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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         unsigned int i = 0;
 50 
 51         bio_for_each_integrity_vec(iv, bio, i) {
 52 
 53                 if (ivprv) {
 54                         if (!BIOVEC_PHYS_MERGEABLE(ivprv, iv))
 55                                 goto new_segment;
 56 
 57                         if (!BIOVEC_SEG_BOUNDARY(q, ivprv, iv))
 58                                 goto new_segment;
 59 
 60                         if (seg_size + iv->bv_len > queue_max_segment_size(q))
 61                                 goto new_segment;
 62 
 63                         seg_size += iv->bv_len;
 64                 } else {
 65 new_segment:
 66                         segments++;
 67                         seg_size = iv->bv_len;
 68                 }
 69 
 70                 ivprv = iv;
 71         }
 72 
 73         return segments;
 74 }
 75 EXPORT_SYMBOL(blk_rq_count_integrity_sg);
 76 
 77 /**
 78  * blk_rq_map_integrity_sg - Map integrity metadata into a scatterlist
 79  * @q:          request queue
 80  * @bio:        bio with integrity metadata attached
 81  * @sglist:     target scatterlist
 82  *
 83  * Description: Map the integrity vectors in request into a
 84  * scatterlist.  The scatterlist must be big enough to hold all
 85  * elements.  I.e. sized using blk_rq_count_integrity_sg().
 86  */
 87 int blk_rq_map_integrity_sg(struct request_queue *q, struct bio *bio,
 88                             struct scatterlist *sglist)
 89 {
 90         struct bio_vec *iv, *ivprv = NULL;
 91         struct scatterlist *sg = NULL;
 92         unsigned int segments = 0;
 93         unsigned int i = 0;
 94 
 95         bio_for_each_integrity_vec(iv, bio, i) {
 96 
 97                 if (ivprv) {
 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->page_link &= ~0x02;
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                 ivprv = iv;
122         }
123 
124         if (sg)
125                 sg_mark_end(sg);
126 
127         return segments;
128 }
129 EXPORT_SYMBOL(blk_rq_map_integrity_sg);
130 
131 /**
132  * blk_integrity_compare - Compare integrity profile of two disks
133  * @gd1:        Disk to compare
134  * @gd2:        Disk to compare
135  *
136  * Description: Meta-devices like DM and MD need to verify that all
137  * sub-devices use the same integrity format before advertising to
138  * upper layers that they can send/receive integrity metadata.  This
139  * function can be used to check whether two gendisk devices have
140  * compatible integrity formats.
141  */
142 int blk_integrity_compare(struct gendisk *gd1, struct gendisk *gd2)
143 {
144         struct blk_integrity *b1 = gd1->integrity;
145         struct blk_integrity *b2 = gd2->integrity;
146 
147         if (!b1 && !b2)
148                 return 0;
149 
150         if (!b1 || !b2)
151                 return -1;
152 
153         if (b1->sector_size != b2->sector_size) {
154                 printk(KERN_ERR "%s: %s/%s sector sz %u != %u\n", __func__,
155                        gd1->disk_name, gd2->disk_name,
156                        b1->sector_size, b2->sector_size);
157                 return -1;
158         }
159 
160         if (b1->tuple_size != b2->tuple_size) {
161                 printk(KERN_ERR "%s: %s/%s tuple sz %u != %u\n", __func__,
162                        gd1->disk_name, gd2->disk_name,
163                        b1->tuple_size, b2->tuple_size);
164                 return -1;
165         }
166 
167         if (b1->tag_size && b2->tag_size && (b1->tag_size != b2->tag_size)) {
168                 printk(KERN_ERR "%s: %s/%s tag sz %u != %u\n", __func__,
169                        gd1->disk_name, gd2->disk_name,
170                        b1->tag_size, b2->tag_size);
171                 return -1;
172         }
173 
174         if (strcmp(b1->name, b2->name)) {
175                 printk(KERN_ERR "%s: %s/%s type %s != %s\n", __func__,
176                        gd1->disk_name, gd2->disk_name,
177                        b1->name, b2->name);
178                 return -1;
179         }
180 
181         return 0;
182 }
183 EXPORT_SYMBOL(blk_integrity_compare);
184 
185 int blk_integrity_merge_rq(struct request_queue *q, struct request *req,
186                            struct request *next)
187 {
188         if (blk_integrity_rq(req) != blk_integrity_rq(next))
189                 return -1;
190 
191         if (req->nr_integrity_segments + next->nr_integrity_segments >
192             q->limits.max_integrity_segments)
193                 return -1;
194 
195         return 0;
196 }
197 EXPORT_SYMBOL(blk_integrity_merge_rq);
198 
199 int blk_integrity_merge_bio(struct request_queue *q, struct request *req,
200                             struct bio *bio)
201 {
202         int nr_integrity_segs;
203         struct bio *next = bio->bi_next;
204 
205         bio->bi_next = NULL;
206         nr_integrity_segs = blk_rq_count_integrity_sg(q, bio);
207         bio->bi_next = next;
208 
209         if (req->nr_integrity_segments + nr_integrity_segs >
210             q->limits.max_integrity_segments)
211                 return -1;
212 
213         req->nr_integrity_segments += nr_integrity_segs;
214 
215         return 0;
216 }
217 EXPORT_SYMBOL(blk_integrity_merge_bio);
218 
219 struct integrity_sysfs_entry {
220         struct attribute attr;
221         ssize_t (*show)(struct blk_integrity *, char *);
222         ssize_t (*store)(struct blk_integrity *, const char *, size_t);
223 };
224 
225 static ssize_t integrity_attr_show(struct kobject *kobj, struct attribute *attr,
226                                    char *page)
227 {
228         struct blk_integrity *bi =
229                 container_of(kobj, struct blk_integrity, kobj);
230         struct integrity_sysfs_entry *entry =
231                 container_of(attr, struct integrity_sysfs_entry, attr);
232 
233         return entry->show(bi, page);
234 }
235 
236 static ssize_t integrity_attr_store(struct kobject *kobj,
237                                     struct attribute *attr, const char *page,
238                                     size_t count)
239 {
240         struct blk_integrity *bi =
241                 container_of(kobj, struct blk_integrity, kobj);
242         struct integrity_sysfs_entry *entry =
243                 container_of(attr, struct integrity_sysfs_entry, attr);
244         ssize_t ret = 0;
245 
246         if (entry->store)
247                 ret = entry->store(bi, page, count);
248 
249         return ret;
250 }
251 
252 static ssize_t integrity_format_show(struct blk_integrity *bi, char *page)
253 {
254         if (bi != NULL && bi->name != NULL)
255                 return sprintf(page, "%s\n", bi->name);
256         else
257                 return sprintf(page, "none\n");
258 }
259 
260 static ssize_t integrity_tag_size_show(struct blk_integrity *bi, char *page)
261 {
262         if (bi != NULL)
263                 return sprintf(page, "%u\n", bi->tag_size);
264         else
265                 return sprintf(page, "\n");
266 }
267 
268 static ssize_t integrity_read_store(struct blk_integrity *bi,
269                                     const char *page, size_t count)
270 {
271         char *p = (char *) page;
272         unsigned long val = simple_strtoul(p, &p, 10);
273 
274         if (val)
275                 bi->flags |= INTEGRITY_FLAG_READ;
276         else
277                 bi->flags &= ~INTEGRITY_FLAG_READ;
278 
279         return count;
280 }
281 
282 static ssize_t integrity_read_show(struct blk_integrity *bi, char *page)
283 {
284         return sprintf(page, "%d\n", (bi->flags & INTEGRITY_FLAG_READ) != 0);
285 }
286 
287 static ssize_t integrity_write_store(struct blk_integrity *bi,
288                                      const char *page, size_t count)
289 {
290         char *p = (char *) page;
291         unsigned long val = simple_strtoul(p, &p, 10);
292 
293         if (val)
294                 bi->flags |= INTEGRITY_FLAG_WRITE;
295         else
296                 bi->flags &= ~INTEGRITY_FLAG_WRITE;
297 
298         return count;
299 }
300 
301 static ssize_t integrity_write_show(struct blk_integrity *bi, char *page)
302 {
303         return sprintf(page, "%d\n", (bi->flags & INTEGRITY_FLAG_WRITE) != 0);
304 }
305 
306 static struct integrity_sysfs_entry integrity_format_entry = {
307         .attr = { .name = "format", .mode = S_IRUGO },
308         .show = integrity_format_show,
309 };
310 
311 static struct integrity_sysfs_entry integrity_tag_size_entry = {
312         .attr = { .name = "tag_size", .mode = S_IRUGO },
313         .show = integrity_tag_size_show,
314 };
315 
316 static struct integrity_sysfs_entry integrity_read_entry = {
317         .attr = { .name = "read_verify", .mode = S_IRUGO | S_IWUSR },
318         .show = integrity_read_show,
319         .store = integrity_read_store,
320 };
321 
322 static struct integrity_sysfs_entry integrity_write_entry = {
323         .attr = { .name = "write_generate", .mode = S_IRUGO | S_IWUSR },
324         .show = integrity_write_show,
325         .store = integrity_write_store,
326 };
327 
328 static struct attribute *integrity_attrs[] = {
329         &integrity_format_entry.attr,
330         &integrity_tag_size_entry.attr,
331         &integrity_read_entry.attr,
332         &integrity_write_entry.attr,
333         NULL,
334 };
335 
336 static const struct sysfs_ops integrity_ops = {
337         .show   = &integrity_attr_show,
338         .store  = &integrity_attr_store,
339 };
340 
341 static int __init blk_dev_integrity_init(void)
342 {
343         integrity_cachep = kmem_cache_create("blkdev_integrity",
344                                              sizeof(struct blk_integrity),
345                                              0, SLAB_PANIC, NULL);
346         return 0;
347 }
348 subsys_initcall(blk_dev_integrity_init);
349 
350 static void blk_integrity_release(struct kobject *kobj)
351 {
352         struct blk_integrity *bi =
353                 container_of(kobj, struct blk_integrity, kobj);
354 
355         kmem_cache_free(integrity_cachep, bi);
356 }
357 
358 static struct kobj_type integrity_ktype = {
359         .default_attrs  = integrity_attrs,
360         .sysfs_ops      = &integrity_ops,
361         .release        = blk_integrity_release,
362 };
363 
364 bool blk_integrity_is_initialized(struct gendisk *disk)
365 {
366         struct blk_integrity *bi = blk_get_integrity(disk);
367 
368         return (bi && bi->name && strcmp(bi->name, bi_unsupported_name) != 0);
369 }
370 EXPORT_SYMBOL(blk_integrity_is_initialized);
371 
372 /**
373  * blk_integrity_register - Register a gendisk as being integrity-capable
374  * @disk:       struct gendisk pointer to make integrity-aware
375  * @template:   optional integrity profile to register
376  *
377  * Description: When a device needs to advertise itself as being able
378  * to send/receive integrity metadata it must use this function to
379  * register the capability with the block layer.  The template is a
380  * blk_integrity struct with values appropriate for the underlying
381  * hardware.  If template is NULL the new profile is allocated but
382  * not filled out. See Documentation/block/data-integrity.txt.
383  */
384 int blk_integrity_register(struct gendisk *disk, struct blk_integrity *template)
385 {
386         struct blk_integrity *bi;
387 
388         BUG_ON(disk == NULL);
389 
390         if (disk->integrity == NULL) {
391                 bi = kmem_cache_alloc(integrity_cachep,
392                                       GFP_KERNEL | __GFP_ZERO);
393                 if (!bi)
394                         return -1;
395 
396                 if (kobject_init_and_add(&bi->kobj, &integrity_ktype,
397                                          &disk_to_dev(disk)->kobj,
398                                          "%s", "integrity")) {
399                         kmem_cache_free(integrity_cachep, bi);
400                         return -1;
401                 }
402 
403                 kobject_uevent(&bi->kobj, KOBJ_ADD);
404 
405                 bi->flags |= INTEGRITY_FLAG_READ | INTEGRITY_FLAG_WRITE;
406                 bi->sector_size = queue_logical_block_size(disk->queue);
407                 disk->integrity = bi;
408         } else
409                 bi = disk->integrity;
410 
411         /* Use the provided profile as template */
412         if (template != NULL) {
413                 bi->name = template->name;
414                 bi->generate_fn = template->generate_fn;
415                 bi->verify_fn = template->verify_fn;
416                 bi->tuple_size = template->tuple_size;
417                 bi->set_tag_fn = template->set_tag_fn;
418                 bi->get_tag_fn = template->get_tag_fn;
419                 bi->tag_size = template->tag_size;
420         } else
421                 bi->name = bi_unsupported_name;
422 
423         return 0;
424 }
425 EXPORT_SYMBOL(blk_integrity_register);
426 
427 /**
428  * blk_integrity_unregister - Remove block integrity profile
429  * @disk:       disk whose integrity profile to deallocate
430  *
431  * Description: This function frees all memory used by the block
432  * integrity profile.  To be called at device teardown.
433  */
434 void blk_integrity_unregister(struct gendisk *disk)
435 {
436         struct blk_integrity *bi;
437 
438         if (!disk || !disk->integrity)
439                 return;
440 
441         bi = disk->integrity;
442 
443         kobject_uevent(&bi->kobj, KOBJ_REMOVE);
444         kobject_del(&bi->kobj);
445         kobject_put(&bi->kobj);
446         disk->integrity = NULL;
447 }
448 EXPORT_SYMBOL(blk_integrity_unregister);
449 

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