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
  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:   integrity profile
 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.  See Documentation/block/data-integrity.txt.
 319 */
 320int blk_integrity_register(struct gendisk *disk, struct blk_integrity *template)
 321{
 322        struct blk_integrity *bi;
 323
 324        BUG_ON(disk == NULL);
 325        BUG_ON(template == 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 = disk->queue->hardsect_size;
 344                disk->integrity = bi;
 345        } else
 346                bi = disk->integrity;
 347
 348        /* Use the provided profile as template */
 349        bi->name = template->name;
 350        bi->generate_fn = template->generate_fn;
 351        bi->verify_fn = template->verify_fn;
 352        bi->tuple_size = template->tuple_size;
 353        bi->set_tag_fn = template->set_tag_fn;
 354        bi->get_tag_fn = template->get_tag_fn;
 355        bi->tag_size = template->tag_size;
 356
 357        return 0;
 358}
 359EXPORT_SYMBOL(blk_integrity_register);
 360
 361/**
 362 * blk_integrity_unregister - Remove block integrity profile
 363 * @disk:       disk whose integrity profile to deallocate
 364 *
 365 * Description: This function frees all memory used by the block
 366 * integrity profile.  To be called at device teardown.
 367 */
 368void blk_integrity_unregister(struct gendisk *disk)
 369{
 370        struct blk_integrity *bi;
 371
 372        if (!disk || !disk->integrity)
 373                return;
 374
 375        bi = disk->integrity;
 376
 377        kobject_uevent(&bi->kobj, KOBJ_REMOVE);
 378        kobject_del(&bi->kobj);
 379        kmem_cache_free(integrity_cachep, bi);
 380        disk->integrity = NULL;
 381}
 382EXPORT_SYMBOL(blk_integrity_unregister);
 383
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