Root/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/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
32static struct kmem_cache *integrity_cachep;
33
34static 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 */
44int 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 {
65new_segment:
66            segments++;
67            seg_size = iv->bv_len;
68        }
69
70        ivprv = iv;
71    }
72
73    return segments;
74}
75EXPORT_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 */
87int 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 {
109new_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}
129EXPORT_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 */
142int 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}
183EXPORT_SYMBOL(blk_integrity_compare);
184
185int 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}
197EXPORT_SYMBOL(blk_integrity_merge_rq);
198
199int 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}
217EXPORT_SYMBOL(blk_integrity_merge_bio);
218
219struct 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
225static 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
236static 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
252static 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
260static 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, "0\n");
266}
267
268static 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
282static 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
287static 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
301static 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
306static struct integrity_sysfs_entry integrity_format_entry = {
307    .attr = { .name = "format", .mode = S_IRUGO },
308    .show = integrity_format_show,
309};
310
311static struct integrity_sysfs_entry integrity_tag_size_entry = {
312    .attr = { .name = "tag_size", .mode = S_IRUGO },
313    .show = integrity_tag_size_show,
314};
315
316static 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
322static 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
328static 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
336static const struct sysfs_ops integrity_ops = {
337    .show = &integrity_attr_show,
338    .store = &integrity_attr_store,
339};
340
341static 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}
348subsys_initcall(blk_dev_integrity_init);
349
350static 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
358static struct kobj_type integrity_ktype = {
359    .default_attrs = integrity_attrs,
360    .sysfs_ops = &integrity_ops,
361    .release = blk_integrity_release,
362};
363
364bool 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}
370EXPORT_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 */
384int 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}
425EXPORT_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 */
434void 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}
448EXPORT_SYMBOL(blk_integrity_unregister);
449

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