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

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