include/linux/bio.h

   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
  25 #ifdef CONFIG_BLOCK
  26 /* struct bio, bio_vec and BIO_* flags are defined in blk_types.h */
  27 #include <linux/blk_types.h>
  28
  29 #define BIO_DEBUG
  30
  31 #ifdef BIO_DEBUG
  32 #define BIO_BUG_ON      BUG_ON
  33 #else
  34 #define BIO_BUG_ON
  35 #endif
  36
  37 #define BIO_MAX_PAGES           256
  38
  39 #define bio_prio(bio)                   (bio)->bi_ioprio
  40 #define bio_set_prio(bio, prio)         ((bio)->bi_ioprio = prio)
  41
  42 #define bio_iter_iovec(bio, iter)                               \
  43         bvec_iter_bvec((bio)->bi_io_vec, (iter))
  44
  45 #define bio_iter_page(bio, iter)                                \
  46         bvec_iter_page((bio)->bi_io_vec, (iter))
  47 #define bio_iter_len(bio, iter)                                 \
  48         bvec_iter_len((bio)->bi_io_vec, (iter))
  49 #define bio_iter_offset(bio, iter)                              \
  50         bvec_iter_offset((bio)->bi_io_vec, (iter))
  51
  52 #define bio_page(bio)           bio_iter_page((bio), (bio)->bi_iter)
  53 #define bio_offset(bio)         bio_iter_offset((bio), (bio)->bi_iter)
  54 #define bio_iovec(bio)          bio_iter_iovec((bio), (bio)->bi_iter)
  55
  56 #define bio_multiple_segments(bio)                              \
  57         ((bio)->bi_iter.bi_size != bio_iovec(bio).bv_len)
  58
  59 #define bvec_iter_sectors(iter) ((iter).bi_size >> 9)
  60 #define bvec_iter_end_sector(iter) ((iter).bi_sector + bvec_iter_sectors((iter)))
  61
  62 #define bio_sectors(bio)        bvec_iter_sectors((bio)->bi_iter)
  63 #define bio_end_sector(bio)     bvec_iter_end_sector((bio)->bi_iter)
  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  */
  74 static 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
  86 static 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
  94 static 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
 102 static 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
 110 static 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 static inline bool bio_full(struct bio *bio)
 119 {
 120         return bio->bi_vcnt >= bio->bi_max_vecs;
 121 }
 122
 123 static inline bool bio_next_segment(const struct bio *bio,
 124                                     struct bvec_iter_all *iter)
 125 {
 126         if (iter->idx >= bio->bi_vcnt)
 127                 return false;
 128
 129         bvec_advance(&bio->bi_io_vec[iter->idx], iter);
 130         return true;
 131 }
 132
 133 /*
 134  * drivers should _never_ use the all version - the bio may have been split
 135  * before it got to the driver and the driver won't own all of it
 136  */
 137 #define bio_for_each_segment_all(bvl, bio, i, iter)                     \
 138         for (i = 0, bvl = bvec_init_iter_all(&iter);                    \
 139              bio_next_segment((bio), &iter); i++)
 140
 141 static 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
 174 static 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  */
 216 static 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
 223 static 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__before_atomic();
 228         }
 229         atomic_set(&bio->__bi_cnt, count);
 230 }
 231
 232 static inline bool bio_flagged(struct bio *bio, unsigned int bit)
 233 {
 234         return (bio->bi_flags & (1U << bit)) != 0;
 235 }
 236
 237 static inline void bio_set_flag(struct bio *bio, unsigned int bit)
 238 {
 239         bio->bi_flags |= (1U << bit);
 240 }
 241
 242 static inline void bio_clear_flag(struct bio *bio, unsigned int bit)
 243 {
 244         bio->bi_flags &= ~(1U << bit);
 245 }
 246
 247 static inline void bio_get_first_bvec(struct bio *bio, struct bio_vec *bv)
 248 {
 249         *bv = bio_iovec(bio);
 250 }
 251
 252 static 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
 279 static 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
 285 static inline struct page *bio_first_page_all(struct bio *bio)
 286 {
 287         return bio_first_bvec_all(bio)->bv_page;
 288 }
 289
 290 static 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
 296 enum 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  */
 307 struct 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
 327 static 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
 335 static 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
 345 static inline sector_t bip_get_seed(struct bio_integrity_payload *bip)
 346 {
 347         return bip->bip_iter.bi_sector;
 348 }
 349
 350 static 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
 358 extern void bio_trim(struct bio *bio, int offset, int size);
 359 extern 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  */
 372 static 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
 381 enum {
 382         BIOSET_NEED_BVECS = BIT(0),
 383         BIOSET_NEED_RESCUER = BIT(1),
 384 };
 385 extern int bioset_init(struct bio_set *, unsigned int, unsigned int, int flags);
 386 extern void bioset_exit(struct bio_set *);
 387 extern int biovec_init_pool(mempool_t *pool, int pool_entries);
 388 extern int bioset_init_from_src(struct bio_set *bs, struct bio_set *src);
 389
 390 extern struct bio *bio_alloc_bioset(gfp_t, unsigned int, struct bio_set *);
 391 extern void bio_put(struct bio *);
 392
 393 extern void __bio_clone_fast(struct bio *, struct bio *);
 394 extern struct bio *bio_clone_fast(struct bio *, gfp_t, struct bio_set *);
 395
 396 extern struct bio_set fs_bio_set;
 397
 398 static 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
 403 static 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
 408 extern blk_qc_t submit_bio(struct bio *);
 409
 410 extern void bio_endio(struct bio *);
 411
 412 static inline void bio_io_error(struct bio *bio)
 413 {
 414         bio->bi_status = BLK_STS_IOERR;
 415         bio_endio(bio);
 416 }
 417
 418 static inline void bio_wouldblock_error(struct bio *bio)
 419 {
 420         bio->bi_status = BLK_STS_AGAIN;
 421         bio_endio(bio);
 422 }
 423
 424 struct request_queue;
 425 extern int bio_phys_segments(struct request_queue *, struct bio *);
 426
 427 extern int submit_bio_wait(struct bio *bio);
 428 extern void bio_advance(struct bio *, unsigned);
 429
 430 extern void bio_init(struct bio *bio, struct bio_vec *table,
 431                      unsigned short max_vecs);
 432 extern void bio_uninit(struct bio *);
 433 extern void bio_reset(struct bio *);
 434 void bio_chain(struct bio *, struct bio *);
 435
 436 extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int);
 437 extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,
 438                            unsigned int, unsigned int);
 439 bool __bio_try_merge_page(struct bio *bio, struct page *page,
 440                 unsigned int len, unsigned int off, bool same_page);
 441 void __bio_add_page(struct bio *bio, struct page *page,
 442                 unsigned int len, unsigned int off);
 443 int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter);
 444 struct rq_map_data;
 445 extern struct bio *bio_map_user_iov(struct request_queue *,
 446                                     struct iov_iter *, gfp_t);
 447 extern void bio_unmap_user(struct bio *);
 448 extern struct bio *bio_map_kern(struct request_queue *, void *, unsigned int,
 449                                 gfp_t);
 450 extern struct bio *bio_copy_kern(struct request_queue *, void *, unsigned int,
 451                                  gfp_t, int);
 452 extern void bio_set_pages_dirty(struct bio *bio);
 453 extern void bio_check_pages_dirty(struct bio *bio);
 454
 455 void generic_start_io_acct(struct request_queue *q, int op,
 456                                 unsigned long sectors, struct hd_struct *part);
 457 void generic_end_io_acct(struct request_queue *q, int op,
 458                                 struct hd_struct *part,
 459                                 unsigned long start_time);
 460
 461 #ifndef ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
 462 # error "You should define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE for your platform"
 463 #endif
 464 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
 465 extern void bio_flush_dcache_pages(struct bio *bi);
 466 #else
 467 static inline void bio_flush_dcache_pages(struct bio *bi)
 468 {
 469 }
 470 #endif
 471
 472 extern void bio_copy_data_iter(struct bio *dst, struct bvec_iter *dst_iter,
 473                                struct bio *src, struct bvec_iter *src_iter);
 474 extern void bio_copy_data(struct bio *dst, struct bio *src);
 475 extern void bio_list_copy_data(struct bio *dst, struct bio *src);
 476 extern void bio_free_pages(struct bio *bio);
 477
 478 extern struct bio *bio_copy_user_iov(struct request_queue *,
 479                                      struct rq_map_data *,
 480                                      struct iov_iter *,
 481                                      gfp_t);
 482 extern int bio_uncopy_user(struct bio *);
 483 void zero_fill_bio_iter(struct bio *bio, struct bvec_iter iter);
 484
 485 static inline void zero_fill_bio(struct bio *bio)
 486 {
 487         zero_fill_bio_iter(bio, bio->bi_iter);
 488 }
 489
 490 extern struct bio_vec *bvec_alloc(gfp_t, int, unsigned long *, mempool_t *);
 491 extern void bvec_free(mempool_t *, struct bio_vec *, unsigned int);
 492 extern unsigned int bvec_nr_vecs(unsigned short idx);
 493 extern const char *bio_devname(struct bio *bio, char *buffer);
 494
 495 #define bio_set_dev(bio, bdev)                  \
 496 do {                                            \
 497         if ((bio)->bi_disk != (bdev)->bd_disk)  \
 498                 bio_clear_flag(bio, BIO_THROTTLED);\
 499         (bio)->bi_disk = (bdev)->bd_disk;       \
 500         (bio)->bi_partno = (bdev)->bd_partno;   \
 501         bio_associate_blkg(bio);                \
 502 } while (0)
 503
 504 #define bio_copy_dev(dst, src)                  \
 505 do {                                            \
 506         (dst)->bi_disk = (src)->bi_disk;        \
 507         (dst)->bi_partno = (src)->bi_partno;    \
 508         bio_clone_blkg_association(dst, src);   \
 509 } while (0)
 510
 511 #define bio_dev(bio) \
 512         disk_devt((bio)->bi_disk)
 513
 514 #if defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
 515 void bio_associate_blkg_from_page(struct bio *bio, struct page *page);
 516 #else
 517 static inline void bio_associate_blkg_from_page(struct bio *bio,
 518                                                 struct page *page) { }
 519 #endif
 520
 521 #ifdef CONFIG_BLK_CGROUP
 522 void bio_disassociate_blkg(struct bio *bio);
 523 void bio_associate_blkg(struct bio *bio);
 524 void bio_associate_blkg_from_css(struct bio *bio,
 525                                  struct cgroup_subsys_state *css);
 526 void bio_clone_blkg_association(struct bio *dst, struct bio *src);
 527 #else   /* CONFIG_BLK_CGROUP */
 528 static inline void bio_disassociate_blkg(struct bio *bio) { }
 529 static inline void bio_associate_blkg(struct bio *bio) { }
 530 static inline void bio_associate_blkg_from_css(struct bio *bio,
 531                                                struct cgroup_subsys_state *css)
 532 { }
 533 static inline void bio_clone_blkg_association(struct bio *dst,
 534                                               struct bio *src) { }
 535 #endif  /* CONFIG_BLK_CGROUP */
 536
 537 #ifdef CONFIG_HIGHMEM
 538 /*
 539  * remember never ever reenable interrupts between a bvec_kmap_irq and
 540  * bvec_kunmap_irq!
 541  */
 542 static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
 543 {
 544         unsigned long addr;
 545
 546         /*
 547          * might not be a highmem page, but the preempt/irq count
 548          * balancing is a lot nicer this way
 549          */
 550         local_irq_save(*flags);
 551         addr = (unsigned long) kmap_atomic(bvec->bv_page);
 552
 553         BUG_ON(addr & ~PAGE_MASK);
 554
 555         return (char *) addr + bvec->bv_offset;
 556 }
 557
 558 static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
 559 {
 560         unsigned long ptr = (unsigned long) buffer & PAGE_MASK;
 561
 562         kunmap_atomic((void *) ptr);
 563         local_irq_restore(*flags);
 564 }
 565
 566 #else
 567 static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
 568 {
 569         return page_address(bvec->bv_page) + bvec->bv_offset;
 570 }
 571
 572 static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
 573 {
 574         *flags = 0;
 575 }
 576 #endif
 577
 578 /*
 579  * BIO list management for use by remapping drivers (e.g. DM or MD) and loop.
 580  *
 581  * A bio_list anchors a singly-linked list of bios chained through the bi_next
 582  * member of the bio.  The bio_list also caches the last list member to allow
 583  * fast access to the tail.
 584  */
 585 struct bio_list {
 586         struct bio *head;
 587         struct bio *tail;
 588 };
 589
 590 static inline int bio_list_empty(const struct bio_list *bl)
 591 {
 592         return bl->head == NULL;
 593 }
 594
 595 static inline void bio_list_init(struct bio_list *bl)
 596 {
 597         bl->head = bl->tail = NULL;
 598 }
 599
 600 #define BIO_EMPTY_LIST  { NULL, NULL }
 601
 602 #define bio_list_for_each(bio, bl) \
 603         for (bio = (bl)->head; bio; bio = bio->bi_next)
 604
 605 static inline unsigned bio_list_size(const struct bio_list *bl)
 606 {
 607         unsigned sz = 0;
 608         struct bio *bio;
 609
 610         bio_list_for_each(bio, bl)
 611                 sz++;
 612
 613         return sz;
 614 }
 615
 616 static inline void bio_list_add(struct bio_list *bl, struct bio *bio)
 617 {
 618         bio->bi_next = NULL;
 619
 620         if (bl->tail)
 621                 bl->tail->bi_next = bio;
 622         else
 623                 bl->head = bio;
 624
 625         bl->tail = bio;
 626 }
 627
 628 static inline void bio_list_add_head(struct bio_list *bl, struct bio *bio)
 629 {
 630         bio->bi_next = bl->head;
 631
 632         bl->head = bio;
 633
 634         if (!bl->tail)
 635                 bl->tail = bio;
 636 }
 637
 638 static inline void bio_list_merge(struct bio_list *bl, struct bio_list *bl2)
 639 {
 640         if (!bl2->head)
 641                 return;
 642
 643         if (bl->tail)
 644                 bl->tail->bi_next = bl2->head;
 645         else
 646                 bl->head = bl2->head;
 647
 648         bl->tail = bl2->tail;
 649 }
 650
 651 static inline void bio_list_merge_head(struct bio_list *bl,
 652                                        struct bio_list *bl2)
 653 {
 654         if (!bl2->head)
 655                 return;
 656
 657         if (bl->head)
 658                 bl2->tail->bi_next = bl->head;
 659         else
 660                 bl->tail = bl2->tail;
 661
 662         bl->head = bl2->head;
 663 }
 664
 665 static inline struct bio *bio_list_peek(struct bio_list *bl)
 666 {
 667         return bl->head;
 668 }
 669
 670 static inline struct bio *bio_list_pop(struct bio_list *bl)
 671 {
 672         struct bio *bio = bl->head;
 673
 674         if (bio) {
 675                 bl->head = bl->head->bi_next;
 676                 if (!bl->head)
 677                         bl->tail = NULL;
 678
 679                 bio->bi_next = NULL;
 680         }
 681
 682         return bio;
 683 }
 684
 685 static inline struct bio *bio_list_get(struct bio_list *bl)
 686 {
 687         struct bio *bio = bl->head;
 688
 689         bl->head = bl->tail = NULL;
 690
 691         return bio;
 692 }
 693
 694 /*
 695  * Increment chain count for the bio. Make sure the CHAIN flag update
 696  * is visible before the raised count.
 697  */
 698 static inline void bio_inc_remaining(struct bio *bio)
 699 {
 700         bio_set_flag(bio, BIO_CHAIN);
 701         smp_mb__before_atomic();
 702         atomic_inc(&bio->__bi_remaining);
 703 }
 704
 705 /*
 706  * bio_set is used to allow other portions of the IO system to
 707  * allocate their own private memory pools for bio and iovec structures.
 708  * These memory pools in turn all allocate from the bio_slab
 709  * and the bvec_slabs[].
 710  */
 711 #define BIO_POOL_SIZE 2
 712
 713 struct bio_set {
 714         struct kmem_cache *bio_slab;
 715         unsigned int front_pad;
 716
 717         mempool_t bio_pool;
 718         mempool_t bvec_pool;
 719 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 720         mempool_t bio_integrity_pool;
 721         mempool_t bvec_integrity_pool;
 722 #endif
 723
 724         /*
 725          * Deadlock avoidance for stacking block drivers: see comments in
 726          * bio_alloc_bioset() for details
 727          */
 728         spinlock_t              rescue_lock;
 729         struct bio_list         rescue_list;
 730         struct work_struct      rescue_work;
 731         struct workqueue_struct *rescue_workqueue;
 732 };
 733
 734 struct biovec_slab {
 735         int nr_vecs;
 736         char *name;
 737         struct kmem_cache *slab;
 738 };
 739
 740 static inline bool bioset_initialized(struct bio_set *bs)
 741 {
 742         return bs->bio_slab != NULL;
 743 }
 744
 745 /*
 746  * a small number of entries is fine, not going to be performance critical.
 747  * basically we just need to survive
 748  */
 749 #define BIO_SPLIT_ENTRIES 2
 750
 751 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 752
 753 #define bip_for_each_vec(bvl, bip, iter)                                \
 754         for_each_bvec(bvl, (bip)->bip_vec, iter, (bip)->bip_iter)
 755
 756 #define bio_for_each_integrity_vec(_bvl, _bio, _iter)                   \
 757         for_each_bio(_bio)                                              \
 758                 bip_for_each_vec(_bvl, _bio->bi_integrity, _iter)
 759
 760 extern struct bio_integrity_payload *bio_integrity_alloc(struct bio *, gfp_t, unsigned int);
 761 extern int bio_integrity_add_page(struct bio *, struct page *, unsigned int, unsigned int);
 762 extern bool bio_integrity_prep(struct bio *);
 763 extern void bio_integrity_advance(struct bio *, unsigned int);
 764 extern void bio_integrity_trim(struct bio *);
 765 extern int bio_integrity_clone(struct bio *, struct bio *, gfp_t);
 766 extern int bioset_integrity_create(struct bio_set *, int);
 767 extern void bioset_integrity_free(struct bio_set *);
 768 extern void bio_integrity_init(void);
 769
 770 #else /* CONFIG_BLK_DEV_INTEGRITY */
 771
 772 static inline void *bio_integrity(struct bio *bio)
 773 {
 774         return NULL;
 775 }
 776
 777 static inline int bioset_integrity_create(struct bio_set *bs, int pool_size)
 778 {
 779         return 0;
 780 }
 781
 782 static inline void bioset_integrity_free (struct bio_set *bs)
 783 {
 784         return;
 785 }
 786
 787 static inline bool bio_integrity_prep(struct bio *bio)
 788 {
 789         return true;
 790 }
 791
 792 static inline int bio_integrity_clone(struct bio *bio, struct bio *bio_src,
 793                                       gfp_t gfp_mask)
 794 {
 795         return 0;
 796 }
 797
 798 static inline void bio_integrity_advance(struct bio *bio,
 799                                          unsigned int bytes_done)
 800 {
 801         return;
 802 }
 803
 804 static inline void bio_integrity_trim(struct bio *bio)
 805 {
 806         return;
 807 }
 808
 809 static inline void bio_integrity_init(void)
 810 {
 811         return;
 812 }
 813
 814 static inline bool bio_integrity_flagged(struct bio *bio, enum bip_flags flag)
 815 {
 816         return false;
 817 }
 818
 819 static inline void *bio_integrity_alloc(struct bio * bio, gfp_t gfp,
 820                                                                 unsigned int nr)
 821 {
 822         return ERR_PTR(-EINVAL);
 823 }
 824
 825 static inline int bio_integrity_add_page(struct bio *bio, struct page *page,
 826                                         unsigned int len, unsigned int offset)
 827 {
 828         return 0;
 829 }
 830
 831 #endif /* CONFIG_BLK_DEV_INTEGRITY */
 832
 833 /*
 834  * Mark a bio as polled. Note that for async polled IO, the caller must
 835  * expect -EWOULDBLOCK if we cannot allocate a request (or other resources).
 836  * We cannot block waiting for requests on polled IO, as those completions
 837  * must be found by the caller. This is different than IRQ driven IO, where
 838  * it's safe to wait for IO to complete.
 839  */
 840 static inline void bio_set_polled(struct bio *bio, struct kiocb *kiocb)
 841 {
 842         bio->bi_opf |= REQ_HIPRI;
 843         if (!is_sync_kiocb(kiocb))
 844                 bio->bi_opf |= REQ_NOWAIT;
 845 }
 846
 847 #endif /* CONFIG_BLOCK */
 848 #endif /* __LINUX_BIO_H */