linux/fs/bio.c
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   1/*
   2 * Copyright (C) 2001 Jens Axboe <axboe@kernel.dk>
   3 *
   4 * This program is free software; you can redistribute it and/or modify
   5 * it under the terms of the GNU General Public License version 2 as
   6 * published by the Free Software Foundation.
   7 *
   8 * This program is distributed in the hope that it will be useful,
   9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11 * GNU General Public License for more details.
  12 *
  13 * You should have received a copy of the GNU General Public Licens
  14 * along with this program; if not, write to the Free Software
  15 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-
  16 *
  17 */
  18#include <linux/mm.h>
  19#include <linux/swap.h>
  20#include <linux/bio.h>
  21#include <linux/blkdev.h>
  22#include <linux/iocontext.h>
  23#include <linux/slab.h>
  24#include <linux/init.h>
  25#include <linux/kernel.h>
  26#include <linux/export.h>
  27#include <linux/mempool.h>
  28#include <linux/workqueue.h>
  29#include <linux/cgroup.h>
  30#include <scsi/sg.h>            /* for struct sg_iovec */
  31
  32#include <trace/events/block.h>
  33
  34/*
  35 * Test patch to inline a certain number of bi_io_vec's inside the bio
  36 * itself, to shrink a bio data allocation from two mempool calls to one
  37 */
  38#define BIO_INLINE_VECS         4
  39
  40static mempool_t *bio_split_pool __read_mostly;
  41
  42/*
  43 * if you change this list, also change bvec_alloc or things will
  44 * break badly! cannot be bigger than what you can fit into an
  45 * unsigned short
  46 */
  47#define BV(x) { .nr_vecs = x, .name = "biovec-"__stringify(x) }
  48static struct biovec_slab bvec_slabs[BIOVEC_NR_POOLS] __read_mostly = {
  49        BV(1), BV(4), BV(16), BV(64), BV(128), BV(BIO_MAX_PAGES),
  50};
  51#undef BV
  52
  53/*
  54 * fs_bio_set is the bio_set containing bio and iovec memory pools used by
  55 * IO code that does not need private memory pools.
  56 */
  57struct bio_set *fs_bio_set;
  58
  59/*
  60 * Our slab pool management
  61 */
  62struct bio_slab {
  63        struct kmem_cache *slab;
  64        unsigned int slab_ref;
  65        unsigned int slab_size;
  66        char name[8];
  67};
  68static DEFINE_MUTEX(bio_slab_lock);
  69static struct bio_slab *bio_slabs;
  70static unsigned int bio_slab_nr, bio_slab_max;
  71
  72static struct kmem_cache *bio_find_or_create_slab(unsigned int extra_size)
  73{
  74        unsigned int sz = sizeof(struct bio) + extra_size;
  75        struct kmem_cache *slab = NULL;
  76        struct bio_slab *bslab;
  77        unsigned int i, entry = -1;
  78
  79        mutex_lock(&bio_slab_lock);
  80
  81        i = 0;
  82        while (i < bio_slab_nr) {
  83                bslab = &bio_slabs[i];
  84
  85                if (!bslab->slab && entry == -1)
  86                        entry = i;
  87                else if (bslab->slab_size == sz) {
  88                        slab = bslab->slab;
  89                        bslab->slab_ref++;
  90                        break;
  91                }
  92                i++;
  93        }
  94
  95        if (slab)
  96                goto out_unlock;
  97
  98        if (bio_slab_nr == bio_slab_max && entry == -1) {
  99                bio_slab_max <<= 1;
 100                bio_slabs = krealloc(bio_slabs,
 101                                     bio_slab_max * sizeof(struct bio_slab),
 102                                     GFP_KERNEL);
 103                if (!bio_slabs)
 104                        goto out_unlock;
 105        }
 106        if (entry == -1)
 107                entry = bio_slab_nr++;
 108
 109        bslab = &bio_slabs[entry];
 110
 111        snprintf(bslab->name, sizeof(bslab->name), "bio-%d", entry);
 112        slab = kmem_cache_create(bslab->name, sz, 0, SLAB_HWCACHE_ALIGN, NULL);
 113        if (!slab)
 114                goto out_unlock;
 115
 116        printk(KERN_INFO "bio: create slab <%s> at %d\n", bslab->name, entry);
 117        bslab->slab = slab;
 118        bslab->slab_ref = 1;
 119        bslab->slab_size = sz;
 120out_unlock:
 121        mutex_unlock(&bio_slab_lock);
 122        return slab;
 123}
 124
 125static void bio_put_slab(struct bio_set *bs)
 126{
 127        struct bio_slab *bslab = NULL;
 128        unsigned int i;
 129
 130        mutex_lock(&bio_slab_lock);
 131
 132        for (i = 0; i < bio_slab_nr; i++) {
 133                if (bs->bio_slab == bio_slabs[i].slab) {
 134                        bslab = &bio_slabs[i];
 135                        break;
 136                }
 137        }
 138
 139        if (WARN(!bslab, KERN_ERR "bio: unable to find slab!\n"))
 140                goto out;
 141
 142        WARN_ON(!bslab->slab_ref);
 143
 144        if (--bslab->slab_ref)
 145                goto out;
 146
 147        kmem_cache_destroy(bslab->slab);
 148        bslab->slab = NULL;
 149
 150out:
 151        mutex_unlock(&bio_slab_lock);
 152}
 153
 154unsigned int bvec_nr_vecs(unsigned short idx)
 155{
 156        return bvec_slabs[idx].nr_vecs;
 157}
 158
 159void bvec_free_bs(struct bio_set *bs, struct bio_vec *bv, unsigned int idx)
 160{
 161        BIO_BUG_ON(idx >= BIOVEC_NR_POOLS);
 162
 163        if (idx == BIOVEC_MAX_IDX)
 164                mempool_free(bv, bs->bvec_pool);
 165        else {
 166                struct biovec_slab *bvs = bvec_slabs + idx;
 167
 168                kmem_cache_free(bvs->slab, bv);
 169        }
 170}
 171
 172struct bio_vec *bvec_alloc_bs(gfp_t gfp_mask, int nr, unsigned long *idx,
 173                              struct bio_set *bs)
 174{
 175        struct bio_vec *bvl;
 176
 177        /*
 178         * see comment near bvec_array define!
 179         */
 180        switch (nr) {
 181        case 1:
 182                *idx = 0;
 183                break;
 184        case 2 ... 4:
 185                *idx = 1;
 186                break;
 187        case 5 ... 16:
 188                *idx = 2;
 189                break;
 190        case 17 ... 64:
 191                *idx = 3;
 192                break;
 193        case 65 ... 128:
 194                *idx = 4;
 195                break;
 196        case 129 ... BIO_MAX_PAGES:
 197                *idx = 5;
 198                break;
 199        default:
 200                return NULL;
 201        }
 202
 203        /*
 204         * idx now points to the pool we want to allocate from. only the
 205         * 1-vec entry pool is mempool backed.
 206         */
 207        if (*idx == BIOVEC_MAX_IDX) {
 208fallback:
 209                bvl = mempool_alloc(bs->bvec_pool, gfp_mask);
 210        } else {
 211                struct biovec_slab *bvs = bvec_slabs + *idx;
 212                gfp_t __gfp_mask = gfp_mask & ~(__GFP_WAIT | __GFP_IO);
 213
 214                /*
 215                 * Make this allocation restricted and don't dump info on
 216                 * allocation failures, since we'll fallback to the mempool
 217                 * in case of failure.
 218                 */
 219                __gfp_mask |= __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN;
 220
 221                /*
 222                 * Try a slab allocation. If this fails and __GFP_WAIT
 223                 * is set, retry with the 1-entry mempool
 224                 */
 225                bvl = kmem_cache_alloc(bvs->slab, __gfp_mask);
 226                if (unlikely(!bvl && (gfp_mask & __GFP_WAIT))) {
 227                        *idx = BIOVEC_MAX_IDX;
 228                        goto fallback;
 229                }
 230        }
 231
 232        return bvl;
 233}
 234
 235void bio_free(struct bio *bio, struct bio_set *bs)
 236{
 237        void *p;
 238
 239        if (bio_has_allocated_vec(bio))
 240                bvec_free_bs(bs, bio->bi_io_vec, BIO_POOL_IDX(bio));
 241
 242        if (bio_integrity(bio))
 243                bio_integrity_free(bio, bs);
 244
 245        /*
 246         * If we have front padding, adjust the bio pointer before freeing
 247         */
 248        p = bio;
 249        if (bs->front_pad)
 250                p -= bs->front_pad;
 251
 252        mempool_free(p, bs->bio_pool);
 253}
 254EXPORT_SYMBOL(bio_free);
 255
 256void bio_init(struct bio *bio)
 257{
 258        memset(bio, 0, sizeof(*bio));
 259        bio->bi_flags = 1 << BIO_UPTODATE;
 260        atomic_set(&bio->bi_cnt, 1);
 261}
 262EXPORT_SYMBOL(bio_init);
 263
 264/**
 265 * bio_alloc_bioset - allocate a bio for I/O
 266 * @gfp_mask:   the GFP_ mask given to the slab allocator
 267 * @nr_iovecs:  number of iovecs to pre-allocate
 268 * @bs:         the bio_set to allocate from.
 269 *
 270 * Description:
 271 *   bio_alloc_bioset will try its own mempool to satisfy the allocation.
 272 *   If %__GFP_WAIT is set then we will block on the internal pool waiting
 273 *   for a &struct bio to become free.
 274 *
 275 *   Note that the caller must set ->bi_destructor on successful return
 276 *   of a bio, to do the appropriate freeing of the bio once the reference
 277 *   count drops to zero.
 278 **/
 279struct bio *bio_alloc_bioset(gfp_t gfp_mask, int nr_iovecs, struct bio_set *bs)
 280{
 281        unsigned long idx = BIO_POOL_NONE;
 282        struct bio_vec *bvl = NULL;
 283        struct bio *bio;
 284        void *p;
 285
 286        p = mempool_alloc(bs->bio_pool, gfp_mask);
 287        if (unlikely(!p))
 288                return NULL;
 289        bio = p + bs->front_pad;
 290
 291        bio_init(bio);
 292
 293        if (unlikely(!nr_iovecs))
 294                goto out_set;
 295
 296        if (nr_iovecs <= BIO_INLINE_VECS) {
 297                bvl = bio->bi_inline_vecs;
 298                nr_iovecs = BIO_INLINE_VECS;
 299        } else {
 300                bvl = bvec_alloc_bs(gfp_mask, nr_iovecs, &idx, bs);
 301                if (unlikely(!bvl))
 302                        goto err_free;
 303
 304                nr_iovecs = bvec_nr_vecs(idx);
 305        }
 306out_set:
 307        bio->bi_flags |= idx << BIO_POOL_OFFSET;
 308        bio->bi_max_vecs = nr_iovecs;
 309        bio->bi_io_vec = bvl;
 310        return bio;
 311
 312err_free:
 313        mempool_free(p, bs->bio_pool);
 314        return NULL;
 315}
 316EXPORT_SYMBOL(bio_alloc_bioset);
 317
 318static void bio_fs_destructor(struct bio *bio)
 319{
 320        bio_free(bio, fs_bio_set);
 321}
 322
 323/**
 324 *      bio_alloc - allocate a new bio, memory pool backed
 325 *      @gfp_mask: allocation mask to use
 326 *      @nr_iovecs: number of iovecs
 327 *
 328 *      bio_alloc will allocate a bio and associated bio_vec array that can hold
 329 *      at least @nr_iovecs entries. Allocations will be done from the
 330 *      fs_bio_set. Also see @bio_alloc_bioset and @bio_kmalloc.
 331 *
 332 *      If %__GFP_WAIT is set, then bio_alloc will always be able to allocate
 333 *      a bio. This is due to the mempool guarantees. To make this work, callers
 334 *      must never allocate more than 1 bio at a time from this pool. Callers
 335 *      that need to allocate more than 1 bio must always submit the previously
 336 *      allocated bio for IO before attempting to allocate a new one. Failure to
 337 *      do so can cause livelocks under memory pressure.
 338 *
 339 *      RETURNS:
 340 *      Pointer to new bio on success, NULL on failure.
 341 */
 342struct bio *bio_alloc(gfp_t gfp_mask, unsigned int nr_iovecs)
 343{
 344        struct bio *bio = bio_alloc_bioset(gfp_mask, nr_iovecs, fs_bio_set);
 345
 346        if (bio)
 347                bio->bi_destructor = bio_fs_destructor;
 348
 349        return bio;
 350}
 351EXPORT_SYMBOL(bio_alloc);
 352
 353static void bio_kmalloc_destructor(struct bio *bio)
 354{
 355        if (bio_integrity(bio))
 356                bio_integrity_free(bio, fs_bio_set);
 357        kfree(bio);
 358}
 359
 360/**
 361 * bio_kmalloc - allocate a bio for I/O using kmalloc()
 362 * @gfp_mask:   the GFP_ mask given to the slab allocator
 363 * @nr_iovecs:  number of iovecs to pre-allocate
 364 *
 365 * Description:
 366 *   Allocate a new bio with @nr_iovecs bvecs.  If @gfp_mask contains
 367 *   %__GFP_WAIT, the allocation is guaranteed to succeed.
 368 *
 369 **/
 370struct bio *bio_kmalloc(gfp_t gfp_mask, unsigned int nr_iovecs)
 371{
 372        struct bio *bio;
 373
 374        if (nr_iovecs > UIO_MAXIOV)
 375                return NULL;
 376
 377        bio = kmalloc(sizeof(struct bio) + nr_iovecs * sizeof(struct bio_vec),
 378                      gfp_mask);
 379        if (unlikely(!bio))
 380                return NULL;
 381
 382        bio_init(bio);
 383        bio->bi_flags |= BIO_POOL_NONE << BIO_POOL_OFFSET;
 384        bio->bi_max_vecs = nr_iovecs;
 385        bio->bi_io_vec = bio->bi_inline_vecs;
 386        bio->bi_destructor = bio_kmalloc_destructor;
 387
 388        return bio;
 389}
 390EXPORT_SYMBOL(bio_kmalloc);
 391
 392void zero_fill_bio(struct bio *bio)
 393{
 394        unsigned long flags;
 395        struct bio_vec *bv;
 396        int i;
 397
 398        bio_for_each_segment(bv, bio, i) {
 399                char *data = bvec_kmap_irq(bv, &flags);
 400                memset(data, 0, bv->bv_len);
 401                flush_dcache_page(bv->bv_page);
 402                bvec_kunmap_irq(data, &flags);
 403        }
 404}
 405EXPORT_SYMBOL(zero_fill_bio);
 406
 407/**
 408 * bio_put - release a reference to a bio
 409 * @bio:   bio to release reference to
 410 *
 411 * Description:
 412 *   Put a reference to a &struct bio, either one you have gotten with
 413 *   bio_alloc, bio_get or bio_clone. The last put of a bio will free it.
 414 **/
 415void bio_put(struct bio *bio)
 416{
 417        BIO_BUG_ON(!atomic_read(&bio->bi_cnt));
 418
 419        /*
 420         * last put frees it
 421         */
 422        if (atomic_dec_and_test(&bio->bi_cnt)) {
 423                bio_disassociate_task(bio);
 424                bio->bi_next = NULL;
 425                bio->bi_destructor(bio);
 426        }
 427}
 428EXPORT_SYMBOL(bio_put);
 429
 430inline int bio_phys_segments(struct request_queue *q, struct bio *bio)
 431{
 432        if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
 433                blk_recount_segments(q, bio);
 434
 435        return bio->bi_phys_segments;
 436}
 437EXPORT_SYMBOL(bio_phys_segments);
 438
 439/**
 440 *      __bio_clone     -       clone a bio
 441 *      @bio: destination bio
 442 *      @bio_src: bio to clone
 443 *
 444 *      Clone a &bio. Caller will own the returned bio, but not
 445 *      the actual data it points to. Reference count of returned
 446 *      bio will be one.
 447 */
 448void __bio_clone(struct bio *bio, struct bio *bio_src)
 449{
 450        memcpy(bio->bi_io_vec, bio_src->bi_io_vec,
 451                bio_src->bi_max_vecs * sizeof(struct bio_vec));
 452
 453        /*
 454         * most users will be overriding ->bi_bdev with a new target,
 455         * so we don't set nor calculate new physical/hw segment counts here
 456         */
 457        bio->bi_sector = bio_src->bi_sector;
 458        bio->bi_bdev = bio_src->bi_bdev;
 459        bio->bi_flags |= 1 << BIO_CLONED;
 460        bio->bi_rw = bio_src->bi_rw;
 461        bio->bi_vcnt = bio_src->bi_vcnt;
 462        bio->bi_size = bio_src->bi_size;
 463        bio->bi_idx = bio_src->bi_idx;
 464}
 465EXPORT_SYMBOL(__bio_clone);
 466
 467/**
 468 *      bio_clone       -       clone a bio
 469 *      @bio: bio to clone
 470 *      @gfp_mask: allocation priority
 471 *
 472 *      Like __bio_clone, only also allocates the returned bio
 473 */
 474struct bio *bio_clone(struct bio *bio, gfp_t gfp_mask)
 475{
 476        struct bio *b = bio_alloc_bioset(gfp_mask, bio->bi_max_vecs, fs_bio_set);
 477
 478        if (!b)
 479                return NULL;
 480
 481        b->bi_destructor = bio_fs_destructor;
 482        __bio_clone(b, bio);
 483
 484        if (bio_integrity(bio)) {
 485                int ret;
 486
 487                ret = bio_integrity_clone(b, bio, gfp_mask, fs_bio_set);
 488
 489                if (ret < 0) {
 490                        bio_put(b);
 491                        return NULL;
 492                }
 493        }
 494
 495        return b;
 496}
 497EXPORT_SYMBOL(bio_clone);
 498
 499/**
 500 *      bio_get_nr_vecs         - return approx number of vecs
 501 *      @bdev:  I/O target
 502 *
 503 *      Return the approximate number of pages we can send to this target.
 504 *      There's no guarantee that you will be able to fit this number of pages
 505 *      into a bio, it does not account for dynamic restrictions that vary
 506 *      on offset.
 507 */
 508int bio_get_nr_vecs(struct block_device *bdev)
 509{
 510        struct request_queue *q = bdev_get_queue(bdev);
 511        int nr_pages;
 512
 513        nr_pages = min_t(unsigned,
 514                     queue_max_segments(q),
 515                     queue_max_sectors(q) / (PAGE_SIZE >> 9) + 1);
 516
 517        return min_t(unsigned, nr_pages, BIO_MAX_PAGES);
 518
 519}
 520EXPORT_SYMBOL(bio_get_nr_vecs);
 521
 522static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page
 523                          *page, unsigned int len, unsigned int offset,
 524                          unsigned short max_sectors)
 525{
 526        int retried_segments = 0;
 527        struct bio_vec *bvec;
 528
 529        /*
 530         * cloned bio must not modify vec list
 531         */
 532        if (unlikely(bio_flagged(bio, BIO_CLONED)))
 533                return 0;
 534
 535        if (((bio->bi_size + len) >> 9) > max_sectors)
 536                return 0;
 537
 538        /*
 539         * For filesystems with a blocksize smaller than the pagesize
 540         * we will often be called with the same page as last time and
 541         * a consecutive offset.  Optimize this special case.
 542         */
 543        if (bio->bi_vcnt > 0) {
 544                struct bio_vec *prev = &bio->bi_io_vec[bio->bi_vcnt - 1];
 545
 546                if (page == prev->bv_page &&
 547                    offset == prev->bv_offset + prev->bv_len) {
 548                        unsigned int prev_bv_len = prev->bv_len;
 549                        prev->bv_len += len;
 550
 551                        if (q->merge_bvec_fn) {
 552                                struct bvec_merge_data bvm = {
 553                                        /* prev_bvec is already charged in
 554                                           bi_size, discharge it in order to
 555                                           simulate merging updated prev_bvec
 556                                           as new bvec. */
 557                                        .bi_bdev = bio->bi_bdev,
 558                                        .bi_sector = bio->bi_sector,
 559                                        .bi_size = bio->bi_size - prev_bv_len,
 560                                        .bi_rw = bio->bi_rw,
 561                                };
 562
 563                                if (q->merge_bvec_fn(q, &bvm, prev) < prev->bv_len) {
 564                                        prev->bv_len -= len;
 565                                        return 0;
 566                                }
 567                        }
 568
 569                        goto done;
 570                }
 571        }
 572
 573        if (bio->bi_vcnt >= bio->bi_max_vecs)
 574                return 0;
 575
 576        /*
 577         * we might lose a segment or two here, but rather that than
 578         * make this too complex.
 579         */
 580
 581        while (bio->bi_phys_segments >= queue_max_segments(q)) {
 582
 583                if (retried_segments)
 584                        return 0;
 585
 586                retried_segments = 1;
 587                blk_recount_segments(q, bio);
 588        }
 589
 590        /*
 591         * setup the new entry, we might clear it again later if we
 592         * cannot add the page
 593         */
 594        bvec = &bio->bi_io_vec[bio->bi_vcnt];
 595        bvec->bv_page = page;
 596        bvec->bv_len = len;
 597        bvec->bv_offset = offset;
 598
 599        /*
 600         * if queue has other restrictions (eg varying max sector size
 601         * depending on offset), it can specify a merge_bvec_fn in the
 602         * queue to get further control
 603         */
 604        if (q->merge_bvec_fn) {
 605                struct bvec_merge_data bvm = {
 606                        .bi_bdev = bio->bi_bdev,
 607                        .bi_sector = bio->bi_sector,
 608                        .bi_size = bio->bi_size,
 609                        .bi_rw = bio->bi_rw,
 610                };
 611
 612                /*
 613                 * merge_bvec_fn() returns number of bytes it can accept
 614                 * at this offset
 615                 */
 616                if (q->merge_bvec_fn(q, &bvm, bvec) < bvec->bv_len) {
 617                        bvec->bv_page = NULL;
 618                        bvec->bv_len = 0;
 619                        bvec->bv_offset = 0;
 620                        return 0;
 621                }
 622        }
 623
 624        /* If we may be able to merge these biovecs, force a recount */
 625        if (bio->bi_vcnt && (BIOVEC_PHYS_MERGEABLE(bvec-1, bvec)))
 626                bio->bi_flags &= ~(1 << BIO_SEG_VALID);
 627
 628        bio->bi_vcnt++;
 629        bio->bi_phys_segments++;
 630 done:
 631        bio->bi_size += len;
 632        return len;
 633}
 634
 635/**
 636 *      bio_add_pc_page -       attempt to add page to bio
 637 *      @q: the target queue
 638 *      @bio: destination bio
 639 *      @page: page to add
 640 *      @len: vec entry length
 641 *      @offset: vec entry offset
 642 *
 643 *      Attempt to add a page to the bio_vec maplist. This can fail for a
 644 *      number of reasons, such as the bio being full or target block device
 645 *      limitations. The target block device must allow bio's up to PAGE_SIZE,
 646 *      so it is always possible to add a single page to an empty bio.
 647 *
 648 *      This should only be used by REQ_PC bios.
 649 */
 650int bio_add_pc_page(struct request_queue *q, struct bio *bio, struct page *page,
 651                    unsigned int len, unsigned int offset)
 652{
 653        return __bio_add_page(q, bio, page, len, offset,
 654                              queue_max_hw_sectors(q));
 655}
 656EXPORT_SYMBOL(bio_add_pc_page);
 657
 658/**
 659 *      bio_add_page    -       attempt to add page to bio
 660 *      @bio: destination bio
 661 *      @page: page to add
 662 *      @len: vec entry length
 663 *      @offset: vec entry offset
 664 *
 665 *      Attempt to add a page to the bio_vec maplist. This can fail for a
 666 *      number of reasons, such as the bio being full or target block device
 667 *      limitations. The target block device must allow bio's up to PAGE_SIZE,
 668 *      so it is always possible to add a single page to an empty bio.
 669 */
 670int bio_add_page(struct bio *bio, struct page *page, unsigned int len,
 671                 unsigned int offset)
 672{
 673        struct request_queue *q = bdev_get_queue(bio->bi_bdev);
 674        return __bio_add_page(q, bio, page, len, offset, queue_max_sectors(q));
 675}
 676EXPORT_SYMBOL(bio_add_page);
 677
 678struct bio_map_data {
 679        struct bio_vec *iovecs;
 680        struct sg_iovec *sgvecs;
 681        int nr_sgvecs;
 682        int is_our_pages;
 683};
 684
 685static void bio_set_map_data(struct bio_map_data *bmd, struct bio *bio,
 686                             struct sg_iovec *iov, int iov_count,
 687                             int is_our_pages)
 688{
 689        memcpy(bmd->iovecs, bio->bi_io_vec, sizeof(struct bio_vec) * bio->bi_vcnt);
 690        memcpy(bmd->sgvecs, iov, sizeof(struct sg_iovec) * iov_count);
 691        bmd->nr_sgvecs = iov_count;
 692        bmd->is_our_pages = is_our_pages;
 693        bio->bi_private = bmd;
 694}
 695
 696static void bio_free_map_data(struct bio_map_data *bmd)
 697{
 698        kfree(bmd->iovecs);
 699        kfree(bmd->sgvecs);
 700        kfree(bmd);
 701}
 702
 703static struct bio_map_data *bio_alloc_map_data(int nr_segs,
 704                                               unsigned int iov_count,
 705                                               gfp_t gfp_mask)
 706{
 707        struct bio_map_data *bmd;
 708
 709        if (iov_count > UIO_MAXIOV)
 710                return NULL;
 711
 712        bmd = kmalloc(sizeof(*bmd), gfp_mask);
 713        if (!bmd)
 714                return NULL;
 715
 716        bmd->iovecs = kmalloc(sizeof(struct bio_vec) * nr_segs, gfp_mask);
 717        if (!bmd->iovecs) {
 718                kfree(bmd);
 719                return NULL;
 720        }
 721
 722        bmd->sgvecs = kmalloc(sizeof(struct sg_iovec) * iov_count, gfp_mask);
 723        if (bmd->sgvecs)
 724                return bmd;
 725
 726        kfree(bmd->iovecs);
 727        kfree(bmd);
 728        return NULL;
 729}
 730
 731static int __bio_copy_iov(struct bio *bio, struct bio_vec *iovecs,
 732                          struct sg_iovec *iov, int iov_count,
 733                          int to_user, int from_user, int do_free_page)
 734{
 735        int ret = 0, i;
 736        struct bio_vec *bvec;
 737        int iov_idx = 0;
 738        unsigned int iov_off = 0;
 739
 740        __bio_for_each_segment(bvec, bio, i, 0) {
 741                char *bv_addr = page_address(bvec->bv_page);
 742                unsigned int bv_len = iovecs[i].bv_len;
 743
 744                while (bv_len && iov_idx < iov_count) {
 745                        unsigned int bytes;
 746                        char __user *iov_addr;
 747
 748                        bytes = min_t(unsigned int,
 749                                      iov[iov_idx].iov_len - iov_off, bv_len);
 750                        iov_addr = iov[iov_idx].iov_base + iov_off;
 751
 752                        if (!ret) {
 753                                if (to_user)
 754                                        ret = copy_to_user(iov_addr, bv_addr,
 755                                                           bytes);
 756
 757                                if (from_user)
 758                                        ret = copy_from_user(bv_addr, iov_addr,
 759                                                             bytes);
 760
 761                                if (ret)
 762                                        ret = -EFAULT;
 763                        }
 764
 765                        bv_len -= bytes;
 766                        bv_addr += bytes;
 767                        iov_addr += bytes;
 768                        iov_off += bytes;
 769
 770                        if (iov[iov_idx].iov_len == iov_off) {
 771                                iov_idx++;
 772                                iov_off = 0;
 773                        }
 774                }
 775
 776                if (do_free_page)
 777                        __free_page(bvec->bv_page);
 778        }
 779
 780        return ret;
 781}
 782
 783/**
 784 *      bio_uncopy_user -       finish previously mapped bio
 785 *      @bio: bio being terminated
 786 *
 787 *      Free pages allocated from bio_copy_user() and write back data
 788 *      to user space in case of a read.
 789 */
 790int bio_uncopy_user(struct bio *bio)
 791{
 792        struct bio_map_data *bmd = bio->bi_private;
 793        int ret = 0;
 794
 795        if (!bio_flagged(bio, BIO_NULL_MAPPED))
 796                ret = __bio_copy_iov(bio, bmd->iovecs, bmd->sgvecs,
 797                                     bmd->nr_sgvecs, bio_data_dir(bio) == READ,
 798                                     0, bmd->is_our_pages);
 799        bio_free_map_data(bmd);
 800        bio_put(bio);
 801        return ret;
 802}
 803EXPORT_SYMBOL(bio_uncopy_user);
 804
 805/**
 806 *      bio_copy_user_iov       -       copy user data to bio
 807 *      @q: destination block queue
 808 *      @map_data: pointer to the rq_map_data holding pages (if necessary)
 809 *      @iov:   the iovec.
 810 *      @iov_count: number of elements in the iovec
 811 *      @write_to_vm: bool indicating writing to pages or not
 812 *      @gfp_mask: memory allocation flags
 813 *
 814 *      Prepares and returns a bio for indirect user io, bouncing data
 815 *      to/from kernel pages as necessary. Must be paired with
 816 *      call bio_uncopy_user() on io completion.
 817 */
 818struct bio *bio_copy_user_iov(struct request_queue *q,
 819                              struct rq_map_data *map_data,
 820                              struct sg_iovec *iov, int iov_count,
 821                              int write_to_vm, gfp_t gfp_mask)
 822{
 823        struct bio_map_data *bmd;
 824        struct bio_vec *bvec;
 825        struct page *page;
 826        struct bio *bio;
 827        int i, ret;
 828        int nr_pages = 0;
 829        unsigned int len = 0;
 830        unsigned int offset = map_data ? map_data->offset & ~PAGE_MASK : 0;
 831
 832        for (i = 0; i < iov_count; i++) {
 833                unsigned long uaddr;
 834                unsigned long end;
 835                unsigned long start;
 836
 837                uaddr = (unsigned long)iov[i].iov_base;
 838                end = (uaddr + iov[i].iov_len + PAGE_SIZE - 1) >> PAGE_SHIFT;
 839                start = uaddr >> PAGE_SHIFT;
 840
 841                /*
 842                 * Overflow, abort
 843                 */
 844                if (end < start)
 845                        return ERR_PTR(-EINVAL);
 846
 847                nr_pages += end - start;
 848                len += iov[i].iov_len;
 849        }
 850
 851        if (offset)
 852                nr_pages++;
 853
 854        bmd = bio_alloc_map_data(nr_pages, iov_count, gfp_mask);
 855        if (!bmd)
 856                return ERR_PTR(-ENOMEM);
 857
 858        ret = -ENOMEM;
 859        bio = bio_kmalloc(gfp_mask, nr_pages);
 860        if (!bio)
 861                goto out_bmd;
 862
 863        if (!write_to_vm)
 864                bio->bi_rw |= REQ_WRITE;
 865
 866        ret = 0;
 867
 868        if (map_data) {
 869                nr_pages = 1 << map_data->page_order;
 870                i = map_data->offset / PAGE_SIZE;
 871        }
 872        while (len) {
 873                unsigned int bytes = PAGE_SIZE;
 874
 875                bytes -= offset;
 876
 877                if (bytes > len)
 878                        bytes = len;
 879
 880                if (map_data) {
 881                        if (i == map_data->nr_entries * nr_pages) {
 882                                ret = -ENOMEM;
 883                                break;
 884                        }
 885
 886                        page = map_data->pages[i / nr_pages];
 887                        page += (i % nr_pages);
 888
 889                        i++;
 890                } else {
 891                        page = alloc_page(q->bounce_gfp | gfp_mask);
 892                        if (!page) {
 893                                ret = -ENOMEM;
 894                                break;
 895                        }
 896                }
 897
 898                if (bio_add_pc_page(q, bio, page, bytes, offset) < bytes)
 899                        break;
 900
 901                len -= bytes;
 902                offset = 0;
 903        }
 904
 905        if (ret)
 906                goto cleanup;
 907
 908        /*
 909         * success
 910         */
 911        if ((!write_to_vm && (!map_data || !map_data->null_mapped)) ||
 912            (map_data && map_data->from_user)) {
 913                ret = __bio_copy_iov(bio, bio->bi_io_vec, iov, iov_count, 0, 1, 0);
 914                if (ret)
 915                        goto cleanup;
 916        }
 917
 918        bio_set_map_data(bmd, bio, iov, iov_count, map_data ? 0 : 1);
 919        return bio;
 920cleanup:
 921        if (!map_data)
 922                bio_for_each_segment(bvec, bio, i)
 923                        __free_page(bvec->bv_page);
 924
 925        bio_put(bio);
 926out_bmd:
 927        bio_free_map_data(bmd);
 928        return ERR_PTR(ret);
 929}
 930
 931/**
 932 *      bio_copy_user   -       copy user data to bio
 933 *      @q: destination block queue
 934 *      @map_data: pointer to the rq_map_data holding pages (if necessary)
 935 *      @uaddr: start of user address
 936 *      @len: length in bytes
 937 *      @write_to_vm: bool indicating writing to pages or not
 938 *      @gfp_mask: memory allocation flags
 939 *
 940 *      Prepares and returns a bio for indirect user io, bouncing data
 941 *      to/from kernel pages as necessary. Must be paired with
 942 *      call bio_uncopy_user() on io completion.
 943 */
 944struct bio *bio_copy_user(struct request_queue *q, struct rq_map_data *map_data,
 945                          unsigned long uaddr, unsigned int len,
 946                          int write_to_vm, gfp_t gfp_mask)
 947{
 948        struct sg_iovec iov;
 949
 950        iov.iov_base = (void __user *)uaddr;
 951        iov.iov_len = len;
 952
 953        return bio_copy_user_iov(q, map_data, &iov, 1, write_to_vm, gfp_mask);
 954}
 955EXPORT_SYMBOL(bio_copy_user);
 956
 957static struct bio *__bio_map_user_iov(struct request_queue *q,
 958                                      struct block_device *bdev,
 959                                      struct sg_iovec *iov, int iov_count,
 960                                      int write_to_vm, gfp_t gfp_mask)
 961{
 962        int i, j;
 963        int nr_pages = 0;
 964        struct page **pages;
 965        struct bio *bio;
 966        int cur_page = 0;
 967        int ret, offset;
 968
 969        for (i = 0; i < iov_count; i++) {
 970                unsigned long uaddr = (unsigned long)iov[i].iov_base;
 971                unsigned long len = iov[i].iov_len;
 972                unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
 973                unsigned long start = uaddr >> PAGE_SHIFT;
 974
 975                /*
 976                 * Overflow, abort
 977                 */
 978                if (end < start)
 979                        return ERR_PTR(-EINVAL);
 980
 981                nr_pages += end - start;
 982                /*
 983                 * buffer must be aligned to at least hardsector size for now
 984                 */
 985                if (uaddr & queue_dma_alignment(q))
 986                        return ERR_PTR(-EINVAL);
 987        }
 988
 989        if (!nr_pages)
 990                return ERR_PTR(-EINVAL);
 991
 992        bio = bio_kmalloc(gfp_mask, nr_pages);
 993        if (!bio)
 994                return ERR_PTR(-ENOMEM);
 995
 996        ret = -ENOMEM;
 997        pages = kcalloc(nr_pages, sizeof(struct page *), gfp_mask);
 998        if (!pages)
 999                goto out;
1000
1001        for (i = 0; i < iov_count; i++) {
1002                unsigned long uaddr = (unsigned long)iov[i].iov_base;
1003                unsigned long len = iov[i].iov_len;
1004                unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1005                unsigned long start = uaddr >> PAGE_SHIFT;
1006                const int local_nr_pages = end - start;
1007                const int page_limit = cur_page + local_nr_pages;
1008
1009                ret = get_user_pages_fast(uaddr, local_nr_pages,
1010                                write_to_vm, &pages[cur_page]);
1011                if (ret < local_nr_pages) {
1012                        ret = -EFAULT;
1013                        goto out_unmap;
1014                }
1015
1016                offset = uaddr & ~PAGE_MASK;
1017                for (j = cur_page; j < page_limit; j++) {
1018                        unsigned int bytes = PAGE_SIZE - offset;
1019
1020                        if (len <= 0)
1021                                break;
1022                        
1023                        if (bytes > len)
1024                                bytes = len;
1025
1026                        /*
1027                         * sorry...
1028                         */
1029                        if (bio_add_pc_page(q, bio, pages[j], bytes, offset) <
1030                                            bytes)
1031                                break;
1032
1033                        len -= bytes;
1034                        offset = 0;
1035                }
1036
1037                cur_page = j;
1038                /*
1039                 * release the pages we didn't map into the bio, if any
1040                 */
1041                while (j < page_limit)
1042                        page_cache_release(pages[j++]);
1043        }
1044
1045        kfree(pages);
1046
1047        /*
1048         * set data direction, and check if mapped pages need bouncing
1049         */
1050        if (!write_to_vm)
1051                bio->bi_rw |= REQ_WRITE;
1052
1053        bio->bi_bdev = bdev;
1054        bio->bi_flags |= (1 << BIO_USER_MAPPED);
1055        return bio;
1056
1057 out_unmap:
1058        for (i = 0; i < nr_pages; i++) {
1059                if(!pages[i])
1060                        break;
1061                page_cache_release(pages[i]);
1062        }
1063 out:
1064        kfree(pages);
1065        bio_put(bio);
1066        return ERR_PTR(ret);
1067}
1068
1069/**
1070 *      bio_map_user    -       map user address into bio
1071 *      @q: the struct request_queue for the bio
1072 *      @bdev: destination block device
1073 *      @uaddr: start of user address
1074 *      @len: length in bytes
1075 *      @write_to_vm: bool indicating writing to pages or not
1076 *      @gfp_mask: memory allocation flags
1077 *
1078 *      Map the user space address into a bio suitable for io to a block
1079 *      device. Returns an error pointer in case of error.
1080 */
1081struct bio *bio_map_user(struct request_queue *q, struct block_device *bdev,
1082                         unsigned long uaddr, unsigned int len, int write_to_vm,
1083                         gfp_t gfp_mask)
1084{
1085        struct sg_iovec iov;
1086
1087        iov.iov_base = (void __user *)uaddr;
1088        iov.iov_len = len;
1089
1090        return bio_map_user_iov(q, bdev, &iov, 1, write_to_vm, gfp_mask);
1091}
1092EXPORT_SYMBOL(bio_map_user);
1093
1094/**
1095 *      bio_map_user_iov - map user sg_iovec table into bio
1096 *      @q: the struct request_queue for the bio
1097 *      @bdev: destination block device
1098 *      @iov:   the iovec.
1099 *      @iov_count: number of elements in the iovec
1100 *      @write_to_vm: bool indicating writing to pages or not
1101 *      @gfp_mask: memory allocation flags
1102 *
1103 *      Map the user space address into a bio suitable for io to a block
1104 *      device. Returns an error pointer in case of error.
1105 */
1106struct bio *bio_map_user_iov(struct request_queue *q, struct block_device *bdev,
1107                             struct sg_iovec *iov, int iov_count,
1108                             int write_to_vm, gfp_t gfp_mask)
1109{
1110        struct bio *bio;
1111
1112        bio = __bio_map_user_iov(q, bdev, iov, iov_count, write_to_vm,
1113                                 gfp_mask);
1114        if (IS_ERR(bio))
1115                return bio;
1116
1117        /*
1118         * subtle -- if __bio_map_user() ended up bouncing a bio,
1119         * it would normally disappear when its bi_end_io is run.
1120         * however, we need it for the unmap, so grab an extra
1121         * reference to it
1122         */
1123        bio_get(bio);
1124
1125        return bio;
1126}
1127
1128static void __bio_unmap_user(struct bio *bio)
1129{
1130        struct bio_vec *bvec;
1131        int i;
1132
1133        /*
1134         * make sure we dirty pages we wrote to
1135         */
1136        __bio_for_each_segment(bvec, bio, i, 0) {
1137                if (bio_data_dir(bio) == READ)
1138                        set_page_dirty_lock(bvec->bv_page);
1139
1140                page_cache_release(bvec->bv_page);
1141        }
1142
1143        bio_put(bio);
1144}
1145
1146/**
1147 *      bio_unmap_user  -       unmap a bio
1148 *      @bio:           the bio being unmapped
1149 *
1150 *      Unmap a bio previously mapped by bio_map_user(). Must be called with
1151 *      a process context.
1152 *
1153 *      bio_unmap_user() may sleep.
1154 */
1155void bio_unmap_user(struct bio *bio)
1156{
1157        __bio_unmap_user(bio);
1158        bio_put(bio);
1159}
1160EXPORT_SYMBOL(bio_unmap_user);
1161
1162static void bio_map_kern_endio(struct bio *bio, int err)
1163{
1164        bio_put(bio);
1165}
1166
1167static struct bio *__bio_map_kern(struct request_queue *q, void *data,
1168                                  unsigned int len, gfp_t gfp_mask)
1169{
1170        unsigned long kaddr = (unsigned long)data;
1171        unsigned long end = (kaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1172        unsigned long start = kaddr >> PAGE_SHIFT;
1173        const int nr_pages = end - start;
1174        int offset, i;
1175        struct bio *bio;
1176
1177        bio = bio_kmalloc(gfp_mask, nr_pages);
1178        if (!bio)
1179                return ERR_PTR(-ENOMEM);
1180
1181        offset = offset_in_page(kaddr);
1182        for (i = 0; i < nr_pages; i++) {
1183                unsigned int bytes = PAGE_SIZE - offset;
1184
1185                if (len <= 0)
1186                        break;
1187
1188                if (bytes > len)
1189                        bytes = len;
1190
1191                if (bio_add_pc_page(q, bio, virt_to_page(data), bytes,
1192                                    offset) < bytes)
1193                        break;
1194
1195                data += bytes;
1196                len -= bytes;
1197                offset = 0;
1198        }
1199
1200        bio->bi_end_io = bio_map_kern_endio;
1201        return bio;
1202}
1203
1204/**
1205 *      bio_map_kern    -       map kernel address into bio
1206 *      @q: the struct request_queue for the bio
1207 *      @data: pointer to buffer to map
1208 *      @len: length in bytes
1209 *      @gfp_mask: allocation flags for bio allocation
1210 *
1211 *      Map the kernel address into a bio suitable for io to a block
1212 *      device. Returns an error pointer in case of error.
1213 */
1214struct bio *bio_map_kern(struct request_queue *q, void *data, unsigned int len,
1215                         gfp_t gfp_mask)
1216{
1217        struct bio *bio;
1218
1219        bio = __bio_map_kern(q, data, len, gfp_mask);
1220        if (IS_ERR(bio))
1221                return bio;
1222
1223        if (bio->bi_size == len)
1224                return bio;
1225
1226        /*
1227         * Don't support partial mappings.
1228         */
1229        bio_put(bio);
1230        return ERR_PTR(-EINVAL);
1231}
1232EXPORT_SYMBOL(bio_map_kern);
1233
1234static void bio_copy_kern_endio(struct bio *bio, int err)
1235{
1236        struct bio_vec *bvec;
1237        const int read = bio_data_dir(bio) == READ;
1238        struct bio_map_data *bmd = bio->bi_private;
1239        int i;
1240        char *p = bmd->sgvecs[0].iov_base;
1241
1242        __bio_for_each_segment(bvec, bio, i, 0) {
1243                char *addr = page_address(bvec->bv_page);
1244                int len = bmd->iovecs[i].bv_len;
1245
1246                if (read)
1247                        memcpy(p, addr, len);
1248
1249                __free_page(bvec->bv_page);
1250                p += len;
1251        }
1252
1253        bio_free_map_data(bmd);
1254        bio_put(bio);
1255}
1256
1257/**
1258 *      bio_copy_kern   -       copy kernel address into bio
1259 *      @q: the struct request_queue for the bio
1260 *      @data: pointer to buffer to copy
1261 *      @len: length in bytes
1262 *      @gfp_mask: allocation flags for bio and page allocation
1263 *      @reading: data direction is READ
1264 *
1265 *      copy the kernel address into a bio suitable for io to a block
1266 *      device. Returns an error pointer in case of error.
1267 */
1268struct bio *bio_copy_kern(struct request_queue *q, void *data, unsigned int len,
1269                          gfp_t gfp_mask, int reading)
1270{
1271        struct bio *bio;
1272        struct bio_vec *bvec;
1273        int i;
1274
1275        bio = bio_copy_user(q, NULL, (unsigned long)data, len, 1, gfp_mask);
1276        if (IS_ERR(bio))
1277                return bio;
1278
1279        if (!reading) {
1280                void *p = data;
1281
1282                bio_for_each_segment(bvec, bio, i) {
1283                        char *addr = page_address(bvec->bv_page);
1284
1285                        memcpy(addr, p, bvec->bv_len);
1286                        p += bvec->bv_len;
1287                }
1288        }
1289
1290        bio->bi_end_io = bio_copy_kern_endio;
1291
1292        return bio;
1293}
1294EXPORT_SYMBOL(bio_copy_kern);
1295
1296/*
1297 * bio_set_pages_dirty() and bio_check_pages_dirty() are support functions
1298 * for performing direct-IO in BIOs.
1299 *
1300 * The problem is that we cannot run set_page_dirty() from interrupt context
1301 * because the required locks are not interrupt-safe.  So what we can do is to
1302 * mark the pages dirty _before_ performing IO.  And in interrupt context,
1303 * check that the pages are still dirty.   If so, fine.  If not, redirty them
1304 * in process context.
1305 *
1306 * We special-case compound pages here: normally this means reads into hugetlb
1307 * pages.  The logic in here doesn't really work right for compound pages
1308 * because the VM does not uniformly chase down the head page in all cases.
1309 * But dirtiness of compound pages is pretty meaningless anyway: the VM doesn't
1310 * handle them at all.  So we skip compound pages here at an early stage.
1311 *
1312 * Note that this code is very hard to test under normal circumstances because
1313 * direct-io pins the pages with get_user_pages().  This makes
1314 * is_page_cache_freeable return false, and the VM will not clean the pages.
1315 * But other code (eg, pdflush) could clean the pages if they are mapped
1316 * pagecache.
1317 *
1318 * Simply disabling the call to bio_set_pages_dirty() is a good way to test the
1319 * deferred bio dirtying paths.
1320 */
1321
1322/*
1323 * bio_set_pages_dirty() will mark all the bio's pages as dirty.
1324 */
1325void bio_set_pages_dirty(struct bio *bio)
1326{
1327        struct bio_vec *bvec = bio->bi_io_vec;
1328        int i;
1329
1330        for (i = 0; i < bio->bi_vcnt; i++) {
1331                struct page *page = bvec[i].bv_page;
1332
1333                if (page && !PageCompound(page))
1334                        set_page_dirty_lock(page);
1335        }
1336}
1337
1338static void bio_release_pages(struct bio *bio)
1339{
1340        struct bio_vec *bvec = bio->bi_io_vec;
1341        int i;
1342
1343        for (i = 0; i < bio->bi_vcnt; i++) {
1344                struct page *page = bvec[i].bv_page;
1345
1346                if (page)
1347                        put_page(page);
1348        }
1349}
1350
1351/*
1352 * bio_check_pages_dirty() will check that all the BIO's pages are still dirty.
1353 * If they are, then fine.  If, however, some pages are clean then they must
1354 * have been written out during the direct-IO read.  So we take another ref on
1355 * the BIO and the offending pages and re-dirty the pages in process context.
1356 *
1357 * It is expected that bio_check_pages_dirty() will wholly own the BIO from
1358 * here on.  It will run one page_cache_release() against each page and will
1359 * run one bio_put() against the BIO.
1360 */
1361
1362static void bio_dirty_fn(struct work_struct *work);
1363
1364static DECLARE_WORK(bio_dirty_work, bio_dirty_fn);
1365static DEFINE_SPINLOCK(bio_dirty_lock);
1366static struct bio *bio_dirty_list;
1367
1368/*
1369 * This runs in process context
1370 */
1371static void bio_dirty_fn(struct work_struct *work)
1372{
1373        unsigned long flags;
1374        struct bio *bio;
1375
1376        spin_lock_irqsave(&bio_dirty_lock, flags);
1377        bio = bio_dirty_list;
1378        bio_dirty_list = NULL;
1379        spin_unlock_irqrestore(&bio_dirty_lock, flags);
1380
1381        while (bio) {
1382                struct bio *next = bio->bi_private;
1383
1384                bio_set_pages_dirty(bio);
1385                bio_release_pages(bio);
1386                bio_put(bio);
1387                bio = next;
1388        }
1389}
1390
1391void bio_check_pages_dirty(struct bio *bio)
1392{
1393        struct bio_vec *bvec = bio->bi_io_vec;
1394        int nr_clean_pages = 0;
1395        int i;
1396
1397        for (i = 0; i < bio->bi_vcnt; i++) {
1398                struct page *page = bvec[i].bv_page;
1399
1400                if (PageDirty(page) || PageCompound(page)) {
1401                        page_cache_release(page);
1402                        bvec[i].bv_page = NULL;
1403                } else {
1404                        nr_clean_pages++;
1405                }
1406        }
1407
1408        if (nr_clean_pages) {
1409                unsigned long flags;
1410
1411                spin_lock_irqsave(&bio_dirty_lock, flags);
1412                bio->bi_private = bio_dirty_list;
1413                bio_dirty_list = bio;
1414                spin_unlock_irqrestore(&bio_dirty_lock, flags);
1415                schedule_work(&bio_dirty_work);
1416        } else {
1417                bio_put(bio);
1418        }
1419}
1420
1421#if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
1422void bio_flush_dcache_pages(struct bio *bi)
1423{
1424        int i;
1425        struct bio_vec *bvec;
1426
1427        bio_for_each_segment(bvec, bi, i)
1428                flush_dcache_page(bvec->bv_page);
1429}
1430EXPORT_SYMBOL(bio_flush_dcache_pages);
1431#endif
1432
1433/**
1434 * bio_endio - end I/O on a bio
1435 * @bio:        bio
1436 * @error:      error, if any
1437 *
1438 * Description:
1439 *   bio_endio() will end I/O on the whole bio. bio_endio() is the
1440 *   preferred way to end I/O on a bio, it takes care of clearing
1441 *   BIO_UPTODATE on error. @error is 0 on success, and and one of the
1442 *   established -Exxxx (-EIO, for instance) error values in case
1443 *   something went wrong. No one should call bi_end_io() directly on a
1444 *   bio unless they own it and thus know that it has an end_io
1445 *   function.
1446 **/
1447void bio_endio(struct bio *bio, int error)
1448{
1449        if (error)
1450                clear_bit(BIO_UPTODATE, &bio->bi_flags);
1451        else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
1452                error = -EIO;
1453
1454        if (bio->bi_end_io)
1455                bio->bi_end_io(bio, error);
1456}
1457EXPORT_SYMBOL(bio_endio);
1458
1459void bio_pair_release(struct bio_pair *bp)
1460{
1461        if (atomic_dec_and_test(&bp->cnt)) {
1462                struct bio *master = bp->bio1.bi_private;
1463
1464                bio_endio(master, bp->error);
1465                mempool_free(bp, bp->bio2.bi_private);
1466        }
1467}
1468EXPORT_SYMBOL(bio_pair_release);
1469
1470static void bio_pair_end_1(struct bio *bi, int err)
1471{
1472        struct bio_pair *bp = container_of(bi, struct bio_pair, bio1);
1473
1474        if (err)
1475                bp->error = err;
1476
1477        bio_pair_release(bp);
1478}
1479
1480static void bio_pair_end_2(struct bio *bi, int err)
1481{
1482        struct bio_pair *bp = container_of(bi, struct bio_pair, bio2);
1483
1484        if (err)
1485                bp->error = err;
1486
1487        bio_pair_release(bp);
1488}
1489
1490/*
1491 * split a bio - only worry about a bio with a single page in its iovec
1492 */
1493struct bio_pair *bio_split(struct bio *bi, int first_sectors)
1494{
1495        struct bio_pair *bp = mempool_alloc(bio_split_pool, GFP_NOIO);
1496
1497        if (!bp)
1498                return bp;
1499
1500        trace_block_split(bdev_get_queue(bi->bi_bdev), bi,
1501                                bi->bi_sector + first_sectors);
1502
1503        BUG_ON(bi->bi_vcnt != 1);
1504        BUG_ON(bi->bi_idx != 0);
1505        atomic_set(&bp->cnt, 3);
1506        bp->error = 0;
1507        bp->bio1 = *bi;
1508        bp->bio2 = *bi;
1509        bp->bio2.bi_sector += first_sectors;
1510        bp->bio2.bi_size -= first_sectors << 9;
1511        bp->bio1.bi_size = first_sectors << 9;
1512
1513        bp->bv1 = bi->bi_io_vec[0];
1514        bp->bv2 = bi->bi_io_vec[0];
1515        bp->bv2.bv_offset += first_sectors << 9;
1516        bp->bv2.bv_len -= first_sectors << 9;
1517        bp->bv1.bv_len = first_sectors << 9;
1518
1519        bp->bio1.bi_io_vec = &bp->bv1;
1520        bp->bio2.bi_io_vec = &bp->bv2;
1521
1522        bp->bio1.bi_max_vecs = 1;
1523        bp->bio2.bi_max_vecs = 1;
1524
1525        bp->bio1.bi_end_io = bio_pair_end_1;
1526        bp->bio2.bi_end_io = bio_pair_end_2;
1527
1528        bp->bio1.bi_private = bi;
1529        bp->bio2.bi_private = bio_split_pool;
1530
1531        if (bio_integrity(bi))
1532                bio_integrity_split(bi, bp, first_sectors);
1533
1534        return bp;
1535}
1536EXPORT_SYMBOL(bio_split);
1537
1538/**
1539 *      bio_sector_offset - Find hardware sector offset in bio
1540 *      @bio:           bio to inspect
1541 *      @index:         bio_vec index
1542 *      @offset:        offset in bv_page
1543 *
1544 *      Return the number of hardware sectors between beginning of bio
1545 *      and an end point indicated by a bio_vec index and an offset
1546 *      within that vector's page.
1547 */
1548sector_t bio_sector_offset(struct bio *bio, unsigned short index,
1549                           unsigned int offset)
1550{
1551        unsigned int sector_sz;
1552        struct bio_vec *bv;
1553        sector_t sectors;
1554        int i;
1555
1556        sector_sz = queue_logical_block_size(bio->bi_bdev->bd_disk->queue);
1557        sectors = 0;
1558
1559        if (index >= bio->bi_idx)
1560                index = bio->bi_vcnt - 1;
1561
1562        __bio_for_each_segment(bv, bio, i, 0) {
1563                if (i == index) {
1564                        if (offset > bv->bv_offset)
1565                                sectors += (offset - bv->bv_offset) / sector_sz;
1566                        break;
1567                }
1568
1569                sectors += bv->bv_len / sector_sz;
1570        }
1571
1572        return sectors;
1573}
1574EXPORT_SYMBOL(bio_sector_offset);
1575
1576/*
1577 * create memory pools for biovec's in a bio_set.
1578 * use the global biovec slabs created for general use.
1579 */
1580static int biovec_create_pools(struct bio_set *bs, int pool_entries)
1581{
1582        struct biovec_slab *bp = bvec_slabs + BIOVEC_MAX_IDX;
1583
1584        bs->bvec_pool = mempool_create_slab_pool(pool_entries, bp->slab);
1585        if (!bs->bvec_pool)
1586                return -ENOMEM;
1587
1588        return 0;
1589}
1590
1591static void biovec_free_pools(struct bio_set *bs)
1592{
1593        mempool_destroy(bs->bvec_pool);
1594}
1595
1596void bioset_free(struct bio_set *bs)
1597{
1598        if (bs->bio_pool)
1599                mempool_destroy(bs->bio_pool);
1600
1601        bioset_integrity_free(bs);
1602        biovec_free_pools(bs);
1603        bio_put_slab(bs);
1604
1605        kfree(bs);
1606}
1607EXPORT_SYMBOL(bioset_free);
1608
1609/**
1610 * bioset_create  - Create a bio_set
1611 * @pool_size:  Number of bio and bio_vecs to cache in the mempool
1612 * @front_pad:  Number of bytes to allocate in front of the returned bio
1613 *
1614 * Description:
1615 *    Set up a bio_set to be used with @bio_alloc_bioset. Allows the caller
1616 *    to ask for a number of bytes to be allocated in front of the bio.
1617 *    Front pad allocation is useful for embedding the bio inside
1618 *    another structure, to avoid allocating extra data to go with the bio.
1619 *    Note that the bio must be embedded at the END of that structure always,
1620 *    or things will break badly.
1621 */
1622struct bio_set *bioset_create(unsigned int pool_size, unsigned int front_pad)
1623{
1624        unsigned int back_pad = BIO_INLINE_VECS * sizeof(struct bio_vec);
1625        struct bio_set *bs;
1626
1627        bs = kzalloc(sizeof(*bs), GFP_KERNEL);
1628        if (!bs)
1629                return NULL;
1630
1631        bs->front_pad = front_pad;
1632
1633        bs->bio_slab = bio_find_or_create_slab(front_pad + back_pad);
1634        if (!bs->bio_slab) {
1635                kfree(bs);
1636                return NULL;
1637        }
1638
1639        bs->bio_pool = mempool_create_slab_pool(pool_size, bs->bio_slab);
1640        if (!bs->bio_pool)
1641                goto bad;
1642
1643        if (!biovec_create_pools(bs, pool_size))
1644                return bs;
1645
1646bad:
1647        bioset_free(bs);
1648        return NULL;
1649}
1650EXPORT_SYMBOL(bioset_create);
1651
1652#ifdef CONFIG_BLK_CGROUP
1653/**
1654 * bio_associate_current - associate a bio with %current
1655 * @bio: target bio
1656 *
1657 * Associate @bio with %current if it hasn't been associated yet.  Block
1658 * layer will treat @bio as if it were issued by %current no matter which
1659 * task actually issues it.
1660 *
1661 * This function takes an extra reference of @task's io_context and blkcg
1662 * which will be put when @bio is released.  The caller must own @bio,
1663 * ensure %current->io_context exists, and is responsible for synchronizing
1664 * calls to this function.
1665 */
1666int bio_associate_current(struct bio *bio)
1667{
1668        struct io_context *ioc;
1669        struct cgroup_subsys_state *css;
1670
1671        if (bio->bi_ioc)
1672                return -EBUSY;
1673
1674        ioc = current->io_context;
1675        if (!ioc)
1676                return -ENOENT;
1677
1678        /* acquire active ref on @ioc and associate */
1679        get_io_context_active(ioc);
1680        bio->bi_ioc = ioc;
1681
1682        /* associate blkcg if exists */
1683        rcu_read_lock();
1684        css = task_subsys_state(current, blkio_subsys_id);
1685        if (css && css_tryget(css))
1686                bio->bi_css = css;
1687        rcu_read_unlock();
1688
1689        return 0;
1690}
1691
1692/**
1693 * bio_disassociate_task - undo bio_associate_current()
1694 * @bio: target bio
1695 */
1696void bio_disassociate_task(struct bio *bio)
1697{
1698        if (bio->bi_ioc) {
1699                put_io_context(bio->bi_ioc);
1700                bio->bi_ioc = NULL;
1701        }
1702        if (bio->bi_css) {
1703                css_put(bio->bi_css);
1704                bio->bi_css = NULL;
1705        }
1706}
1707
1708#endif /* CONFIG_BLK_CGROUP */
1709
1710static void __init biovec_init_slabs(void)
1711{
1712        int i;
1713
1714        for (i = 0; i < BIOVEC_NR_POOLS; i++) {
1715                int size;
1716                struct biovec_slab *bvs = bvec_slabs + i;
1717
1718                if (bvs->nr_vecs <= BIO_INLINE_VECS) {
1719                        bvs->slab = NULL;
1720                        continue;
1721                }
1722
1723                size = bvs->nr_vecs * sizeof(struct bio_vec);
1724                bvs->slab = kmem_cache_create(bvs->name, size, 0,
1725                                SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
1726        }
1727}
1728
1729static int __init init_bio(void)
1730{
1731        bio_slab_max = 2;
1732        bio_slab_nr = 0;
1733        bio_slabs = kzalloc(bio_slab_max * sizeof(struct bio_slab), GFP_KERNEL);
1734        if (!bio_slabs)
1735                panic("bio: can't allocate bios\n");
1736
1737        bio_integrity_init();
1738        biovec_init_slabs();
1739
1740        fs_bio_set = bioset_create(BIO_POOL_SIZE, 0);
1741        if (!fs_bio_set)
1742                panic("bio: can't allocate bios\n");
1743
1744        if (bioset_integrity_create(fs_bio_set, BIO_POOL_SIZE))
1745                panic("bio: can't create integrity pool\n");
1746
1747        bio_split_pool = mempool_create_kmalloc_pool(BIO_SPLIT_ENTRIES,
1748                                                     sizeof(struct bio_pair));
1749        if (!bio_split_pool)
1750                panic("bio: can't create split pool\n");
1751
1752        return 0;
1753}
1754subsys_initcall(init_bio);
1755
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