linux/include/linux/bio.h
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   1/* SPDX-License-Identifier: GPL-2.0 */
   2/*
   3 * Copyright (C) 2001 Jens Axboe <axboe@suse.de>
   4 */
   5#ifndef __LINUX_BIO_H
   6#define __LINUX_BIO_H
   7
   8#include <linux/highmem.h>
   9#include <linux/mempool.h>
  10#include <linux/ioprio.h>
  11
  12#ifdef CONFIG_BLOCK
  13/* struct bio, bio_vec and BIO_* flags are defined in blk_types.h */
  14#include <linux/blk_types.h>
  15
  16#define BIO_DEBUG
  17
  18#ifdef BIO_DEBUG
  19#define BIO_BUG_ON      BUG_ON
  20#else
  21#define BIO_BUG_ON
  22#endif
  23
  24#define BIO_MAX_PAGES           256
  25
  26#define bio_prio(bio)                   (bio)->bi_ioprio
  27#define bio_set_prio(bio, prio)         ((bio)->bi_ioprio = prio)
  28
  29#define bio_iter_iovec(bio, iter)                               \
  30        bvec_iter_bvec((bio)->bi_io_vec, (iter))
  31
  32#define bio_iter_page(bio, iter)                                \
  33        bvec_iter_page((bio)->bi_io_vec, (iter))
  34#define bio_iter_len(bio, iter)                                 \
  35        bvec_iter_len((bio)->bi_io_vec, (iter))
  36#define bio_iter_offset(bio, iter)                              \
  37        bvec_iter_offset((bio)->bi_io_vec, (iter))
  38
  39#define bio_page(bio)           bio_iter_page((bio), (bio)->bi_iter)
  40#define bio_offset(bio)         bio_iter_offset((bio), (bio)->bi_iter)
  41#define bio_iovec(bio)          bio_iter_iovec((bio), (bio)->bi_iter)
  42
  43#define bio_multiple_segments(bio)                              \
  44        ((bio)->bi_iter.bi_size != bio_iovec(bio).bv_len)
  45
  46#define bvec_iter_sectors(iter) ((iter).bi_size >> 9)
  47#define bvec_iter_end_sector(iter) ((iter).bi_sector + bvec_iter_sectors((iter)))
  48
  49#define bio_sectors(bio)        bvec_iter_sectors((bio)->bi_iter)
  50#define bio_end_sector(bio)     bvec_iter_end_sector((bio)->bi_iter)
  51
  52/*
  53 * Return the data direction, READ or WRITE.
  54 */
  55#define bio_data_dir(bio) \
  56        (op_is_write(bio_op(bio)) ? WRITE : READ)
  57
  58/*
  59 * Check whether this bio carries any data or not. A NULL bio is allowed.
  60 */
  61static inline bool bio_has_data(struct bio *bio)
  62{
  63        if (bio &&
  64            bio->bi_iter.bi_size &&
  65            bio_op(bio) != REQ_OP_DISCARD &&
  66            bio_op(bio) != REQ_OP_SECURE_ERASE &&
  67            bio_op(bio) != REQ_OP_WRITE_ZEROES)
  68                return true;
  69
  70        return false;
  71}
  72
  73static inline bool bio_no_advance_iter(struct bio *bio)
  74{
  75        return bio_op(bio) == REQ_OP_DISCARD ||
  76               bio_op(bio) == REQ_OP_SECURE_ERASE ||
  77               bio_op(bio) == REQ_OP_WRITE_SAME ||
  78               bio_op(bio) == REQ_OP_WRITE_ZEROES;
  79}
  80
  81static inline bool bio_mergeable(struct bio *bio)
  82{
  83        if (bio->bi_opf & REQ_NOMERGE_FLAGS)
  84                return false;
  85
  86        return true;
  87}
  88
  89static inline unsigned int bio_cur_bytes(struct bio *bio)
  90{
  91        if (bio_has_data(bio))
  92                return bio_iovec(bio).bv_len;
  93        else /* dataless requests such as discard */
  94                return bio->bi_iter.bi_size;
  95}
  96
  97static inline void *bio_data(struct bio *bio)
  98{
  99        if (bio_has_data(bio))
 100                return page_address(bio_page(bio)) + bio_offset(bio);
 101
 102        return NULL;
 103}
 104
 105static inline bool bio_full(struct bio *bio)
 106{
 107        return bio->bi_vcnt >= bio->bi_max_vecs;
 108}
 109
 110static inline bool bio_next_segment(const struct bio *bio,
 111                                    struct bvec_iter_all *iter)
 112{
 113        if (iter->idx >= bio->bi_vcnt)
 114                return false;
 115
 116        bvec_advance(&bio->bi_io_vec[iter->idx], iter);
 117        return true;
 118}
 119
 120/*
 121 * drivers should _never_ use the all version - the bio may have been split
 122 * before it got to the driver and the driver won't own all of it
 123 */
 124#define bio_for_each_segment_all(bvl, bio, iter) \
 125        for (bvl = bvec_init_iter_all(&iter); bio_next_segment((bio), &iter); )
 126
 127static inline void bio_advance_iter(struct bio *bio, struct bvec_iter *iter,
 128                                    unsigned bytes)
 129{
 130        iter->bi_sector += bytes >> 9;
 131
 132        if (bio_no_advance_iter(bio))
 133                iter->bi_size -= bytes;
 134        else
 135                bvec_iter_advance(bio->bi_io_vec, iter, bytes);
 136                /* TODO: It is reasonable to complete bio with error here. */
 137}
 138
 139#define __bio_for_each_segment(bvl, bio, iter, start)                   \
 140        for (iter = (start);                                            \
 141             (iter).bi_size &&                                          \
 142                ((bvl = bio_iter_iovec((bio), (iter))), 1);             \
 143             bio_advance_iter((bio), &(iter), (bvl).bv_len))
 144
 145#define bio_for_each_segment(bvl, bio, iter)                            \
 146        __bio_for_each_segment(bvl, bio, iter, (bio)->bi_iter)
 147
 148#define __bio_for_each_bvec(bvl, bio, iter, start)              \
 149        for (iter = (start);                                            \
 150             (iter).bi_size &&                                          \
 151                ((bvl = mp_bvec_iter_bvec((bio)->bi_io_vec, (iter))), 1); \
 152             bio_advance_iter((bio), &(iter), (bvl).bv_len))
 153
 154/* iterate over multi-page bvec */
 155#define bio_for_each_bvec(bvl, bio, iter)                       \
 156        __bio_for_each_bvec(bvl, bio, iter, (bio)->bi_iter)
 157
 158#define bio_iter_last(bvec, iter) ((iter).bi_size == (bvec).bv_len)
 159
 160static inline unsigned bio_segments(struct bio *bio)
 161{
 162        unsigned segs = 0;
 163        struct bio_vec bv;
 164        struct bvec_iter iter;
 165
 166        /*
 167         * We special case discard/write same/write zeroes, because they
 168         * interpret bi_size differently:
 169         */
 170
 171        switch (bio_op(bio)) {
 172        case REQ_OP_DISCARD:
 173        case REQ_OP_SECURE_ERASE:
 174        case REQ_OP_WRITE_ZEROES:
 175                return 0;
 176        case REQ_OP_WRITE_SAME:
 177                return 1;
 178        default:
 179                break;
 180        }
 181
 182        bio_for_each_segment(bv, bio, iter)
 183                segs++;
 184
 185        return segs;
 186}
 187
 188/*
 189 * get a reference to a bio, so it won't disappear. the intended use is
 190 * something like:
 191 *
 192 * bio_get(bio);
 193 * submit_bio(rw, bio);
 194 * if (bio->bi_flags ...)
 195 *      do_something
 196 * bio_put(bio);
 197 *
 198 * without the bio_get(), it could potentially complete I/O before submit_bio
 199 * returns. and then bio would be freed memory when if (bio->bi_flags ...)
 200 * runs
 201 */
 202static inline void bio_get(struct bio *bio)
 203{
 204        bio->bi_flags |= (1 << BIO_REFFED);
 205        smp_mb__before_atomic();
 206        atomic_inc(&bio->__bi_cnt);
 207}
 208
 209static inline void bio_cnt_set(struct bio *bio, unsigned int count)
 210{
 211        if (count != 1) {
 212                bio->bi_flags |= (1 << BIO_REFFED);
 213                smp_mb();
 214        }
 215        atomic_set(&bio->__bi_cnt, count);
 216}
 217
 218static inline bool bio_flagged(struct bio *bio, unsigned int bit)
 219{
 220        return (bio->bi_flags & (1U << bit)) != 0;
 221}
 222
 223static inline void bio_set_flag(struct bio *bio, unsigned int bit)
 224{
 225        bio->bi_flags |= (1U << bit);
 226}
 227
 228static inline void bio_clear_flag(struct bio *bio, unsigned int bit)
 229{
 230        bio->bi_flags &= ~(1U << bit);
 231}
 232
 233static inline void bio_get_first_bvec(struct bio *bio, struct bio_vec *bv)
 234{
 235        *bv = bio_iovec(bio);
 236}
 237
 238static inline void bio_get_last_bvec(struct bio *bio, struct bio_vec *bv)
 239{
 240        struct bvec_iter iter = bio->bi_iter;
 241        int idx;
 242
 243        if (unlikely(!bio_multiple_segments(bio))) {
 244                *bv = bio_iovec(bio);
 245                return;
 246        }
 247
 248        bio_advance_iter(bio, &iter, iter.bi_size);
 249
 250        if (!iter.bi_bvec_done)
 251                idx = iter.bi_idx - 1;
 252        else    /* in the middle of bvec */
 253                idx = iter.bi_idx;
 254
 255        *bv = bio->bi_io_vec[idx];
 256
 257        /*
 258         * iter.bi_bvec_done records actual length of the last bvec
 259         * if this bio ends in the middle of one io vector
 260         */
 261        if (iter.bi_bvec_done)
 262                bv->bv_len = iter.bi_bvec_done;
 263}
 264
 265static inline struct bio_vec *bio_first_bvec_all(struct bio *bio)
 266{
 267        WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED));
 268        return bio->bi_io_vec;
 269}
 270
 271static inline struct page *bio_first_page_all(struct bio *bio)
 272{
 273        return bio_first_bvec_all(bio)->bv_page;
 274}
 275
 276static inline struct bio_vec *bio_last_bvec_all(struct bio *bio)
 277{
 278        WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED));
 279        return &bio->bi_io_vec[bio->bi_vcnt - 1];
 280}
 281
 282enum bip_flags {
 283        BIP_BLOCK_INTEGRITY     = 1 << 0, /* block layer owns integrity data */
 284        BIP_MAPPED_INTEGRITY    = 1 << 1, /* ref tag has been remapped */
 285        BIP_CTRL_NOCHECK        = 1 << 2, /* disable HBA integrity checking */
 286        BIP_DISK_NOCHECK        = 1 << 3, /* disable disk integrity checking */
 287        BIP_IP_CHECKSUM         = 1 << 4, /* IP checksum */
 288};
 289
 290/*
 291 * bio integrity payload
 292 */
 293struct bio_integrity_payload {
 294        struct bio              *bip_bio;       /* parent bio */
 295
 296        struct bvec_iter        bip_iter;
 297
 298        unsigned short          bip_slab;       /* slab the bip came from */
 299        unsigned short          bip_vcnt;       /* # of integrity bio_vecs */
 300        unsigned short          bip_max_vcnt;   /* integrity bio_vec slots */
 301        unsigned short          bip_flags;      /* control flags */
 302
 303        struct bvec_iter        bio_iter;       /* for rewinding parent bio */
 304
 305        struct work_struct      bip_work;       /* I/O completion */
 306
 307        struct bio_vec          *bip_vec;
 308        struct bio_vec          bip_inline_vecs[0];/* embedded bvec array */
 309};
 310
 311#if defined(CONFIG_BLK_DEV_INTEGRITY)
 312
 313static inline struct bio_integrity_payload *bio_integrity(struct bio *bio)
 314{
 315        if (bio->bi_opf & REQ_INTEGRITY)
 316                return bio->bi_integrity;
 317
 318        return NULL;
 319}
 320
 321static inline bool bio_integrity_flagged(struct bio *bio, enum bip_flags flag)
 322{
 323        struct bio_integrity_payload *bip = bio_integrity(bio);
 324
 325        if (bip)
 326                return bip->bip_flags & flag;
 327
 328        return false;
 329}
 330
 331static inline sector_t bip_get_seed(struct bio_integrity_payload *bip)
 332{
 333        return bip->bip_iter.bi_sector;
 334}
 335
 336static inline void bip_set_seed(struct bio_integrity_payload *bip,
 337                                sector_t seed)
 338{
 339        bip->bip_iter.bi_sector = seed;
 340}
 341
 342#endif /* CONFIG_BLK_DEV_INTEGRITY */
 343
 344extern void bio_trim(struct bio *bio, int offset, int size);
 345extern struct bio *bio_split(struct bio *bio, int sectors,
 346                             gfp_t gfp, struct bio_set *bs);
 347
 348/**
 349 * bio_next_split - get next @sectors from a bio, splitting if necessary
 350 * @bio:        bio to split
 351 * @sectors:    number of sectors to split from the front of @bio
 352 * @gfp:        gfp mask
 353 * @bs:         bio set to allocate from
 354 *
 355 * Returns a bio representing the next @sectors of @bio - if the bio is smaller
 356 * than @sectors, returns the original bio unchanged.
 357 */
 358static inline struct bio *bio_next_split(struct bio *bio, int sectors,
 359                                         gfp_t gfp, struct bio_set *bs)
 360{
 361        if (sectors >= bio_sectors(bio))
 362                return bio;
 363
 364        return bio_split(bio, sectors, gfp, bs);
 365}
 366
 367enum {
 368        BIOSET_NEED_BVECS = BIT(0),
 369        BIOSET_NEED_RESCUER = BIT(1),
 370};
 371extern int bioset_init(struct bio_set *, unsigned int, unsigned int, int flags);
 372extern void bioset_exit(struct bio_set *);
 373extern int biovec_init_pool(mempool_t *pool, int pool_entries);
 374extern int bioset_init_from_src(struct bio_set *bs, struct bio_set *src);
 375
 376extern struct bio *bio_alloc_bioset(gfp_t, unsigned int, struct bio_set *);
 377extern void bio_put(struct bio *);
 378
 379extern void __bio_clone_fast(struct bio *, struct bio *);
 380extern struct bio *bio_clone_fast(struct bio *, gfp_t, struct bio_set *);
 381
 382extern struct bio_set fs_bio_set;
 383
 384static inline struct bio *bio_alloc(gfp_t gfp_mask, unsigned int nr_iovecs)
 385{
 386        return bio_alloc_bioset(gfp_mask, nr_iovecs, &fs_bio_set);
 387}
 388
 389static inline struct bio *bio_kmalloc(gfp_t gfp_mask, unsigned int nr_iovecs)
 390{
 391        return bio_alloc_bioset(gfp_mask, nr_iovecs, NULL);
 392}
 393
 394extern blk_qc_t submit_bio(struct bio *);
 395
 396extern void bio_endio(struct bio *);
 397
 398static inline void bio_io_error(struct bio *bio)
 399{
 400        bio->bi_status = BLK_STS_IOERR;
 401        bio_endio(bio);
 402}
 403
 404static inline void bio_wouldblock_error(struct bio *bio)
 405{
 406        bio->bi_status = BLK_STS_AGAIN;
 407        bio_endio(bio);
 408}
 409
 410struct request_queue;
 411extern int bio_phys_segments(struct request_queue *, struct bio *);
 412
 413extern int submit_bio_wait(struct bio *bio);
 414extern void bio_advance(struct bio *, unsigned);
 415
 416extern void bio_init(struct bio *bio, struct bio_vec *table,
 417                     unsigned short max_vecs);
 418extern void bio_uninit(struct bio *);
 419extern void bio_reset(struct bio *);
 420void bio_chain(struct bio *, struct bio *);
 421
 422extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int);
 423extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,
 424                           unsigned int, unsigned int);
 425bool __bio_try_merge_page(struct bio *bio, struct page *page,
 426                unsigned int len, unsigned int off, bool *same_page);
 427void __bio_add_page(struct bio *bio, struct page *page,
 428                unsigned int len, unsigned int off);
 429int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter);
 430struct rq_map_data;
 431extern struct bio *bio_map_user_iov(struct request_queue *,
 432                                    struct iov_iter *, gfp_t);
 433extern void bio_unmap_user(struct bio *);
 434extern struct bio *bio_map_kern(struct request_queue *, void *, unsigned int,
 435                                gfp_t);
 436extern struct bio *bio_copy_kern(struct request_queue *, void *, unsigned int,
 437                                 gfp_t, int);
 438extern void bio_set_pages_dirty(struct bio *bio);
 439extern void bio_check_pages_dirty(struct bio *bio);
 440
 441void generic_start_io_acct(struct request_queue *q, int op,
 442                                unsigned long sectors, struct hd_struct *part);
 443void generic_end_io_acct(struct request_queue *q, int op,
 444                                struct hd_struct *part,
 445                                unsigned long start_time);
 446
 447#ifndef ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
 448# error "You should define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE for your platform"
 449#endif
 450#if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
 451extern void bio_flush_dcache_pages(struct bio *bi);
 452#else
 453static inline void bio_flush_dcache_pages(struct bio *bi)
 454{
 455}
 456#endif
 457
 458extern void bio_copy_data_iter(struct bio *dst, struct bvec_iter *dst_iter,
 459                               struct bio *src, struct bvec_iter *src_iter);
 460extern void bio_copy_data(struct bio *dst, struct bio *src);
 461extern void bio_list_copy_data(struct bio *dst, struct bio *src);
 462extern void bio_free_pages(struct bio *bio);
 463
 464extern struct bio *bio_copy_user_iov(struct request_queue *,
 465                                     struct rq_map_data *,
 466                                     struct iov_iter *,
 467                                     gfp_t);
 468extern int bio_uncopy_user(struct bio *);
 469void zero_fill_bio_iter(struct bio *bio, struct bvec_iter iter);
 470
 471static inline void zero_fill_bio(struct bio *bio)
 472{
 473        zero_fill_bio_iter(bio, bio->bi_iter);
 474}
 475
 476extern struct bio_vec *bvec_alloc(gfp_t, int, unsigned long *, mempool_t *);
 477extern void bvec_free(mempool_t *, struct bio_vec *, unsigned int);
 478extern unsigned int bvec_nr_vecs(unsigned short idx);
 479extern const char *bio_devname(struct bio *bio, char *buffer);
 480
 481#define bio_set_dev(bio, bdev)                  \
 482do {                                            \
 483        if ((bio)->bi_disk != (bdev)->bd_disk)  \
 484                bio_clear_flag(bio, BIO_THROTTLED);\
 485        (bio)->bi_disk = (bdev)->bd_disk;       \
 486        (bio)->bi_partno = (bdev)->bd_partno;   \
 487        bio_associate_blkg(bio);                \
 488} while (0)
 489
 490#define bio_copy_dev(dst, src)                  \
 491do {                                            \
 492        (dst)->bi_disk = (src)->bi_disk;        \
 493        (dst)->bi_partno = (src)->bi_partno;    \
 494        bio_clone_blkg_association(dst, src);   \
 495} while (0)
 496
 497#define bio_dev(bio) \
 498        disk_devt((bio)->bi_disk)
 499
 500#if defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
 501void bio_associate_blkg_from_page(struct bio *bio, struct page *page);
 502#else
 503static inline void bio_associate_blkg_from_page(struct bio *bio,
 504                                                struct page *page) { }
 505#endif
 506
 507#ifdef CONFIG_BLK_CGROUP
 508void bio_disassociate_blkg(struct bio *bio);
 509void bio_associate_blkg(struct bio *bio);
 510void bio_associate_blkg_from_css(struct bio *bio,
 511                                 struct cgroup_subsys_state *css);
 512void bio_clone_blkg_association(struct bio *dst, struct bio *src);
 513#else   /* CONFIG_BLK_CGROUP */
 514static inline void bio_disassociate_blkg(struct bio *bio) { }
 515static inline void bio_associate_blkg(struct bio *bio) { }
 516static inline void bio_associate_blkg_from_css(struct bio *bio,
 517                                               struct cgroup_subsys_state *css)
 518{ }
 519static inline void bio_clone_blkg_association(struct bio *dst,
 520                                              struct bio *src) { }
 521#endif  /* CONFIG_BLK_CGROUP */
 522
 523#ifdef CONFIG_HIGHMEM
 524/*
 525 * remember never ever reenable interrupts between a bvec_kmap_irq and
 526 * bvec_kunmap_irq!
 527 */
 528static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
 529{
 530        unsigned long addr;
 531
 532        /*
 533         * might not be a highmem page, but the preempt/irq count
 534         * balancing is a lot nicer this way
 535         */
 536        local_irq_save(*flags);
 537        addr = (unsigned long) kmap_atomic(bvec->bv_page);
 538
 539        BUG_ON(addr & ~PAGE_MASK);
 540
 541        return (char *) addr + bvec->bv_offset;
 542}
 543
 544static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
 545{
 546        unsigned long ptr = (unsigned long) buffer & PAGE_MASK;
 547
 548        kunmap_atomic((void *) ptr);
 549        local_irq_restore(*flags);
 550}
 551
 552#else
 553static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
 554{
 555        return page_address(bvec->bv_page) + bvec->bv_offset;
 556}
 557
 558static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
 559{
 560        *flags = 0;
 561}
 562#endif
 563
 564/*
 565 * BIO list management for use by remapping drivers (e.g. DM or MD) and loop.
 566 *
 567 * A bio_list anchors a singly-linked list of bios chained through the bi_next
 568 * member of the bio.  The bio_list also caches the last list member to allow
 569 * fast access to the tail.
 570 */
 571struct bio_list {
 572        struct bio *head;
 573        struct bio *tail;
 574};
 575
 576static inline int bio_list_empty(const struct bio_list *bl)
 577{
 578        return bl->head == NULL;
 579}
 580
 581static inline void bio_list_init(struct bio_list *bl)
 582{
 583        bl->head = bl->tail = NULL;
 584}
 585
 586#define BIO_EMPTY_LIST  { NULL, NULL }
 587
 588#define bio_list_for_each(bio, bl) \
 589        for (bio = (bl)->head; bio; bio = bio->bi_next)
 590
 591static inline unsigned bio_list_size(const struct bio_list *bl)
 592{
 593        unsigned sz = 0;
 594        struct bio *bio;
 595
 596        bio_list_for_each(bio, bl)
 597                sz++;
 598
 599        return sz;
 600}
 601
 602static inline void bio_list_add(struct bio_list *bl, struct bio *bio)
 603{
 604        bio->bi_next = NULL;
 605
 606        if (bl->tail)
 607                bl->tail->bi_next = bio;
 608        else
 609                bl->head = bio;
 610
 611        bl->tail = bio;
 612}
 613
 614static inline void bio_list_add_head(struct bio_list *bl, struct bio *bio)
 615{
 616        bio->bi_next = bl->head;
 617
 618        bl->head = bio;
 619
 620        if (!bl->tail)
 621                bl->tail = bio;
 622}
 623
 624static inline void bio_list_merge(struct bio_list *bl, struct bio_list *bl2)
 625{
 626        if (!bl2->head)
 627                return;
 628
 629        if (bl->tail)
 630                bl->tail->bi_next = bl2->head;
 631        else
 632                bl->head = bl2->head;
 633
 634        bl->tail = bl2->tail;
 635}
 636
 637static inline void bio_list_merge_head(struct bio_list *bl,
 638                                       struct bio_list *bl2)
 639{
 640        if (!bl2->head)
 641                return;
 642
 643        if (bl->head)
 644                bl2->tail->bi_next = bl->head;
 645        else
 646                bl->tail = bl2->tail;
 647
 648        bl->head = bl2->head;
 649}
 650
 651static inline struct bio *bio_list_peek(struct bio_list *bl)
 652{
 653        return bl->head;
 654}
 655
 656static inline struct bio *bio_list_pop(struct bio_list *bl)
 657{
 658        struct bio *bio = bl->head;
 659
 660        if (bio) {
 661                bl->head = bl->head->bi_next;
 662                if (!bl->head)
 663                        bl->tail = NULL;
 664
 665                bio->bi_next = NULL;
 666        }
 667
 668        return bio;
 669}
 670
 671static inline struct bio *bio_list_get(struct bio_list *bl)
 672{
 673        struct bio *bio = bl->head;
 674
 675        bl->head = bl->tail = NULL;
 676
 677        return bio;
 678}
 679
 680/*
 681 * Increment chain count for the bio. Make sure the CHAIN flag update
 682 * is visible before the raised count.
 683 */
 684static inline void bio_inc_remaining(struct bio *bio)
 685{
 686        bio_set_flag(bio, BIO_CHAIN);
 687        smp_mb__before_atomic();
 688        atomic_inc(&bio->__bi_remaining);
 689}
 690
 691/*
 692 * bio_set is used to allow other portions of the IO system to
 693 * allocate their own private memory pools for bio and iovec structures.
 694 * These memory pools in turn all allocate from the bio_slab
 695 * and the bvec_slabs[].
 696 */
 697#define BIO_POOL_SIZE 2
 698
 699struct bio_set {
 700        struct kmem_cache *bio_slab;
 701        unsigned int front_pad;
 702
 703        mempool_t bio_pool;
 704        mempool_t bvec_pool;
 705#if defined(CONFIG_BLK_DEV_INTEGRITY)
 706        mempool_t bio_integrity_pool;
 707        mempool_t bvec_integrity_pool;
 708#endif
 709
 710        /*
 711         * Deadlock avoidance for stacking block drivers: see comments in
 712         * bio_alloc_bioset() for details
 713         */
 714        spinlock_t              rescue_lock;
 715        struct bio_list         rescue_list;
 716        struct work_struct      rescue_work;
 717        struct workqueue_struct *rescue_workqueue;
 718};
 719
 720struct biovec_slab {
 721        int nr_vecs;
 722        char *name;
 723        struct kmem_cache *slab;
 724};
 725
 726static inline bool bioset_initialized(struct bio_set *bs)
 727{
 728        return bs->bio_slab != NULL;
 729}
 730
 731/*
 732 * a small number of entries is fine, not going to be performance critical.
 733 * basically we just need to survive
 734 */
 735#define BIO_SPLIT_ENTRIES 2
 736
 737#if defined(CONFIG_BLK_DEV_INTEGRITY)
 738
 739#define bip_for_each_vec(bvl, bip, iter)                                \
 740        for_each_bvec(bvl, (bip)->bip_vec, iter, (bip)->bip_iter)
 741
 742#define bio_for_each_integrity_vec(_bvl, _bio, _iter)                   \
 743        for_each_bio(_bio)                                              \
 744                bip_for_each_vec(_bvl, _bio->bi_integrity, _iter)
 745
 746extern struct bio_integrity_payload *bio_integrity_alloc(struct bio *, gfp_t, unsigned int);
 747extern int bio_integrity_add_page(struct bio *, struct page *, unsigned int, unsigned int);
 748extern bool bio_integrity_prep(struct bio *);
 749extern void bio_integrity_advance(struct bio *, unsigned int);
 750extern void bio_integrity_trim(struct bio *);
 751extern int bio_integrity_clone(struct bio *, struct bio *, gfp_t);
 752extern int bioset_integrity_create(struct bio_set *, int);
 753extern void bioset_integrity_free(struct bio_set *);
 754extern void bio_integrity_init(void);
 755
 756#else /* CONFIG_BLK_DEV_INTEGRITY */
 757
 758static inline void *bio_integrity(struct bio *bio)
 759{
 760        return NULL;
 761}
 762
 763static inline int bioset_integrity_create(struct bio_set *bs, int pool_size)
 764{
 765        return 0;
 766}
 767
 768static inline void bioset_integrity_free (struct bio_set *bs)
 769{
 770        return;
 771}
 772
 773static inline bool bio_integrity_prep(struct bio *bio)
 774{
 775        return true;
 776}
 777
 778static inline int bio_integrity_clone(struct bio *bio, struct bio *bio_src,
 779                                      gfp_t gfp_mask)
 780{
 781        return 0;
 782}
 783
 784static inline void bio_integrity_advance(struct bio *bio,
 785                                         unsigned int bytes_done)
 786{
 787        return;
 788}
 789
 790static inline void bio_integrity_trim(struct bio *bio)
 791{
 792        return;
 793}
 794
 795static inline void bio_integrity_init(void)
 796{
 797        return;
 798}
 799
 800static inline bool bio_integrity_flagged(struct bio *bio, enum bip_flags flag)
 801{
 802        return false;
 803}
 804
 805static inline void *bio_integrity_alloc(struct bio * bio, gfp_t gfp,
 806                                                                unsigned int nr)
 807{
 808        return ERR_PTR(-EINVAL);
 809}
 810
 811static inline int bio_integrity_add_page(struct bio *bio, struct page *page,
 812                                        unsigned int len, unsigned int offset)
 813{
 814        return 0;
 815}
 816
 817#endif /* CONFIG_BLK_DEV_INTEGRITY */
 818
 819/*
 820 * Mark a bio as polled. Note that for async polled IO, the caller must
 821 * expect -EWOULDBLOCK if we cannot allocate a request (or other resources).
 822 * We cannot block waiting for requests on polled IO, as those completions
 823 * must be found by the caller. This is different than IRQ driven IO, where
 824 * it's safe to wait for IO to complete.
 825 */
 826static inline void bio_set_polled(struct bio *bio, struct kiocb *kiocb)
 827{
 828        bio->bi_opf |= REQ_HIPRI;
 829        if (!is_sync_kiocb(kiocb))
 830                bio->bi_opf |= REQ_NOWAIT;
 831}
 832
 833#endif /* CONFIG_BLOCK */
 834#endif /* __LINUX_BIO_H */
 835