue *q, struct request *req,
191 struct request *next)
192 {
193 if (blk_integrity_rq(req) == 0 && blk_integrity_rq(next) == 0)
194 return true;
195
196 if (blk_integrity_rq(req) == 0 || blk_integrity_rq(next) == 0)
197 return false;
198
199 if (bio_integrity(req->bio)->bip_flags !=
200 bio_integrity(next->bio)->bip_flags)
201 return false;
202
203 if (req->nr_integrity_segments + next->nr_integrity_segments >
204 q->limits.max_integrity_segments)
205 return false;
206
207 if (integrity_req_gap_back_merge(req, next->bio))
208 return false;
209
210 return true;
211 }
212 EXPORT_SYMBOL(blk_integrity_merge_rq);
213
214 bool blk_integrity_merge_bio(struct request_queue *q, struct request *req,
215 struct bio *bio)
216 {
217 int nr_integrity_segs;
218 struct bio *next = bio->bi_next;
219
220 if (blk_integrity_rq(req) == 0 && bio_integrity(bio) == NULL)
221 return true;
222
223 if (blk_integrity_rq(req) == 0 || bio_integrity(bio) == NULL)
224 return false;
225
226 if (bio_integrity(req->bio)->bip_flags != bio_integrity(bio)->bip_flags)
227 return false;
228
229 bio->bi_next = NULL;
230 nr_integrity_segs = blk_rq_count_integrity_sg(q, bio);
231 bio->bi_next = next;
232
233 if (req->nr_integrity_segments + nr_integrity_segs >
234 q->limits.max_integrity_segments)
235 return false;
236
237 req->nr_integrity_segments += nr_integrity_segs;
238
239 return true;
240 }
241 EXPORT_SYMBOL(blk_integrity_merge_bio);
242
243 struct integrity_sysfs_entry {
244 struct attribute attr;
245 ssize_t (*show)(struct blk_integrity *, char *);
246 ssize_t (*store)(struct blk_integrity *, const char *, size_t);
247 };
248
249 static ssize_t integrity_attr_show(struct kobject *kobj, struct attribute *attr,
250 char *page)
251 {
252 struct blk_integrity *bi =
253 container_of(kobj, struct blk_integrity, kobj);
254 struct integrity_sysfs_entry *entry =
255 container_of(attr, struct integrity_sysfs_entry, attr);
256
257 return entry->show(bi, page);
258 }
259
260 static ssize_t integrity_attr_store(struct kobject *kobj,
261 struct attribute *attr, const char *page,
262 size_t count)
263 {
264 struct blk_integrity *bi =
265 container_of(kobj, struct blk_integrity, kobj);
266 struct integrity_sysfs_entry *entry =
267 container_of(attr, struct integrity_sysfs_entry, attr);
268 ssize_t ret = 0;
269
270 if (entry->store)
271 ret = entry->store(bi, page, count);
272
273 return ret;
274 }
275
276 static ssize_t integrity_format_show(struct blk_integrity *bi, char *page)
277 {
278 if (bi != NULL && bi->name != NULL)
279 return sprintf(page, "%s\n", bi->name);
280 else
281 return sprintf(page, "none\n");
282 }
283
284 static ssize_t integrity_tag_size_show(struct blk_integrity *bi, char *page)
285 {
286 if (bi != NULL)
287 return sprintf(page, "%u\n", bi->tag_size);
288 else
289 return sprintf(page, "0\n");
290 }
291
292 static ssize_t integrity_verify_store(struct blk_integrity *bi,
293 const char *page, size_t count)
294 {
295 char *p = (char *) page;
296 unsigned long val = simple_strtoul(p, &p, 10);
297
298 if (val)
299 bi->flags |= BLK_INTEGRITY_VERIFY;
300 else
301 bi->flags &= ~BLK_INTEGRITY_VERIFY;
302
303 return count;
304 }
305
306 static ssize_t integrity_verify_show(struct blk_integrity *bi, char *page)
307 {
308 return sprintf(page, "%d\n", (bi->flags & BLK_INTEGRITY_VERIFY) != 0);
309 }
310
311 static ssize_t integrity_generate_store(struct blk_integrity *bi,
312 const char *page, size_t count)
313 {
314 char *p = (char *) page;
315 unsigned long val = simple_strtoul(p, &p, 10);
316
317 if (val)
318 bi->flags |= BLK_INTEGRITY_GENERATE;
319 else
320 bi->flags &= ~BLK_INTEGRITY_GENERATE;
321
322 return count;
323 }
324
325 static ssize_t integrity_generate_show(struct blk_integrity *bi, char *page)
326 {
327 return sprintf(page, "%d\n", (bi->flags & BLK_INTEGRITY_GENERATE) != 0);
328 }
329
330 static ssize_t integrity_device_show(struct blk_integrity *bi, char *page)
331 {
332 return sprintf(page, "%u\n",
333 (bi->flags & BLK_INTEGRITY_DEVICE_CAPABLE) != 0);
334 }
335
336 static struct integrity_sysfs_entry integrity_format_entry = {
337 .attr = { .name = "format", .mode = S_IRUGO },
338 .show = integrity_format_show,
339 };
340
341 static struct integrity_sysfs_entry integrity_tag_size_entry = {
342 .attr = { .name = "tag_size", .mode = S_IRUGO },
343 .show = integrity_tag_size_show,
344 };
345
346 static struct integrity_sysfs_entry integrity_verify_entry = {
347 .attr = { .name = "read_verify", .mode = S_IRUGO | S_IWUSR },
348 .show = integrity_verify_show,
349 .store = integrity_verify_store,
350 };
351
352 static struct integrity_sysfs_entry integrity_generate_entry = {
353 .attr = { .name = "write_generate", .mode = S_IRUGO | S_IWUSR },
354 .show = integrity_generate_show,
355 .store = integrity_generate_store,
356 };
357
358 static struct integrity_sysfs_entry integrity_device_entry = {
359 .attr = { .name = "device_is_integrity_capable", .mode = S_IRUGO },
360 .show = integrity_device_show,
361 };
362
363 static struct attribute *integrity_attrs[] = {
364 &integrity_format_entry.attr,
365 &integrity_tag_size_entry.attr,
366 &integrity_verify_entry.attr,
367 &integrity_generate_entry.attr,
368 &integrity_device_entry.attr,
369 NULL,
370 };
371
372 static const struct sysfs_ops integrity_ops = {
373 .show = &integrity_attr_show,
374 .store = &integrity_attr_store,
375 };
376
377 static int __init blk_dev_integrity_init(void)
378 {
379 integrity_cachep = kmem_cache_create("blkdev_integrity",
380 sizeof(struct blk_integrity),
381 0, SLAB_PANIC, NULL);
382 return 0;
383 }
384 subsys_initcall(blk_dev_integrity_init);
385
386 static void blk_integrity_release(struct kobject *kobj)
387 {
388 struct blk_integrity *bi =
389 container_of(kobj, struct blk_integrity, kobj);
390
391 kmem_cache_free(integrity_cachep, bi);
392 }
393
394 static struct kobj_type integrity_ktype = {
395 .default_attrs = integrity_attrs,
396 .sysfs_ops = &integrity_ops,
397 .release = blk_integrity_release,
398 };
399
400 bool blk_integrity_is_initialized(struct gendisk *disk)
401 {
402 struct blk_integrity *bi = blk_get_integrity(disk);
403
404 return (bi && bi->name && strcmp(bi->name, bi_unsupported_name) != 0);
405 }
406 EXPORT_SYMBOL(blk_integrity_is_initialized);
407
408 /**
409 * blk_integrity_register - Register a gendisk as being integrity-capable
410 * @disk: struct gendisk pointer to make integrity-aware
411 * @template: optional integrity profile to register
412 *
413 * Description: When a device needs to advertise itself as being able
414 * to send/receive integrity metadata it must use this function to
415 * register the capability with the block layer. The template is a
416 * blk_integrity struct with values appropriate for the underlying
417 * hardware. If template is NULL the new profile is allocated but
418 * not filled out. See Documentation/block/data-integrity.txt.
419 */
420 int blk_integrity_register(struct gendisk *disk, struct blk_integrity *template)
421 {
422 struct blk_integrity *bi;
423
424 BUG_ON(disk == NULL);
425
426 if (disk->integrity == NULL) {
427 bi = kmem_cache_alloc(integrity_cachep,
428 GFP_KERNEL | __GFP_ZERO);
429 if (!bi)
430 return -1;
431
432 if (kobject_init_and_add(&bi->kobj, &integrity_ktype,
433 &disk_to_dev(disk)->kobj,
434 "%s", "integrity")) {
435 kmem_cache_free(integrity_cachep, bi);
436 return -1;
437 }
438
439 kobject_uevent(&bi->kobj, KOBJ_ADD);
440
441 bi->flags |= BLK_INTEGRITY_VERIFY | BLK_INTEGRITY_GENERATE;
442 bi->interval = queue_logical_block_size(disk->queue);
443 disk->integrity = bi;
444 } else
445 bi = disk->integrity;
446
447 /* Use the provided profile as template */
448 if (template != NULL) {
449 bi->name = template->name;
450 bi->generate_fn = template->generate_fn;
451 bi->verify_fn = template->verify_fn;
452 bi->tuple_size = template->tuple_size;
453 bi->tag_size = template->tag_size;
454 bi->flags |= template->flags;
455 } else
456 bi->name = bi_unsupported_name;
457
458 disk->queue->backing_dev_info.capabilities |= BDI_CAP_STABLE_WRITES;
459
460 return 0;
461 }
462 EXPORT_SYMBOL(blk_integrity_register);
463
464 /**
465 * blk_integrity_unregister - Remove block integrity profile
466 * @disk: disk whose integrity profile to deallocate
467 *
468 * Description: This function frees all memory used by the block
469 * integrity profile. To be called at device teardown.
470 */
471 void blk_integrity_unregister(struct gendisk *disk)
472 {
473 struct blk_integrity *bi;
474
475 if (!disk || !disk->integrity)
476 return;
477
478 disk->queue->backing_dev_info.capabilities &= ~BDI_CAP_STABLE_WRITES;
479
480 bi = disk->integrity;
481
482 kobject_uevent(&bi->kobj, KOBJ_REMOVE);
483 kobject_del(&bi->kobj);
484 kobject_put(&bi->kobj);
485 disk->integrity = NULL;
486 }
487 EXPORT_SYMBOL(blk_integrity_unregister);