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