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/backing-dev.h>
  25 #include <linux/mempool.h>
  26 #include <linux/bio.h>
  27 #include <linux/scatterlist.h>
  28 #include <linux/export.h>
  29 #include <linux/slab.h>
  30
  31 #include "blk.h"
  32
  33 static struct kmem_cache *integrity_cachep;
  34
  35 static const char *bi_unsupported_name = "unsupported";
  36
  37 /**
  38  * blk_rq_count_integrity_sg - Count number of integrity scatterlist elements
  39  * @q:          request queue
  40  * @bio:        bio with integrity metadata attached
  41  *
  42  * Description: Returns the number of elements required in a
  43  * scatterlist corresponding to the integrity metadata in a bio.
  44  */
  45 int blk_rq_count_integrity_sg(struct request_queue *q, struct bio *bio)
  46 {
  47         struct bio_vec iv, ivprv = { NULL };
  48         unsigned int segments = 0;
  49         unsigned int seg_size = 0;
  50         struct bvec_iter iter;
  51         int prev = 0;
  52
  53         bio_for_each_integrity_vec(iv, bio, iter) {
  54
  55                 if (prev) {
  56                         if (!BIOVEC_PHYS_MERGEABLE(&ivprv, &iv))
  57                                 goto new_segment;
  58
  59                         if (!BIOVEC_SEG_BOUNDARY(q, &ivprv, &iv))
  60                                 goto new_segment;
  61
  62                         if (seg_size + iv.bv_len > queue_max_segment_size(q))
  63                                 goto new_segment;
  64
  65                         seg_size += iv.bv_len;
  66                 } else {
  67 new_segment:
  68                         segments++;
  69                         seg_size = iv.bv_len;
  70                 }
  71
  72                 prev = 1;
  73                 ivprv = iv;
  74         }
  75
  76         return segments;
  77 }
  78 EXPORT_SYMBOL(blk_rq_count_integrity_sg);
  79
  80 /**
  81  * blk_rq_map_integrity_sg - Map integrity metadata into a scatterlist
  82  * @q:          request queue
  83  * @bio:        bio with integrity metadata attached
  84  * @sglist:     target scatterlist
  85  *
  86  * Description: Map the integrity vectors in request into a
  87  * scatterlist.  The scatterlist must be big enough to hold all
  88  * elements.  I.e. sized using blk_rq_count_integrity_sg().
  89  */
  90 int blk_rq_map_integrity_sg(struct request_queue *q, struct bio *bio,
  91                             struct scatterlist *sglist)
  92 {
  93         struct bio_vec iv, ivprv = { NULL };
  94         struct scatterlist *sg = NULL;
  95         unsigned int segments = 0;
  96         struct bvec_iter iter;
  97         int prev = 0;
  98
  99         bio_for_each_integrity_vec(iv, bio, iter) {
 100
 101                 if (prev) {
 102                         if (!BIOVEC_PHYS_MERGEABLE(&ivprv, &iv))
 103                                 goto new_segment;
 104
 105                         if (!BIOVEC_SEG_BOUNDARY(q, &ivprv, &iv))
 106                                 goto new_segment;
 107
 108                         if (sg->length + iv.bv_len > queue_max_segment_size(q))
 109                                 goto new_segment;
 110
 111                         sg->length += iv.bv_len;
 112                 } else {
 113 new_segment:
 114                         if (!sg)
 115                                 sg = sglist;
 116                         else {
 117                                 sg_unmark_end(sg);
 118                                 sg = sg_next(sg);
 119                         }
 120
 121                         sg_set_page(sg, iv.bv_page, iv.bv_len, iv.bv_offset);
 122                         segments++;
 123                 }
 124
 125                 prev = 1;
 126                 ivprv = iv;
 127         }
 128
 129         if (sg)
 130                 sg_mark_end(sg);
 131
 132         return segments;
 133 }
 134 EXPORT_SYMBOL(blk_rq_map_integrity_sg);
 135
 136 /**
 137  * blk_integrity_compare - Compare integrity profile of two disks
 138  * @gd1:        Disk to compare
 139  * @gd2:        Disk to compare
 140  *
 141  * Description: Meta-devices like DM and MD need to verify that all
 142  * sub-devices use the same integrity format before advertising to
 143  * upper layers that they can send/receive integrity metadata.  This
 144  * function can be used to check whether two gendisk devices have
 145  * compatible integrity formats.
 146  */
 147 int blk_integrity_compare(struct gendisk *gd1, struct gendisk *gd2)
 148 {
 149         struct blk_integrity *b1 = gd1->integrity;
 150         struct blk_integrity *b2 = gd2->integrity;
 151
 152         if (!b1 && !b2)
 153                 return 0;
 154
 155         if (!b1 || !b2)
 156                 return -1;
 157
 158         if (b1->interval != b2->interval) {
 159                 pr_err("%s: %s/%s protection interval %u != %u\n",
 160                        __func__, gd1->disk_name, gd2->disk_name,
 161                        b1->interval, b2->interval);
 162                 return -1;
 163         }
 164
 165         if (b1->tuple_size != b2->tuple_size) {
 166                 printk(KERN_ERR "%s: %s/%s tuple sz %u != %u\n", __func__,
 167                        gd1->disk_name, gd2->disk_name,
 168                        b1->tuple_size, b2->tuple_size);
 169                 return -1;
 170         }
 171
 172         if (b1->tag_size && b2->tag_size && (b1->tag_size != b2->tag_size)) {
 173                 printk(KERN_ERR "%s: %s/%s tag sz %u != %u\n", __func__,
 174                        gd1->disk_name, gd2->disk_name,
 175                        b1->tag_size, b2->tag_size);
 176                 return -1;
 177         }
 178
 179         if (strcmp(b1->name, b2->name)) {
 180                 printk(KERN_ERR "%s: %s/%s type %s != %s\n", __func__,
 181                        gd1->disk_name, gd2->disk_name,
 182                        b1->name, b2->name);
 183                 return -1;
 184         }
 185
 186         return 0;
 187 }
 188 EXPORT_SYMBOL(blk_integrity_compare);
 189
 190 bool blk_integrity_merge_rq(struct request_queue *q, struct request *req,
 191                             struct request *next)
 192 {
 193         if (blk_integrity_rq(req) == 0 && blk_integrity_rq(next) == 0)
 194                 return true;
 195
 196         if (blk_integrity_rq(req) == 0 || blk_integrity_rq(next) == 0)
 197                 return false;
 198
 199         if (bio_integrity(req->bio)->bip_flags !=
 200             bio_integrity(next->bio)->bip_flags)
 201                 return false;
 202
 203         if (req->nr_integrity_segments + next->nr_integrity_segments >
 204             q->limits.max_integrity_segments)
 205                 return false;
 206
 207         if (integrity_req_gap_back_merge(req, next->bio))
 208                 return false;
 209
 210         return true;
 211 }
 212 EXPORT_SYMBOL(blk_integrity_merge_rq);
 213
 214 bool blk_integrity_merge_bio(struct request_queue *q, struct request *req,
 215                              struct bio *bio)
 216 {
 217         int nr_integrity_segs;
 218         struct bio *next = bio->bi_next;
 219
 220         if (blk_integrity_rq(req) == 0 && bio_integrity(bio) == NULL)
 221                 return true;
 222
 223         if (blk_integrity_rq(req) == 0 || bio_integrity(bio) == NULL)
 224                 return false;
 225
 226         if (bio_integrity(req->bio)->bip_flags != bio_integrity(bio)->bip_flags)
 227                 return false;
 228
 229         bio->bi_next = NULL;
 230         nr_integrity_segs = blk_rq_count_integrity_sg(q, bio);
 231         bio->bi_next = next;
 232
 233         if (req->nr_integrity_segments + nr_integrity_segs >
 234             q->limits.max_integrity_segments)
 235                 return false;
 236
 237         req->nr_integrity_segments += nr_integrity_segs;
 238
 239         return true;
 240 }
 241 EXPORT_SYMBOL(blk_integrity_merge_bio);
 242
 243 struct integrity_sysfs_entry {
 244         struct attribute attr;
 245         ssize_t (*show)(struct blk_integrity *, char *);
 246         ssize_t (*store)(struct blk_integrity *, const char *, size_t);
 247 };
 248
 249 static ssize_t integrity_attr_show(struct kobject *kobj, struct attribute *attr,
 250                                    char *page)
 251 {
 252         struct blk_integrity *bi =
 253                 container_of(kobj, struct blk_integrity, kobj);
 254         struct integrity_sysfs_entry *entry =
 255                 container_of(attr, struct integrity_sysfs_entry, attr);
 256
 257         return entry->show(bi, page);
 258 }
 259
 260 static ssize_t integrity_attr_store(struct kobject *kobj,
 261                                     struct attribute *attr, const char *page,
 262                                     size_t count)
 263 {
 264         struct blk_integrity *bi =
 265                 container_of(kobj, struct blk_integrity, kobj);
 266         struct integrity_sysfs_entry *entry =
 267                 container_of(attr, struct integrity_sysfs_entry, attr);
 268         ssize_t ret = 0;
 269
 270         if (entry->store)
 271                 ret = entry->store(bi, page, count);
 272
 273         return ret;
 274 }
 275
 276 static ssize_t integrity_format_show(struct blk_integrity *bi, char *page)
 277 {
 278         if (bi != NULL && bi->name != NULL)
 279                 return sprintf(page, "%s\n", bi->name);
 280         else
 281                 return sprintf(page, "none\n");
 282 }
 283
 284 static ssize_t integrity_tag_size_show(struct blk_integrity *bi, char *page)
 285 {
 286         if (bi != NULL)
 287                 return sprintf(page, "%u\n", bi->tag_size);
 288         else
 289                 return sprintf(page, "0\n");
 290 }
 291
 292 static ssize_t integrity_verify_store(struct blk_integrity *bi,
 293                                       const char *page, size_t count)
 294 {
 295         char *p = (char *) page;
 296         unsigned long val = simple_strtoul(p, &p, 10);
 297
 298         if (val)
 299                 bi->flags |= BLK_INTEGRITY_VERIFY;
 300         else
 301                 bi->flags &= ~BLK_INTEGRITY_VERIFY;
 302
 303         return count;
 304 }
 305
 306 static ssize_t integrity_verify_show(struct blk_integrity *bi, char *page)
 307 {
 308         return sprintf(page, "%d\n", (bi->flags & BLK_INTEGRITY_VERIFY) != 0);
 309 }
 310
 311 static ssize_t integrity_generate_store(struct blk_integrity *bi,
 312                                         const char *page, size_t count)
 313 {
 314         char *p = (char *) page;
 315         unsigned long val = simple_strtoul(p, &p, 10);
 316
 317         if (val)
 318                 bi->flags |= BLK_INTEGRITY_GENERATE;
 319         else
 320                 bi->flags &= ~BLK_INTEGRITY_GENERATE;
 321
 322         return count;
 323 }
 324
 325 static ssize_t integrity_generate_show(struct blk_integrity *bi, char *page)
 326 {
 327         return sprintf(page, "%d\n", (bi->flags & BLK_INTEGRITY_GENERATE) != 0);
 328 }
 329
 330 static ssize_t integrity_device_show(struct blk_integrity *bi, char *page)
 331 {
 332         return sprintf(page, "%u\n",
 333                        (bi->flags & BLK_INTEGRITY_DEVICE_CAPABLE) != 0);
 334 }
 335
 336 static struct integrity_sysfs_entry integrity_format_entry = {
 337         .attr = { .name = "format", .mode = S_IRUGO },
 338         .show = integrity_format_show,
 339 };
 340
 341 static struct integrity_sysfs_entry integrity_tag_size_entry = {
 342         .attr = { .name = "tag_size", .mode = S_IRUGO },
 343         .show = integrity_tag_size_show,
 344 };
 345
 346 static struct integrity_sysfs_entry integrity_verify_entry = {
 347         .attr = { .name = "read_verify", .mode = S_IRUGO | S_IWUSR },
 348         .show = integrity_verify_show,
 349         .store = integrity_verify_store,
 350 };
 351
 352 static struct integrity_sysfs_entry integrity_generate_entry = {
 353         .attr = { .name = "write_generate", .mode = S_IRUGO | S_IWUSR },
 354         .show = integrity_generate_show,
 355         .store = integrity_generate_store,
 356 };
 357
 358 static struct integrity_sysfs_entry integrity_device_entry = {
 359         .attr = { .name = "device_is_integrity_capable", .mode = S_IRUGO },
 360         .show = integrity_device_show,
 361 };
 362
 363 static struct attribute *integrity_attrs[] = {
 364         &integrity_format_entry.attr,
 365         &integrity_tag_size_entry.attr,
 366         &integrity_verify_entry.attr,
 367         &integrity_generate_entry.attr,
 368         &integrity_device_entry.attr,
 369         NULL,
 370 };
 371
 372 static const struct sysfs_ops integrity_ops = {
 373         .show   = &integrity_attr_show,
 374         .store  = &integrity_attr_store,
 375 };
 376
 377 static int __init blk_dev_integrity_init(void)
 378 {
 379         integrity_cachep = kmem_cache_create("blkdev_integrity",
 380                                              sizeof(struct blk_integrity),
 381                                              0, SLAB_PANIC, NULL);
 382         return 0;
 383 }
 384 subsys_initcall(blk_dev_integrity_init);
 385
 386 static void blk_integrity_release(struct kobject *kobj)
 387 {
 388         struct blk_integrity *bi =
 389                 container_of(kobj, struct blk_integrity, kobj);
 390
 391         kmem_cache_free(integrity_cachep, bi);
 392 }
 393
 394 static struct kobj_type integrity_ktype = {
 395         .default_attrs  = integrity_attrs,
 396         .sysfs_ops      = &integrity_ops,
 397         .release        = blk_integrity_release,
 398 };
 399
 400 bool blk_integrity_is_initialized(struct gendisk *disk)
 401 {
 402         struct blk_integrity *bi = blk_get_integrity(disk);
 403
 404         return (bi && bi->name && strcmp(bi->name, bi_unsupported_name) != 0);
 405 }
 406 EXPORT_SYMBOL(blk_integrity_is_initialized);
 407
 408 /**
 409  * blk_integrity_register - Register a gendisk as being integrity-capable
 410  * @disk:       struct gendisk pointer to make integrity-aware
 411  * @template:   optional integrity profile to register
 412  *
 413  * Description: When a device needs to advertise itself as being able
 414  * to send/receive integrity metadata it must use this function to
 415  * register the capability with the block layer.  The template is a
 416  * blk_integrity struct with values appropriate for the underlying
 417  * hardware.  If template is NULL the new profile is allocated but
 418  * not filled out. See Documentation/block/data-integrity.txt.
 419  */
 420 int blk_integrity_register(struct gendisk *disk, struct blk_integrity *template)
 421 {
 422         struct blk_integrity *bi;
 423
 424         BUG_ON(disk == NULL);
 425
 426         if (disk->integrity == NULL) {
 427                 bi = kmem_cache_alloc(integrity_cachep,
 428                                       GFP_KERNEL | __GFP_ZERO);
 429                 if (!bi)
 430                         return -1;
 431
 432                 if (kobject_init_and_add(&bi->kobj, &integrity_ktype,
 433                                          &disk_to_dev(disk)->kobj,
 434                                          "%s", "integrity")) {
 435                         kmem_cache_free(integrity_cachep, bi);
 436                         return -1;
 437                 }
 438
 439                 kobject_uevent(&bi->kobj, KOBJ_ADD);
 440
 441                 bi->flags |= BLK_INTEGRITY_VERIFY | BLK_INTEGRITY_GENERATE;
 442                 bi->interval = queue_logical_block_size(disk->queue);
 443                 disk->integrity = bi;
 444         } else
 445                 bi = disk->integrity;
 446
 447         /* Use the provided profile as template */
 448         if (template != NULL) {
 449                 bi->name = template->name;
 450                 bi->generate_fn = template->generate_fn;
 451                 bi->verify_fn = template->verify_fn;
 452                 bi->tuple_size = template->tuple_size;
 453                 bi->tag_size = template->tag_size;
 454                 bi->flags |= template->flags;
 455         } else
 456                 bi->name = bi_unsupported_name;
 457
 458         disk->queue->backing_dev_info.capabilities |= BDI_CAP_STABLE_WRITES;
 459
 460         return 0;
 461 }
 462 EXPORT_SYMBOL(blk_integrity_register);
 463
 464 /**
 465  * blk_integrity_unregister - Remove block integrity profile
 466  * @disk:       disk whose integrity profile to deallocate
 467  *
 468  * Description: This function frees all memory used by the block
 469  * integrity profile.  To be called at device teardown.
 470  */
 471 void blk_integrity_unregister(struct gendisk *disk)
 472 {
 473         struct blk_integrity *bi;
 474
 475         if (!disk || !disk->integrity)
 476                 return;
 477
 478         disk->queue->backing_dev_info.capabilities &= ~BDI_CAP_STABLE_WRITES;
 479
 480         bi = disk->integrity;
 481
 482         kobject_uevent(&bi->kobj, KOBJ_REMOVE);
 483         kobject_del(&bi->kobj);
 484         kobject_put(&bi->kobj);
 485         disk->integrity = NULL;
 486 }
 487 EXPORT_SYMBOL(blk_integrity_unregister);