linux/include/linux/bio.h
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   1/*
   2 * Copyright (C) 2001 Jens Axboe <axboe@suse.de>
   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 *
  11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 * GNU General Public License for more details.
  13 *
  14 * You should have received a copy of the GNU General Public Licens
  15 * along with this program; if not, write to the Free Software
  16 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-
  17 */
  18#ifndef __LINUX_BIO_H
  19#define __LINUX_BIO_H
  20
  21#include <linux/highmem.h>
  22#include <linux/mempool.h>
  23#include <linux/ioprio.h>
  24#include <linux/bug.h>
  25
  26#ifdef CONFIG_BLOCK
  27
  28#include <asm/io.h>
  29
  30/* struct bio, bio_vec and BIO_* flags are defined in blk_types.h */
  31#include <linux/blk_types.h>
  32
  33#define BIO_DEBUG
  34
  35#ifdef BIO_DEBUG
  36#define BIO_BUG_ON      BUG_ON
  37#else
  38#define BIO_BUG_ON
  39#endif
  40
  41#define BIO_MAX_PAGES           256
  42
  43#define bio_prio(bio)                   (bio)->bi_ioprio
  44#define bio_set_prio(bio, prio)         ((bio)->bi_ioprio = prio)
  45
  46#define bio_iter_iovec(bio, iter)                               \
  47        bvec_iter_bvec((bio)->bi_io_vec, (iter))
  48
  49#define bio_iter_page(bio, iter)                                \
  50        bvec_iter_page((bio)->bi_io_vec, (iter))
  51#define bio_iter_len(bio, iter)                                 \
  52        bvec_iter_len((bio)->bi_io_vec, (iter))
  53#define bio_iter_offset(bio, iter)                              \
  54        bvec_iter_offset((bio)->bi_io_vec, (iter))
  55
  56#define bio_page(bio)           bio_iter_page((bio), (bio)->bi_iter)
  57#define bio_offset(bio)         bio_iter_offset((bio), (bio)->bi_iter)
  58#define bio_iovec(bio)          bio_iter_iovec((bio), (bio)->bi_iter)
  59
  60#define bio_multiple_segments(bio)                              \
  61        ((bio)->bi_iter.bi_size != bio_iovec(bio).bv_len)
  62#define bio_sectors(bio)        ((bio)->bi_iter.bi_size >> 9)
  63#define bio_end_sector(bio)     ((bio)->bi_iter.bi_sector + bio_sectors((bio)))
  64
  65/*
  66 * Return the data direction, READ or WRITE.
  67 */
  68#define bio_data_dir(bio) \
  69        (op_is_write(bio_op(bio)) ? WRITE : READ)
  70
  71/*
  72 * Check whether this bio carries any data or not. A NULL bio is allowed.
  73 */
  74static inline bool bio_has_data(struct bio *bio)
  75{
  76        if (bio &&
  77            bio->bi_iter.bi_size &&
  78            bio_op(bio) != REQ_OP_DISCARD &&
  79            bio_op(bio) != REQ_OP_SECURE_ERASE &&
  80            bio_op(bio) != REQ_OP_WRITE_ZEROES)
  81                return true;
  82
  83        return false;
  84}
  85
  86static inline bool bio_no_advance_iter(struct bio *bio)
  87{
  88        return bio_op(bio) == REQ_OP_DISCARD ||
  89               bio_op(bio) == REQ_OP_SECURE_ERASE ||
  90               bio_op(bio) == REQ_OP_WRITE_SAME ||
  91               bio_op(bio) == REQ_OP_WRITE_ZEROES;
  92}
  93
  94static inline bool bio_mergeable(struct bio *bio)
  95{
  96        if (bio->bi_opf & REQ_NOMERGE_FLAGS)
  97                return false;
  98
  99        return true;
 100}
 101
 102static inline unsigned int bio_cur_bytes(struct bio *bio)
 103{
 104        if (bio_has_data(bio))
 105                return bio_iovec(bio).bv_len;
 106        else /* dataless requests such as discard */
 107                return bio->bi_iter.bi_size;
 108}
 109
 110static inline void *bio_data(struct bio *bio)
 111{
 112        if (bio_has_data(bio))
 113                return page_address(bio_page(bio)) + bio_offset(bio);
 114
 115        return NULL;
 116}
 117
 118/*
 119 * will die
 120 */
 121#define bvec_to_phys(bv)        (page_to_phys((bv)->bv_page) + (unsigned long) (bv)->bv_offset)
 122
 123/*
 124 * queues that have highmem support enabled may still need to revert to
 125 * PIO transfers occasionally and thus map high pages temporarily. For
 126 * permanent PIO fall back, user is probably better off disabling highmem
 127 * I/O completely on that queue (see ide-dma for example)
 128 */
 129#define __bio_kmap_atomic(bio, iter)                            \
 130        (kmap_atomic(bio_iter_iovec((bio), (iter)).bv_page) +   \
 131                bio_iter_iovec((bio), (iter)).bv_offset)
 132
 133#define __bio_kunmap_atomic(addr)       kunmap_atomic(addr)
 134
 135/*
 136 * merge helpers etc
 137 */
 138
 139/* Default implementation of BIOVEC_PHYS_MERGEABLE */
 140#define __BIOVEC_PHYS_MERGEABLE(vec1, vec2)     \
 141        ((bvec_to_phys((vec1)) + (vec1)->bv_len) == bvec_to_phys((vec2)))
 142
 143/*
 144 * allow arch override, for eg virtualized architectures (put in asm/io.h)
 145 */
 146#ifndef BIOVEC_PHYS_MERGEABLE
 147#define BIOVEC_PHYS_MERGEABLE(vec1, vec2)       \
 148        __BIOVEC_PHYS_MERGEABLE(vec1, vec2)
 149#endif
 150
 151#define __BIO_SEG_BOUNDARY(addr1, addr2, mask) \
 152        (((addr1) | (mask)) == (((addr2) - 1) | (mask)))
 153#define BIOVEC_SEG_BOUNDARY(q, b1, b2) \
 154        __BIO_SEG_BOUNDARY(bvec_to_phys((b1)), bvec_to_phys((b2)) + (b2)->bv_len, queue_segment_boundary((q)))
 155
 156/*
 157 * drivers should _never_ use the all version - the bio may have been split
 158 * before it got to the driver and the driver won't own all of it
 159 */
 160#define bio_for_each_segment_all(bvl, bio, i)                           \
 161        for (i = 0, bvl = (bio)->bi_io_vec; i < (bio)->bi_vcnt; i++, bvl++)
 162
 163static inline void bio_advance_iter(struct bio *bio, struct bvec_iter *iter,
 164                                    unsigned bytes)
 165{
 166        iter->bi_sector += bytes >> 9;
 167
 168        if (bio_no_advance_iter(bio)) {
 169                iter->bi_size -= bytes;
 170                iter->bi_done += bytes;
 171        } else {
 172                bvec_iter_advance(bio->bi_io_vec, iter, bytes);
 173                /* TODO: It is reasonable to complete bio with error here. */
 174        }
 175}
 176
 177static inline bool bio_rewind_iter(struct bio *bio, struct bvec_iter *iter,
 178                unsigned int bytes)
 179{
 180        iter->bi_sector -= bytes >> 9;
 181
 182        if (bio_no_advance_iter(bio)) {
 183                iter->bi_size += bytes;
 184                iter->bi_done -= bytes;
 185                return true;
 186        }
 187
 188        return bvec_iter_rewind(bio->bi_io_vec, iter, bytes);
 189}
 190
 191#define __bio_for_each_segment(bvl, bio, iter, start)                   \
 192        for (iter = (start);                                            \
 193             (iter).bi_size &&                                          \
 194                ((bvl = bio_iter_iovec((bio), (iter))), 1);             \
 195             bio_advance_iter((bio), &(iter), (bvl).bv_len))
 196
 197#define bio_for_each_segment(bvl, bio, iter)                            \
 198        __bio_for_each_segment(bvl, bio, iter, (bio)->bi_iter)
 199
 200#define bio_iter_last(bvec, iter) ((iter).bi_size == (bvec).bv_len)
 201
 202static inline unsigned bio_segments(struct bio *bio)
 203{
 204        unsigned segs = 0;
 205        struct bio_vec bv;
 206        struct bvec_iter iter;
 207
 208        /*
 209         * We special case discard/write same/write zeroes, because they
 210         * interpret bi_size differently:
 211         */
 212
 213        switch (bio_op(bio)) {
 214        case REQ_OP_DISCARD:
 215        case REQ_OP_SECURE_ERASE:
 216        case REQ_OP_WRITE_ZEROES:
 217                return 0;
 218        case REQ_OP_WRITE_SAME:
 219                return 1;
 220        default:
 221                break;
 222        }
 223
 224        bio_for_each_segment(bv, bio, iter)
 225                segs++;
 226
 227        return segs;
 228}
 229
 230/*
 231 * get a reference to a bio, so it won't disappear. the intended use is
 232 * something like:
 233 *
 234 * bio_get(bio);
 235 * submit_bio(rw, bio);
 236 * if (bio->bi_flags ...)
 237 *      do_something
 238 * bio_put(bio);
 239 *
 240 * without the bio_get(), it could potentially complete I/O before submit_bio
 241 * returns. and then bio would be freed memory when if (bio->bi_flags ...)
 242 * runs
 243 */
 244static inline void bio_get(struct bio *bio)
 245{
 246        bio->bi_flags |= (1 << BIO_REFFED);
 247        smp_mb__before_atomic();
 248        atomic_inc(&bio->__bi_cnt);
 249}
 250
 251static inline void bio_cnt_set(struct bio *bio, unsigned int count)
 252{
 253        if (count != 1) {
 254                bio->bi_flags |= (1 << BIO_REFFED);
 255                smp_mb__before_atomic();
 256        }
 257        atomic_set(&bio->__bi_cnt, count);
 258}
 259
 260static inline bool bio_flagged(struct bio *bio, unsigned int bit)
 261{
 262        return (bio->bi_flags & (1U << bit)) != 0;
 263}
 264
 265static inline void bio_set_flag(struct bio *bio, unsigned int bit)
 266{
 267        bio->bi_flags |= (1U << bit);
 268}
 269
 270static inline void bio_clear_flag(struct bio *bio, unsigned int bit)
 271{
 272        bio->bi_flags &= ~(1U << bit);
 273}
 274
 275static inline void bio_get_first_bvec(struct bio *bio, struct bio_vec *bv)
 276{
 277        *bv = bio_iovec(bio);
 278}
 279
 280static inline void bio_get_last_bvec(struct bio *bio, struct bio_vec *bv)
 281{
 282        struct bvec_iter iter = bio->bi_iter;
 283        int idx;
 284
 285        if (unlikely(!bio_multiple_segments(bio))) {
 286                *bv = bio_iovec(bio);
 287                return;
 288        }
 289
 290        bio_advance_iter(bio, &iter, iter.bi_size);
 291
 292        if (!iter.bi_bvec_done)
 293                idx = iter.bi_idx - 1;
 294        else    /* in the middle of bvec */
 295                idx = iter.bi_idx;
 296
 297        *bv = bio->bi_io_vec[idx];
 298
 299        /*
 300         * iter.bi_bvec_done records actual length of the last bvec
 301         * if this bio ends in the middle of one io vector
 302         */
 303        if (iter.bi_bvec_done)
 304                bv->bv_len = iter.bi_bvec_done;
 305}
 306
 307enum bip_flags {
 308        BIP_BLOCK_INTEGRITY     = 1 << 0, /* block layer owns integrity data */
 309        BIP_MAPPED_INTEGRITY    = 1 << 1, /* ref tag has been remapped */
 310        BIP_CTRL_NOCHECK        = 1 << 2, /* disable HBA integrity checking */
 311        BIP_DISK_NOCHECK        = 1 << 3, /* disable disk integrity checking */
 312        BIP_IP_CHECKSUM         = 1 << 4, /* IP checksum */
 313};
 314
 315/*
 316 * bio integrity payload
 317 */
 318struct bio_integrity_payload {
 319        struct bio              *bip_bio;       /* parent bio */
 320
 321        struct bvec_iter        bip_iter;
 322
 323        unsigned short          bip_slab;       /* slab the bip came from */
 324        unsigned short          bip_vcnt;       /* # of integrity bio_vecs */
 325        unsigned short          bip_max_vcnt;   /* integrity bio_vec slots */
 326        unsigned short          bip_flags;      /* control flags */
 327
 328        struct work_struct      bip_work;       /* I/O completion */
 329
 330        struct bio_vec          *bip_vec;
 331        struct bio_vec          bip_inline_vecs[0];/* embedded bvec array */
 332};
 333
 334#if defined(CONFIG_BLK_DEV_INTEGRITY)
 335
 336static inline struct bio_integrity_payload *bio_integrity(struct bio *bio)
 337{
 338        if (bio->bi_opf & REQ_INTEGRITY)
 339                return bio->bi_integrity;
 340
 341        return NULL;
 342}
 343
 344static inline bool bio_integrity_flagged(struct bio *bio, enum bip_flags flag)
 345{
 346        struct bio_integrity_payload *bip = bio_integrity(bio);
 347
 348        if (bip)
 349                return bip->bip_flags & flag;
 350
 351        return false;
 352}
 353
 354static inline sector_t bip_get_seed(struct bio_integrity_payload *bip)
 355{
 356        return bip->bip_iter.bi_sector;
 357}
 358
 359static inline void bip_set_seed(struct bio_integrity_payload *bip,
 360                                sector_t seed)
 361{
 362        bip->bip_iter.bi_sector = seed;
 363}
 364
 365#endif /* CONFIG_BLK_DEV_INTEGRITY */
 366
 367extern void bio_trim(struct bio *bio, int offset, int size);
 368extern struct bio *bio_split(struct bio *bio, int sectors,
 369                             gfp_t gfp, struct bio_set *bs);
 370
 371/**
 372 * bio_next_split - get next @sectors from a bio, splitting if necessary
 373 * @bio:        bio to split
 374 * @sectors:    number of sectors to split from the front of @bio
 375 * @gfp:        gfp mask
 376 * @bs:         bio set to allocate from
 377 *
 378 * Returns a bio representing the next @sectors of @bio - if the bio is smaller
 379 * than @sectors, returns the original bio unchanged.
 380 */
 381static inline struct bio *bio_next_split(struct bio *bio, int sectors,
 382                                         gfp_t gfp, struct bio_set *bs)
 383{
 384        if (sectors >= bio_sectors(bio))
 385                return bio;
 386
 387        return bio_split(bio, sectors, gfp, bs);
 388}
 389
 390extern struct bio_set *bioset_create(unsigned int, unsigned int, int flags);
 391enum {
 392        BIOSET_NEED_BVECS = BIT(0),
 393        BIOSET_NEED_RESCUER = BIT(1),
 394};
 395extern void bioset_free(struct bio_set *);
 396extern mempool_t *biovec_create_pool(int pool_entries);
 397
 398extern struct bio *bio_alloc_bioset(gfp_t, unsigned int, struct bio_set *);
 399extern void bio_put(struct bio *);
 400
 401extern void __bio_clone_fast(struct bio *, struct bio *);
 402extern struct bio *bio_clone_fast(struct bio *, gfp_t, struct bio_set *);
 403extern struct bio *bio_clone_bioset(struct bio *, gfp_t, struct bio_set *bs);
 404
 405extern struct bio_set *fs_bio_set;
 406
 407static inline struct bio *bio_alloc(gfp_t gfp_mask, unsigned int nr_iovecs)
 408{
 409        return bio_alloc_bioset(gfp_mask, nr_iovecs, fs_bio_set);
 410}
 411
 412static inline struct bio *bio_kmalloc(gfp_t gfp_mask, unsigned int nr_iovecs)
 413{
 414        return bio_alloc_bioset(gfp_mask, nr_iovecs, NULL);
 415}
 416
 417static inline struct bio *bio_clone_kmalloc(struct bio *bio, gfp_t gfp_mask)
 418{
 419        return bio_clone_bioset(bio, gfp_mask, NULL);
 420
 421}
 422
 423extern blk_qc_t submit_bio(struct bio *);
 424
 425extern void bio_endio(struct bio *);
 426
 427static inline void bio_io_error(struct bio *bio)
 428{
 429        bio->bi_status = BLK_STS_IOERR;
 430        bio_endio(bio);
 431}
 432
 433static inline void bio_wouldblock_error(struct bio *bio)
 434{
 435        bio->bi_status = BLK_STS_AGAIN;
 436        bio_endio(bio);
 437}
 438
 439struct request_queue;
 440extern int bio_phys_segments(struct request_queue *, struct bio *);
 441
 442extern int submit_bio_wait(struct bio *bio);
 443extern void bio_advance(struct bio *, unsigned);
 444
 445extern void bio_init(struct bio *bio, struct bio_vec *table,
 446                     unsigned short max_vecs);
 447extern void bio_uninit(struct bio *);
 448extern void bio_reset(struct bio *);
 449void bio_chain(struct bio *, struct bio *);
 450
 451extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int);
 452extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,
 453                           unsigned int, unsigned int);
 454int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter);
 455struct rq_map_data;
 456extern struct bio *bio_map_user_iov(struct request_queue *,
 457                                    const struct iov_iter *, gfp_t);
 458extern void bio_unmap_user(struct bio *);
 459extern struct bio *bio_map_kern(struct request_queue *, void *, unsigned int,
 460                                gfp_t);
 461extern struct bio *bio_copy_kern(struct request_queue *, void *, unsigned int,
 462                                 gfp_t, int);
 463extern void bio_set_pages_dirty(struct bio *bio);
 464extern void bio_check_pages_dirty(struct bio *bio);
 465
 466void generic_start_io_acct(int rw, unsigned long sectors,
 467                           struct hd_struct *part);
 468void generic_end_io_acct(int rw, struct hd_struct *part,
 469                         unsigned long start_time);
 470
 471#ifndef ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
 472# error "You should define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE for your platform"
 473#endif
 474#if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
 475extern void bio_flush_dcache_pages(struct bio *bi);
 476#else
 477static inline void bio_flush_dcache_pages(struct bio *bi)
 478{
 479}
 480#endif
 481
 482extern void bio_copy_data(struct bio *dst, struct bio *src);
 483extern int bio_alloc_pages(struct bio *bio, gfp_t gfp);
 484extern void bio_free_pages(struct bio *bio);
 485
 486extern struct bio *bio_copy_user_iov(struct request_queue *,
 487                                     struct rq_map_data *,
 488                                     const struct iov_iter *,
 489                                     gfp_t);
 490extern int bio_uncopy_user(struct bio *);
 491void zero_fill_bio(struct bio *bio);
 492extern struct bio_vec *bvec_alloc(gfp_t, int, unsigned long *, mempool_t *);
 493extern void bvec_free(mempool_t *, struct bio_vec *, unsigned int);
 494extern unsigned int bvec_nr_vecs(unsigned short idx);
 495
 496#ifdef CONFIG_BLK_CGROUP
 497int bio_associate_blkcg(struct bio *bio, struct cgroup_subsys_state *blkcg_css);
 498int bio_associate_current(struct bio *bio);
 499void bio_disassociate_task(struct bio *bio);
 500void bio_clone_blkcg_association(struct bio *dst, struct bio *src);
 501#else   /* CONFIG_BLK_CGROUP */
 502static inline int bio_associate_blkcg(struct bio *bio,
 503                        struct cgroup_subsys_state *blkcg_css) { return 0; }
 504static inline int bio_associate_current(struct bio *bio) { return -ENOENT; }
 505static inline void bio_disassociate_task(struct bio *bio) { }
 506static inline void bio_clone_blkcg_association(struct bio *dst,
 507                        struct bio *src) { }
 508#endif  /* CONFIG_BLK_CGROUP */
 509
 510#ifdef CONFIG_HIGHMEM
 511/*
 512 * remember never ever reenable interrupts between a bvec_kmap_irq and
 513 * bvec_kunmap_irq!
 514 */
 515static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
 516{
 517        unsigned long addr;
 518
 519        /*
 520         * might not be a highmem page, but the preempt/irq count
 521         * balancing is a lot nicer this way
 522         */
 523        local_irq_save(*flags);
 524        addr = (unsigned long) kmap_atomic(bvec->bv_page);
 525
 526        BUG_ON(addr & ~PAGE_MASK);
 527
 528        return (char *) addr + bvec->bv_offset;
 529}
 530
 531static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
 532{
 533        unsigned long ptr = (unsigned long) buffer & PAGE_MASK;
 534
 535        kunmap_atomic((void *) ptr);
 536        local_irq_restore(*flags);
 537}
 538
 539#else
 540static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
 541{
 542        return page_address(bvec->bv_page) + bvec->bv_offset;
 543}
 544
 545static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
 546{
 547        *flags = 0;
 548}
 549#endif
 550
 551static inline char *__bio_kmap_irq(struct bio *bio, struct bvec_iter iter,
 552                                   unsigned long *flags)
 553{
 554        return bvec_kmap_irq(&bio_iter_iovec(bio, iter), flags);
 555}
 556#define __bio_kunmap_irq(buf, flags)    bvec_kunmap_irq(buf, flags)
 557
 558#define bio_kmap_irq(bio, flags) \
 559        __bio_kmap_irq((bio), (bio)->bi_iter, (flags))
 560#define bio_kunmap_irq(buf,flags)       __bio_kunmap_irq(buf, flags)
 561
 562/*
 563 * BIO list management for use by remapping drivers (e.g. DM or MD) and loop.
 564 *
 565 * A bio_list anchors a singly-linked list of bios chained through the bi_next
 566 * member of the bio.  The bio_list also caches the last list member to allow
 567 * fast access to the tail.
 568 */
 569struct bio_list {
 570        struct bio *head;
 571        struct bio *tail;
 572};
 573
 574static inline int bio_list_empty(const struct bio_list *bl)
 575{
 576        return bl->head == NULL;
 577}
 578
 579static inline void bio_list_init(struct bio_list *bl)
 580{
 581        bl->head = bl->tail = NULL;
 582}
 583
 584#define BIO_EMPTY_LIST  { NULL, NULL }
 585
 586#define bio_list_for_each(bio, bl) \
 587        for (bio = (bl)->head; bio; bio = bio->bi_next)
 588
 589static inline unsigned bio_list_size(const struct bio_list *bl)
 590{
 591        unsigned sz = 0;
 592        struct bio *bio;
 593
 594        bio_list_for_each(bio, bl)
 595                sz++;
 596
 597        return sz;
 598}
 599
 600static inline void bio_list_add(struct bio_list *bl, struct bio *bio)
 601{
 602        bio->bi_next = NULL;
 603
 604        if (bl->tail)
 605                bl->tail->bi_next = bio;
 606        else
 607                bl->head = bio;
 608
 609        bl->tail = bio;
 610}
 611
 612static inline void bio_list_add_head(struct bio_list *bl, struct bio *bio)
 613{
 614        bio->bi_next = bl->head;
 615
 616        bl->head = bio;
 617
 618        if (!bl->tail)
 619                bl->tail = bio;
 620}
 621
 622static inline void bio_list_merge(struct bio_list *bl, struct bio_list *bl2)
 623{
 624        if (!bl2->head)
 625                return;
 626
 627        if (bl->tail)
 628                bl->tail->bi_next = bl2->head;
 629        else
 630                bl->head = bl2->head;
 631
 632        bl->tail = bl2->tail;
 633}
 634
 635static inline void bio_list_merge_head(struct bio_list *bl,
 636                                       struct bio_list *bl2)
 637{
 638        if (!bl2->head)
 639                return;
 640
 641        if (bl->head)
 642                bl2->tail->bi_next = bl->head;
 643        else
 644                bl->tail = bl2->tail;
 645
 646        bl->head = bl2->head;
 647}
 648
 649static inline struct bio *bio_list_peek(struct bio_list *bl)
 650{
 651        return bl->head;
 652}
 653
 654static inline struct bio *bio_list_pop(struct bio_list *bl)
 655{
 656        struct bio *bio = bl->head;
 657
 658        if (bio) {
 659                bl->head = bl->head->bi_next;
 660                if (!bl->head)
 661                        bl->tail = NULL;
 662
 663                bio->bi_next = NULL;
 664        }
 665
 666        return bio;
 667}
 668
 669static inline struct bio *bio_list_get(struct bio_list *bl)
 670{
 671        struct bio *bio = bl->head;
 672
 673        bl->head = bl->tail = NULL;
 674
 675        return bio;
 676}
 677
 678/*
 679 * Increment chain count for the bio. Make sure the CHAIN flag update
 680 * is visible before the raised count.
 681 */
 682static inline void bio_inc_remaining(struct bio *bio)
 683{
 684        bio_set_flag(bio, BIO_CHAIN);
 685        smp_mb__before_atomic();
 686        atomic_inc(&bio->__bi_remaining);
 687}
 688
 689/*
 690 * bio_set is used to allow other portions of the IO system to
 691 * allocate their own private memory pools for bio and iovec structures.
 692 * These memory pools in turn all allocate from the bio_slab
 693 * and the bvec_slabs[].
 694 */
 695#define BIO_POOL_SIZE 2
 696
 697struct bio_set {
 698        struct kmem_cache *bio_slab;
 699        unsigned int front_pad;
 700
 701        mempool_t *bio_pool;
 702        mempool_t *bvec_pool;
 703#if defined(CONFIG_BLK_DEV_INTEGRITY)
 704        mempool_t *bio_integrity_pool;
 705        mempool_t *bvec_integrity_pool;
 706#endif
 707
 708        /*
 709         * Deadlock avoidance for stacking block drivers: see comments in
 710         * bio_alloc_bioset() for details
 711         */
 712        spinlock_t              rescue_lock;
 713        struct bio_list         rescue_list;
 714        struct work_struct      rescue_work;
 715        struct workqueue_struct *rescue_workqueue;
 716};
 717
 718struct biovec_slab {
 719        int nr_vecs;
 720        char *name;
 721        struct kmem_cache *slab;
 722};
 723
 724/*
 725 * a small number of entries is fine, not going to be performance critical.
 726 * basically we just need to survive
 727 */
 728#define BIO_SPLIT_ENTRIES 2
 729
 730#if defined(CONFIG_BLK_DEV_INTEGRITY)
 731
 732#define bip_for_each_vec(bvl, bip, iter)                                \
 733        for_each_bvec(bvl, (bip)->bip_vec, iter, (bip)->bip_iter)
 734
 735#define bio_for_each_integrity_vec(_bvl, _bio, _iter)                   \
 736        for_each_bio(_bio)                                              \
 737                bip_for_each_vec(_bvl, _bio->bi_integrity, _iter)
 738
 739extern struct bio_integrity_payload *bio_integrity_alloc(struct bio *, gfp_t, unsigned int);
 740extern int bio_integrity_add_page(struct bio *, struct page *, unsigned int, unsigned int);
 741extern bool bio_integrity_prep(struct bio *);
 742extern void bio_integrity_advance(struct bio *, unsigned int);
 743extern void bio_integrity_trim(struct bio *);
 744extern int bio_integrity_clone(struct bio *, struct bio *, gfp_t);
 745extern int bioset_integrity_create(struct bio_set *, int);
 746extern void bioset_integrity_free(struct bio_set *);
 747extern void bio_integrity_init(void);
 748
 749#else /* CONFIG_BLK_DEV_INTEGRITY */
 750
 751static inline void *bio_integrity(struct bio *bio)
 752{
 753        return NULL;
 754}
 755
 756static inline int bioset_integrity_create(struct bio_set *bs, int pool_size)
 757{
 758        return 0;
 759}
 760
 761static inline void bioset_integrity_free (struct bio_set *bs)
 762{
 763        return;
 764}
 765
 766static inline bool bio_integrity_prep(struct bio *bio)
 767{
 768        return true;
 769}
 770
 771static inline int bio_integrity_clone(struct bio *bio, struct bio *bio_src,
 772                                      gfp_t gfp_mask)
 773{
 774        return 0;
 775}
 776
 777static inline void bio_integrity_advance(struct bio *bio,
 778                                         unsigned int bytes_done)
 779{
 780        return;
 781}
 782
 783static inline void bio_integrity_trim(struct bio *bio)
 784{
 785        return;
 786}
 787
 788static inline void bio_integrity_init(void)
 789{
 790        return;
 791}
 792
 793static inline bool bio_integrity_flagged(struct bio *bio, enum bip_flags flag)
 794{
 795        return false;
 796}
 797
 798static inline void *bio_integrity_alloc(struct bio * bio, gfp_t gfp,
 799                                                                unsigned int nr)
 800{
 801        return ERR_PTR(-EINVAL);
 802}
 803
 804static inline int bio_integrity_add_page(struct bio *bio, struct page *page,
 805                                        unsigned int len, unsigned int offset)
 806{
 807        return 0;
 808}
 809
 810#endif /* CONFIG_BLK_DEV_INTEGRITY */
 811
 812#endif /* CONFIG_BLOCK */
 813#endif /* __LINUX_BIO_H */
 814