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