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/slab.h>
28
29#include "blk.h"
30
31static struct kmem_cache *integrity_cachep;
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 */
41int 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    unsigned int i = 0;
47
48    bio_for_each_integrity_vec(iv, bio, i) {
49
50        if (ivprv) {
51            if (!BIOVEC_PHYS_MERGEABLE(ivprv, iv))
52                goto new_segment;
53
54            if (!BIOVEC_SEG_BOUNDARY(q, ivprv, iv))
55                goto new_segment;
56
57            if (seg_size + iv->bv_len > queue_max_segment_size(q))
58                goto new_segment;
59
60            seg_size += iv->bv_len;
61        } else {
62new_segment:
63            segments++;
64            seg_size = iv->bv_len;
65        }
66
67        ivprv = iv;
68    }
69
70    return segments;
71}
72EXPORT_SYMBOL(blk_rq_count_integrity_sg);
73
74/**
75 * blk_rq_map_integrity_sg - Map integrity metadata into a scatterlist
76 * @q: request queue
77 * @bio: bio with integrity metadata attached
78 * @sglist: target scatterlist
79 *
80 * Description: Map the integrity vectors in request into a
81 * scatterlist. The scatterlist must be big enough to hold all
82 * elements. I.e. sized using blk_rq_count_integrity_sg().
83 */
84int blk_rq_map_integrity_sg(struct request_queue *q, struct bio *bio,
85                struct scatterlist *sglist)
86{
87    struct bio_vec *iv, *ivprv = NULL;
88    struct scatterlist *sg = NULL;
89    unsigned int segments = 0;
90    unsigned int i = 0;
91
92    bio_for_each_integrity_vec(iv, bio, i) {
93
94        if (ivprv) {
95            if (!BIOVEC_PHYS_MERGEABLE(ivprv, iv))
96                goto new_segment;
97
98            if (!BIOVEC_SEG_BOUNDARY(q, ivprv, iv))
99                goto new_segment;
100
101            if (sg->length + iv->bv_len > queue_max_segment_size(q))
102                goto new_segment;
103
104            sg->length += iv->bv_len;
105        } else {
106new_segment:
107            if (!sg)
108                sg = sglist;
109            else {
110                sg->page_link &= ~0x02;
111                sg = sg_next(sg);
112            }
113
114            sg_set_page(sg, iv->bv_page, iv->bv_len, iv->bv_offset);
115            segments++;
116        }
117
118        ivprv = iv;
119    }
120
121    if (sg)
122        sg_mark_end(sg);
123
124    return segments;
125}
126EXPORT_SYMBOL(blk_rq_map_integrity_sg);
127
128/**
129 * blk_integrity_compare - Compare integrity profile of two disks
130 * @gd1: Disk to compare
131 * @gd2: Disk to compare
132 *
133 * Description: Meta-devices like DM and MD need to verify that all
134 * sub-devices use the same integrity format before advertising to
135 * upper layers that they can send/receive integrity metadata. This
136 * function can be used to check whether two gendisk devices have
137 * compatible integrity formats.
138 */
139int blk_integrity_compare(struct gendisk *gd1, struct gendisk *gd2)
140{
141    struct blk_integrity *b1 = gd1->integrity;
142    struct blk_integrity *b2 = gd2->integrity;
143
144    if (!b1 && !b2)
145        return 0;
146
147    if (!b1 || !b2)
148        return -1;
149
150    if (b1->sector_size != b2->sector_size) {
151        printk(KERN_ERR "%s: %s/%s sector sz %u != %u\n", __func__,
152               gd1->disk_name, gd2->disk_name,
153               b1->sector_size, b2->sector_size);
154        return -1;
155    }
156
157    if (b1->tuple_size != b2->tuple_size) {
158        printk(KERN_ERR "%s: %s/%s tuple sz %u != %u\n", __func__,
159               gd1->disk_name, gd2->disk_name,
160               b1->tuple_size, b2->tuple_size);
161        return -1;
162    }
163
164    if (b1->tag_size && b2->tag_size && (b1->tag_size != b2->tag_size)) {
165        printk(KERN_ERR "%s: %s/%s tag sz %u != %u\n", __func__,
166               gd1->disk_name, gd2->disk_name,
167               b1->tag_size, b2->tag_size);
168        return -1;
169    }
170
171    if (strcmp(b1->name, b2->name)) {
172        printk(KERN_ERR "%s: %s/%s type %s != %s\n", __func__,
173               gd1->disk_name, gd2->disk_name,
174               b1->name, b2->name);
175        return -1;
176    }
177
178    return 0;
179}
180EXPORT_SYMBOL(blk_integrity_compare);
181
182int blk_integrity_merge_rq(struct request_queue *q, struct request *req,
183               struct request *next)
184{
185    if (blk_integrity_rq(req) != blk_integrity_rq(next))
186        return -1;
187
188    if (req->nr_integrity_segments + next->nr_integrity_segments >
189        q->limits.max_integrity_segments)
190        return -1;
191
192    return 0;
193}
194EXPORT_SYMBOL(blk_integrity_merge_rq);
195
196int blk_integrity_merge_bio(struct request_queue *q, struct request *req,
197                struct bio *bio)
198{
199    int nr_integrity_segs;
200    struct bio *next = bio->bi_next;
201
202    bio->bi_next = NULL;
203    nr_integrity_segs = blk_rq_count_integrity_sg(q, bio);
204    bio->bi_next = next;
205
206    if (req->nr_integrity_segments + nr_integrity_segs >
207        q->limits.max_integrity_segments)
208        return -1;
209
210    req->nr_integrity_segments += nr_integrity_segs;
211
212    return 0;
213}
214EXPORT_SYMBOL(blk_integrity_merge_bio);
215
216struct integrity_sysfs_entry {
217    struct attribute attr;
218    ssize_t (*show)(struct blk_integrity *, char *);
219    ssize_t (*store)(struct blk_integrity *, const char *, size_t);
220};
221
222static ssize_t integrity_attr_show(struct kobject *kobj, struct attribute *attr,
223                   char *page)
224{
225    struct blk_integrity *bi =
226        container_of(kobj, struct blk_integrity, kobj);
227    struct integrity_sysfs_entry *entry =
228        container_of(attr, struct integrity_sysfs_entry, attr);
229
230    return entry->show(bi, page);
231}
232
233static ssize_t integrity_attr_store(struct kobject *kobj,
234                    struct attribute *attr, const char *page,
235                    size_t count)
236{
237    struct blk_integrity *bi =
238        container_of(kobj, struct blk_integrity, kobj);
239    struct integrity_sysfs_entry *entry =
240        container_of(attr, struct integrity_sysfs_entry, attr);
241    ssize_t ret = 0;
242
243    if (entry->store)
244        ret = entry->store(bi, page, count);
245
246    return ret;
247}
248
249static ssize_t integrity_format_show(struct blk_integrity *bi, char *page)
250{
251    if (bi != NULL && bi->name != NULL)
252        return sprintf(page, "%s\n", bi->name);
253    else
254        return sprintf(page, "none\n");
255}
256
257static ssize_t integrity_tag_size_show(struct blk_integrity *bi, char *page)
258{
259    if (bi != NULL)
260        return sprintf(page, "%u\n", bi->tag_size);
261    else
262        return sprintf(page, "0\n");
263}
264
265static ssize_t integrity_read_store(struct blk_integrity *bi,
266                    const char *page, size_t count)
267{
268    char *p = (char *) page;
269    unsigned long val = simple_strtoul(p, &p, 10);
270
271    if (val)
272        bi->flags |= INTEGRITY_FLAG_READ;
273    else
274        bi->flags &= ~INTEGRITY_FLAG_READ;
275
276    return count;
277}
278
279static ssize_t integrity_read_show(struct blk_integrity *bi, char *page)
280{
281    return sprintf(page, "%d\n", (bi->flags & INTEGRITY_FLAG_READ) != 0);
282}
283
284static ssize_t integrity_write_store(struct blk_integrity *bi,
285                     const char *page, size_t count)
286{
287    char *p = (char *) page;
288    unsigned long val = simple_strtoul(p, &p, 10);
289
290    if (val)
291        bi->flags |= INTEGRITY_FLAG_WRITE;
292    else
293        bi->flags &= ~INTEGRITY_FLAG_WRITE;
294
295    return count;
296}
297
298static ssize_t integrity_write_show(struct blk_integrity *bi, char *page)
299{
300    return sprintf(page, "%d\n", (bi->flags & INTEGRITY_FLAG_WRITE) != 0);
301}
302
303static struct integrity_sysfs_entry integrity_format_entry = {
304    .attr = { .name = "format", .mode = S_IRUGO },
305    .show = integrity_format_show,
306};
307
308static struct integrity_sysfs_entry integrity_tag_size_entry = {
309    .attr = { .name = "tag_size", .mode = S_IRUGO },
310    .show = integrity_tag_size_show,
311};
312
313static struct integrity_sysfs_entry integrity_read_entry = {
314    .attr = { .name = "read_verify", .mode = S_IRUGO | S_IWUSR },
315    .show = integrity_read_show,
316    .store = integrity_read_store,
317};
318
319static struct integrity_sysfs_entry integrity_write_entry = {
320    .attr = { .name = "write_generate", .mode = S_IRUGO | S_IWUSR },
321    .show = integrity_write_show,
322    .store = integrity_write_store,
323};
324
325static struct attribute *integrity_attrs[] = {
326    &integrity_format_entry.attr,
327    &integrity_tag_size_entry.attr,
328    &integrity_read_entry.attr,
329    &integrity_write_entry.attr,
330    NULL,
331};
332
333static const struct sysfs_ops integrity_ops = {
334    .show = &integrity_attr_show,
335    .store = &integrity_attr_store,
336};
337
338static int __init blk_dev_integrity_init(void)
339{
340    integrity_cachep = kmem_cache_create("blkdev_integrity",
341                         sizeof(struct blk_integrity),
342                         0, SLAB_PANIC, NULL);
343    return 0;
344}
345subsys_initcall(blk_dev_integrity_init);
346
347static void blk_integrity_release(struct kobject *kobj)
348{
349    struct blk_integrity *bi =
350        container_of(kobj, struct blk_integrity, kobj);
351
352    kmem_cache_free(integrity_cachep, bi);
353}
354
355static struct kobj_type integrity_ktype = {
356    .default_attrs = integrity_attrs,
357    .sysfs_ops = &integrity_ops,
358    .release = blk_integrity_release,
359};
360
361/**
362 * blk_integrity_register - Register a gendisk as being integrity-capable
363 * @disk: struct gendisk pointer to make integrity-aware
364 * @template: optional integrity profile to register
365 *
366 * Description: When a device needs to advertise itself as being able
367 * to send/receive integrity metadata it must use this function to
368 * register the capability with the block layer. The template is a
369 * blk_integrity struct with values appropriate for the underlying
370 * hardware. If template is NULL the new profile is allocated but
371 * not filled out. See Documentation/block/data-integrity.txt.
372 */
373int blk_integrity_register(struct gendisk *disk, struct blk_integrity *template)
374{
375    struct blk_integrity *bi;
376
377    BUG_ON(disk == NULL);
378
379    if (disk->integrity == NULL) {
380        bi = kmem_cache_alloc(integrity_cachep,
381                      GFP_KERNEL | __GFP_ZERO);
382        if (!bi)
383            return -1;
384
385        if (kobject_init_and_add(&bi->kobj, &integrity_ktype,
386                     &disk_to_dev(disk)->kobj,
387                     "%s", "integrity")) {
388            kmem_cache_free(integrity_cachep, bi);
389            return -1;
390        }
391
392        kobject_uevent(&bi->kobj, KOBJ_ADD);
393
394        bi->flags |= INTEGRITY_FLAG_READ | INTEGRITY_FLAG_WRITE;
395        bi->sector_size = queue_logical_block_size(disk->queue);
396        disk->integrity = bi;
397    } else
398        bi = disk->integrity;
399
400    /* Use the provided profile as template */
401    if (template != NULL) {
402        bi->name = template->name;
403        bi->generate_fn = template->generate_fn;
404        bi->verify_fn = template->verify_fn;
405        bi->tuple_size = template->tuple_size;
406        bi->set_tag_fn = template->set_tag_fn;
407        bi->get_tag_fn = template->get_tag_fn;
408        bi->tag_size = template->tag_size;
409    } else
410        bi->name = "unsupported";
411
412    return 0;
413}
414EXPORT_SYMBOL(blk_integrity_register);
415
416/**
417 * blk_integrity_unregister - Remove block integrity profile
418 * @disk: disk whose integrity profile to deallocate
419 *
420 * Description: This function frees all memory used by the block
421 * integrity profile. To be called at device teardown.
422 */
423void blk_integrity_unregister(struct gendisk *disk)
424{
425    struct blk_integrity *bi;
426
427    if (!disk || !disk->integrity)
428        return;
429
430    bi = disk->integrity;
431
432    kobject_uevent(&bi->kobj, KOBJ_REMOVE);
433    kobject_del(&bi->kobj);
434    kobject_put(&bi->kobj);
435    disk->integrity = NULL;
436}
437EXPORT_SYMBOL(blk_integrity_unregister);
438

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