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/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_unmark_end(sg);
 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        disk->queue->backing_dev_info.capabilities |= BDI_CAP_STABLE_WRITES;
 424
 425        return 0;
 426}
 427EXPORT_SYMBOL(blk_integrity_register);
 428
 429/**
 430 * blk_integrity_unregister - Remove block integrity profile
 431 * @disk:       disk whose integrity profile to deallocate
 432 *
 433 * Description: This function frees all memory used by the block
 434 * integrity profile.  To be called at device teardown.
 435 */
 436void blk_integrity_unregister(struct gendisk *disk)
 437{
 438        struct blk_integrity *bi;
 439
 440        if (!disk || !disk->integrity)
 441                return;
 442
 443        disk->queue->backing_dev_info.capabilities &= ~BDI_CAP_STABLE_WRITES;
 444
 445        bi = disk->integrity;
 446
 447        kobject_uevent(&bi->kobj, KOBJ_REMOVE);
 448        kobject_del(&bi->kobj);
 449        kobject_put(&bi->kobj);
 450        disk->integrity = NULL;
 451}
 452EXPORT_SYMBOL(blk_integrity_unregister);
 453
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