block/bio-integrity.c

   1 /*
   2  * bio-integrity.c - bio data integrity extensions
   3  *
   4  * Copyright (C) 2007, 2008, 2009 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/export.h>
  26 #include <linux/bio.h>
  27 #include <linux/workqueue.h>
  28 #include <linux/slab.h>
  29
  30 #define BIP_INLINE_VECS 4
  31
  32 static struct kmem_cache *bip_slab;
  33 static struct workqueue_struct *kintegrityd_wq;
  34
  35 void blk_flush_integrity(void)
  36 {
  37         flush_workqueue(kintegrityd_wq);
  38 }
  39
  40 /**
  41  * bio_integrity_alloc - Allocate integrity payload and attach it to bio
  42  * @bio:        bio to attach integrity metadata to
  43  * @gfp_mask:   Memory allocation mask
  44  * @nr_vecs:    Number of integrity metadata scatter-gather elements
  45  *
  46  * Description: This function prepares a bio for attaching integrity
  47  * metadata.  nr_vecs specifies the maximum number of pages containing
  48  * integrity metadata that can be attached.
  49  */
  50 struct bio_integrity_payload *bio_integrity_alloc(struct bio *bio,
  51                                                   gfp_t gfp_mask,
  52                                                   unsigned int nr_vecs)
  53 {
  54         struct bio_integrity_payload *bip;
  55         struct bio_set *bs = bio->bi_pool;
  56         unsigned long idx = BIO_POOL_NONE;
  57         unsigned inline_vecs;
  58
  59         if (!bs || !bs->bio_integrity_pool) {
  60                 bip = kmalloc(sizeof(struct bio_integrity_payload) +
  61                               sizeof(struct bio_vec) * nr_vecs, gfp_mask);
  62                 inline_vecs = nr_vecs;
  63         } else {
  64                 bip = mempool_alloc(bs->bio_integrity_pool, gfp_mask);
  65                 inline_vecs = BIP_INLINE_VECS;
  66         }
  67
  68         if (unlikely(!bip))
  69                 return NULL;
  70
  71         memset(bip, 0, sizeof(*bip));
  72
  73         if (nr_vecs > inline_vecs) {
  74                 bip->bip_vec = bvec_alloc(gfp_mask, nr_vecs, &idx,
  75                                           bs->bvec_integrity_pool);
  76                 if (!bip->bip_vec)
  77                         goto err;
  78                 bip->bip_max_vcnt = bvec_nr_vecs(idx);
  79         } else {
  80                 bip->bip_vec = bip->bip_inline_vecs;
  81                 bip->bip_max_vcnt = inline_vecs;
  82         }
  83
  84         bip->bip_slab = idx;
  85         bip->bip_bio = bio;
  86         bio->bi_integrity = bip;
  87         bio->bi_rw |= REQ_INTEGRITY;
  88
  89         return bip;
  90 err:
  91         mempool_free(bip, bs->bio_integrity_pool);
  92         return NULL;
  93 }
  94 EXPORT_SYMBOL(bio_integrity_alloc);
  95
  96 /**
  97  * bio_integrity_free - Free bio integrity payload
  98  * @bio:        bio containing bip to be freed
  99  *
 100  * Description: Used to free the integrity portion of a bio. Usually
 101  * called from bio_free().
 102  */
 103 void bio_integrity_free(struct bio *bio)
 104 {
 105         struct bio_integrity_payload *bip = bio_integrity(bio);
 106         struct bio_set *bs = bio->bi_pool;
 107
 108         if (bip->bip_flags & BIP_BLOCK_INTEGRITY)
 109                 kfree(page_address(bip->bip_vec->bv_page) +
 110                       bip->bip_vec->bv_offset);
 111
 112         if (bs && bs->bio_integrity_pool) {
 113                 if (bip->bip_slab != BIO_POOL_NONE)
 114                         bvec_free(bs->bvec_integrity_pool, bip->bip_vec,
 115                                   bip->bip_slab);
 116
 117                 mempool_free(bip, bs->bio_integrity_pool);
 118         } else {
 119                 kfree(bip);
 120         }
 121
 122         bio->bi_integrity = NULL;
 123 }
 124 EXPORT_SYMBOL(bio_integrity_free);
 125
 126 /**
 127  * bio_integrity_add_page - Attach integrity metadata
 128  * @bio:        bio to update
 129  * @page:       page containing integrity metadata
 130  * @len:        number of bytes of integrity metadata in page
 131  * @offset:     start offset within page
 132  *
 133  * Description: Attach a page containing integrity metadata to bio.
 134  */
 135 int bio_integrity_add_page(struct bio *bio, struct page *page,
 136                            unsigned int len, unsigned int offset)
 137 {
 138         struct bio_integrity_payload *bip = bio_integrity(bio);
 139         struct bio_vec *iv;
 140
 141         if (bip->bip_vcnt >= bip->bip_max_vcnt) {
 142                 printk(KERN_ERR "%s: bip_vec full\n", __func__);
 143                 return 0;
 144         }
 145
 146         iv = bip->bip_vec + bip->bip_vcnt;
 147
 148         if (bip->bip_vcnt &&
 149             bvec_gap_to_prev(bdev_get_queue(bio->bi_bdev),
 150                              &bip->bip_vec[bip->bip_vcnt - 1], offset))
 151                 return 0;
 152
 153         iv->bv_page = page;
 154         iv->bv_len = len;
 155         iv->bv_offset = offset;
 156         bip->bip_vcnt++;
 157
 158         return len;
 159 }
 160 EXPORT_SYMBOL(bio_integrity_add_page);
 161
 162 /**
 163  * bio_integrity_enabled - Check whether integrity can be passed
 164  * @bio:        bio to check
 165  *
 166  * Description: Determines whether bio_integrity_prep() can be called
 167  * on this bio or not.  bio data direction and target device must be
 168  * set prior to calling.  The functions honors the write_generate and
 169  * read_verify flags in sysfs.
 170  */
 171 bool bio_integrity_enabled(struct bio *bio)
 172 {
 173         struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);
 174
 175         if (!bio_is_rw(bio))
 176                 return false;
 177
 178         /* Already protected? */
 179         if (bio_integrity(bio))
 180                 return false;
 181
 182         if (bi == NULL)
 183                 return false;
 184
 185         if (bio_data_dir(bio) == READ && bi->profile->verify_fn != NULL &&
 186             (bi->flags & BLK_INTEGRITY_VERIFY))
 187                 return true;
 188
 189         if (bio_data_dir(bio) == WRITE && bi->profile->generate_fn != NULL &&
 190             (bi->flags & BLK_INTEGRITY_GENERATE))
 191                 return true;
 192
 193         return false;
 194 }
 195 EXPORT_SYMBOL(bio_integrity_enabled);
 196
 197 /**
 198  * bio_integrity_intervals - Return number of integrity intervals for a bio
 199  * @bi:         blk_integrity profile for device
 200  * @sectors:    Size of the bio in 512-byte sectors
 201  *
 202  * Description: The block layer calculates everything in 512 byte
 203  * sectors but integrity metadata is done in terms of the data integrity
 204  * interval size of the storage device.  Convert the block layer sectors
 205  * to the appropriate number of integrity intervals.
 206  */
 207 static inline unsigned int bio_integrity_intervals(struct blk_integrity *bi,
 208                                                    unsigned int sectors)
 209 {
 210         return sectors >> (bi->interval_exp - 9);
 211 }
 212
 213 static inline unsigned int bio_integrity_bytes(struct blk_integrity *bi,
 214                                                unsigned int sectors)
 215 {
 216         return bio_integrity_intervals(bi, sectors) * bi->tuple_size;
 217 }
 218
 219 /**
 220  * bio_integrity_process - Process integrity metadata for a bio
 221  * @bio:        bio to generate/verify integrity metadata for
 222  * @proc_fn:    Pointer to the relevant processing function
 223  */
 224 static int bio_integrity_process(struct bio *bio,
 225                                  integrity_processing_fn *proc_fn)
 226 {
 227         struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);
 228         struct blk_integrity_iter iter;
 229         struct bvec_iter bviter;
 230         struct bio_vec bv;
 231         struct bio_integrity_payload *bip = bio_integrity(bio);
 232         unsigned int ret = 0;
 233         void *prot_buf = page_address(bip->bip_vec->bv_page) +
 234                 bip->bip_vec->bv_offset;
 235
 236         iter.disk_name = bio->bi_bdev->bd_disk->disk_name;
 237         iter.interval = 1 << bi->interval_exp;
 238         iter.seed = bip_get_seed(bip);
 239         iter.prot_buf = prot_buf;
 240
 241         bio_for_each_segment(bv, bio, bviter) {
 242                 void *kaddr = kmap_atomic(bv.bv_page);
 243
 244                 iter.data_buf = kaddr + bv.bv_offset;
 245                 iter.data_size = bv.bv_len;
 246
 247                 ret = proc_fn(&iter);
 248                 if (ret) {
 249                         kunmap_atomic(kaddr);
 250                         return ret;
 251                 }
 252
 253                 kunmap_atomic(kaddr);
 254         }
 255         return ret;
 256 }
 257
 258 /**
 259  * bio_integrity_prep - Prepare bio for integrity I/O
 260  * @bio:        bio to prepare
 261  *
 262  * Description: Allocates a buffer for integrity metadata, maps the
 263  * pages and attaches them to a bio.  The bio must have data
 264  * direction, target device and start sector set priot to calling.  In
 265  * the WRITE case, integrity metadata will be generated using the
 266  * block device's integrity function.  In the READ case, the buffer
 267  * will be prepared for DMA and a suitable end_io handler set up.
 268  */
 269 int bio_integrity_prep(struct bio *bio)
 270 {
 271         struct bio_integrity_payload *bip;
 272         struct blk_integrity *bi;
 273         struct request_queue *q;
 274         void *buf;
 275         unsigned long start, end;
 276         unsigned int len, nr_pages;
 277         unsigned int bytes, offset, i;
 278         unsigned int intervals;
 279
 280         bi = bdev_get_integrity(bio->bi_bdev);
 281         q = bdev_get_queue(bio->bi_bdev);
 282         BUG_ON(bi == NULL);
 283         BUG_ON(bio_integrity(bio));
 284
 285         intervals = bio_integrity_intervals(bi, bio_sectors(bio));
 286
 287         /* Allocate kernel buffer for protection data */
 288         len = intervals * bi->tuple_size;
 289         buf = kmalloc(len, GFP_NOIO | q->bounce_gfp);
 290         if (unlikely(buf == NULL)) {
 291                 printk(KERN_ERR "could not allocate integrity buffer\n");
 292                 return -ENOMEM;
 293         }
 294
 295         end = (((unsigned long) buf) + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
 296         start = ((unsigned long) buf) >> PAGE_SHIFT;
 297         nr_pages = end - start;
 298
 299         /* Allocate bio integrity payload and integrity vectors */
 300         bip = bio_integrity_alloc(bio, GFP_NOIO, nr_pages);
 301         if (unlikely(bip == NULL)) {
 302                 printk(KERN_ERR "could not allocate data integrity bioset\n");
 303                 kfree(buf);
 304                 return -EIO;
 305         }
 306
 307         bip->bip_flags |= BIP_BLOCK_INTEGRITY;
 308         bip->bip_iter.bi_size = len;
 309         bip_set_seed(bip, bio->bi_iter.bi_sector);
 310
 311         if (bi->flags & BLK_INTEGRITY_IP_CHECKSUM)
 312                 bip->bip_flags |= BIP_IP_CHECKSUM;
 313
 314         /* Map it */
 315         offset = offset_in_page(buf);
 316         for (i = 0 ; i < nr_pages ; i++) {
 317                 int ret;
 318                 bytes = PAGE_SIZE - offset;
 319
 320                 if (len <= 0)
 321                         break;
 322
 323                 if (bytes > len)
 324                         bytes = len;
 325
 326                 ret = bio_integrity_add_page(bio, virt_to_page(buf),
 327                                              bytes, offset);
 328
 329                 if (ret == 0)
 330                         return 0;
 331
 332                 if (ret < bytes)
 333                         break;
 334
 335                 buf += bytes;
 336                 len -= bytes;
 337                 offset = 0;
 338         }
 339
 340         /* Install custom I/O completion handler if read verify is enabled */
 341         if (bio_data_dir(bio) == READ) {
 342                 bip->bip_end_io = bio->bi_end_io;
 343                 bio->bi_end_io = bio_integrity_endio;
 344         }
 345
 346         /* Auto-generate integrity metadata if this is a write */
 347         if (bio_data_dir(bio) == WRITE)
 348                 bio_integrity_process(bio, bi->profile->generate_fn);
 349
 350         return 0;
 351 }
 352 EXPORT_SYMBOL(bio_integrity_prep);
 353
 354 /**
 355  * bio_integrity_verify_fn - Integrity I/O completion worker
 356  * @work:       Work struct stored in bio to be verified
 357  *
 358  * Description: This workqueue function is called to complete a READ
 359  * request.  The function verifies the transferred integrity metadata
 360  * and then calls the original bio end_io function.
 361  */
 362 static void bio_integrity_verify_fn(struct work_struct *work)
 363 {
 364         struct bio_integrity_payload *bip =
 365                 container_of(work, struct bio_integrity_payload, bip_work);
 366         struct bio *bio = bip->bip_bio;
 367         struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);
 368
 369         bio->bi_error = bio_integrity_process(bio, bi->profile->verify_fn);
 370
 371         /* Restore original bio completion handler */
 372         bio->bi_end_io = bip->bip_end_io;
 373         bio_endio(bio);
 374 }
 375
 376 /**
 377  * bio_integrity_endio - Integrity I/O completion function
 378  * @bio:        Protected bio
 379  * @error:      Pointer to errno
 380  *
 381  * Description: Completion for integrity I/O
 382  *
 383  * Normally I/O completion is done in interrupt context.  However,
 384  * verifying I/O integrity is a time-consuming task which must be run
 385  * in process context.  This function postpones completion
 386  * accordingly.
 387  */
 388 void bio_integrity_endio(struct bio *bio)
 389 {
 390         struct bio_integrity_payload *bip = bio_integrity(bio);
 391
 392         BUG_ON(bip->bip_bio != bio);
 393
 394         /* In case of an I/O error there is no point in verifying the
 395          * integrity metadata.  Restore original bio end_io handler
 396          * and run it.
 397          */
 398         if (bio->bi_error) {
 399                 bio->bi_end_io = bip->bip_end_io;
 400                 bio_endio(bio);
 401
 402                 return;
 403         }
 404
 405         INIT_WORK(&bip->bip_work, bio_integrity_verify_fn);
 406         queue_work(kintegrityd_wq, &bip->bip_work);
 407 }
 408 EXPORT_SYMBOL(bio_integrity_endio);
 409
 410 /**
 411  * bio_integrity_advance - Advance integrity vector
 412  * @bio:        bio whose integrity vector to update
 413  * @bytes_done: number of data bytes that have been completed
 414  *
 415  * Description: This function calculates how many integrity bytes the
 416  * number of completed data bytes correspond to and advances the
 417  * integrity vector accordingly.
 418  */
 419 void bio_integrity_advance(struct bio *bio, unsigned int bytes_done)
 420 {
 421         struct bio_integrity_payload *bip = bio_integrity(bio);
 422         struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);
 423         unsigned bytes = bio_integrity_bytes(bi, bytes_done >> 9);
 424
 425         bvec_iter_advance(bip->bip_vec, &bip->bip_iter, bytes);
 426 }
 427 EXPORT_SYMBOL(bio_integrity_advance);
 428
 429 /**
 430  * bio_integrity_trim - Trim integrity vector
 431  * @bio:        bio whose integrity vector to update
 432  * @offset:     offset to first data sector
 433  * @sectors:    number of data sectors
 434  *
 435  * Description: Used to trim the integrity vector in a cloned bio.
 436  * The ivec will be advanced corresponding to 'offset' data sectors
 437  * and the length will be truncated corresponding to 'len' data
 438  * sectors.
 439  */
 440 void bio_integrity_trim(struct bio *bio, unsigned int offset,
 441                         unsigned int sectors)
 442 {
 443         struct bio_integrity_payload *bip = bio_integrity(bio);
 444         struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);
 445
 446         bio_integrity_advance(bio, offset << 9);
 447         bip->bip_iter.bi_size = bio_integrity_bytes(bi, sectors);
 448 }
 449 EXPORT_SYMBOL(bio_integrity_trim);
 450
 451 /**
 452  * bio_integrity_clone - Callback for cloning bios with integrity metadata
 453  * @bio:        New bio
 454  * @bio_src:    Original bio
 455  * @gfp_mask:   Memory allocation mask
 456  *
 457  * Description: Called to allocate a bip when cloning a bio
 458  */
 459 int bio_integrity_clone(struct bio *bio, struct bio *bio_src,
 460                         gfp_t gfp_mask)
 461 {
 462         struct bio_integrity_payload *bip_src = bio_integrity(bio_src);
 463         struct bio_integrity_payload *bip;
 464
 465         BUG_ON(bip_src == NULL);
 466
 467         bip = bio_integrity_alloc(bio, gfp_mask, bip_src->bip_vcnt);
 468
 469         if (bip == NULL)
 470                 return -EIO;
 471
 472         memcpy(bip->bip_vec, bip_src->bip_vec,
 473                bip_src->bip_vcnt * sizeof(struct bio_vec));
 474
 475         bip->bip_vcnt = bip_src->bip_vcnt;
 476         bip->bip_iter = bip_src->bip_iter;
 477
 478         return 0;
 479 }
 480 EXPORT_SYMBOL(bio_integrity_clone);
 481
 482 int bioset_integrity_create(struct bio_set *bs, int pool_size)
 483 {
 484         if (bs->bio_integrity_pool)
 485                 return 0;
 486
 487         bs->bio_integrity_pool = mempool_create_slab_pool(pool_size, bip_slab);
 488         if (!bs->bio_integrity_pool)
 489                 return -1;
 490
 491         bs->bvec_integrity_pool = biovec_create_pool(pool_size);
 492         if (!bs->bvec_integrity_pool) {
 493                 mempool_destroy(bs->bio_integrity_pool);
 494                 return -1;
 495         }
 496
 497         return 0;
 498 }
 499 EXPORT_SYMBOL(bioset_integrity_create);
 500
 501 void bioset_integrity_free(struct bio_set *bs)
 502 {
 503         if (bs->bio_integrity_pool)
 504                 mempool_destroy(bs->bio_integrity_pool);
 505
 506         if (bs->bvec_integrity_pool)
 507                 mempool_destroy(bs->bvec_integrity_pool);
 508 }
 509 EXPORT_SYMBOL(bioset_integrity_free);
 510
 511 void __init bio_integrity_init(void)
 512 {
 513         /*
 514          * kintegrityd won't block much but may burn a lot of CPU cycles.
 515          * Make it highpri CPU intensive wq with max concurrency of 1.
 516          */
 517         kintegrityd_wq = alloc_workqueue("kintegrityd", WQ_MEM_RECLAIM |
 518                                          WQ_HIGHPRI | WQ_CPU_INTENSIVE, 1);
 519         if (!kintegrityd_wq)
 520                 panic("Failed to create kintegrityd\n");
 521
 522         bip_slab = kmem_cache_create("bio_integrity_payload",
 523                                      sizeof(struct bio_integrity_payload) +
 524                                      sizeof(struct bio_vec) * BIP_INLINE_VECS,
 525                                      0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
 526 }