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