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
 105/**
 106 * bio_full - check if the bio is full
 107 * @bio:        bio to check
 108 * @len:        length of one segment to be added
 109 *
 110 * Return true if @bio is full and one segment with @len bytes can't be
 111 * added to the bio, otherwise return false
 112 */
 113static inline bool bio_full(struct bio *bio, unsigned len)
 114{
 115        if (bio->bi_vcnt >= bio->bi_max_vecs)
 116                return true;
 117
 118        if (bio->bi_iter.bi_size > UINT_MAX - len)
 119                return true;
 120
 121        return false;
 122}
 123
 124static inline bool bio_next_segment(const struct bio *bio,
 125                                    struct bvec_iter_all *iter)
 126{
 127        if (iter->idx >= bio->bi_vcnt)
 128                return false;
 129
 130        bvec_advance(&bio->bi_io_vec[iter->idx], iter);
 131        return true;
 132}
 133
 134/*
 135 * drivers should _never_ use the all version - the bio may have been split
 136 * before it got to the driver and the driver won't own all of it
 137 */
 138#define bio_for_each_segment_all(bvl, bio, iter) \
 139        for (bvl = bvec_init_iter_all(&iter); bio_next_segment((bio), &iter); )
 140
 141static inline void bio_advance_iter(struct bio *bio, struct bvec_iter *iter,
 142                                    unsigned bytes)
 143{
 144        iter->bi_sector += bytes >> 9;
 145
 146        if (bio_no_advance_iter(bio))
 147                iter->bi_size -= bytes;
 148        else
 149                bvec_iter_advance(bio->bi_io_vec, iter, bytes);
 150                /* TODO: It is reasonable to complete bio with error here. */
 151}
 152
 153#define __bio_for_each_segment(bvl, bio, iter, start)                   \
 154        for (iter = (start);                                            \
 155             (iter).bi_size &&                                          \
 156                ((bvl = bio_iter_iovec((bio), (iter))), 1);             \
 157             bio_advance_iter((bio), &(iter), (bvl).bv_len))
 158
 159#define bio_for_each_segment(bvl, bio, iter)                            \
 160        __bio_for_each_segment(bvl, bio, iter, (bio)->bi_iter)
 161
 162#define __bio_for_each_bvec(bvl, bio, iter, start)              \
 163        for (iter = (start);                                            \
 164             (iter).bi_size &&                                          \
 165                ((bvl = mp_bvec_iter_bvec((bio)->bi_io_vec, (iter))), 1); \
 166             bio_advance_iter((bio), &(iter), (bvl).bv_len))
 167
 168/* iterate over multi-page bvec */
 169#define bio_for_each_bvec(bvl, bio, iter)                       \
 170        __bio_for_each_bvec(bvl, bio, iter, (bio)->bi_iter)
 171
 172#define bio_iter_last(bvec, iter) ((iter).bi_size == (bvec).bv_len)
 173
 174static inline unsigned bio_segments(struct bio *bio)
 175{
 176        unsigned segs = 0;
 177        struct bio_vec bv;
 178        struct bvec_iter iter;
 179
 180        /*
 181         * We special case discard/write same/write zeroes, because they
 182         * interpret bi_size differently:
 183         */
 184
 185        switch (bio_op(bio)) {
 186        case REQ_OP_DISCARD:
 187        case REQ_OP_SECURE_ERASE:
 188        case REQ_OP_WRITE_ZEROES:
 189                return 0;
 190        case REQ_OP_WRITE_SAME:
 191                return 1;
 192        default:
 193                break;
 194        }
 195
 196        bio_for_each_segment(bv, bio, iter)
 197                segs++;
 198
 199        return segs;
 200}
 201
 202/*
 203 * get a reference to a bio, so it won't disappear. the intended use is
 204 * something like:
 205 *
 206 * bio_get(bio);
 207 * submit_bio(rw, bio);
 208 * if (bio->bi_flags ...)
 209 *      do_something
 210 * bio_put(bio);
 211 *
 212 * without the bio_get(), it could potentially complete I/O before submit_bio
 213 * returns. and then bio would be freed memory when if (bio->bi_flags ...)
 214 * runs
 215 */
 216static inline void bio_get(struct bio *bio)
 217{
 218        bio->bi_flags |= (1 << BIO_REFFED);
 219        smp_mb__before_atomic();
 220        atomic_inc(&bio->__bi_cnt);
 221}
 222
 223static inline void bio_cnt_set(struct bio *bio, unsigned int count)
 224{
 225        if (count != 1) {
 226                bio->bi_flags |= (1 << BIO_REFFED);
 227                smp_mb();
 228        }
 229        atomic_set(&bio->__bi_cnt, count);
 230}
 231
 232static inline bool bio_flagged(struct bio *bio, unsigned int bit)
 233{
 234        return (bio->bi_flags & (1U << bit)) != 0;
 235}
 236
 237static inline void bio_set_flag(struct bio *bio, unsigned int bit)
 238{
 239        bio->bi_flags |= (1U << bit);
 240}
 241
 242static inline void bio_clear_flag(struct bio *bio, unsigned int bit)
 243{
 244        bio->bi_flags &= ~(1U << bit);
 245}
 246
 247static inline void bio_get_first_bvec(struct bio *bio, struct bio_vec *bv)
 248{
 249        *bv = bio_iovec(bio);
 250}
 251
 252static inline void bio_get_last_bvec(struct bio *bio, struct bio_vec *bv)
 253{
 254        struct bvec_iter iter = bio->bi_iter;
 255        int idx;
 256
 257        if (unlikely(!bio_multiple_segments(bio))) {
 258                *bv = bio_iovec(bio);
 259                return;
 260        }
 261
 262        bio_advance_iter(bio, &iter, iter.bi_size);
 263
 264        if (!iter.bi_bvec_done)
 265                idx = iter.bi_idx - 1;
 266        else    /* in the middle of bvec */
 267                idx = iter.bi_idx;
 268
 269        *bv = bio->bi_io_vec[idx];
 270
 271        /*
 272         * iter.bi_bvec_done records actual length of the last bvec
 273         * if this bio ends in the middle of one io vector
 274         */
 275        if (iter.bi_bvec_done)
 276                bv->bv_len = iter.bi_bvec_done;
 277}
 278
 279static inline struct bio_vec *bio_first_bvec_all(struct bio *bio)
 280{
 281        WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED));
 282        return bio->bi_io_vec;
 283}
 284
 285static inline struct page *bio_first_page_all(struct bio *bio)
 286{
 287        return bio_first_bvec_all(bio)->bv_page;
 288}
 289
 290static inline struct bio_vec *bio_last_bvec_all(struct bio *bio)
 291{
 292        WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED));
 293        return &bio->bi_io_vec[bio->bi_vcnt - 1];
 294}
 295
 296enum bip_flags {
 297        BIP_BLOCK_INTEGRITY     = 1 << 0, /* block layer owns integrity data */
 298        BIP_MAPPED_INTEGRITY    = 1 << 1, /* ref tag has been remapped */
 299        BIP_CTRL_NOCHECK        = 1 << 2, /* disable HBA integrity checking */
 300        BIP_DISK_NOCHECK        = 1 << 3, /* disable disk integrity checking */
 301        BIP_IP_CHECKSUM         = 1 << 4, /* IP checksum */
 302};
 303
 304/*
 305 * bio integrity payload
 306 */
 307struct bio_integrity_payload {
 308        struct bio              *bip_bio;       /* parent bio */
 309
 310        struct bvec_iter        bip_iter;
 311
 312        unsigned short          bip_slab;       /* slab the bip came from */
 313        unsigned short          bip_vcnt;       /* # of integrity bio_vecs */
 314        unsigned short          bip_max_vcnt;   /* integrity bio_vec slots */
 315        unsigned short          bip_flags;      /* control flags */
 316
 317        struct bvec_iter        bio_iter;       /* for rewinding parent bio */
 318
 319        struct work_struct      bip_work;       /* I/O completion */
 320
 321        struct bio_vec          *bip_vec;
 322        struct bio_vec          bip_inline_vecs[0];/* embedded bvec array */
 323};
 324
 325#if defined(CONFIG_BLK_DEV_INTEGRITY)
 326
 327static inline struct bio_integrity_payload *bio_integrity(struct bio *bio)
 328{
 329        if (bio->bi_opf & REQ_INTEGRITY)
 330                return bio->bi_integrity;
 331
 332        return NULL;
 333}
 334
 335static inline bool bio_integrity_flagged(struct bio *bio, enum bip_flags flag)
 336{
 337        struct bio_integrity_payload *bip = bio_integrity(bio);
 338
 339        if (bip)
 340                return bip->bip_flags & flag;
 341
 342        return false;
 343}
 344
 345static inline sector_t bip_get_seed(struct bio_integrity_payload *bip)
 346{
 347        return bip->bip_iter.bi_sector;
 348}
 349
 350static inline void bip_set_seed(struct bio_integrity_payload *bip,
 351                                sector_t seed)
 352{
 353        bip->bip_iter.bi_sector = seed;
 354}
 355
 356#endif /* CONFIG_BLK_DEV_INTEGRITY */
 357
 358extern void bio_trim(struct bio *bio, int offset, int size);
 359extern struct bio *bio_split(struct bio *bio, int sectors,
 360                             gfp_t gfp, struct bio_set *bs);
 361
 362/**
 363 * bio_next_split - get next @sectors from a bio, splitting if necessary
 364 * @bio:        bio to split
 365 * @sectors:    number of sectors to split from the front of @bio
 366 * @gfp:        gfp mask
 367 * @bs:         bio set to allocate from
 368 *
 369 * Returns a bio representing the next @sectors of @bio - if the bio is smaller
 370 * than @sectors, returns the original bio unchanged.
 371 */
 372static inline struct bio *bio_next_split(struct bio *bio, int sectors,
 373                                         gfp_t gfp, struct bio_set *bs)
 374{
 375        if (sectors >= bio_sectors(bio))
 376                return bio;
 377
 378        return bio_split(bio, sectors, gfp, bs);
 379}
 380
 381enum {
 382        BIOSET_NEED_BVECS = BIT(0),
 383        BIOSET_NEED_RESCUER = BIT(1),
 384};
 385extern int bioset_init(struct bio_set *, unsigned int, unsigned int, int flags);
 386extern void bioset_exit(struct bio_set *);
 387extern int biovec_init_pool(mempool_t *pool, int pool_entries);
 388extern int bioset_init_from_src(struct bio_set *bs, struct bio_set *src);
 389
 390extern struct bio *bio_alloc_bioset(gfp_t, unsigned int, struct bio_set *);
 391extern void bio_put(struct bio *);
 392
 393extern void __bio_clone_fast(struct bio *, struct bio *);
 394extern struct bio *bio_clone_fast(struct bio *, gfp_t, struct bio_set *);
 395
 396extern struct bio_set fs_bio_set;
 397
 398static inline struct bio *bio_alloc(gfp_t gfp_mask, unsigned int nr_iovecs)
 399{
 400        return bio_alloc_bioset(gfp_mask, nr_iovecs, &fs_bio_set);
 401}
 402
 403static inline struct bio *bio_kmalloc(gfp_t gfp_mask, unsigned int nr_iovecs)
 404{
 405        return bio_alloc_bioset(gfp_mask, nr_iovecs, NULL);
 406}
 407
 408extern blk_qc_t submit_bio(struct bio *);
 409
 410extern void bio_endio(struct bio *);
 411
 412static inline void bio_io_error(struct bio *bio)
 413{
 414        bio->bi_status = BLK_STS_IOERR;
 415        bio_endio(bio);
 416}
 417
 418static inline void bio_wouldblock_error(struct bio *bio)
 419{
 420        bio->bi_status = BLK_STS_AGAIN;
 421        bio_endio(bio);
 422}
 423
 424struct request_queue;
 425
 426extern int submit_bio_wait(struct bio *bio);
 427extern void bio_advance(struct bio *, unsigned);
 428
 429extern void bio_init(struct bio *bio, struct bio_vec *table,
 430                     unsigned short max_vecs);
 431extern void bio_uninit(struct bio *);
 432extern void bio_reset(struct bio *);
 433void bio_chain(struct bio *, struct bio *);
 434
 435extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int);
 436extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,
 437                           unsigned int, unsigned int);
 438bool __bio_try_merge_page(struct bio *bio, struct page *page,
 439                unsigned int len, unsigned int off, bool *same_page);
 440void __bio_add_page(struct bio *bio, struct page *page,
 441                unsigned int len, unsigned int off);
 442int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter);
 443void bio_release_pages(struct bio *bio, bool mark_dirty);
 444struct rq_map_data;
 445extern struct bio *bio_map_user_iov(struct request_queue *,
 446                                    struct iov_iter *, gfp_t);
 447extern void bio_unmap_user(struct bio *);
 448extern struct bio *bio_map_kern(struct request_queue *, void *, unsigned int,
 449                                gfp_t);
 450extern struct bio *bio_copy_kern(struct request_queue *, void *, unsigned int,
 451                                 gfp_t, int);
 452extern void bio_set_pages_dirty(struct bio *bio);
 453extern void bio_check_pages_dirty(struct bio *bio);
 454
 455void generic_start_io_acct(struct request_queue *q, int op,
 456                                unsigned long sectors, struct hd_struct *part);
 457void generic_end_io_acct(struct request_queue *q, int op,
 458                                struct hd_struct *part,
 459                                unsigned long start_time);
 460
 461extern void bio_copy_data_iter(struct bio *dst, struct bvec_iter *dst_iter,
 462                               struct bio *src, struct bvec_iter *src_iter);
 463extern void bio_copy_data(struct bio *dst, struct bio *src);
 464extern void bio_list_copy_data(struct bio *dst, struct bio *src);
 465extern void bio_free_pages(struct bio *bio);
 466
 467extern struct bio *bio_copy_user_iov(struct request_queue *,
 468                                     struct rq_map_data *,
 469                                     struct iov_iter *,
 470                                     gfp_t);
 471extern int bio_uncopy_user(struct bio *);
 472void zero_fill_bio_iter(struct bio *bio, struct bvec_iter iter);
 473
 474static inline void zero_fill_bio(struct bio *bio)
 475{
 476        zero_fill_bio_iter(bio, bio->bi_iter);
 477}
 478
 479extern struct bio_vec *bvec_alloc(gfp_t, int, unsigned long *, mempool_t *);
 480extern void bvec_free(mempool_t *, struct bio_vec *, unsigned int);
 481extern unsigned int bvec_nr_vecs(unsigned short idx);
 482extern const char *bio_devname(struct bio *bio, char *buffer);
 483
 484#define bio_set_dev(bio, bdev)                  \
 485do {                                            \
 486        if ((bio)->bi_disk != (bdev)->bd_disk)  \
 487                bio_clear_flag(bio, BIO_THROTTLED);\
 488        (bio)->bi_disk = (bdev)->bd_disk;       \
 489        (bio)->bi_partno = (bdev)->bd_partno;   \
 490        bio_associate_blkg(bio);                \
 491} while (0)
 492
 493#define bio_copy_dev(dst, src)                  \
 494do {                                            \
 495        (dst)->bi_disk = (src)->bi_disk;        \
 496        (dst)->bi_partno = (src)->bi_partno;    \
 497        bio_clone_blkg_association(dst, src);   \
 498} while (0)
 499
 500#define bio_dev(bio) \
 501        disk_devt((bio)->bi_disk)
 502
 503#if defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
 504void bio_associate_blkg_from_page(struct bio *bio, struct page *page);
 505#else
 506static inline void bio_associate_blkg_from_page(struct bio *bio,
 507                                                struct page *page) { }
 508#endif
 509
 510#ifdef CONFIG_BLK_CGROUP
 511void bio_disassociate_blkg(struct bio *bio);
 512void bio_associate_blkg(struct bio *bio);
 513void bio_associate_blkg_from_css(struct bio *bio,
 514                                 struct cgroup_subsys_state *css);
 515void bio_clone_blkg_association(struct bio *dst, struct bio *src);
 516#else   /* CONFIG_BLK_CGROUP */
 517static inline void bio_disassociate_blkg(struct bio *bio) { }
 518static inline void bio_associate_blkg(struct bio *bio) { }
 519static inline void bio_associate_blkg_from_css(struct bio *bio,
 520                                               struct cgroup_subsys_state *css)
 521{ }
 522static inline void bio_clone_blkg_association(struct bio *dst,
 523                                              struct bio *src) { }
 524#endif  /* CONFIG_BLK_CGROUP */
 525
 526#ifdef CONFIG_HIGHMEM
 527/*
 528 * remember never ever reenable interrupts between a bvec_kmap_irq and
 529 * bvec_kunmap_irq!
 530 */
 531static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
 532{
 533        unsigned long addr;
 534
 535        /*
 536         * might not be a highmem page, but the preempt/irq count
 537         * balancing is a lot nicer this way
 538         */
 539        local_irq_save(*flags);
 540        addr = (unsigned long) kmap_atomic(bvec->bv_page);
 541
 542        BUG_ON(addr & ~PAGE_MASK);
 543
 544        return (char *) addr + bvec->bv_offset;
 545}
 546
 547static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
 548{
 549        unsigned long ptr = (unsigned long) buffer & PAGE_MASK;
 550
 551        kunmap_atomic((void *) ptr);
 552        local_irq_restore(*flags);
 553}
 554
 555#else
 556static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
 557{
 558        return page_address(bvec->bv_page) + bvec->bv_offset;
 559}
 560
 561static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
 562{
 563        *flags = 0;
 564}
 565#endif
 566
 567/*
 568 * BIO list management for use by remapping drivers (e.g. DM or MD) and loop.
 569 *
 570 * A bio_list anchors a singly-linked list of bios chained through the bi_next
 571 * member of the bio.  The bio_list also caches the last list member to allow
 572 * fast access to the tail.
 573 */
 574struct bio_list {
 575        struct bio *head;
 576        struct bio *tail;
 577};
 578
 579static inline int bio_list_empty(const struct bio_list *bl)
 580{
 581        return bl->head == NULL;
 582}
 583
 584static inline void bio_list_init(struct bio_list *bl)
 585{
 586        bl->head = bl->tail = NULL;
 587}
 588
 589#define BIO_EMPTY_LIST  { NULL, NULL }
 590
 591#define bio_list_for_each(bio, bl) \
 592        for (bio = (bl)->head; bio; bio = bio->bi_next)
 593
 594static inline unsigned bio_list_size(const struct bio_list *bl)
 595{
 596        unsigned sz = 0;
 597        struct bio *bio;
 598
 599        bio_list_for_each(bio, bl)
 600                sz++;
 601
 602        return sz;
 603}
 604
 605static inline void bio_list_add(struct bio_list *bl, struct bio *bio)
 606{
 607        bio->bi_next = NULL;
 608
 609        if (bl->tail)
 610                bl->tail->bi_next = bio;
 611        else
 612                bl->head = bio;
 613
 614        bl->tail = bio;
 615}
 616
 617static inline void bio_list_add_head(struct bio_list *bl, struct bio *bio)
 618{
 619        bio->bi_next = bl->head;
 620
 621        bl->head = bio;
 622
 623        if (!bl->tail)
 624                bl->tail = bio;
 625}
 626
 627static inline void bio_list_merge(struct bio_list *bl, struct bio_list *bl2)
 628{
 629        if (!bl2->head)
 630                return;
 631
 632        if (bl->tail)
 633                bl->tail->bi_next = bl2->head;
 634        else
 635                bl->head = bl2->head;
 636
 637        bl->tail = bl2->tail;
 638}
 639
 640static inline void bio_list_merge_head(struct bio_list *bl,
 641                                       struct bio_list *bl2)
 642{
 643        if (!bl2->head)
 644                return;
 645
 646        if (bl->head)
 647                bl2->tail->bi_next = bl->head;
 648        else
 649                bl->tail = bl2->tail;
 650
 651        bl->head = bl2->head;
 652}
 653
 654static inline struct bio *bio_list_peek(struct bio_list *bl)
 655{
 656        return bl->head;
 657}
 658
 659static inline struct bio *bio_list_pop(struct bio_list *bl)
 660{
 661        struct bio *bio = bl->head;
 662
 663        if (bio) {
 664                bl->head = bl->head->bi_next;
 665                if (!bl->head)
 666                        bl->tail = NULL;
 667
 668                bio->bi_next = NULL;
 669        }
 670
 671        return bio;
 672}
 673
 674static inline struct bio *bio_list_get(struct bio_list *bl)
 675{
 676        struct bio *bio = bl->head;
 677
 678        bl->head = bl->tail = NULL;
 679
 680        return bio;
 681}
 682
 683/*
 684 * Increment chain count for the bio. Make sure the CHAIN flag update
 685 * is visible before the raised count.
 686 */
 687static inline void bio_inc_remaining(struct bio *bio)
 688{
 689        bio_set_flag(bio, BIO_CHAIN);
 690        smp_mb__before_atomic();
 691        atomic_inc(&bio->__bi_remaining);
 692}
 693
 694/*
 695 * bio_set is used to allow other portions of the IO system to
 696 * allocate their own private memory pools for bio and iovec structures.
 697 * These memory pools in turn all allocate from the bio_slab
 698 * and the bvec_slabs[].
 699 */
 700#define BIO_POOL_SIZE 2
 701
 702struct bio_set {
 703        struct kmem_cache *bio_slab;
 704        unsigned int front_pad;
 705
 706        mempool_t bio_pool;
 707        mempool_t bvec_pool;
 708#if defined(CONFIG_BLK_DEV_INTEGRITY)
 709        mempool_t bio_integrity_pool;
 710        mempool_t bvec_integrity_pool;
 711#endif
 712
 713        /*
 714         * Deadlock avoidance for stacking block drivers: see comments in
 715         * bio_alloc_bioset() for details
 716         */
 717        spinlock_t              rescue_lock;
 718        struct bio_list         rescue_list;
 719        struct work_struct      rescue_work;
 720        struct workqueue_struct *rescue_workqueue;
 721};
 722
 723struct biovec_slab {
 724        int nr_vecs;
 725        char *name;
 726        struct kmem_cache *slab;
 727};
 728
 729static inline bool bioset_initialized(struct bio_set *bs)
 730{
 731        return bs->bio_slab != NULL;
 732}
 733
 734/*
 735 * a small number of entries is fine, not going to be performance critical.
 736 * basically we just need to survive
 737 */
 738#define BIO_SPLIT_ENTRIES 2
 739
 740#if defined(CONFIG_BLK_DEV_INTEGRITY)
 741
 742#define bip_for_each_vec(bvl, bip, iter)                                \
 743        for_each_bvec(bvl, (bip)->bip_vec, iter, (bip)->bip_iter)
 744
 745#define bio_for_each_integrity_vec(_bvl, _bio, _iter)                   \
 746        for_each_bio(_bio)                                              \
 747                bip_for_each_vec(_bvl, _bio->bi_integrity, _iter)
 748
 749extern struct bio_integrity_payload *bio_integrity_alloc(struct bio *, gfp_t, unsigned int);
 750extern int bio_integrity_add_page(struct bio *, struct page *, unsigned int, unsigned int);
 751extern bool bio_integrity_prep(struct bio *);
 752extern void bio_integrity_advance(struct bio *, unsigned int);
 753extern void bio_integrity_trim(struct bio *);
 754extern int bio_integrity_clone(struct bio *, struct bio *, gfp_t);
 755extern int bioset_integrity_create(struct bio_set *, int);
 756extern void bioset_integrity_free(struct bio_set *);
 757extern void bio_integrity_init(void);
 758
 759#else /* CONFIG_BLK_DEV_INTEGRITY */
 760
 761static inline void *bio_integrity(struct bio *bio)
 762{
 763        return NULL;
 764}
 765
 766static inline int bioset_integrity_create(struct bio_set *bs, int pool_size)
 767{
 768        return 0;
 769}
 770
 771static inline void bioset_integrity_free (struct bio_set *bs)
 772{
 773        return;
 774}
 775
 776static inline bool bio_integrity_prep(struct bio *bio)
 777{
 778        return true;
 779}
 780
 781static inline int bio_integrity_clone(struct bio *bio, struct bio *bio_src,
 782                                      gfp_t gfp_mask)
 783{
 784        return 0;
 785}
 786
 787static inline void bio_integrity_advance(struct bio *bio,
 788                                         unsigned int bytes_done)
 789{
 790        return;
 791}
 792
 793static inline void bio_integrity_trim(struct bio *bio)
 794{
 795        return;
 796}
 797
 798static inline void bio_integrity_init(void)
 799{
 800        return;
 801}
 802
 803static inline bool bio_integrity_flagged(struct bio *bio, enum bip_flags flag)
 804{
 805        return false;
 806}
 807
 808static inline void *bio_integrity_alloc(struct bio * bio, gfp_t gfp,
 809                                                                unsigned int nr)
 810{
 811        return ERR_PTR(-EINVAL);
 812}
 813
 814static inline int bio_integrity_add_page(struct bio *bio, struct page *page,
 815                                        unsigned int len, unsigned int offset)
 816{
 817        return 0;
 818}
 819
 820#endif /* CONFIG_BLK_DEV_INTEGRITY */
 821
 822/*
 823 * Mark a bio as polled. Note that for async polled IO, the caller must
 824 * expect -EWOULDBLOCK if we cannot allocate a request (or other resources).
 825 * We cannot block waiting for requests on polled IO, as those completions
 826 * must be found by the caller. This is different than IRQ driven IO, where
 827 * it's safe to wait for IO to complete.
 828 */
 829static inline void bio_set_polled(struct bio *bio, struct kiocb *kiocb)
 830{
 831        bio->bi_opf |= REQ_HIPRI;
 832        if (!is_sync_kiocb(kiocb))
 833                bio->bi_opf |= REQ_NOWAIT;
 834}
 835
 836#endif /* CONFIG_BLOCK */
 837#endif /* __LINUX_BIO_H */
 838