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 #include "blk.h"
  30
  31 #define BIP_INLINE_VECS 4
  32
  33 static struct kmem_cache *bip_slab;
  34 static struct workqueue_struct *kintegrityd_wq;
  35
  36 void blk_flush_integrity(void)
  37 {
  38         flush_workqueue(kintegrityd_wq);
  39 }
  40
  41 /**
  42  * bio_integrity_alloc - Allocate integrity payload and attach it to bio
  43  * @bio:        bio to attach integrity metadata to
  44  * @gfp_mask:   Memory allocation mask
  45  * @nr_vecs:    Number of integrity metadata scatter-gather elements
  46  *
  47  * Description: This function prepares a bio for attaching integrity
  48  * metadata.  nr_vecs specifies the maximum number of pages containing
  49  * integrity metadata that can be attached.
  50  */
  51 struct bio_integrity_payload *bio_integrity_alloc(struct bio *bio,
  52                                                   gfp_t gfp_mask,
  53                                                   unsigned int nr_vecs)
  54 {
  55         struct bio_integrity_payload *bip;
  56         struct bio_set *bs = bio->bi_pool;
  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 ERR_PTR(-ENOMEM);
  70
  71         memset(bip, 0, sizeof(*bip));
  72
  73         if (nr_vecs > inline_vecs) {
  74                 unsigned long idx = 0;
  75
  76                 bip->bip_vec = bvec_alloc(gfp_mask, nr_vecs, &idx,
  77                                           bs->bvec_integrity_pool);
  78                 if (!bip->bip_vec)
  79                         goto err;
  80                 bip->bip_max_vcnt = bvec_nr_vecs(idx);
  81                 bip->bip_slab = idx;
  82         } else {
  83                 bip->bip_vec = bip->bip_inline_vecs;
  84                 bip->bip_max_vcnt = inline_vecs;
  85         }
  86
  87         bip->bip_bio = bio;
  88         bio->bi_integrity = bip;
  89         bio->bi_opf |= REQ_INTEGRITY;
  90
  91         return bip;
  92 err:
  93         mempool_free(bip, bs->bio_integrity_pool);
  94         return ERR_PTR(-ENOMEM);
  95 }
  96 EXPORT_SYMBOL(bio_integrity_alloc);
  97
  98 /**
  99  * bio_integrity_free - Free bio integrity payload
 100  * @bio:        bio containing bip to be freed
 101  *
 102  * Description: Used to free the integrity portion of a bio. Usually
 103  * called from bio_free().
 104  */
 105 static void bio_integrity_free(struct bio *bio)
 106 {
 107         struct bio_integrity_payload *bip = bio_integrity(bio);
 108         struct bio_set *bs = bio->bi_pool;
 109
 110         if (bip->bip_flags & BIP_BLOCK_INTEGRITY)
 111                 kfree(page_address(bip->bip_vec->bv_page) +
 112                       bip->bip_vec->bv_offset);
 113
 114         if (bs && bs->bio_integrity_pool) {
 115                 bvec_free(bs->bvec_integrity_pool, bip->bip_vec, 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         bio->bi_opf &= ~REQ_INTEGRITY;
 124 }
 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(bio->bi_disk->queue,
 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_intervals - Return number of integrity intervals for a bio
 164  * @bi:         blk_integrity profile for device
 165  * @sectors:    Size of the bio in 512-byte sectors
 166  *
 167  * Description: The block layer calculates everything in 512 byte
 168  * sectors but integrity metadata is done in terms of the data integrity
 169  * interval size of the storage device.  Convert the block layer sectors
 170  * to the appropriate number of integrity intervals.
 171  */
 172 static inline unsigned int bio_integrity_intervals(struct blk_integrity *bi,
 173                                                    unsigned int sectors)
 174 {
 175         return sectors >> (bi->interval_exp - 9);
 176 }
 177
 178 static inline unsigned int bio_integrity_bytes(struct blk_integrity *bi,
 179                                                unsigned int sectors)
 180 {
 181         return bio_integrity_intervals(bi, sectors) * bi->tuple_size;
 182 }
 183
 184 /**
 185  * bio_integrity_process - Process integrity metadata for a bio
 186  * @bio:        bio to generate/verify integrity metadata for
 187  * @proc_iter:  iterator to process
 188  * @proc_fn:    Pointer to the relevant processing function
 189  */
 190 static blk_status_t bio_integrity_process(struct bio *bio,
 191                 struct bvec_iter *proc_iter, integrity_processing_fn *proc_fn)
 192 {
 193         struct blk_integrity *bi = blk_get_integrity(bio->bi_disk);
 194         struct blk_integrity_iter iter;
 195         struct bvec_iter bviter;
 196         struct bio_vec bv;
 197         struct bio_integrity_payload *bip = bio_integrity(bio);
 198         blk_status_t ret = BLK_STS_OK;
 199         void *prot_buf = page_address(bip->bip_vec->bv_page) +
 200                 bip->bip_vec->bv_offset;
 201
 202         iter.disk_name = bio->bi_disk->disk_name;
 203         iter.interval = 1 << bi->interval_exp;
 204         iter.seed = proc_iter->bi_sector;
 205         iter.prot_buf = prot_buf;
 206
 207         __bio_for_each_segment(bv, bio, bviter, *proc_iter) {
 208                 void *kaddr = kmap_atomic(bv.bv_page);
 209
 210                 iter.data_buf = kaddr + bv.bv_offset;
 211                 iter.data_size = bv.bv_len;
 212
 213                 ret = proc_fn(&iter);
 214                 if (ret) {
 215                         kunmap_atomic(kaddr);
 216                         return ret;
 217                 }
 218
 219                 kunmap_atomic(kaddr);
 220         }
 221         return ret;
 222 }
 223
 224 /**
 225  * bio_integrity_prep - Prepare bio for integrity I/O
 226  * @bio:        bio to prepare
 227  *
 228  * Description:  Checks if the bio already has an integrity payload attached.
 229  * If it does, the payload has been generated by another kernel subsystem,
 230  * and we just pass it through. Otherwise allocates integrity payload.
 231  * The bio must have data direction, target device and start sector set priot
 232  * to calling.  In the WRITE case, integrity metadata will be generated using
 233  * the block device's integrity function.  In the READ case, the buffer
 234  * will be prepared for DMA and a suitable end_io handler set up.
 235  */
 236 bool bio_integrity_prep(struct bio *bio)
 237 {
 238         struct bio_integrity_payload *bip;
 239         struct blk_integrity *bi = blk_get_integrity(bio->bi_disk);
 240         struct request_queue *q = bio->bi_disk->queue;
 241         void *buf;
 242         unsigned long start, end;
 243         unsigned int len, nr_pages;
 244         unsigned int bytes, offset, i;
 245         unsigned int intervals;
 246         blk_status_t status;
 247
 248         if (!bi)
 249                 return true;
 250
 251         if (bio_op(bio) != REQ_OP_READ && bio_op(bio) != REQ_OP_WRITE)
 252                 return true;
 253
 254         if (!bio_sectors(bio))
 255                 return true;
 256
 257         /* Already protected? */
 258         if (bio_integrity(bio))
 259                 return true;
 260
 261         if (bio_data_dir(bio) == READ) {
 262                 if (!bi->profile->verify_fn ||
 263                     !(bi->flags & BLK_INTEGRITY_VERIFY))
 264                         return true;
 265         } else {
 266                 if (!bi->profile->generate_fn ||
 267                     !(bi->flags & BLK_INTEGRITY_GENERATE))
 268                         return true;
 269         }
 270         intervals = bio_integrity_intervals(bi, bio_sectors(bio));
 271
 272         /* Allocate kernel buffer for protection data */
 273         len = intervals * bi->tuple_size;
 274         buf = kmalloc(len, GFP_NOIO | q->bounce_gfp);
 275         status = BLK_STS_RESOURCE;
 276         if (unlikely(buf == NULL)) {
 277                 printk(KERN_ERR "could not allocate integrity buffer\n");
 278                 goto err_end_io;
 279         }
 280
 281         end = (((unsigned long) buf) + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
 282         start = ((unsigned long) buf) >> PAGE_SHIFT;
 283         nr_pages = end - start;
 284
 285         /* Allocate bio integrity payload and integrity vectors */
 286         bip = bio_integrity_alloc(bio, GFP_NOIO, nr_pages);
 287         if (IS_ERR(bip)) {
 288                 printk(KERN_ERR "could not allocate data integrity bioset\n");
 289                 kfree(buf);
 290                 status = BLK_STS_RESOURCE;
 291                 goto err_end_io;
 292         }
 293
 294         bip->bip_flags |= BIP_BLOCK_INTEGRITY;
 295         bip->bip_iter.bi_size = len;
 296         bip_set_seed(bip, bio->bi_iter.bi_sector);
 297
 298         if (bi->flags & BLK_INTEGRITY_IP_CHECKSUM)
 299                 bip->bip_flags |= BIP_IP_CHECKSUM;
 300
 301         /* Map it */
 302         offset = offset_in_page(buf);
 303         for (i = 0 ; i < nr_pages ; i++) {
 304                 int ret;
 305                 bytes = PAGE_SIZE - offset;
 306
 307                 if (len <= 0)
 308                         break;
 309
 310                 if (bytes > len)
 311                         bytes = len;
 312
 313                 ret = bio_integrity_add_page(bio, virt_to_page(buf),
 314                                              bytes, offset);
 315
 316                 if (ret == 0) {
 317                         printk(KERN_ERR "could not attach integrity payload\n");
 318                         status = BLK_STS_RESOURCE;
 319                         goto err_end_io;
 320                 }
 321
 322                 if (ret < bytes)
 323                         break;
 324
 325                 buf += bytes;
 326                 len -= bytes;
 327                 offset = 0;
 328         }
 329
 330         /* Auto-generate integrity metadata if this is a write */
 331         if (bio_data_dir(bio) == WRITE) {
 332                 bio_integrity_process(bio, &bio->bi_iter,
 333                                       bi->profile->generate_fn);
 334         }
 335         return true;
 336
 337 err_end_io:
 338         bio->bi_status = status;
 339         bio_endio(bio);
 340         return false;
 341
 342 }
 343 EXPORT_SYMBOL(bio_integrity_prep);
 344
 345 /**
 346  * bio_integrity_verify_fn - Integrity I/O completion worker
 347  * @work:       Work struct stored in bio to be verified
 348  *
 349  * Description: This workqueue function is called to complete a READ
 350  * request.  The function verifies the transferred integrity metadata
 351  * and then calls the original bio end_io function.
 352  */
 353 static void bio_integrity_verify_fn(struct work_struct *work)
 354 {
 355         struct bio_integrity_payload *bip =
 356                 container_of(work, struct bio_integrity_payload, bip_work);
 357         struct bio *bio = bip->bip_bio;
 358         struct blk_integrity *bi = blk_get_integrity(bio->bi_disk);
 359         struct bvec_iter iter = bio->bi_iter;
 360
 361         /*
 362          * At the moment verify is called bio's iterator was advanced
 363          * during split and completion, we need to rewind iterator to
 364          * it's original position.
 365          */
 366         if (bio_rewind_iter(bio, &iter, iter.bi_done)) {
 367                 bio->bi_status = bio_integrity_process(bio, &iter,
 368                                                        bi->profile->verify_fn);
 369         } else {
 370                 bio->bi_status = BLK_STS_IOERR;
 371         }
 372
 373         bio_integrity_free(bio);
 374         bio_endio(bio);
 375 }
 376
 377 /**
 378  * __bio_integrity_endio - Integrity I/O completion function
 379  * @bio:        Protected bio
 380  * @error:      Pointer to errno
 381  *
 382  * Description: Completion for integrity I/O
 383  *
 384  * Normally I/O completion is done in interrupt context.  However,
 385  * verifying I/O integrity is a time-consuming task which must be run
 386  * in process context.  This function postpones completion
 387  * accordingly.
 388  */
 389 bool __bio_integrity_endio(struct bio *bio)
 390 {
 391         struct blk_integrity *bi = blk_get_integrity(bio->bi_disk);
 392         struct bio_integrity_payload *bip = bio_integrity(bio);
 393
 394         if (bio_op(bio) == REQ_OP_READ && !bio->bi_status &&
 395             (bip->bip_flags & BIP_BLOCK_INTEGRITY) && bi->profile->verify_fn) {
 396                 INIT_WORK(&bip->bip_work, bio_integrity_verify_fn);
 397                 queue_work(kintegrityd_wq, &bip->bip_work);
 398                 return false;
 399         }
 400
 401         bio_integrity_free(bio);
 402         return true;
 403 }
 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 = blk_get_integrity(bio->bi_disk);
 418         unsigned bytes = bio_integrity_bytes(bi, bytes_done >> 9);
 419
 420         bip->bip_iter.bi_sector += bytes_done >> 9;
 421         bvec_iter_advance(bip->bip_vec, &bip->bip_iter, bytes);
 422 }
 423 EXPORT_SYMBOL(bio_integrity_advance);
 424
 425 /**
 426  * bio_integrity_trim - Trim integrity vector
 427  * @bio:        bio whose integrity vector to update
 428  *
 429  * Description: Used to trim the integrity vector in a cloned bio.
 430  */
 431 void bio_integrity_trim(struct bio *bio)
 432 {
 433         struct bio_integrity_payload *bip = bio_integrity(bio);
 434         struct blk_integrity *bi = blk_get_integrity(bio->bi_disk);
 435
 436         bip->bip_iter.bi_size = bio_integrity_bytes(bi, bio_sectors(bio));
 437 }
 438 EXPORT_SYMBOL(bio_integrity_trim);
 439
 440 /**
 441  * bio_integrity_clone - Callback for cloning bios with integrity metadata
 442  * @bio:        New bio
 443  * @bio_src:    Original bio
 444  * @gfp_mask:   Memory allocation mask
 445  *
 446  * Description: Called to allocate a bip when cloning a bio
 447  */
 448 int bio_integrity_clone(struct bio *bio, struct bio *bio_src,
 449                         gfp_t gfp_mask)
 450 {
 451         struct bio_integrity_payload *bip_src = bio_integrity(bio_src);
 452         struct bio_integrity_payload *bip;
 453
 454         BUG_ON(bip_src == NULL);
 455
 456         bip = bio_integrity_alloc(bio, gfp_mask, bip_src->bip_vcnt);
 457         if (IS_ERR(bip))
 458                 return PTR_ERR(bip);
 459
 460         memcpy(bip->bip_vec, bip_src->bip_vec,
 461                bip_src->bip_vcnt * sizeof(struct bio_vec));
 462
 463         bip->bip_vcnt = bip_src->bip_vcnt;
 464         bip->bip_iter = bip_src->bip_iter;
 465
 466         return 0;
 467 }
 468 EXPORT_SYMBOL(bio_integrity_clone);
 469
 470 int bioset_integrity_create(struct bio_set *bs, int pool_size)
 471 {
 472         if (bs->bio_integrity_pool)
 473                 return 0;
 474
 475         bs->bio_integrity_pool = mempool_create_slab_pool(pool_size, bip_slab);
 476         if (!bs->bio_integrity_pool)
 477                 return -1;
 478
 479         bs->bvec_integrity_pool = biovec_create_pool(pool_size);
 480         if (!bs->bvec_integrity_pool) {
 481                 mempool_destroy(bs->bio_integrity_pool);
 482                 return -1;
 483         }
 484
 485         return 0;
 486 }
 487 EXPORT_SYMBOL(bioset_integrity_create);
 488
 489 void bioset_integrity_free(struct bio_set *bs)
 490 {
 491         if (bs->bio_integrity_pool)
 492                 mempool_destroy(bs->bio_integrity_pool);
 493
 494         if (bs->bvec_integrity_pool)
 495                 mempool_destroy(bs->bvec_integrity_pool);
 496 }
 497 EXPORT_SYMBOL(bioset_integrity_free);
 498
 499 void __init bio_integrity_init(void)
 500 {
 501         /*
 502          * kintegrityd won't block much but may burn a lot of CPU cycles.
 503          * Make it highpri CPU intensive wq with max concurrency of 1.
 504          */
 505         kintegrityd_wq = alloc_workqueue("kintegrityd", WQ_MEM_RECLAIM |
 506                                          WQ_HIGHPRI | WQ_CPU_INTENSIVE, 1);
 507         if (!kintegrityd_wq)
 508                 panic("Failed to create kintegrityd\n");
 509
 510         bip_slab = kmem_cache_create("bio_integrity_payload",
 511                                      sizeof(struct bio_integrity_payload) +
 512                                      sizeof(struct bio_vec) * BIP_INLINE_VECS,
 513                                      0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
 514 }