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
  31 static struct kmem_cache *integrity_cachep;
  32
  33 static const char *bi_unsupported_name = "unsupported";
  34
  35 /**
  36  * blk_rq_count_integrity_sg - Count number of integrity scatterlist elements
  37  * @q:          request queue
  38  * @bio:        bio with integrity metadata attached
  39  *
  40  * Description: Returns the number of elements required in a
  41  * scatterlist corresponding to the integrity metadata in a bio.
  42  */
  43 int blk_rq_count_integrity_sg(struct request_queue *q, struct bio *bio)
  44 {
  45         struct bio_vec *iv, *ivprv = NULL;
  46         unsigned int segments = 0;
  47         unsigned int seg_size = 0;
  48         unsigned int i = 0;
  49
  50         bio_for_each_integrity_vec(iv, bio, i) {
  51
  52                 if (ivprv) {
  53                         if (!BIOVEC_PHYS_MERGEABLE(ivprv, iv))
  54                                 goto new_segment;
  55
  56                         if (!BIOVEC_SEG_BOUNDARY(q, ivprv, iv))
  57                                 goto new_segment;
  58
  59                         if (seg_size + iv->bv_len > queue_max_segment_size(q))
  60                                 goto new_segment;
  61
  62                         seg_size += iv->bv_len;
  63                 } else {
  64 new_segment:
  65                         segments++;
  66                         seg_size = iv->bv_len;
  67                 }
  68
  69                 ivprv = iv;
  70         }
  71
  72         return segments;
  73 }
  74 EXPORT_SYMBOL(blk_rq_count_integrity_sg);
  75
  76 /**
  77  * blk_rq_map_integrity_sg - Map integrity metadata into a scatterlist
  78  * @q:          request queue
  79  * @bio:        bio with integrity metadata attached
  80  * @sglist:     target scatterlist
  81  *
  82  * Description: Map the integrity vectors in request into a
  83  * scatterlist.  The scatterlist must be big enough to hold all
  84  * elements.  I.e. sized using blk_rq_count_integrity_sg().
  85  */
  86 int blk_rq_map_integrity_sg(struct request_queue *q, struct bio *bio,
  87                             struct scatterlist *sglist)
  88 {
  89         struct bio_vec *iv, *ivprv = NULL;
  90         struct scatterlist *sg = NULL;
  91         unsigned int segments = 0;
  92         unsigned int i = 0;
  93
  94         bio_for_each_integrity_vec(iv, bio, i) {
  95
  96                 if (ivprv) {
  97                         if (!BIOVEC_PHYS_MERGEABLE(ivprv, iv))
  98                                 goto new_segment;
  99
 100                         if (!BIOVEC_SEG_BOUNDARY(q, ivprv, iv))
 101                                 goto new_segment;
 102
 103                         if (sg->length + iv->bv_len > queue_max_segment_size(q))
 104                                 goto new_segment;
 105
 106                         sg->length += iv->bv_len;
 107                 } else {
 108 new_segment:
 109                         if (!sg)
 110                                 sg = sglist;
 111                         else {
 112                                 sg->page_link &= ~0x02;
 113                                 sg = sg_next(sg);
 114                         }
 115
 116                         sg_set_page(sg, iv->bv_page, iv->bv_len, iv->bv_offset);
 117                         segments++;
 118                 }
 119
 120                 ivprv = iv;
 121         }
 122
 123         if (sg)
 124                 sg_mark_end(sg);
 125
 126         return segments;
 127 }
 128 EXPORT_SYMBOL(blk_rq_map_integrity_sg);
 129
 130 /**
 131  * blk_integrity_compare - Compare integrity profile of two disks
 132  * @gd1:        Disk to compare
 133  * @gd2:        Disk to compare
 134  *
 135  * Description: Meta-devices like DM and MD need to verify that all
 136  * sub-devices use the same integrity format before advertising to
 137  * upper layers that they can send/receive integrity metadata.  This
 138  * function can be used to check whether two gendisk devices have
 139  * compatible integrity formats.
 140  */
 141 int blk_integrity_compare(struct gendisk *gd1, struct gendisk *gd2)
 142 {
 143         struct blk_integrity *b1 = gd1->integrity;
 144         struct blk_integrity *b2 = gd2->integrity;
 145
 146         if (!b1 && !b2)
 147                 return 0;
 148
 149         if (!b1 || !b2)
 150                 return -1;
 151
 152         if (b1->sector_size != b2->sector_size) {
 153                 printk(KERN_ERR "%s: %s/%s sector sz %u != %u\n", __func__,
 154                        gd1->disk_name, gd2->disk_name,
 155                        b1->sector_size, b2->sector_size);
 156                 return -1;
 157         }
 158
 159         if (b1->tuple_size != b2->tuple_size) {
 160                 printk(KERN_ERR "%s: %s/%s tuple sz %u != %u\n", __func__,
 161                        gd1->disk_name, gd2->disk_name,
 162                        b1->tuple_size, b2->tuple_size);
 163                 return -1;
 164         }
 165
 166         if (b1->tag_size && b2->tag_size && (b1->tag_size != b2->tag_size)) {
 167                 printk(KERN_ERR "%s: %s/%s tag sz %u != %u\n", __func__,
 168                        gd1->disk_name, gd2->disk_name,
 169                        b1->tag_size, b2->tag_size);
 170                 return -1;
 171         }
 172
 173         if (strcmp(b1->name, b2->name)) {
 174                 printk(KERN_ERR "%s: %s/%s type %s != %s\n", __func__,
 175                        gd1->disk_name, gd2->disk_name,
 176                        b1->name, b2->name);
 177                 return -1;
 178         }
 179
 180         return 0;
 181 }
 182 EXPORT_SYMBOL(blk_integrity_compare);
 183
 184 int blk_integrity_merge_rq(struct request_queue *q, struct request *req,
 185                            struct request *next)
 186 {
 187         if (blk_integrity_rq(req) != blk_integrity_rq(next))
 188                 return -1;
 189
 190         if (req->nr_integrity_segments + next->nr_integrity_segments >
 191             q->limits.max_integrity_segments)
 192                 return -1;
 193
 194         return 0;
 195 }
 196 EXPORT_SYMBOL(blk_integrity_merge_rq);
 197
 198 int blk_integrity_merge_bio(struct request_queue *q, struct request *req,
 199                             struct bio *bio)
 200 {
 201         int nr_integrity_segs;
 202         struct bio *next = bio->bi_next;
 203
 204         bio->bi_next = NULL;
 205         nr_integrity_segs = blk_rq_count_integrity_sg(q, bio);
 206         bio->bi_next = next;
 207
 208         if (req->nr_integrity_segments + nr_integrity_segs >
 209             q->limits.max_integrity_segments)
 210                 return -1;
 211
 212         req->nr_integrity_segments += nr_integrity_segs;
 213
 214         return 0;
 215 }
 216 EXPORT_SYMBOL(blk_integrity_merge_bio);
 217
 218 struct integrity_sysfs_entry {
 219         struct attribute attr;
 220         ssize_t (*show)(struct blk_integrity *, char *);
 221         ssize_t (*store)(struct blk_integrity *, const char *, size_t);
 222 };
 223
 224 static ssize_t integrity_attr_show(struct kobject *kobj, struct attribute *attr,
 225                                    char *page)
 226 {
 227         struct blk_integrity *bi =
 228                 container_of(kobj, struct blk_integrity, kobj);
 229         struct integrity_sysfs_entry *entry =
 230                 container_of(attr, struct integrity_sysfs_entry, attr);
 231
 232         return entry->show(bi, page);
 233 }
 234
 235 static ssize_t integrity_attr_store(struct kobject *kobj,
 236                                     struct attribute *attr, const char *page,
 237                                     size_t count)
 238 {
 239         struct blk_integrity *bi =
 240                 container_of(kobj, struct blk_integrity, kobj);
 241         struct integrity_sysfs_entry *entry =
 242                 container_of(attr, struct integrity_sysfs_entry, attr);
 243         ssize_t ret = 0;
 244
 245         if (entry->store)
 246                 ret = entry->store(bi, page, count);
 247
 248         return ret;
 249 }
 250
 251 static ssize_t integrity_format_show(struct blk_integrity *bi, char *page)
 252 {
 253         if (bi != NULL && bi->name != NULL)
 254                 return sprintf(page, "%s\n", bi->name);
 255         else
 256                 return sprintf(page, "none\n");
 257 }
 258
 259 static ssize_t integrity_tag_size_show(struct blk_integrity *bi, char *page)
 260 {
 261         if (bi != NULL)
 262                 return sprintf(page, "%u\n", bi->tag_size);
 263         else
 264                 return sprintf(page, "0\n");
 265 }
 266
 267 static ssize_t integrity_read_store(struct blk_integrity *bi,
 268                                     const char *page, size_t count)
 269 {
 270         char *p = (char *) page;
 271         unsigned long val = simple_strtoul(p, &p, 10);
 272
 273         if (val)
 274                 bi->flags |= INTEGRITY_FLAG_READ;
 275         else
 276                 bi->flags &= ~INTEGRITY_FLAG_READ;
 277
 278         return count;
 279 }
 280
 281 static ssize_t integrity_read_show(struct blk_integrity *bi, char *page)
 282 {
 283         return sprintf(page, "%d\n", (bi->flags & INTEGRITY_FLAG_READ) != 0);
 284 }
 285
 286 static ssize_t integrity_write_store(struct blk_integrity *bi,
 287                                      const char *page, size_t count)
 288 {
 289         char *p = (char *) page;
 290         unsigned long val = simple_strtoul(p, &p, 10);
 291
 292         if (val)
 293                 bi->flags |= INTEGRITY_FLAG_WRITE;
 294         else
 295                 bi->flags &= ~INTEGRITY_FLAG_WRITE;
 296
 297         return count;
 298 }
 299
 300 static ssize_t integrity_write_show(struct blk_integrity *bi, char *page)
 301 {
 302         return sprintf(page, "%d\n", (bi->flags & INTEGRITY_FLAG_WRITE) != 0);
 303 }
 304
 305 static struct integrity_sysfs_entry integrity_format_entry = {
 306         .attr = { .name = "format", .mode = S_IRUGO },
 307         .show = integrity_format_show,
 308 };
 309
 310 static struct integrity_sysfs_entry integrity_tag_size_entry = {
 311         .attr = { .name = "tag_size", .mode = S_IRUGO },
 312         .show = integrity_tag_size_show,
 313 };
 314
 315 static struct integrity_sysfs_entry integrity_read_entry = {
 316         .attr = { .name = "read_verify", .mode = S_IRUGO | S_IWUSR },
 317         .show = integrity_read_show,
 318         .store = integrity_read_store,
 319 };
 320
 321 static struct integrity_sysfs_entry integrity_write_entry = {
 322         .attr = { .name = "write_generate", .mode = S_IRUGO | S_IWUSR },
 323         .show = integrity_write_show,
 324         .store = integrity_write_store,
 325 };
 326
 327 static struct attribute *integrity_attrs[] = {
 328         &integrity_format_entry.attr,
 329         &integrity_tag_size_entry.attr,
 330         &integrity_read_entry.attr,
 331         &integrity_write_entry.attr,
 332         NULL,
 333 };
 334
 335 static const struct sysfs_ops integrity_ops = {
 336         .show   = &integrity_attr_show,
 337         .store  = &integrity_attr_store,
 338 };
 339
 340 static int __init blk_dev_integrity_init(void)
 341 {
 342         integrity_cachep = kmem_cache_create("blkdev_integrity",
 343                                              sizeof(struct blk_integrity),
 344                                              0, SLAB_PANIC, NULL);
 345         return 0;
 346 }
 347 subsys_initcall(blk_dev_integrity_init);
 348
 349 static void blk_integrity_release(struct kobject *kobj)
 350 {
 351         struct blk_integrity *bi =
 352                 container_of(kobj, struct blk_integrity, kobj);
 353
 354         kmem_cache_free(integrity_cachep, bi);
 355 }
 356
 357 static struct kobj_type integrity_ktype = {
 358         .default_attrs  = integrity_attrs,
 359         .sysfs_ops      = &integrity_ops,
 360         .release        = blk_integrity_release,
 361 };
 362
 363 bool blk_integrity_is_initialized(struct gendisk *disk)
 364 {
 365         struct blk_integrity *bi = blk_get_integrity(disk);
 366
 367         return (bi && bi->name && strcmp(bi->name, bi_unsupported_name) != 0);
 368 }
 369 EXPORT_SYMBOL(blk_integrity_is_initialized);
 370
 371 /**
 372  * blk_integrity_register - Register a gendisk as being integrity-capable
 373  * @disk:       struct gendisk pointer to make integrity-aware
 374  * @template:   optional integrity profile to register
 375  *
 376  * Description: When a device needs to advertise itself as being able
 377  * to send/receive integrity metadata it must use this function to
 378  * register the capability with the block layer.  The template is a
 379  * blk_integrity struct with values appropriate for the underlying
 380  * hardware.  If template is NULL the new profile is allocated but
 381  * not filled out. See Documentation/block/data-integrity.txt.
 382  */
 383 int blk_integrity_register(struct gendisk *disk, struct blk_integrity *template)
 384 {
 385         struct blk_integrity *bi;
 386
 387         BUG_ON(disk == NULL);
 388
 389         if (disk->integrity == NULL) {
 390                 bi = kmem_cache_alloc(integrity_cachep,
 391                                       GFP_KERNEL | __GFP_ZERO);
 392                 if (!bi)
 393                         return -1;
 394
 395                 if (kobject_init_and_add(&bi->kobj, &integrity_ktype,
 396                                          &disk_to_dev(disk)->kobj,
 397                                          "%s", "integrity")) {
 398                         kmem_cache_free(integrity_cachep, bi);
 399                         return -1;
 400                 }
 401
 402                 kobject_uevent(&bi->kobj, KOBJ_ADD);
 403
 404                 bi->flags |= INTEGRITY_FLAG_READ | INTEGRITY_FLAG_WRITE;
 405                 bi->sector_size = queue_logical_block_size(disk->queue);
 406                 disk->integrity = bi;
 407         } else
 408                 bi = disk->integrity;
 409
 410         /* Use the provided profile as template */
 411         if (template != NULL) {
 412                 bi->name = template->name;
 413                 bi->generate_fn = template->generate_fn;
 414                 bi->verify_fn = template->verify_fn;
 415                 bi->tuple_size = template->tuple_size;
 416                 bi->set_tag_fn = template->set_tag_fn;
 417                 bi->get_tag_fn = template->get_tag_fn;
 418                 bi->tag_size = template->tag_size;
 419         } else
 420                 bi->name = bi_unsupported_name;
 421
 422         return 0;
 423 }
 424 EXPORT_SYMBOL(blk_integrity_register);
 425
 426 /**
 427  * blk_integrity_unregister - Remove block integrity profile
 428  * @disk:       disk whose integrity profile to deallocate
 429  *
 430  * Description: This function frees all memory used by the block
 431  * integrity profile.  To be called at device teardown.
 432  */
 433 void blk_integrity_unregister(struct gendisk *disk)
 434 {
 435         struct blk_integrity *bi;
 436
 437         if (!disk || !disk->integrity)
 438                 return;
 439
 440         bi = disk->integrity;
 441
 442         kobject_uevent(&bi->kobj, KOBJ_REMOVE);
 443         kobject_del(&bi->kobj);
 444         kobject_put(&bi->kobj);
 445         disk->integrity = NULL;
 446 }
 447 EXPORT_SYMBOL(blk_integrity_unregister);