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Linux/block/blk-integrity.c

  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 /**
 34  * blk_rq_count_integrity_sg - Count number of integrity scatterlist elements
 35  * @q:          request queue
 36  * @bio:        bio with integrity metadata attached
 37  *
 38  * Description: Returns the number of elements required in a
 39  * scatterlist corresponding to the integrity metadata in a bio.
 40  */
 41 int blk_rq_count_integrity_sg(struct request_queue *q, struct bio *bio)
 42 {
 43         struct bio_vec iv, ivprv = { NULL };
 44         unsigned int segments = 0;
 45         unsigned int seg_size = 0;
 46         struct bvec_iter iter;
 47         int prev = 0;
 48 
 49         bio_for_each_integrity_vec(iv, bio, iter) {
 50 
 51                 if (prev) {
 52                         if (!BIOVEC_PHYS_MERGEABLE(&ivprv, &iv))
 53                                 goto new_segment;
 54 
 55                         if (!BIOVEC_SEG_BOUNDARY(q, &ivprv, &iv))
 56                                 goto new_segment;
 57 
 58                         if (seg_size + iv.bv_len > queue_max_segment_size(q))
 59                                 goto new_segment;
 60 
 61                         seg_size += iv.bv_len;
 62                 } else {
 63 new_segment:
 64                         segments++;
 65                         seg_size = iv.bv_len;
 66                 }
 67 
 68                 prev = 1;
 69                 ivprv = iv;
 70         }
 71 
 72         return segments;
 73 }
 74 EXPORT_SYMBOL(blk_rq_count_integrity_sg);
 75 
 76 /**
 77  * blk_rq_map_integrity_sg - Map integrity metadata into a scatterlist
 78  * @q:          request queue
 79  * @bio:        bio with integrity metadata attached
 80  * @sglist:     target scatterlist
 81  *
 82  * Description: Map the integrity vectors in request into a
 83  * scatterlist.  The scatterlist must be big enough to hold all
 84  * elements.  I.e. sized using blk_rq_count_integrity_sg().
 85  */
 86 int blk_rq_map_integrity_sg(struct request_queue *q, struct bio *bio,
 87                             struct scatterlist *sglist)
 88 {
 89         struct bio_vec iv, ivprv = { NULL };
 90         struct scatterlist *sg = NULL;
 91         unsigned int segments = 0;
 92         struct bvec_iter iter;
 93         int prev = 0;
 94 
 95         bio_for_each_integrity_vec(iv, bio, iter) {
 96 
 97                 if (prev) {
 98                         if (!BIOVEC_PHYS_MERGEABLE(&ivprv, &iv))
 99                                 goto new_segment;
100 
101                         if (!BIOVEC_SEG_BOUNDARY(q, &ivprv, &iv))
102                                 goto new_segment;
103 
104                         if (sg->length + iv.bv_len > queue_max_segment_size(q))
105                                 goto new_segment;
106 
107                         sg->length += iv.bv_len;
108                 } else {
109 new_segment:
110                         if (!sg)
111                                 sg = sglist;
112                         else {
113                                 sg_unmark_end(sg);
114                                 sg = sg_next(sg);
115                         }
116 
117                         sg_set_page(sg, iv.bv_page, iv.bv_len, iv.bv_offset);
118                         segments++;
119                 }
120 
121                 prev = 1;
122                 ivprv = iv;
123         }
124 
125         if (sg)
126                 sg_mark_end(sg);
127 
128         return segments;
129 }
130 EXPORT_SYMBOL(blk_rq_map_integrity_sg);
131 
132 /**
133  * blk_integrity_compare - Compare integrity profile of two disks
134  * @gd1:        Disk to compare
135  * @gd2:        Disk to compare
136  *
137  * Description: Meta-devices like DM and MD need to verify that all
138  * sub-devices use the same integrity format before advertising to
139  * upper layers that they can send/receive integrity metadata.  This
140  * function can be used to check whether two gendisk devices have
141  * compatible integrity formats.
142  */
143 int blk_integrity_compare(struct gendisk *gd1, struct gendisk *gd2)
144 {
145         struct blk_integrity *b1 = &gd1->queue->integrity;
146         struct blk_integrity *b2 = &gd2->queue->integrity;
147 
148         if (!b1->profile && !b2->profile)
149                 return 0;
150 
151         if (!b1->profile || !b2->profile)
152                 return -1;
153 
154         if (b1->interval_exp != b2->interval_exp) {
155                 pr_err("%s: %s/%s protection interval %u != %u\n",
156                        __func__, gd1->disk_name, gd2->disk_name,
157                        1 << b1->interval_exp, 1 << b2->interval_exp);
158                 return -1;
159         }
160 
161         if (b1->tuple_size != b2->tuple_size) {
162                 pr_err("%s: %s/%s tuple sz %u != %u\n", __func__,
163                        gd1->disk_name, gd2->disk_name,
164                        b1->tuple_size, b2->tuple_size);
165                 return -1;
166         }
167 
168         if (b1->tag_size && b2->tag_size && (b1->tag_size != b2->tag_size)) {
169                 pr_err("%s: %s/%s tag sz %u != %u\n", __func__,
170                        gd1->disk_name, gd2->disk_name,
171                        b1->tag_size, b2->tag_size);
172                 return -1;
173         }
174 
175         if (b1->profile != b2->profile) {
176                 pr_err("%s: %s/%s type %s != %s\n", __func__,
177                        gd1->disk_name, gd2->disk_name,
178                        b1->profile->name, b2->profile->name);
179                 return -1;
180         }
181 
182         return 0;
183 }
184 EXPORT_SYMBOL(blk_integrity_compare);
185 
186 bool blk_integrity_merge_rq(struct request_queue *q, struct request *req,
187                             struct request *next)
188 {
189         if (blk_integrity_rq(req) == 0 && blk_integrity_rq(next) == 0)
190                 return true;
191 
192         if (blk_integrity_rq(req) == 0 || blk_integrity_rq(next) == 0)
193                 return false;
194 
195         if (bio_integrity(req->bio)->bip_flags !=
196             bio_integrity(next->bio)->bip_flags)
197                 return false;
198 
199         if (req->nr_integrity_segments + next->nr_integrity_segments >
200             q->limits.max_integrity_segments)
201                 return false;
202 
203         if (integrity_req_gap_back_merge(req, next->bio))
204                 return false;
205 
206         return true;
207 }
208 EXPORT_SYMBOL(blk_integrity_merge_rq);
209 
210 bool blk_integrity_merge_bio(struct request_queue *q, struct request *req,
211                              struct bio *bio)
212 {
213         int nr_integrity_segs;
214         struct bio *next = bio->bi_next;
215 
216         if (blk_integrity_rq(req) == 0 && bio_integrity(bio) == NULL)
217                 return true;
218 
219         if (blk_integrity_rq(req) == 0 || bio_integrity(bio) == NULL)
220                 return false;
221 
222         if (bio_integrity(req->bio)->bip_flags != bio_integrity(bio)->bip_flags)
223                 return false;
224 
225         bio->bi_next = NULL;
226         nr_integrity_segs = blk_rq_count_integrity_sg(q, bio);
227         bio->bi_next = next;
228 
229         if (req->nr_integrity_segments + nr_integrity_segs >
230             q->limits.max_integrity_segments)
231                 return false;
232 
233         req->nr_integrity_segments += nr_integrity_segs;
234 
235         return true;
236 }
237 EXPORT_SYMBOL(blk_integrity_merge_bio);
238 
239 struct integrity_sysfs_entry {
240         struct attribute attr;
241         ssize_t (*show)(struct blk_integrity *, char *);
242         ssize_t (*store)(struct blk_integrity *, const char *, size_t);
243 };
244 
245 static ssize_t integrity_attr_show(struct kobject *kobj, struct attribute *attr,
246                                    char *page)
247 {
248         struct gendisk *disk = container_of(kobj, struct gendisk, integrity_kobj);
249         struct blk_integrity *bi = &disk->queue->integrity;
250         struct integrity_sysfs_entry *entry =
251                 container_of(attr, struct integrity_sysfs_entry, attr);
252 
253         return entry->show(bi, page);
254 }
255 
256 static ssize_t integrity_attr_store(struct kobject *kobj,
257                                     struct attribute *attr, const char *page,
258                                     size_t count)
259 {
260         struct gendisk *disk = container_of(kobj, struct gendisk, integrity_kobj);
261         struct blk_integrity *bi = &disk->queue->integrity;
262         struct integrity_sysfs_entry *entry =
263                 container_of(attr, struct integrity_sysfs_entry, attr);
264         ssize_t ret = 0;
265 
266         if (entry->store)
267                 ret = entry->store(bi, page, count);
268 
269         return ret;
270 }
271 
272 static ssize_t integrity_format_show(struct blk_integrity *bi, char *page)
273 {
274         if (bi->profile && bi->profile->name)
275                 return sprintf(page, "%s\n", bi->profile->name);
276         else
277                 return sprintf(page, "none\n");
278 }
279 
280 static ssize_t integrity_tag_size_show(struct blk_integrity *bi, char *page)
281 {
282         return sprintf(page, "%u\n", bi->tag_size);
283 }
284 
285 static ssize_t integrity_interval_show(struct blk_integrity *bi, char *page)
286 {
287         return sprintf(page, "%u\n",
288                        bi->interval_exp ? 1 << bi->interval_exp : 0);
289 }
290 
291 static ssize_t integrity_verify_store(struct blk_integrity *bi,
292                                       const char *page, size_t count)
293 {
294         char *p = (char *) page;
295         unsigned long val = simple_strtoul(p, &p, 10);
296 
297         if (val)
298                 bi->flags |= BLK_INTEGRITY_VERIFY;
299         else
300                 bi->flags &= ~BLK_INTEGRITY_VERIFY;
301 
302         return count;
303 }
304 
305 static ssize_t integrity_verify_show(struct blk_integrity *bi, char *page)
306 {
307         return sprintf(page, "%d\n", (bi->flags & BLK_INTEGRITY_VERIFY) != 0);
308 }
309 
310 static ssize_t integrity_generate_store(struct blk_integrity *bi,
311                                         const char *page, size_t count)
312 {
313         char *p = (char *) page;
314         unsigned long val = simple_strtoul(p, &p, 10);
315 
316         if (val)
317                 bi->flags |= BLK_INTEGRITY_GENERATE;
318         else
319                 bi->flags &= ~BLK_INTEGRITY_GENERATE;
320 
321         return count;
322 }
323 
324 static ssize_t integrity_generate_show(struct blk_integrity *bi, char *page)
325 {
326         return sprintf(page, "%d\n", (bi->flags & BLK_INTEGRITY_GENERATE) != 0);
327 }
328 
329 static ssize_t integrity_device_show(struct blk_integrity *bi, char *page)
330 {
331         return sprintf(page, "%u\n",
332                        (bi->flags & BLK_INTEGRITY_DEVICE_CAPABLE) != 0);
333 }
334 
335 static struct integrity_sysfs_entry integrity_format_entry = {
336         .attr = { .name = "format", .mode = S_IRUGO },
337         .show = integrity_format_show,
338 };
339 
340 static struct integrity_sysfs_entry integrity_tag_size_entry = {
341         .attr = { .name = "tag_size", .mode = S_IRUGO },
342         .show = integrity_tag_size_show,
343 };
344 
345 static struct integrity_sysfs_entry integrity_interval_entry = {
346         .attr = { .name = "protection_interval_bytes", .mode = S_IRUGO },
347         .show = integrity_interval_show,
348 };
349 
350 static struct integrity_sysfs_entry integrity_verify_entry = {
351         .attr = { .name = "read_verify", .mode = S_IRUGO | S_IWUSR },
352         .show = integrity_verify_show,
353         .store = integrity_verify_store,
354 };
355 
356 static struct integrity_sysfs_entry integrity_generate_entry = {
357         .attr = { .name = "write_generate", .mode = S_IRUGO | S_IWUSR },
358         .show = integrity_generate_show,
359         .store = integrity_generate_store,
360 };
361 
362 static struct integrity_sysfs_entry integrity_device_entry = {
363         .attr = { .name = "device_is_integrity_capable", .mode = S_IRUGO },
364         .show = integrity_device_show,
365 };
366 
367 static struct attribute *integrity_attrs[] = {
368         &integrity_format_entry.attr,
369         &integrity_tag_size_entry.attr,
370         &integrity_interval_entry.attr,
371         &integrity_verify_entry.attr,
372         &integrity_generate_entry.attr,
373         &integrity_device_entry.attr,
374         NULL,
375 };
376 
377 static const struct sysfs_ops integrity_ops = {
378         .show   = &integrity_attr_show,
379         .store  = &integrity_attr_store,
380 };
381 
382 static struct kobj_type integrity_ktype = {
383         .default_attrs  = integrity_attrs,
384         .sysfs_ops      = &integrity_ops,
385 };
386 
387 static int blk_integrity_nop_fn(struct blk_integrity_iter *iter)
388 {
389         return 0;
390 }
391 
392 static struct blk_integrity_profile nop_profile = {
393         .name = "nop",
394         .generate_fn = blk_integrity_nop_fn,
395         .verify_fn = blk_integrity_nop_fn,
396 };
397 
398 /**
399  * blk_integrity_register - Register a gendisk as being integrity-capable
400  * @disk:       struct gendisk pointer to make integrity-aware
401  * @template:   block integrity profile to register
402  *
403  * Description: When a device needs to advertise itself as being able to
404  * send/receive integrity metadata it must use this function to register
405  * the capability with the block layer. The template is a blk_integrity
406  * struct with values appropriate for the underlying hardware. See
407  * Documentation/block/data-integrity.txt.
408  */
409 void blk_integrity_register(struct gendisk *disk, struct blk_integrity *template)
410 {
411         struct blk_integrity *bi = &disk->queue->integrity;
412 
413         bi->flags = BLK_INTEGRITY_VERIFY | BLK_INTEGRITY_GENERATE |
414                 template->flags;
415         bi->interval_exp = ilog2(queue_logical_block_size(disk->queue));
416         bi->profile = template->profile ? template->profile : &nop_profile;
417         bi->tuple_size = template->tuple_size;
418         bi->tag_size = template->tag_size;
419 
420         blk_integrity_revalidate(disk);
421 }
422 EXPORT_SYMBOL(blk_integrity_register);
423 
424 /**
425  * blk_integrity_unregister - Unregister block integrity profile
426  * @disk:       disk whose integrity profile to unregister
427  *
428  * Description: This function unregisters the integrity capability from
429  * a block device.
430  */
431 void blk_integrity_unregister(struct gendisk *disk)
432 {
433         blk_integrity_revalidate(disk);
434         memset(&disk->queue->integrity, 0, sizeof(struct blk_integrity));
435 }
436 EXPORT_SYMBOL(blk_integrity_unregister);
437 
438 void blk_integrity_revalidate(struct gendisk *disk)
439 {
440         struct blk_integrity *bi = &disk->queue->integrity;
441 
442         if (!(disk->flags & GENHD_FL_UP))
443                 return;
444 
445         if (bi->profile)
446                 disk->queue->backing_dev_info.capabilities |=
447                         BDI_CAP_STABLE_WRITES;
448         else
449                 disk->queue->backing_dev_info.capabilities &=
450                         ~BDI_CAP_STABLE_WRITES;
451 }
452 
453 void blk_integrity_add(struct gendisk *disk)
454 {
455         if (kobject_init_and_add(&disk->integrity_kobj, &integrity_ktype,
456                                  &disk_to_dev(disk)->kobj, "%s", "integrity"))
457                 return;
458 
459         kobject_uevent(&disk->integrity_kobj, KOBJ_ADD);
460 }
461 
462 void blk_integrity_del(struct gendisk *disk)
463 {
464         kobject_uevent(&disk->integrity_kobj, KOBJ_REMOVE);
465         kobject_del(&disk->integrity_kobj);
466         kobject_put(&disk->integrity_kobj);
467 }
468 

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