include/linux/bio.h

   1 /*
   2  * 2.5 block I/O model
   3  *
   4  * Copyright (C) 2001 Jens Axboe <axboe@suse.de>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public Licens
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-
  19  */
  20 #ifndef __LINUX_BIO_H
  21 #define __LINUX_BIO_H
  22
  23 #include <linux/highmem.h>
  24 #include <linux/mempool.h>
  25 #include <linux/ioprio.h>
  26 #include <linux/bug.h>
  27
  28 #ifdef CONFIG_BLOCK
  29
  30 #include <asm/io.h>
  31
  32 /* struct bio, bio_vec and BIO_* flags are defined in blk_types.h */
  33 #include <linux/blk_types.h>
  34
  35 #define BIO_DEBUG
  36
  37 #ifdef BIO_DEBUG
  38 #define BIO_BUG_ON      BUG_ON
  39 #else
  40 #define BIO_BUG_ON
  41 #endif
  42
  43 #define BIO_MAX_PAGES           256
  44
  45 #define bio_prio(bio)                   (bio)->bi_ioprio
  46 #define bio_set_prio(bio, prio)         ((bio)->bi_ioprio = prio)
  47
  48 #define bio_iter_iovec(bio, iter)                               \
  49         bvec_iter_bvec((bio)->bi_io_vec, (iter))
  50
  51 #define bio_iter_page(bio, iter)                                \
  52         bvec_iter_page((bio)->bi_io_vec, (iter))
  53 #define bio_iter_len(bio, iter)                                 \
  54         bvec_iter_len((bio)->bi_io_vec, (iter))
  55 #define bio_iter_offset(bio, iter)                              \
  56         bvec_iter_offset((bio)->bi_io_vec, (iter))
  57
  58 #define bio_page(bio)           bio_iter_page((bio), (bio)->bi_iter)
  59 #define bio_offset(bio)         bio_iter_offset((bio), (bio)->bi_iter)
  60 #define bio_iovec(bio)          bio_iter_iovec((bio), (bio)->bi_iter)
  61
  62 #define bio_multiple_segments(bio)                              \
  63         ((bio)->bi_iter.bi_size != bio_iovec(bio).bv_len)
  64 #define bio_sectors(bio)        ((bio)->bi_iter.bi_size >> 9)
  65 #define bio_end_sector(bio)     ((bio)->bi_iter.bi_sector + bio_sectors((bio)))
  66
  67 /*
  68  * Check whether this bio carries any data or not. A NULL bio is allowed.
  69  */
  70 static inline bool bio_has_data(struct bio *bio)
  71 {
  72         if (bio &&
  73             bio->bi_iter.bi_size &&
  74             bio_op(bio) != REQ_OP_DISCARD &&
  75             bio_op(bio) != REQ_OP_SECURE_ERASE)
  76                 return true;
  77
  78         return false;
  79 }
  80
  81 static inline bool bio_no_advance_iter(struct bio *bio)
  82 {
  83         return bio_op(bio) == REQ_OP_DISCARD ||
  84                bio_op(bio) == REQ_OP_SECURE_ERASE ||
  85                bio_op(bio) == REQ_OP_WRITE_SAME;
  86 }
  87
  88 static inline bool bio_is_rw(struct bio *bio)
  89 {
  90         if (!bio_has_data(bio))
  91                 return false;
  92
  93         if (bio_no_advance_iter(bio))
  94                 return false;
  95
  96         return true;
  97 }
  98
  99 static inline bool bio_mergeable(struct bio *bio)
 100 {
 101         if (bio->bi_opf & REQ_NOMERGE_FLAGS)
 102                 return false;
 103
 104         return true;
 105 }
 106
 107 static inline unsigned int bio_cur_bytes(struct bio *bio)
 108 {
 109         if (bio_has_data(bio))
 110                 return bio_iovec(bio).bv_len;
 111         else /* dataless requests such as discard */
 112                 return bio->bi_iter.bi_size;
 113 }
 114
 115 static inline void *bio_data(struct bio *bio)
 116 {
 117         if (bio_has_data(bio))
 118                 return page_address(bio_page(bio)) + bio_offset(bio);
 119
 120         return NULL;
 121 }
 122
 123 /*
 124  * will die
 125  */
 126 #define bio_to_phys(bio)        (page_to_phys(bio_page((bio))) + (unsigned long) bio_offset((bio)))
 127 #define bvec_to_phys(bv)        (page_to_phys((bv)->bv_page) + (unsigned long) (bv)->bv_offset)
 128
 129 /*
 130  * queues that have highmem support enabled may still need to revert to
 131  * PIO transfers occasionally and thus map high pages temporarily. For
 132  * permanent PIO fall back, user is probably better off disabling highmem
 133  * I/O completely on that queue (see ide-dma for example)
 134  */
 135 #define __bio_kmap_atomic(bio, iter)                            \
 136         (kmap_atomic(bio_iter_iovec((bio), (iter)).bv_page) +   \
 137                 bio_iter_iovec((bio), (iter)).bv_offset)
 138
 139 #define __bio_kunmap_atomic(addr)       kunmap_atomic(addr)
 140
 141 /*
 142  * merge helpers etc
 143  */
 144
 145 /* Default implementation of BIOVEC_PHYS_MERGEABLE */
 146 #define __BIOVEC_PHYS_MERGEABLE(vec1, vec2)     \
 147         ((bvec_to_phys((vec1)) + (vec1)->bv_len) == bvec_to_phys((vec2)))
 148
 149 /*
 150  * allow arch override, for eg virtualized architectures (put in asm/io.h)
 151  */
 152 #ifndef BIOVEC_PHYS_MERGEABLE
 153 #define BIOVEC_PHYS_MERGEABLE(vec1, vec2)       \
 154         __BIOVEC_PHYS_MERGEABLE(vec1, vec2)
 155 #endif
 156
 157 #define __BIO_SEG_BOUNDARY(addr1, addr2, mask) \
 158         (((addr1) | (mask)) == (((addr2) - 1) | (mask)))
 159 #define BIOVEC_SEG_BOUNDARY(q, b1, b2) \
 160         __BIO_SEG_BOUNDARY(bvec_to_phys((b1)), bvec_to_phys((b2)) + (b2)->bv_len, queue_segment_boundary((q)))
 161
 162 /*
 163  * drivers should _never_ use the all version - the bio may have been split
 164  * before it got to the driver and the driver won't own all of it
 165  */
 166 #define bio_for_each_segment_all(bvl, bio, i)                           \
 167         for (i = 0, bvl = (bio)->bi_io_vec; i < (bio)->bi_vcnt; i++, bvl++)
 168
 169 static inline void bio_advance_iter(struct bio *bio, struct bvec_iter *iter,
 170                                     unsigned bytes)
 171 {
 172         iter->bi_sector += bytes >> 9;
 173
 174         if (bio_no_advance_iter(bio))
 175                 iter->bi_size -= bytes;
 176         else
 177                 bvec_iter_advance(bio->bi_io_vec, iter, bytes);
 178 }
 179
 180 #define __bio_for_each_segment(bvl, bio, iter, start)                   \
 181         for (iter = (start);                                            \
 182              (iter).bi_size &&                                          \
 183                 ((bvl = bio_iter_iovec((bio), (iter))), 1);             \
 184              bio_advance_iter((bio), &(iter), (bvl).bv_len))
 185
 186 #define bio_for_each_segment(bvl, bio, iter)                            \
 187         __bio_for_each_segment(bvl, bio, iter, (bio)->bi_iter)
 188
 189 #define bio_iter_last(bvec, iter) ((iter).bi_size == (bvec).bv_len)
 190
 191 static inline unsigned bio_segments(struct bio *bio)
 192 {
 193         unsigned segs = 0;
 194         struct bio_vec bv;
 195         struct bvec_iter iter;
 196
 197         /*
 198          * We special case discard/write same, because they interpret bi_size
 199          * differently:
 200          */
 201
 202         if (bio_op(bio) == REQ_OP_DISCARD)
 203                 return 1;
 204
 205         if (bio_op(bio) == REQ_OP_SECURE_ERASE)
 206                 return 1;
 207
 208         if (bio_op(bio) == REQ_OP_WRITE_SAME)
 209                 return 1;
 210
 211         bio_for_each_segment(bv, bio, iter)
 212                 segs++;
 213
 214         return segs;
 215 }
 216
 217 /*
 218  * get a reference to a bio, so it won't disappear. the intended use is
 219  * something like:
 220  *
 221  * bio_get(bio);
 222  * submit_bio(rw, bio);
 223  * if (bio->bi_flags ...)
 224  *      do_something
 225  * bio_put(bio);
 226  *
 227  * without the bio_get(), it could potentially complete I/O before submit_bio
 228  * returns. and then bio would be freed memory when if (bio->bi_flags ...)
 229  * runs
 230  */
 231 static inline void bio_get(struct bio *bio)
 232 {
 233         bio->bi_flags |= (1 << BIO_REFFED);
 234         smp_mb__before_atomic();
 235         atomic_inc(&bio->__bi_cnt);
 236 }
 237
 238 static inline void bio_cnt_set(struct bio *bio, unsigned int count)
 239 {
 240         if (count != 1) {
 241                 bio->bi_flags |= (1 << BIO_REFFED);
 242                 smp_mb__before_atomic();
 243         }
 244         atomic_set(&bio->__bi_cnt, count);
 245 }
 246
 247 static inline bool bio_flagged(struct bio *bio, unsigned int bit)
 248 {
 249         return (bio->bi_flags & (1U << bit)) != 0;
 250 }
 251
 252 static inline void bio_set_flag(struct bio *bio, unsigned int bit)
 253 {
 254         bio->bi_flags |= (1U << bit);
 255 }
 256
 257 static inline void bio_clear_flag(struct bio *bio, unsigned int bit)
 258 {
 259         bio->bi_flags &= ~(1U << bit);
 260 }
 261
 262 static inline void bio_get_first_bvec(struct bio *bio, struct bio_vec *bv)
 263 {
 264         *bv = bio_iovec(bio);
 265 }
 266
 267 static inline void bio_get_last_bvec(struct bio *bio, struct bio_vec *bv)
 268 {
 269         struct bvec_iter iter = bio->bi_iter;
 270         int idx;
 271
 272         if (unlikely(!bio_multiple_segments(bio))) {
 273                 *bv = bio_iovec(bio);
 274                 return;
 275         }
 276
 277         bio_advance_iter(bio, &iter, iter.bi_size);
 278
 279         if (!iter.bi_bvec_done)
 280                 idx = iter.bi_idx - 1;
 281         else    /* in the middle of bvec */
 282                 idx = iter.bi_idx;
 283
 284         *bv = bio->bi_io_vec[idx];
 285
 286         /*
 287          * iter.bi_bvec_done records actual length of the last bvec
 288          * if this bio ends in the middle of one io vector
 289          */
 290         if (iter.bi_bvec_done)
 291                 bv->bv_len = iter.bi_bvec_done;
 292 }
 293
 294 enum bip_flags {
 295         BIP_BLOCK_INTEGRITY     = 1 << 0, /* block layer owns integrity data */
 296         BIP_MAPPED_INTEGRITY    = 1 << 1, /* ref tag has been remapped */
 297         BIP_CTRL_NOCHECK        = 1 << 2, /* disable HBA integrity checking */
 298         BIP_DISK_NOCHECK        = 1 << 3, /* disable disk integrity checking */
 299         BIP_IP_CHECKSUM         = 1 << 4, /* IP checksum */
 300 };
 301
 302 /*
 303  * bio integrity payload
 304  */
 305 struct bio_integrity_payload {
 306         struct bio              *bip_bio;       /* parent bio */
 307
 308         struct bvec_iter        bip_iter;
 309
 310         bio_end_io_t            *bip_end_io;    /* saved I/O completion fn */
 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 work_struct      bip_work;       /* I/O completion */
 318
 319         struct bio_vec          *bip_vec;
 320         struct bio_vec          bip_inline_vecs[0];/* embedded bvec array */
 321 };
 322
 323 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 324
 325 static inline struct bio_integrity_payload *bio_integrity(struct bio *bio)
 326 {
 327         if (bio->bi_opf & REQ_INTEGRITY)
 328                 return bio->bi_integrity;
 329
 330         return NULL;
 331 }
 332
 333 static inline bool bio_integrity_flagged(struct bio *bio, enum bip_flags flag)
 334 {
 335         struct bio_integrity_payload *bip = bio_integrity(bio);
 336
 337         if (bip)
 338                 return bip->bip_flags & flag;
 339
 340         return false;
 341 }
 342
 343 static inline sector_t bip_get_seed(struct bio_integrity_payload *bip)
 344 {
 345         return bip->bip_iter.bi_sector;
 346 }
 347
 348 static inline void bip_set_seed(struct bio_integrity_payload *bip,
 349                                 sector_t seed)
 350 {
 351         bip->bip_iter.bi_sector = seed;
 352 }
 353
 354 #endif /* CONFIG_BLK_DEV_INTEGRITY */
 355
 356 extern void bio_trim(struct bio *bio, int offset, int size);
 357 extern struct bio *bio_split(struct bio *bio, int sectors,
 358                              gfp_t gfp, struct bio_set *bs);
 359
 360 /**
 361  * bio_next_split - get next @sectors from a bio, splitting if necessary
 362  * @bio:        bio to split
 363  * @sectors:    number of sectors to split from the front of @bio
 364  * @gfp:        gfp mask
 365  * @bs:         bio set to allocate from
 366  *
 367  * Returns a bio representing the next @sectors of @bio - if the bio is smaller
 368  * than @sectors, returns the original bio unchanged.
 369  */
 370 static inline struct bio *bio_next_split(struct bio *bio, int sectors,
 371                                          gfp_t gfp, struct bio_set *bs)
 372 {
 373         if (sectors >= bio_sectors(bio))
 374                 return bio;
 375
 376         return bio_split(bio, sectors, gfp, bs);
 377 }
 378
 379 extern struct bio_set *bioset_create(unsigned int, unsigned int);
 380 extern struct bio_set *bioset_create_nobvec(unsigned int, unsigned int);
 381 extern void bioset_free(struct bio_set *);
 382 extern mempool_t *biovec_create_pool(int pool_entries);
 383
 384 extern struct bio *bio_alloc_bioset(gfp_t, int, struct bio_set *);
 385 extern void bio_put(struct bio *);
 386
 387 extern void __bio_clone_fast(struct bio *, struct bio *);
 388 extern struct bio *bio_clone_fast(struct bio *, gfp_t, struct bio_set *);
 389 extern struct bio *bio_clone_bioset(struct bio *, gfp_t, struct bio_set *bs);
 390
 391 extern struct bio_set *fs_bio_set;
 392
 393 static inline struct bio *bio_alloc(gfp_t gfp_mask, unsigned int nr_iovecs)
 394 {
 395         return bio_alloc_bioset(gfp_mask, nr_iovecs, fs_bio_set);
 396 }
 397
 398 static inline struct bio *bio_clone(struct bio *bio, gfp_t gfp_mask)
 399 {
 400         return bio_clone_bioset(bio, gfp_mask, 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 static inline struct bio *bio_clone_kmalloc(struct bio *bio, gfp_t gfp_mask)
 409 {
 410         return bio_clone_bioset(bio, gfp_mask, NULL);
 411
 412 }
 413
 414 extern void bio_endio(struct bio *);
 415
 416 static inline void bio_io_error(struct bio *bio)
 417 {
 418         bio->bi_error = -EIO;
 419         bio_endio(bio);
 420 }
 421
 422 struct request_queue;
 423 extern int bio_phys_segments(struct request_queue *, struct bio *);
 424
 425 extern int submit_bio_wait(struct bio *bio);
 426 extern void bio_advance(struct bio *, unsigned);
 427
 428 extern void bio_init(struct bio *);
 429 extern void bio_reset(struct bio *);
 430 void bio_chain(struct bio *, struct bio *);
 431
 432 extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int);
 433 extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,
 434                            unsigned int, unsigned int);
 435 struct rq_map_data;
 436 extern struct bio *bio_map_user_iov(struct request_queue *,
 437                                     const struct iov_iter *, gfp_t);
 438 extern void bio_unmap_user(struct bio *);
 439 extern struct bio *bio_map_kern(struct request_queue *, void *, unsigned int,
 440                                 gfp_t);
 441 extern struct bio *bio_copy_kern(struct request_queue *, void *, unsigned int,
 442                                  gfp_t, int);
 443 extern void bio_set_pages_dirty(struct bio *bio);
 444 extern void bio_check_pages_dirty(struct bio *bio);
 445
 446 void generic_start_io_acct(int rw, unsigned long sectors,
 447                            struct hd_struct *part);
 448 void generic_end_io_acct(int rw, struct hd_struct *part,
 449                          unsigned long start_time);
 450
 451 #ifndef ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
 452 # error "You should define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE for your platform"
 453 #endif
 454 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
 455 extern void bio_flush_dcache_pages(struct bio *bi);
 456 #else
 457 static inline void bio_flush_dcache_pages(struct bio *bi)
 458 {
 459 }
 460 #endif
 461
 462 extern void bio_copy_data(struct bio *dst, struct bio *src);
 463 extern int bio_alloc_pages(struct bio *bio, gfp_t gfp);
 464
 465 extern struct bio *bio_copy_user_iov(struct request_queue *,
 466                                      struct rq_map_data *,
 467                                      const struct iov_iter *,
 468                                      gfp_t);
 469 extern int bio_uncopy_user(struct bio *);
 470 void zero_fill_bio(struct bio *bio);
 471 extern struct bio_vec *bvec_alloc(gfp_t, int, unsigned long *, mempool_t *);
 472 extern void bvec_free(mempool_t *, struct bio_vec *, unsigned int);
 473 extern unsigned int bvec_nr_vecs(unsigned short idx);
 474
 475 #ifdef CONFIG_BLK_CGROUP
 476 int bio_associate_blkcg(struct bio *bio, struct cgroup_subsys_state *blkcg_css);
 477 int bio_associate_current(struct bio *bio);
 478 void bio_disassociate_task(struct bio *bio);
 479 void bio_clone_blkcg_association(struct bio *dst, struct bio *src);
 480 #else   /* CONFIG_BLK_CGROUP */
 481 static inline int bio_associate_blkcg(struct bio *bio,
 482                         struct cgroup_subsys_state *blkcg_css) { return 0; }
 483 static inline int bio_associate_current(struct bio *bio) { return -ENOENT; }
 484 static inline void bio_disassociate_task(struct bio *bio) { }
 485 static inline void bio_clone_blkcg_association(struct bio *dst,
 486                         struct bio *src) { }
 487 #endif  /* CONFIG_BLK_CGROUP */
 488
 489 #ifdef CONFIG_HIGHMEM
 490 /*
 491  * remember never ever reenable interrupts between a bvec_kmap_irq and
 492  * bvec_kunmap_irq!
 493  */
 494 static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
 495 {
 496         unsigned long addr;
 497
 498         /*
 499          * might not be a highmem page, but the preempt/irq count
 500          * balancing is a lot nicer this way
 501          */
 502         local_irq_save(*flags);
 503         addr = (unsigned long) kmap_atomic(bvec->bv_page);
 504
 505         BUG_ON(addr & ~PAGE_MASK);
 506
 507         return (char *) addr + bvec->bv_offset;
 508 }
 509
 510 static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
 511 {
 512         unsigned long ptr = (unsigned long) buffer & PAGE_MASK;
 513
 514         kunmap_atomic((void *) ptr);
 515         local_irq_restore(*flags);
 516 }
 517
 518 #else
 519 static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
 520 {
 521         return page_address(bvec->bv_page) + bvec->bv_offset;
 522 }
 523
 524 static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
 525 {
 526         *flags = 0;
 527 }
 528 #endif
 529
 530 static inline char *__bio_kmap_irq(struct bio *bio, struct bvec_iter iter,
 531                                    unsigned long *flags)
 532 {
 533         return bvec_kmap_irq(&bio_iter_iovec(bio, iter), flags);
 534 }
 535 #define __bio_kunmap_irq(buf, flags)    bvec_kunmap_irq(buf, flags)
 536
 537 #define bio_kmap_irq(bio, flags) \
 538         __bio_kmap_irq((bio), (bio)->bi_iter, (flags))
 539 #define bio_kunmap_irq(buf,flags)       __bio_kunmap_irq(buf, flags)
 540
 541 /*
 542  * BIO list management for use by remapping drivers (e.g. DM or MD) and loop.
 543  *
 544  * A bio_list anchors a singly-linked list of bios chained through the bi_next
 545  * member of the bio.  The bio_list also caches the last list member to allow
 546  * fast access to the tail.
 547  */
 548 struct bio_list {
 549         struct bio *head;
 550         struct bio *tail;
 551 };
 552
 553 static inline int bio_list_empty(const struct bio_list *bl)
 554 {
 555         return bl->head == NULL;
 556 }
 557
 558 static inline void bio_list_init(struct bio_list *bl)
 559 {
 560         bl->head = bl->tail = NULL;
 561 }
 562
 563 #define BIO_EMPTY_LIST  { NULL, NULL }
 564
 565 #define bio_list_for_each(bio, bl) \
 566         for (bio = (bl)->head; bio; bio = bio->bi_next)
 567
 568 static inline unsigned bio_list_size(const struct bio_list *bl)
 569 {
 570         unsigned sz = 0;
 571         struct bio *bio;
 572
 573         bio_list_for_each(bio, bl)
 574                 sz++;
 575
 576         return sz;
 577 }
 578
 579 static inline void bio_list_add(struct bio_list *bl, struct bio *bio)
 580 {
 581         bio->bi_next = NULL;
 582
 583         if (bl->tail)
 584                 bl->tail->bi_next = bio;
 585         else
 586                 bl->head = bio;
 587
 588         bl->tail = bio;
 589 }
 590
 591 static inline void bio_list_add_head(struct bio_list *bl, struct bio *bio)
 592 {
 593         bio->bi_next = bl->head;
 594
 595         bl->head = bio;
 596
 597         if (!bl->tail)
 598                 bl->tail = bio;
 599 }
 600
 601 static inline void bio_list_merge(struct bio_list *bl, struct bio_list *bl2)
 602 {
 603         if (!bl2->head)
 604                 return;
 605
 606         if (bl->tail)
 607                 bl->tail->bi_next = bl2->head;
 608         else
 609                 bl->head = bl2->head;
 610
 611         bl->tail = bl2->tail;
 612 }
 613
 614 static inline void bio_list_merge_head(struct bio_list *bl,
 615                                        struct bio_list *bl2)
 616 {
 617         if (!bl2->head)
 618                 return;
 619
 620         if (bl->head)
 621                 bl2->tail->bi_next = bl->head;
 622         else
 623                 bl->tail = bl2->tail;
 624
 625         bl->head = bl2->head;
 626 }
 627
 628 static inline struct bio *bio_list_peek(struct bio_list *bl)
 629 {
 630         return bl->head;
 631 }
 632
 633 static inline struct bio *bio_list_pop(struct bio_list *bl)
 634 {
 635         struct bio *bio = bl->head;
 636
 637         if (bio) {
 638                 bl->head = bl->head->bi_next;
 639                 if (!bl->head)
 640                         bl->tail = NULL;
 641
 642                 bio->bi_next = NULL;
 643         }
 644
 645         return bio;
 646 }
 647
 648 static inline struct bio *bio_list_get(struct bio_list *bl)
 649 {
 650         struct bio *bio = bl->head;
 651
 652         bl->head = bl->tail = NULL;
 653
 654         return bio;
 655 }
 656
 657 /*
 658  * Increment chain count for the bio. Make sure the CHAIN flag update
 659  * is visible before the raised count.
 660  */
 661 static inline void bio_inc_remaining(struct bio *bio)
 662 {
 663         bio_set_flag(bio, BIO_CHAIN);
 664         smp_mb__before_atomic();
 665         atomic_inc(&bio->__bi_remaining);
 666 }
 667
 668 /*
 669  * bio_set is used to allow other portions of the IO system to
 670  * allocate their own private memory pools for bio and iovec structures.
 671  * These memory pools in turn all allocate from the bio_slab
 672  * and the bvec_slabs[].
 673  */
 674 #define BIO_POOL_SIZE 2
 675
 676 struct bio_set {
 677         struct kmem_cache *bio_slab;
 678         unsigned int front_pad;
 679
 680         mempool_t *bio_pool;
 681         mempool_t *bvec_pool;
 682 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 683         mempool_t *bio_integrity_pool;
 684         mempool_t *bvec_integrity_pool;
 685 #endif
 686
 687         /*
 688          * Deadlock avoidance for stacking block drivers: see comments in
 689          * bio_alloc_bioset() for details
 690          */
 691         spinlock_t              rescue_lock;
 692         struct bio_list         rescue_list;
 693         struct work_struct      rescue_work;
 694         struct workqueue_struct *rescue_workqueue;
 695 };
 696
 697 struct biovec_slab {
 698         int nr_vecs;
 699         char *name;
 700         struct kmem_cache *slab;
 701 };
 702
 703 /*
 704  * a small number of entries is fine, not going to be performance critical.
 705  * basically we just need to survive
 706  */
 707 #define BIO_SPLIT_ENTRIES 2
 708
 709 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 710
 711 #define bip_for_each_vec(bvl, bip, iter)                                \
 712         for_each_bvec(bvl, (bip)->bip_vec, iter, (bip)->bip_iter)
 713
 714 #define bio_for_each_integrity_vec(_bvl, _bio, _iter)                   \
 715         for_each_bio(_bio)                                              \
 716                 bip_for_each_vec(_bvl, _bio->bi_integrity, _iter)
 717
 718 extern struct bio_integrity_payload *bio_integrity_alloc(struct bio *, gfp_t, unsigned int);
 719 extern void bio_integrity_free(struct bio *);
 720 extern int bio_integrity_add_page(struct bio *, struct page *, unsigned int, unsigned int);
 721 extern bool bio_integrity_enabled(struct bio *bio);
 722 extern int bio_integrity_prep(struct bio *);
 723 extern void bio_integrity_endio(struct bio *);
 724 extern void bio_integrity_advance(struct bio *, unsigned int);
 725 extern void bio_integrity_trim(struct bio *, unsigned int, unsigned int);
 726 extern int bio_integrity_clone(struct bio *, struct bio *, gfp_t);
 727 extern int bioset_integrity_create(struct bio_set *, int);
 728 extern void bioset_integrity_free(struct bio_set *);
 729 extern void bio_integrity_init(void);
 730
 731 #else /* CONFIG_BLK_DEV_INTEGRITY */
 732
 733 static inline void *bio_integrity(struct bio *bio)
 734 {
 735         return NULL;
 736 }
 737
 738 static inline bool bio_integrity_enabled(struct bio *bio)
 739 {
 740         return false;
 741 }
 742
 743 static inline int bioset_integrity_create(struct bio_set *bs, int pool_size)
 744 {
 745         return 0;
 746 }
 747
 748 static inline void bioset_integrity_free (struct bio_set *bs)
 749 {
 750         return;
 751 }
 752
 753 static inline int bio_integrity_prep(struct bio *bio)
 754 {
 755         return 0;
 756 }
 757
 758 static inline void bio_integrity_free(struct bio *bio)
 759 {
 760         return;
 761 }
 762
 763 static inline int bio_integrity_clone(struct bio *bio, struct bio *bio_src,
 764                                       gfp_t gfp_mask)
 765 {
 766         return 0;
 767 }
 768
 769 static inline void bio_integrity_advance(struct bio *bio,
 770                                          unsigned int bytes_done)
 771 {
 772         return;
 773 }
 774
 775 static inline void bio_integrity_trim(struct bio *bio, unsigned int offset,
 776                                       unsigned int sectors)
 777 {
 778         return;
 779 }
 780
 781 static inline void bio_integrity_init(void)
 782 {
 783         return;
 784 }
 785
 786 static inline bool bio_integrity_flagged(struct bio *bio, enum bip_flags flag)
 787 {
 788         return false;
 789 }
 790
 791 static inline void *bio_integrity_alloc(struct bio * bio, gfp_t gfp,
 792                                                                 unsigned int nr)
 793 {
 794         return ERR_PTR(-EINVAL);
 795 }
 796
 797 static inline int bio_integrity_add_page(struct bio *bio, struct page *page,
 798                                         unsigned int len, unsigned int offset)
 799 {
 800         return 0;
 801 }
 802
 803 #endif /* CONFIG_BLK_DEV_INTEGRITY */
 804
 805 #endif /* CONFIG_BLOCK */
 806 #endif /* __LINUX_BIO_H */