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Linux/block/blk-integrity.c

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

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