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 || !mempool_initialized(&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 && mempool_initialized(&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_process - Process integrity metadata for a bio
 164  * @bio:        bio to generate/verify integrity metadata for
 165  * @proc_iter:  iterator to process
 166  * @proc_fn:    Pointer to the relevant processing function
 167  */
 168 static blk_status_t bio_integrity_process(struct bio *bio,
 169                 struct bvec_iter *proc_iter, integrity_processing_fn *proc_fn)
 170 {
 171         struct blk_integrity *bi = blk_get_integrity(bio->bi_disk);
 172         struct blk_integrity_iter iter;
 173         struct bvec_iter bviter;
 174         struct bio_vec bv;
 175         struct bio_integrity_payload *bip = bio_integrity(bio);
 176         blk_status_t ret = BLK_STS_OK;
 177         void *prot_buf = page_address(bip->bip_vec->bv_page) +
 178                 bip->bip_vec->bv_offset;
 179
 180         iter.disk_name = bio->bi_disk->disk_name;
 181         iter.interval = 1 << bi->interval_exp;
 182         iter.seed = proc_iter->bi_sector;
 183         iter.prot_buf = prot_buf;
 184
 185         __bio_for_each_segment(bv, bio, bviter, *proc_iter) {
 186                 void *kaddr = kmap_atomic(bv.bv_page);
 187
 188                 iter.data_buf = kaddr + bv.bv_offset;
 189                 iter.data_size = bv.bv_len;
 190
 191                 ret = proc_fn(&iter);
 192                 if (ret) {
 193                         kunmap_atomic(kaddr);
 194                         return ret;
 195                 }
 196
 197                 kunmap_atomic(kaddr);
 198         }
 199         return ret;
 200 }
 201
 202 /**
 203  * bio_integrity_prep - Prepare bio for integrity I/O
 204  * @bio:        bio to prepare
 205  *
 206  * Description:  Checks if the bio already has an integrity payload attached.
 207  * If it does, the payload has been generated by another kernel subsystem,
 208  * and we just pass it through. Otherwise allocates integrity payload.
 209  * The bio must have data direction, target device and start sector set priot
 210  * to calling.  In the WRITE case, integrity metadata will be generated using
 211  * the block device's integrity function.  In the READ case, the buffer
 212  * will be prepared for DMA and a suitable end_io handler set up.
 213  */
 214 bool bio_integrity_prep(struct bio *bio)
 215 {
 216         struct bio_integrity_payload *bip;
 217         struct blk_integrity *bi = blk_get_integrity(bio->bi_disk);
 218         struct request_queue *q = bio->bi_disk->queue;
 219         void *buf;
 220         unsigned long start, end;
 221         unsigned int len, nr_pages;
 222         unsigned int bytes, offset, i;
 223         unsigned int intervals;
 224         blk_status_t status;
 225
 226         if (!bi)
 227                 return true;
 228
 229         if (bio_op(bio) != REQ_OP_READ && bio_op(bio) != REQ_OP_WRITE)
 230                 return true;
 231
 232         if (!bio_sectors(bio))
 233                 return true;
 234
 235         /* Already protected? */
 236         if (bio_integrity(bio))
 237                 return true;
 238
 239         if (bio_data_dir(bio) == READ) {
 240                 if (!bi->profile->verify_fn ||
 241                     !(bi->flags & BLK_INTEGRITY_VERIFY))
 242                         return true;
 243         } else {
 244                 if (!bi->profile->generate_fn ||
 245                     !(bi->flags & BLK_INTEGRITY_GENERATE))
 246                         return true;
 247         }
 248         intervals = bio_integrity_intervals(bi, bio_sectors(bio));
 249
 250         /* Allocate kernel buffer for protection data */
 251         len = intervals * bi->tuple_size;
 252         buf = kmalloc(len, GFP_NOIO | q->bounce_gfp);
 253         status = BLK_STS_RESOURCE;
 254         if (unlikely(buf == NULL)) {
 255                 printk(KERN_ERR "could not allocate integrity buffer\n");
 256                 goto err_end_io;
 257         }
 258
 259         end = (((unsigned long) buf) + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
 260         start = ((unsigned long) buf) >> PAGE_SHIFT;
 261         nr_pages = end - start;
 262
 263         /* Allocate bio integrity payload and integrity vectors */
 264         bip = bio_integrity_alloc(bio, GFP_NOIO, nr_pages);
 265         if (IS_ERR(bip)) {
 266                 printk(KERN_ERR "could not allocate data integrity bioset\n");
 267                 kfree(buf);
 268                 status = BLK_STS_RESOURCE;
 269                 goto err_end_io;
 270         }
 271
 272         bip->bip_flags |= BIP_BLOCK_INTEGRITY;
 273         bip->bip_iter.bi_size = len;
 274         bip_set_seed(bip, bio->bi_iter.bi_sector);
 275
 276         if (bi->flags & BLK_INTEGRITY_IP_CHECKSUM)
 277                 bip->bip_flags |= BIP_IP_CHECKSUM;
 278
 279         /* Map it */
 280         offset = offset_in_page(buf);
 281         for (i = 0 ; i < nr_pages ; i++) {
 282                 int ret;
 283                 bytes = PAGE_SIZE - offset;
 284
 285                 if (len <= 0)
 286                         break;
 287
 288                 if (bytes > len)
 289                         bytes = len;
 290
 291                 ret = bio_integrity_add_page(bio, virt_to_page(buf),
 292                                              bytes, offset);
 293
 294                 if (ret == 0)
 295                         return false;
 296
 297                 if (ret < bytes)
 298                         break;
 299
 300                 buf += bytes;
 301                 len -= bytes;
 302                 offset = 0;
 303         }
 304
 305         /* Auto-generate integrity metadata if this is a write */
 306         if (bio_data_dir(bio) == WRITE) {
 307                 bio_integrity_process(bio, &bio->bi_iter,
 308                                       bi->profile->generate_fn);
 309         } else {
 310                 bip->bio_iter = bio->bi_iter;
 311         }
 312         return true;
 313
 314 err_end_io:
 315         bio->bi_status = status;
 316         bio_endio(bio);
 317         return false;
 318
 319 }
 320 EXPORT_SYMBOL(bio_integrity_prep);
 321
 322 /**
 323  * bio_integrity_verify_fn - Integrity I/O completion worker
 324  * @work:       Work struct stored in bio to be verified
 325  *
 326  * Description: This workqueue function is called to complete a READ
 327  * request.  The function verifies the transferred integrity metadata
 328  * and then calls the original bio end_io function.
 329  */
 330 static void bio_integrity_verify_fn(struct work_struct *work)
 331 {
 332         struct bio_integrity_payload *bip =
 333                 container_of(work, struct bio_integrity_payload, bip_work);
 334         struct bio *bio = bip->bip_bio;
 335         struct blk_integrity *bi = blk_get_integrity(bio->bi_disk);
 336
 337         /*
 338          * At the moment verify is called bio's iterator was advanced
 339          * during split and completion, we need to rewind iterator to
 340          * it's original position.
 341          */
 342         bio->bi_status = bio_integrity_process(bio, &bip->bio_iter,
 343                                                 bi->profile->verify_fn);
 344         bio_integrity_free(bio);
 345         bio_endio(bio);
 346 }
 347
 348 /**
 349  * __bio_integrity_endio - Integrity I/O completion function
 350  * @bio:        Protected bio
 351  *
 352  * Description: Completion for integrity I/O
 353  *
 354  * Normally I/O completion is done in interrupt context.  However,
 355  * verifying I/O integrity is a time-consuming task which must be run
 356  * in process context.  This function postpones completion
 357  * accordingly.
 358  */
 359 bool __bio_integrity_endio(struct bio *bio)
 360 {
 361         struct blk_integrity *bi = blk_get_integrity(bio->bi_disk);
 362         struct bio_integrity_payload *bip = bio_integrity(bio);
 363
 364         if (bio_op(bio) == REQ_OP_READ && !bio->bi_status &&
 365             (bip->bip_flags & BIP_BLOCK_INTEGRITY) && bi->profile->verify_fn) {
 366                 INIT_WORK(&bip->bip_work, bio_integrity_verify_fn);
 367                 queue_work(kintegrityd_wq, &bip->bip_work);
 368                 return false;
 369         }
 370
 371         bio_integrity_free(bio);
 372         return true;
 373 }
 374
 375 /**
 376  * bio_integrity_advance - Advance integrity vector
 377  * @bio:        bio whose integrity vector to update
 378  * @bytes_done: number of data bytes that have been completed
 379  *
 380  * Description: This function calculates how many integrity bytes the
 381  * number of completed data bytes correspond to and advances the
 382  * integrity vector accordingly.
 383  */
 384 void bio_integrity_advance(struct bio *bio, unsigned int bytes_done)
 385 {
 386         struct bio_integrity_payload *bip = bio_integrity(bio);
 387         struct blk_integrity *bi = blk_get_integrity(bio->bi_disk);
 388         unsigned bytes = bio_integrity_bytes(bi, bytes_done >> 9);
 389
 390         bip->bip_iter.bi_sector += bytes_done >> 9;
 391         bvec_iter_advance(bip->bip_vec, &bip->bip_iter, bytes);
 392 }
 393
 394 /**
 395  * bio_integrity_trim - Trim integrity vector
 396  * @bio:        bio whose integrity vector to update
 397  *
 398  * Description: Used to trim the integrity vector in a cloned bio.
 399  */
 400 void bio_integrity_trim(struct bio *bio)
 401 {
 402         struct bio_integrity_payload *bip = bio_integrity(bio);
 403         struct blk_integrity *bi = blk_get_integrity(bio->bi_disk);
 404
 405         bip->bip_iter.bi_size = bio_integrity_bytes(bi, bio_sectors(bio));
 406 }
 407 EXPORT_SYMBOL(bio_integrity_trim);
 408
 409 /**
 410  * bio_integrity_clone - Callback for cloning bios with integrity metadata
 411  * @bio:        New bio
 412  * @bio_src:    Original bio
 413  * @gfp_mask:   Memory allocation mask
 414  *
 415  * Description: Called to allocate a bip when cloning a bio
 416  */
 417 int bio_integrity_clone(struct bio *bio, struct bio *bio_src,
 418                         gfp_t gfp_mask)
 419 {
 420         struct bio_integrity_payload *bip_src = bio_integrity(bio_src);
 421         struct bio_integrity_payload *bip;
 422
 423         BUG_ON(bip_src == NULL);
 424
 425         bip = bio_integrity_alloc(bio, gfp_mask, bip_src->bip_vcnt);
 426         if (IS_ERR(bip))
 427                 return PTR_ERR(bip);
 428
 429         memcpy(bip->bip_vec, bip_src->bip_vec,
 430                bip_src->bip_vcnt * sizeof(struct bio_vec));
 431
 432         bip->bip_vcnt = bip_src->bip_vcnt;
 433         bip->bip_iter = bip_src->bip_iter;
 434
 435         return 0;
 436 }
 437 EXPORT_SYMBOL(bio_integrity_clone);
 438
 439 int bioset_integrity_create(struct bio_set *bs, int pool_size)
 440 {
 441         if (mempool_initialized(&bs->bio_integrity_pool))
 442                 return 0;
 443
 444         if (mempool_init_slab_pool(&bs->bio_integrity_pool,
 445                                    pool_size, bip_slab))
 446                 return -1;
 447
 448         if (biovec_init_pool(&bs->bvec_integrity_pool, pool_size)) {
 449                 mempool_exit(&bs->bio_integrity_pool);
 450                 return -1;
 451         }
 452
 453         return 0;
 454 }
 455 EXPORT_SYMBOL(bioset_integrity_create);
 456
 457 void bioset_integrity_free(struct bio_set *bs)
 458 {
 459         mempool_exit(&bs->bio_integrity_pool);
 460         mempool_exit(&bs->bvec_integrity_pool);
 461 }
 462
 463 void __init bio_integrity_init(void)
 464 {
 465         /*
 466          * kintegrityd won't block much but may burn a lot of CPU cycles.
 467          * Make it highpri CPU intensive wq with max concurrency of 1.
 468          */
 469         kintegrityd_wq = alloc_workqueue("kintegrityd", WQ_MEM_RECLAIM |
 470                                          WQ_HIGHPRI | WQ_CPU_INTENSIVE, 1);
 471         if (!kintegrityd_wq)
 472                 panic("Failed to create kintegrityd\n");
 473
 474         bip_slab = kmem_cache_create("bio_integrity_payload",
 475                                      sizeof(struct bio_integrity_payload) +
 476                                      sizeof(struct bio_vec) * BIP_INLINE_VECS,
 477                                      0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
 478 }