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
  28 #include "blk.h"
  29
  30 static 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  */
  39 int 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 }
  58 EXPORT_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  */
  69 int 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 {
  88 new_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 }
 108 EXPORT_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  */
 121 int 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 }
 162 EXPORT_SYMBOL(blk_integrity_compare);
 163
 164 struct 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
 170 static 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
 181 static 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
 197 static 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
 205 static 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
 213 static 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
 227 static 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
 232 static 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
 246 static 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
 251 static struct integrity_sysfs_entry integrity_format_entry = {
 252         .attr = { .name = "format", .mode = S_IRUGO },
 253         .show = integrity_format_show,
 254 };
 255
 256 static struct integrity_sysfs_entry integrity_tag_size_entry = {
 257         .attr = { .name = "tag_size", .mode = S_IRUGO },
 258         .show = integrity_tag_size_show,
 259 };
 260
 261 static 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
 267 static 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
 273 static 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
 281 static struct sysfs_ops integrity_ops = {
 282         .show   = &integrity_attr_show,
 283         .store  = &integrity_attr_store,
 284 };
 285
 286 static 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 }
 293 subsys_initcall(blk_dev_integrity_init);
 294
 295 static 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
 303 static 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:   optional integrity profile to register
 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.  If template is NULL the new profile is allocated but
 319  * not filled out. See Documentation/block/data-integrity.txt.
 320  */
 321 int blk_integrity_register(struct gendisk *disk, struct blk_integrity *template)
 322 {
 323         struct blk_integrity *bi;
 324
 325         BUG_ON(disk == 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         if (template != NULL) {
 350                 bi->name = template->name;
 351                 bi->generate_fn = template->generate_fn;
 352                 bi->verify_fn = template->verify_fn;
 353                 bi->tuple_size = template->tuple_size;
 354                 bi->set_tag_fn = template->set_tag_fn;
 355                 bi->get_tag_fn = template->get_tag_fn;
 356                 bi->tag_size = template->tag_size;
 357         } else
 358                 bi->name = "unsupported";
 359
 360         return 0;
 361 }
 362 EXPORT_SYMBOL(blk_integrity_register);
 363
 364 /**
 365  * blk_integrity_unregister - Remove block integrity profile
 366  * @disk:       disk whose integrity profile to deallocate
 367  *
 368  * Description: This function frees all memory used by the block
 369  * integrity profile.  To be called at device teardown.
 370  */
 371 void blk_integrity_unregister(struct gendisk *disk)
 372 {
 373         struct blk_integrity *bi;
 374
 375         if (!disk || !disk->integrity)
 376                 return;
 377
 378         bi = disk->integrity;
 379
 380         kobject_uevent(&bi->kobj, KOBJ_REMOVE);
 381         kobject_del(&bi->kobj);
 382         kmem_cache_free(integrity_cachep, bi);
 383         disk->integrity = NULL;
 384 }
 385 EXPORT_SYMBOL(blk_integrity_unregister);