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 /**
  36  * bio_integrity_alloc - Allocate integrity payload and attach it to bio
  37  * @bio:        bio to attach integrity metadata to
  38  * @gfp_mask:   Memory allocation mask
  39  * @nr_vecs:    Number of integrity metadata scatter-gather elements
  40  *
  41  * Description: This function prepares a bio for attaching integrity
  42  * metadata.  nr_vecs specifies the maximum number of pages containing
  43  * integrity metadata that can be attached.
  44  */
  45 struct bio_integrity_payload *bio_integrity_alloc(struct bio *bio,
  46                                                   gfp_t gfp_mask,
  47                                                   unsigned int nr_vecs)
  48 {
  49         struct bio_integrity_payload *bip;
  50         struct bio_set *bs = bio->bi_pool;
  51         unsigned long idx = BIO_POOL_NONE;
  52         unsigned inline_vecs;
  53
  54         if (!bs || !bs->bio_integrity_pool) {
  55                 bip = kmalloc(sizeof(struct bio_integrity_payload) +
  56                               sizeof(struct bio_vec) * nr_vecs, gfp_mask);
  57                 inline_vecs = nr_vecs;
  58         } else {
  59                 bip = mempool_alloc(bs->bio_integrity_pool, gfp_mask);
  60                 inline_vecs = BIP_INLINE_VECS;
  61         }
  62
  63         if (unlikely(!bip))
  64                 return NULL;
  65
  66         memset(bip, 0, sizeof(*bip));
  67
  68         if (nr_vecs > inline_vecs) {
  69                 bip->bip_vec = bvec_alloc(gfp_mask, nr_vecs, &idx,
  70                                           bs->bvec_integrity_pool);
  71                 if (!bip->bip_vec)
  72                         goto err;
  73                 bip->bip_max_vcnt = bvec_nr_vecs(idx);
  74         } else {
  75                 bip->bip_vec = bip->bip_inline_vecs;
  76                 bip->bip_max_vcnt = inline_vecs;
  77         }
  78
  79         bip->bip_slab = idx;
  80         bip->bip_bio = bio;
  81         bio->bi_integrity = bip;
  82         bio->bi_rw |= REQ_INTEGRITY;
  83
  84         return bip;
  85 err:
  86         mempool_free(bip, bs->bio_integrity_pool);
  87         return NULL;
  88 }
  89 EXPORT_SYMBOL(bio_integrity_alloc);
  90
  91 /**
  92  * bio_integrity_free - Free bio integrity payload
  93  * @bio:        bio containing bip to be freed
  94  *
  95  * Description: Used to free the integrity portion of a bio. Usually
  96  * called from bio_free().
  97  */
  98 void bio_integrity_free(struct bio *bio)
  99 {
 100         struct bio_integrity_payload *bip = bio_integrity(bio);
 101         struct bio_set *bs = bio->bi_pool;
 102
 103         if (bip->bip_flags & BIP_BLOCK_INTEGRITY)
 104                 kfree(page_address(bip->bip_vec->bv_page) +
 105                       bip->bip_vec->bv_offset);
 106
 107         if (bs && bs->bio_integrity_pool) {
 108                 if (bip->bip_slab != BIO_POOL_NONE)
 109                         bvec_free(bs->bvec_integrity_pool, bip->bip_vec,
 110                                   bip->bip_slab);
 111
 112                 mempool_free(bip, bs->bio_integrity_pool);
 113         } else {
 114                 kfree(bip);
 115         }
 116
 117         bio->bi_integrity = NULL;
 118 }
 119 EXPORT_SYMBOL(bio_integrity_free);
 120
 121 /**
 122  * bio_integrity_add_page - Attach integrity metadata
 123  * @bio:        bio to update
 124  * @page:       page containing integrity metadata
 125  * @len:        number of bytes of integrity metadata in page
 126  * @offset:     start offset within page
 127  *
 128  * Description: Attach a page containing integrity metadata to bio.
 129  */
 130 int bio_integrity_add_page(struct bio *bio, struct page *page,
 131                            unsigned int len, unsigned int offset)
 132 {
 133         struct bio_integrity_payload *bip = bio_integrity(bio);
 134         struct bio_vec *iv;
 135
 136         if (bip->bip_vcnt >= bip->bip_max_vcnt) {
 137                 printk(KERN_ERR "%s: bip_vec full\n", __func__);
 138                 return 0;
 139         }
 140
 141         iv = bip->bip_vec + bip->bip_vcnt;
 142
 143         if (bip->bip_vcnt &&
 144             bvec_gap_to_prev(bdev_get_queue(bio->bi_bdev),
 145                              &bip->bip_vec[bip->bip_vcnt - 1], offset))
 146                 return 0;
 147
 148         iv->bv_page = page;
 149         iv->bv_len = len;
 150         iv->bv_offset = offset;
 151         bip->bip_vcnt++;
 152
 153         return len;
 154 }
 155 EXPORT_SYMBOL(bio_integrity_add_page);
 156
 157 /**
 158  * bio_integrity_enabled - Check whether integrity can be passed
 159  * @bio:        bio to check
 160  *
 161  * Description: Determines whether bio_integrity_prep() can be called
 162  * on this bio or not.  bio data direction and target device must be
 163  * set prior to calling.  The functions honors the write_generate and
 164  * read_verify flags in sysfs.
 165  */
 166 bool bio_integrity_enabled(struct bio *bio)
 167 {
 168         struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);
 169
 170         if (!bio_is_rw(bio))
 171                 return false;
 172
 173         /* Already protected? */
 174         if (bio_integrity(bio))
 175                 return false;
 176
 177         if (bi == NULL)
 178                 return false;
 179
 180         if (bio_data_dir(bio) == READ && bi->verify_fn != NULL &&
 181             (bi->flags & BLK_INTEGRITY_VERIFY))
 182                 return true;
 183
 184         if (bio_data_dir(bio) == WRITE && bi->generate_fn != NULL &&
 185             (bi->flags & BLK_INTEGRITY_GENERATE))
 186                 return true;
 187
 188         return false;
 189 }
 190 EXPORT_SYMBOL(bio_integrity_enabled);
 191
 192 /**
 193  * bio_integrity_intervals - Return number of integrity intervals for a bio
 194  * @bi:         blk_integrity profile for device
 195  * @sectors:    Size of the bio in 512-byte sectors
 196  *
 197  * Description: The block layer calculates everything in 512 byte
 198  * sectors but integrity metadata is done in terms of the data integrity
 199  * interval size of the storage device.  Convert the block layer sectors
 200  * to the appropriate number of integrity intervals.
 201  */
 202 static inline unsigned int bio_integrity_intervals(struct blk_integrity *bi,
 203                                                    unsigned int sectors)
 204 {
 205         return sectors >> (ilog2(bi->interval) - 9);
 206 }
 207
 208 static inline unsigned int bio_integrity_bytes(struct blk_integrity *bi,
 209                                                unsigned int sectors)
 210 {
 211         return bio_integrity_intervals(bi, sectors) * bi->tuple_size;
 212 }
 213
 214 /**
 215  * bio_integrity_process - Process integrity metadata for a bio
 216  * @bio:        bio to generate/verify integrity metadata for
 217  * @proc_fn:    Pointer to the relevant processing function
 218  */
 219 static int bio_integrity_process(struct bio *bio,
 220                                  integrity_processing_fn *proc_fn)
 221 {
 222         struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);
 223         struct blk_integrity_iter iter;
 224         struct bvec_iter bviter;
 225         struct bio_vec bv;
 226         struct bio_integrity_payload *bip = bio_integrity(bio);
 227         unsigned int ret = 0;
 228         void *prot_buf = page_address(bip->bip_vec->bv_page) +
 229                 bip->bip_vec->bv_offset;
 230
 231         iter.disk_name = bio->bi_bdev->bd_disk->disk_name;
 232         iter.interval = bi->interval;
 233         iter.seed = bip_get_seed(bip);
 234         iter.prot_buf = prot_buf;
 235
 236         bio_for_each_segment(bv, bio, bviter) {
 237                 void *kaddr = kmap_atomic(bv.bv_page);
 238
 239                 iter.data_buf = kaddr + bv.bv_offset;
 240                 iter.data_size = bv.bv_len;
 241
 242                 ret = proc_fn(&iter);
 243                 if (ret) {
 244                         kunmap_atomic(kaddr);
 245                         return ret;
 246                 }
 247
 248                 kunmap_atomic(kaddr);
 249         }
 250         return ret;
 251 }
 252
 253 /**
 254  * bio_integrity_prep - Prepare bio for integrity I/O
 255  * @bio:        bio to prepare
 256  *
 257  * Description: Allocates a buffer for integrity metadata, maps the
 258  * pages and attaches them to a bio.  The bio must have data
 259  * direction, target device and start sector set priot to calling.  In
 260  * the WRITE case, integrity metadata will be generated using the
 261  * block device's integrity function.  In the READ case, the buffer
 262  * will be prepared for DMA and a suitable end_io handler set up.
 263  */
 264 int bio_integrity_prep(struct bio *bio)
 265 {
 266         struct bio_integrity_payload *bip;
 267         struct blk_integrity *bi;
 268         struct request_queue *q;
 269         void *buf;
 270         unsigned long start, end;
 271         unsigned int len, nr_pages;
 272         unsigned int bytes, offset, i;
 273         unsigned int intervals;
 274
 275         bi = bdev_get_integrity(bio->bi_bdev);
 276         q = bdev_get_queue(bio->bi_bdev);
 277         BUG_ON(bi == NULL);
 278         BUG_ON(bio_integrity(bio));
 279
 280         intervals = bio_integrity_intervals(bi, bio_sectors(bio));
 281
 282         /* Allocate kernel buffer for protection data */
 283         len = intervals * bi->tuple_size;
 284         buf = kmalloc(len, GFP_NOIO | q->bounce_gfp);
 285         if (unlikely(buf == NULL)) {
 286                 printk(KERN_ERR "could not allocate integrity buffer\n");
 287                 return -ENOMEM;
 288         }
 289
 290         end = (((unsigned long) buf) + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
 291         start = ((unsigned long) buf) >> PAGE_SHIFT;
 292         nr_pages = end - start;
 293
 294         /* Allocate bio integrity payload and integrity vectors */
 295         bip = bio_integrity_alloc(bio, GFP_NOIO, nr_pages);
 296         if (unlikely(bip == NULL)) {
 297                 printk(KERN_ERR "could not allocate data integrity bioset\n");
 298                 kfree(buf);
 299                 return -EIO;
 300         }
 301
 302         bip->bip_flags |= BIP_BLOCK_INTEGRITY;
 303         bip->bip_iter.bi_size = len;
 304         bip_set_seed(bip, bio->bi_iter.bi_sector);
 305
 306         if (bi->flags & BLK_INTEGRITY_IP_CHECKSUM)
 307                 bip->bip_flags |= BIP_IP_CHECKSUM;
 308
 309         /* Map it */
 310         offset = offset_in_page(buf);
 311         for (i = 0 ; i < nr_pages ; i++) {
 312                 int ret;
 313                 bytes = PAGE_SIZE - offset;
 314
 315                 if (len <= 0)
 316                         break;
 317
 318                 if (bytes > len)
 319                         bytes = len;
 320
 321                 ret = bio_integrity_add_page(bio, virt_to_page(buf),
 322                                              bytes, offset);
 323
 324                 if (ret == 0)
 325                         return 0;
 326
 327                 if (ret < bytes)
 328                         break;
 329
 330                 buf += bytes;
 331                 len -= bytes;
 332                 offset = 0;
 333         }
 334
 335         /* Install custom I/O completion handler if read verify is enabled */
 336         if (bio_data_dir(bio) == READ) {
 337                 bip->bip_end_io = bio->bi_end_io;
 338                 bio->bi_end_io = bio_integrity_endio;
 339         }
 340
 341         /* Auto-generate integrity metadata if this is a write */
 342         if (bio_data_dir(bio) == WRITE)
 343                 bio_integrity_process(bio, bi->generate_fn);
 344
 345         return 0;
 346 }
 347 EXPORT_SYMBOL(bio_integrity_prep);
 348
 349 /**
 350  * bio_integrity_verify_fn - Integrity I/O completion worker
 351  * @work:       Work struct stored in bio to be verified
 352  *
 353  * Description: This workqueue function is called to complete a READ
 354  * request.  The function verifies the transferred integrity metadata
 355  * and then calls the original bio end_io function.
 356  */
 357 static void bio_integrity_verify_fn(struct work_struct *work)
 358 {
 359         struct bio_integrity_payload *bip =
 360                 container_of(work, struct bio_integrity_payload, bip_work);
 361         struct bio *bio = bip->bip_bio;
 362         struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);
 363
 364         bio->bi_error = bio_integrity_process(bio, bi->verify_fn);
 365
 366         /* Restore original bio completion handler */
 367         bio->bi_end_io = bip->bip_end_io;
 368         bio_endio(bio);
 369 }
 370
 371 /**
 372  * bio_integrity_endio - Integrity I/O completion function
 373  * @bio:        Protected bio
 374  * @error:      Pointer to errno
 375  *
 376  * Description: Completion for integrity I/O
 377  *
 378  * Normally I/O completion is done in interrupt context.  However,
 379  * verifying I/O integrity is a time-consuming task which must be run
 380  * in process context.  This function postpones completion
 381  * accordingly.
 382  */
 383 void bio_integrity_endio(struct bio *bio)
 384 {
 385         struct bio_integrity_payload *bip = bio_integrity(bio);
 386
 387         BUG_ON(bip->bip_bio != bio);
 388
 389         /* In case of an I/O error there is no point in verifying the
 390          * integrity metadata.  Restore original bio end_io handler
 391          * and run it.
 392          */
 393         if (bio->bi_error) {
 394                 bio->bi_end_io = bip->bip_end_io;
 395                 bio_endio(bio);
 396
 397                 return;
 398         }
 399
 400         INIT_WORK(&bip->bip_work, bio_integrity_verify_fn);
 401         queue_work(kintegrityd_wq, &bip->bip_work);
 402 }
 403 EXPORT_SYMBOL(bio_integrity_endio);
 404
 405 /**
 406  * bio_integrity_advance - Advance integrity vector
 407  * @bio:        bio whose integrity vector to update
 408  * @bytes_done: number of data bytes that have been completed
 409  *
 410  * Description: This function calculates how many integrity bytes the
 411  * number of completed data bytes correspond to and advances the
 412  * integrity vector accordingly.
 413  */
 414 void bio_integrity_advance(struct bio *bio, unsigned int bytes_done)
 415 {
 416         struct bio_integrity_payload *bip = bio_integrity(bio);
 417         struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);
 418         unsigned bytes = bio_integrity_bytes(bi, bytes_done >> 9);
 419
 420         bvec_iter_advance(bip->bip_vec, &bip->bip_iter, bytes);
 421 }
 422 EXPORT_SYMBOL(bio_integrity_advance);
 423
 424 /**
 425  * bio_integrity_trim - Trim integrity vector
 426  * @bio:        bio whose integrity vector to update
 427  * @offset:     offset to first data sector
 428  * @sectors:    number of data sectors
 429  *
 430  * Description: Used to trim the integrity vector in a cloned bio.
 431  * The ivec will be advanced corresponding to 'offset' data sectors
 432  * and the length will be truncated corresponding to 'len' data
 433  * sectors.
 434  */
 435 void bio_integrity_trim(struct bio *bio, unsigned int offset,
 436                         unsigned int sectors)
 437 {
 438         struct bio_integrity_payload *bip = bio_integrity(bio);
 439         struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);
 440
 441         bio_integrity_advance(bio, offset << 9);
 442         bip->bip_iter.bi_size = bio_integrity_bytes(bi, sectors);
 443 }
 444 EXPORT_SYMBOL(bio_integrity_trim);
 445
 446 /**
 447  * bio_integrity_clone - Callback for cloning bios with integrity metadata
 448  * @bio:        New bio
 449  * @bio_src:    Original bio
 450  * @gfp_mask:   Memory allocation mask
 451  *
 452  * Description: Called to allocate a bip when cloning a bio
 453  */
 454 int bio_integrity_clone(struct bio *bio, struct bio *bio_src,
 455                         gfp_t gfp_mask)
 456 {
 457         struct bio_integrity_payload *bip_src = bio_integrity(bio_src);
 458         struct bio_integrity_payload *bip;
 459
 460         BUG_ON(bip_src == NULL);
 461
 462         bip = bio_integrity_alloc(bio, gfp_mask, bip_src->bip_vcnt);
 463
 464         if (bip == NULL)
 465                 return -EIO;
 466
 467         memcpy(bip->bip_vec, bip_src->bip_vec,
 468                bip_src->bip_vcnt * sizeof(struct bio_vec));
 469
 470         bip->bip_vcnt = bip_src->bip_vcnt;
 471         bip->bip_iter = bip_src->bip_iter;
 472
 473         return 0;
 474 }
 475 EXPORT_SYMBOL(bio_integrity_clone);
 476
 477 int bioset_integrity_create(struct bio_set *bs, int pool_size)
 478 {
 479         if (bs->bio_integrity_pool)
 480                 return 0;
 481
 482         bs->bio_integrity_pool = mempool_create_slab_pool(pool_size, bip_slab);
 483         if (!bs->bio_integrity_pool)
 484                 return -1;
 485
 486         bs->bvec_integrity_pool = biovec_create_pool(pool_size);
 487         if (!bs->bvec_integrity_pool) {
 488                 mempool_destroy(bs->bio_integrity_pool);
 489                 return -1;
 490         }
 491
 492         return 0;
 493 }
 494 EXPORT_SYMBOL(bioset_integrity_create);
 495
 496 void bioset_integrity_free(struct bio_set *bs)
 497 {
 498         if (bs->bio_integrity_pool)
 499                 mempool_destroy(bs->bio_integrity_pool);
 500
 501         if (bs->bvec_integrity_pool)
 502                 mempool_destroy(bs->bvec_integrity_pool);
 503 }
 504 EXPORT_SYMBOL(bioset_integrity_free);
 505
 506 void __init bio_integrity_init(void)
 507 {
 508         /*
 509          * kintegrityd won't block much but may burn a lot of CPU cycles.
 510          * Make it highpri CPU intensive wq with max concurrency of 1.
 511          */
 512         kintegrityd_wq = alloc_workqueue("kintegrityd", WQ_MEM_RECLAIM |
 513                                          WQ_HIGHPRI | WQ_CPU_INTENSIVE, 1);
 514         if (!kintegrityd_wq)
 515                 panic("Failed to create kintegrityd\n");
 516
 517         bip_slab = kmem_cache_create("bio_integrity_payload",
 518                                      sizeof(struct bio_integrity_payload) +
 519                                      sizeof(struct bio_vec) * BIP_INLINE_VECS,
 520                                      0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
 521 }