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