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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/slab.h>
 28 
 29 #include "blk.h"
 30 
 31 static struct kmem_cache *integrity_cachep;
 32 
 33 /**
 34  * blk_rq_count_integrity_sg - Count number of integrity scatterlist elements
 35  * @rq:         request with integrity metadata attached
 36  *
 37  * Description: Returns the number of elements required in a
 38  * scatterlist corresponding to the integrity metadata in a request.
 39  */
 40 int blk_rq_count_integrity_sg(struct request *rq)
 41 {
 42         struct bio_vec *iv, *ivprv;
 43         struct req_iterator iter;
 44         unsigned int segments;
 45 
 46         ivprv = NULL;
 47         segments = 0;
 48 
 49         rq_for_each_integrity_segment(iv, rq, iter) {
 50 
 51                 if (!ivprv || !BIOVEC_PHYS_MERGEABLE(ivprv, iv))
 52                         segments++;
 53 
 54                 ivprv = iv;
 55         }
 56 
 57         return segments;
 58 }
 59 EXPORT_SYMBOL(blk_rq_count_integrity_sg);
 60 
 61 /**
 62  * blk_rq_map_integrity_sg - Map integrity metadata into a scatterlist
 63  * @rq:         request with integrity metadata attached
 64  * @sglist:     target scatterlist
 65  *
 66  * Description: Map the integrity vectors in request into a
 67  * scatterlist.  The scatterlist must be big enough to hold all
 68  * elements.  I.e. sized using blk_rq_count_integrity_sg().
 69  */
 70 int blk_rq_map_integrity_sg(struct request *rq, struct scatterlist *sglist)
 71 {
 72         struct bio_vec *iv, *ivprv;
 73         struct req_iterator iter;
 74         struct scatterlist *sg;
 75         unsigned int segments;
 76 
 77         ivprv = NULL;
 78         sg = NULL;
 79         segments = 0;
 80 
 81         rq_for_each_integrity_segment(iv, rq, iter) {
 82 
 83                 if (ivprv) {
 84                         if (!BIOVEC_PHYS_MERGEABLE(ivprv, iv))
 85                                 goto new_segment;
 86 
 87                         sg->length += iv->bv_len;
 88                 } else {
 89 new_segment:
 90                         if (!sg)
 91                                 sg = sglist;
 92                         else {
 93                                 sg->page_link &= ~0x02;
 94                                 sg = sg_next(sg);
 95                         }
 96 
 97                         sg_set_page(sg, iv->bv_page, iv->bv_len, iv->bv_offset);
 98                         segments++;
 99                 }
100 
101                 ivprv = iv;
102         }
103 
104         if (sg)
105                 sg_mark_end(sg);
106 
107         return segments;
108 }
109 EXPORT_SYMBOL(blk_rq_map_integrity_sg);
110 
111 /**
112  * blk_integrity_compare - Compare integrity profile of two disks
113  * @gd1:        Disk to compare
114  * @gd2:        Disk to compare
115  *
116  * Description: Meta-devices like DM and MD need to verify that all
117  * sub-devices use the same integrity format before advertising to
118  * upper layers that they can send/receive integrity metadata.  This
119  * function can be used to check whether two gendisk devices have
120  * compatible integrity formats.
121  */
122 int blk_integrity_compare(struct gendisk *gd1, struct gendisk *gd2)
123 {
124         struct blk_integrity *b1 = gd1->integrity;
125         struct blk_integrity *b2 = gd2->integrity;
126 
127         if (!b1 && !b2)
128                 return 0;
129 
130         if (!b1 || !b2)
131                 return -1;
132 
133         if (b1->sector_size != b2->sector_size) {
134                 printk(KERN_ERR "%s: %s/%s sector sz %u != %u\n", __func__,
135                        gd1->disk_name, gd2->disk_name,
136                        b1->sector_size, b2->sector_size);
137                 return -1;
138         }
139 
140         if (b1->tuple_size != b2->tuple_size) {
141                 printk(KERN_ERR "%s: %s/%s tuple sz %u != %u\n", __func__,
142                        gd1->disk_name, gd2->disk_name,
143                        b1->tuple_size, b2->tuple_size);
144                 return -1;
145         }
146 
147         if (b1->tag_size && b2->tag_size && (b1->tag_size != b2->tag_size)) {
148                 printk(KERN_ERR "%s: %s/%s tag sz %u != %u\n", __func__,
149                        gd1->disk_name, gd2->disk_name,
150                        b1->tag_size, b2->tag_size);
151                 return -1;
152         }
153 
154         if (strcmp(b1->name, b2->name)) {
155                 printk(KERN_ERR "%s: %s/%s type %s != %s\n", __func__,
156                        gd1->disk_name, gd2->disk_name,
157                        b1->name, b2->name);
158                 return -1;
159         }
160 
161         return 0;
162 }
163 EXPORT_SYMBOL(blk_integrity_compare);
164 
165 struct integrity_sysfs_entry {
166         struct attribute attr;
167         ssize_t (*show)(struct blk_integrity *, char *);
168         ssize_t (*store)(struct blk_integrity *, const char *, size_t);
169 };
170 
171 static ssize_t integrity_attr_show(struct kobject *kobj, struct attribute *attr,
172                                    char *page)
173 {
174         struct blk_integrity *bi =
175                 container_of(kobj, struct blk_integrity, kobj);
176         struct integrity_sysfs_entry *entry =
177                 container_of(attr, struct integrity_sysfs_entry, attr);
178 
179         return entry->show(bi, page);
180 }
181 
182 static ssize_t integrity_attr_store(struct kobject *kobj,
183                                     struct attribute *attr, const char *page,
184                                     size_t count)
185 {
186         struct blk_integrity *bi =
187                 container_of(kobj, struct blk_integrity, kobj);
188         struct integrity_sysfs_entry *entry =
189                 container_of(attr, struct integrity_sysfs_entry, attr);
190         ssize_t ret = 0;
191 
192         if (entry->store)
193                 ret = entry->store(bi, page, count);
194 
195         return ret;
196 }
197 
198 static ssize_t integrity_format_show(struct blk_integrity *bi, char *page)
199 {
200         if (bi != NULL && bi->name != NULL)
201                 return sprintf(page, "%s\n", bi->name);
202         else
203                 return sprintf(page, "none\n");
204 }
205 
206 static ssize_t integrity_tag_size_show(struct blk_integrity *bi, char *page)
207 {
208         if (bi != NULL)
209                 return sprintf(page, "%u\n", bi->tag_size);
210         else
211                 return sprintf(page, "\n");
212 }
213 
214 static ssize_t integrity_read_store(struct blk_integrity *bi,
215                                     const char *page, size_t count)
216 {
217         char *p = (char *) page;
218         unsigned long val = simple_strtoul(p, &p, 10);
219 
220         if (val)
221                 bi->flags |= INTEGRITY_FLAG_READ;
222         else
223                 bi->flags &= ~INTEGRITY_FLAG_READ;
224 
225         return count;
226 }
227 
228 static ssize_t integrity_read_show(struct blk_integrity *bi, char *page)
229 {
230         return sprintf(page, "%d\n", (bi->flags & INTEGRITY_FLAG_READ) != 0);
231 }
232 
233 static ssize_t integrity_write_store(struct blk_integrity *bi,
234                                      const char *page, size_t count)
235 {
236         char *p = (char *) page;
237         unsigned long val = simple_strtoul(p, &p, 10);
238 
239         if (val)
240                 bi->flags |= INTEGRITY_FLAG_WRITE;
241         else
242                 bi->flags &= ~INTEGRITY_FLAG_WRITE;
243 
244         return count;
245 }
246 
247 static ssize_t integrity_write_show(struct blk_integrity *bi, char *page)
248 {
249         return sprintf(page, "%d\n", (bi->flags & INTEGRITY_FLAG_WRITE) != 0);
250 }
251 
252 static struct integrity_sysfs_entry integrity_format_entry = {
253         .attr = { .name = "format", .mode = S_IRUGO },
254         .show = integrity_format_show,
255 };
256 
257 static struct integrity_sysfs_entry integrity_tag_size_entry = {
258         .attr = { .name = "tag_size", .mode = S_IRUGO },
259         .show = integrity_tag_size_show,
260 };
261 
262 static struct integrity_sysfs_entry integrity_read_entry = {
263         .attr = { .name = "read_verify", .mode = S_IRUGO | S_IWUSR },
264         .show = integrity_read_show,
265         .store = integrity_read_store,
266 };
267 
268 static struct integrity_sysfs_entry integrity_write_entry = {
269         .attr = { .name = "write_generate", .mode = S_IRUGO | S_IWUSR },
270         .show = integrity_write_show,
271         .store = integrity_write_store,
272 };
273 
274 static struct attribute *integrity_attrs[] = {
275         &integrity_format_entry.attr,
276         &integrity_tag_size_entry.attr,
277         &integrity_read_entry.attr,
278         &integrity_write_entry.attr,
279         NULL,
280 };
281 
282 static const struct sysfs_ops integrity_ops = {
283         .show   = &integrity_attr_show,
284         .store  = &integrity_attr_store,
285 };
286 
287 static int __init blk_dev_integrity_init(void)
288 {
289         integrity_cachep = kmem_cache_create("blkdev_integrity",
290                                              sizeof(struct blk_integrity),
291                                              0, SLAB_PANIC, NULL);
292         return 0;
293 }
294 subsys_initcall(blk_dev_integrity_init);
295 
296 static void blk_integrity_release(struct kobject *kobj)
297 {
298         struct blk_integrity *bi =
299                 container_of(kobj, struct blk_integrity, kobj);
300 
301         kmem_cache_free(integrity_cachep, bi);
302 }
303 
304 static struct kobj_type integrity_ktype = {
305         .default_attrs  = integrity_attrs,
306         .sysfs_ops      = &integrity_ops,
307         .release        = blk_integrity_release,
308 };
309 
310 /**
311  * blk_integrity_register - Register a gendisk as being integrity-capable
312  * @disk:       struct gendisk pointer to make integrity-aware
313  * @template:   optional integrity profile to register
314  *
315  * Description: When a device needs to advertise itself as being able
316  * to send/receive integrity metadata it must use this function to
317  * register the capability with the block layer.  The template is a
318  * blk_integrity struct with values appropriate for the underlying
319  * hardware.  If template is NULL the new profile is allocated but
320  * not filled out. See Documentation/block/data-integrity.txt.
321  */
322 int blk_integrity_register(struct gendisk *disk, struct blk_integrity *template)
323 {
324         struct blk_integrity *bi;
325 
326         BUG_ON(disk == NULL);
327 
328         if (disk->integrity == NULL) {
329                 bi = kmem_cache_alloc(integrity_cachep,
330                                       GFP_KERNEL | __GFP_ZERO);
331                 if (!bi)
332                         return -1;
333 
334                 if (kobject_init_and_add(&bi->kobj, &integrity_ktype,
335                                          &disk_to_dev(disk)->kobj,
336                                          "%s", "integrity")) {
337                         kmem_cache_free(integrity_cachep, bi);
338                         return -1;
339                 }
340 
341                 kobject_uevent(&bi->kobj, KOBJ_ADD);
342 
343                 bi->flags |= INTEGRITY_FLAG_READ | INTEGRITY_FLAG_WRITE;
344                 bi->sector_size = queue_logical_block_size(disk->queue);
345                 disk->integrity = bi;
346         } else
347                 bi = disk->integrity;
348 
349         /* Use the provided profile as template */
350         if (template != NULL) {
351                 bi->name = template->name;
352                 bi->generate_fn = template->generate_fn;
353                 bi->verify_fn = template->verify_fn;
354                 bi->tuple_size = template->tuple_size;
355                 bi->set_tag_fn = template->set_tag_fn;
356                 bi->get_tag_fn = template->get_tag_fn;
357                 bi->tag_size = template->tag_size;
358         } else
359                 bi->name = "unsupported";
360 
361         return 0;
362 }
363 EXPORT_SYMBOL(blk_integrity_register);
364 
365 /**
366  * blk_integrity_unregister - Remove block integrity profile
367  * @disk:       disk whose integrity profile to deallocate
368  *
369  * Description: This function frees all memory used by the block
370  * integrity profile.  To be called at device teardown.
371  */
372 void blk_integrity_unregister(struct gendisk *disk)
373 {
374         struct blk_integrity *bi;
375 
376         if (!disk || !disk->integrity)
377                 return;
378 
379         bi = disk->integrity;
380 
381         kobject_uevent(&bi->kobj, KOBJ_REMOVE);
382         kobject_del(&bi->kobj);
383         kobject_put(&bi->kobj);
384         kmem_cache_free(integrity_cachep, bi);
385         disk->integrity = NULL;
386 }
387 EXPORT_SYMBOL(blk_integrity_unregister);
388 

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