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 #define BIO_MAX_SIZE            (BIO_MAX_PAGES << PAGE_CACHE_SHIFT)
  45 #define BIO_MAX_SECTORS         (BIO_MAX_SIZE >> 9)
  46
  47 /*
  48  * upper 16 bits of bi_rw define the io priority of this bio
  49  */
  50 #define BIO_PRIO_SHIFT  (8 * sizeof(unsigned long) - IOPRIO_BITS)
  51 #define bio_prio(bio)   ((bio)->bi_rw >> BIO_PRIO_SHIFT)
  52 #define bio_prio_valid(bio)     ioprio_valid(bio_prio(bio))
  53
  54 #define bio_set_prio(bio, prio)         do {                    \
  55         WARN_ON(prio >= (1 << IOPRIO_BITS));                    \
  56         (bio)->bi_rw &= ((1UL << BIO_PRIO_SHIFT) - 1);          \
  57         (bio)->bi_rw |= ((unsigned long) (prio) << BIO_PRIO_SHIFT);     \
  58 } while (0)
  59
  60 /*
  61  * various member access, note that bio_data should of course not be used
  62  * on highmem page vectors
  63  */
  64 #define __bvec_iter_bvec(bvec, iter)    (&(bvec)[(iter).bi_idx])
  65
  66 #define bvec_iter_page(bvec, iter)                              \
  67         (__bvec_iter_bvec((bvec), (iter))->bv_page)
  68
  69 #define bvec_iter_len(bvec, iter)                               \
  70         min((iter).bi_size,                                     \
  71             __bvec_iter_bvec((bvec), (iter))->bv_len - (iter).bi_bvec_done)
  72
  73 #define bvec_iter_offset(bvec, iter)                            \
  74         (__bvec_iter_bvec((bvec), (iter))->bv_offset + (iter).bi_bvec_done)
  75
  76 #define bvec_iter_bvec(bvec, iter)                              \
  77 ((struct bio_vec) {                                             \
  78         .bv_page        = bvec_iter_page((bvec), (iter)),       \
  79         .bv_len         = bvec_iter_len((bvec), (iter)),        \
  80         .bv_offset      = bvec_iter_offset((bvec), (iter)),     \
  81 })
  82
  83 #define bio_iter_iovec(bio, iter)                               \
  84         bvec_iter_bvec((bio)->bi_io_vec, (iter))
  85
  86 #define bio_iter_page(bio, iter)                                \
  87         bvec_iter_page((bio)->bi_io_vec, (iter))
  88 #define bio_iter_len(bio, iter)                                 \
  89         bvec_iter_len((bio)->bi_io_vec, (iter))
  90 #define bio_iter_offset(bio, iter)                              \
  91         bvec_iter_offset((bio)->bi_io_vec, (iter))
  92
  93 #define bio_page(bio)           bio_iter_page((bio), (bio)->bi_iter)
  94 #define bio_offset(bio)         bio_iter_offset((bio), (bio)->bi_iter)
  95 #define bio_iovec(bio)          bio_iter_iovec((bio), (bio)->bi_iter)
  96
  97 #define bio_multiple_segments(bio)                              \
  98         ((bio)->bi_iter.bi_size != bio_iovec(bio).bv_len)
  99 #define bio_sectors(bio)        ((bio)->bi_iter.bi_size >> 9)
 100 #define bio_end_sector(bio)     ((bio)->bi_iter.bi_sector + bio_sectors((bio)))
 101
 102 /*
 103  * Check whether this bio carries any data or not. A NULL bio is allowed.
 104  */
 105 static inline bool bio_has_data(struct bio *bio)
 106 {
 107         if (bio &&
 108             bio->bi_iter.bi_size &&
 109             !(bio->bi_rw & REQ_DISCARD))
 110                 return true;
 111
 112         return false;
 113 }
 114
 115 static inline bool bio_is_rw(struct bio *bio)
 116 {
 117         if (!bio_has_data(bio))
 118                 return false;
 119
 120         if (bio->bi_rw & BIO_NO_ADVANCE_ITER_MASK)
 121                 return false;
 122
 123         return true;
 124 }
 125
 126 static inline bool bio_mergeable(struct bio *bio)
 127 {
 128         if (bio->bi_rw & REQ_NOMERGE_FLAGS)
 129                 return false;
 130
 131         return true;
 132 }
 133
 134 static inline unsigned int bio_cur_bytes(struct bio *bio)
 135 {
 136         if (bio_has_data(bio))
 137                 return bio_iovec(bio).bv_len;
 138         else /* dataless requests such as discard */
 139                 return bio->bi_iter.bi_size;
 140 }
 141
 142 static inline void *bio_data(struct bio *bio)
 143 {
 144         if (bio_has_data(bio))
 145                 return page_address(bio_page(bio)) + bio_offset(bio);
 146
 147         return NULL;
 148 }
 149
 150 /*
 151  * will die
 152  */
 153 #define bio_to_phys(bio)        (page_to_phys(bio_page((bio))) + (unsigned long) bio_offset((bio)))
 154 #define bvec_to_phys(bv)        (page_to_phys((bv)->bv_page) + (unsigned long) (bv)->bv_offset)
 155
 156 /*
 157  * queues that have highmem support enabled may still need to revert to
 158  * PIO transfers occasionally and thus map high pages temporarily. For
 159  * permanent PIO fall back, user is probably better off disabling highmem
 160  * I/O completely on that queue (see ide-dma for example)
 161  */
 162 #define __bio_kmap_atomic(bio, iter)                            \
 163         (kmap_atomic(bio_iter_iovec((bio), (iter)).bv_page) +   \
 164                 bio_iter_iovec((bio), (iter)).bv_offset)
 165
 166 #define __bio_kunmap_atomic(addr)       kunmap_atomic(addr)
 167
 168 /*
 169  * merge helpers etc
 170  */
 171
 172 /* Default implementation of BIOVEC_PHYS_MERGEABLE */
 173 #define __BIOVEC_PHYS_MERGEABLE(vec1, vec2)     \
 174         ((bvec_to_phys((vec1)) + (vec1)->bv_len) == bvec_to_phys((vec2)))
 175
 176 /*
 177  * allow arch override, for eg virtualized architectures (put in asm/io.h)
 178  */
 179 #ifndef BIOVEC_PHYS_MERGEABLE
 180 #define BIOVEC_PHYS_MERGEABLE(vec1, vec2)       \
 181         __BIOVEC_PHYS_MERGEABLE(vec1, vec2)
 182 #endif
 183
 184 #define __BIO_SEG_BOUNDARY(addr1, addr2, mask) \
 185         (((addr1) | (mask)) == (((addr2) - 1) | (mask)))
 186 #define BIOVEC_SEG_BOUNDARY(q, b1, b2) \
 187         __BIO_SEG_BOUNDARY(bvec_to_phys((b1)), bvec_to_phys((b2)) + (b2)->bv_len, queue_segment_boundary((q)))
 188
 189 /*
 190  * drivers should _never_ use the all version - the bio may have been split
 191  * before it got to the driver and the driver won't own all of it
 192  */
 193 #define bio_for_each_segment_all(bvl, bio, i)                           \
 194         for (i = 0, bvl = (bio)->bi_io_vec; i < (bio)->bi_vcnt; i++, bvl++)
 195
 196 static inline void bvec_iter_advance(struct bio_vec *bv, struct bvec_iter *iter,
 197                                      unsigned bytes)
 198 {
 199         WARN_ONCE(bytes > iter->bi_size,
 200                   "Attempted to advance past end of bvec iter\n");
 201
 202         while (bytes) {
 203                 unsigned len = min(bytes, bvec_iter_len(bv, *iter));
 204
 205                 bytes -= len;
 206                 iter->bi_size -= len;
 207                 iter->bi_bvec_done += len;
 208
 209                 if (iter->bi_bvec_done == __bvec_iter_bvec(bv, *iter)->bv_len) {
 210                         iter->bi_bvec_done = 0;
 211                         iter->bi_idx++;
 212                 }
 213         }
 214 }
 215
 216 #define for_each_bvec(bvl, bio_vec, iter, start)                        \
 217         for (iter = (start);                                            \
 218              (iter).bi_size &&                                          \
 219                 ((bvl = bvec_iter_bvec((bio_vec), (iter))), 1); \
 220              bvec_iter_advance((bio_vec), &(iter), (bvl).bv_len))
 221
 222
 223 static inline void bio_advance_iter(struct bio *bio, struct bvec_iter *iter,
 224                                     unsigned bytes)
 225 {
 226         iter->bi_sector += bytes >> 9;
 227
 228         if (bio->bi_rw & BIO_NO_ADVANCE_ITER_MASK)
 229                 iter->bi_size -= bytes;
 230         else
 231                 bvec_iter_advance(bio->bi_io_vec, iter, bytes);
 232 }
 233
 234 #define __bio_for_each_segment(bvl, bio, iter, start)                   \
 235         for (iter = (start);                                            \
 236              (iter).bi_size &&                                          \
 237                 ((bvl = bio_iter_iovec((bio), (iter))), 1);             \
 238              bio_advance_iter((bio), &(iter), (bvl).bv_len))
 239
 240 #define bio_for_each_segment(bvl, bio, iter)                            \
 241         __bio_for_each_segment(bvl, bio, iter, (bio)->bi_iter)
 242
 243 #define bio_iter_last(bvec, iter) ((iter).bi_size == (bvec).bv_len)
 244
 245 static inline unsigned bio_segments(struct bio *bio)
 246 {
 247         unsigned segs = 0;
 248         struct bio_vec bv;
 249         struct bvec_iter iter;
 250
 251         /*
 252          * We special case discard/write same, because they interpret bi_size
 253          * differently:
 254          */
 255
 256         if (bio->bi_rw & REQ_DISCARD)
 257                 return 1;
 258
 259         if (bio->bi_rw & REQ_WRITE_SAME)
 260                 return 1;
 261
 262         bio_for_each_segment(bv, bio, iter)
 263                 segs++;
 264
 265         return segs;
 266 }
 267
 268 /*
 269  * get a reference to a bio, so it won't disappear. the intended use is
 270  * something like:
 271  *
 272  * bio_get(bio);
 273  * submit_bio(rw, bio);
 274  * if (bio->bi_flags ...)
 275  *      do_something
 276  * bio_put(bio);
 277  *
 278  * without the bio_get(), it could potentially complete I/O before submit_bio
 279  * returns. and then bio would be freed memory when if (bio->bi_flags ...)
 280  * runs
 281  */
 282 static inline void bio_get(struct bio *bio)
 283 {
 284         bio->bi_flags |= (1 << BIO_REFFED);
 285         smp_mb__before_atomic();
 286         atomic_inc(&bio->__bi_cnt);
 287 }
 288
 289 static inline void bio_cnt_set(struct bio *bio, unsigned int count)
 290 {
 291         if (count != 1) {
 292                 bio->bi_flags |= (1 << BIO_REFFED);
 293                 smp_mb__before_atomic();
 294         }
 295         atomic_set(&bio->__bi_cnt, count);
 296 }
 297
 298 static inline bool bio_flagged(struct bio *bio, unsigned int bit)
 299 {
 300         return (bio->bi_flags & (1U << bit)) != 0;
 301 }
 302
 303 static inline void bio_set_flag(struct bio *bio, unsigned int bit)
 304 {
 305         bio->bi_flags |= (1U << bit);
 306 }
 307
 308 static inline void bio_clear_flag(struct bio *bio, unsigned int bit)
 309 {
 310         bio->bi_flags &= ~(1U << bit);
 311 }
 312
 313 static inline void bio_get_first_bvec(struct bio *bio, struct bio_vec *bv)
 314 {
 315         *bv = bio_iovec(bio);
 316 }
 317
 318 static inline void bio_get_last_bvec(struct bio *bio, struct bio_vec *bv)
 319 {
 320         struct bvec_iter iter = bio->bi_iter;
 321         int idx;
 322
 323         if (unlikely(!bio_multiple_segments(bio))) {
 324                 *bv = bio_iovec(bio);
 325                 return;
 326         }
 327
 328         bio_advance_iter(bio, &iter, iter.bi_size);
 329
 330         if (!iter.bi_bvec_done)
 331                 idx = iter.bi_idx - 1;
 332         else    /* in the middle of bvec */
 333                 idx = iter.bi_idx;
 334
 335         *bv = bio->bi_io_vec[idx];
 336
 337         /*
 338          * iter.bi_bvec_done records actual length of the last bvec
 339          * if this bio ends in the middle of one io vector
 340          */
 341         if (iter.bi_bvec_done)
 342                 bv->bv_len = iter.bi_bvec_done;
 343 }
 344
 345 enum bip_flags {
 346         BIP_BLOCK_INTEGRITY     = 1 << 0, /* block layer owns integrity data */
 347         BIP_MAPPED_INTEGRITY    = 1 << 1, /* ref tag has been remapped */
 348         BIP_CTRL_NOCHECK        = 1 << 2, /* disable HBA integrity checking */
 349         BIP_DISK_NOCHECK        = 1 << 3, /* disable disk integrity checking */
 350         BIP_IP_CHECKSUM         = 1 << 4, /* IP checksum */
 351 };
 352
 353 /*
 354  * bio integrity payload
 355  */
 356 struct bio_integrity_payload {
 357         struct bio              *bip_bio;       /* parent bio */
 358
 359         struct bvec_iter        bip_iter;
 360
 361         bio_end_io_t            *bip_end_io;    /* saved I/O completion fn */
 362
 363         unsigned short          bip_slab;       /* slab the bip came from */
 364         unsigned short          bip_vcnt;       /* # of integrity bio_vecs */
 365         unsigned short          bip_max_vcnt;   /* integrity bio_vec slots */
 366         unsigned short          bip_flags;      /* control flags */
 367
 368         struct work_struct      bip_work;       /* I/O completion */
 369
 370         struct bio_vec          *bip_vec;
 371         struct bio_vec          bip_inline_vecs[0];/* embedded bvec array */
 372 };
 373
 374 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 375
 376 static inline struct bio_integrity_payload *bio_integrity(struct bio *bio)
 377 {
 378         if (bio->bi_rw & REQ_INTEGRITY)
 379                 return bio->bi_integrity;
 380
 381         return NULL;
 382 }
 383
 384 static inline bool bio_integrity_flagged(struct bio *bio, enum bip_flags flag)
 385 {
 386         struct bio_integrity_payload *bip = bio_integrity(bio);
 387
 388         if (bip)
 389                 return bip->bip_flags & flag;
 390
 391         return false;
 392 }
 393
 394 static inline sector_t bip_get_seed(struct bio_integrity_payload *bip)
 395 {
 396         return bip->bip_iter.bi_sector;
 397 }
 398
 399 static inline void bip_set_seed(struct bio_integrity_payload *bip,
 400                                 sector_t seed)
 401 {
 402         bip->bip_iter.bi_sector = seed;
 403 }
 404
 405 #endif /* CONFIG_BLK_DEV_INTEGRITY */
 406
 407 extern void bio_trim(struct bio *bio, int offset, int size);
 408 extern struct bio *bio_split(struct bio *bio, int sectors,
 409                              gfp_t gfp, struct bio_set *bs);
 410
 411 /**
 412  * bio_next_split - get next @sectors from a bio, splitting if necessary
 413  * @bio:        bio to split
 414  * @sectors:    number of sectors to split from the front of @bio
 415  * @gfp:        gfp mask
 416  * @bs:         bio set to allocate from
 417  *
 418  * Returns a bio representing the next @sectors of @bio - if the bio is smaller
 419  * than @sectors, returns the original bio unchanged.
 420  */
 421 static inline struct bio *bio_next_split(struct bio *bio, int sectors,
 422                                          gfp_t gfp, struct bio_set *bs)
 423 {
 424         if (sectors >= bio_sectors(bio))
 425                 return bio;
 426
 427         return bio_split(bio, sectors, gfp, bs);
 428 }
 429
 430 extern struct bio_set *bioset_create(unsigned int, unsigned int);
 431 extern struct bio_set *bioset_create_nobvec(unsigned int, unsigned int);
 432 extern void bioset_free(struct bio_set *);
 433 extern mempool_t *biovec_create_pool(int pool_entries);
 434
 435 extern struct bio *bio_alloc_bioset(gfp_t, int, struct bio_set *);
 436 extern void bio_put(struct bio *);
 437
 438 extern void __bio_clone_fast(struct bio *, struct bio *);
 439 extern struct bio *bio_clone_fast(struct bio *, gfp_t, struct bio_set *);
 440 extern struct bio *bio_clone_bioset(struct bio *, gfp_t, struct bio_set *bs);
 441
 442 extern struct bio_set *fs_bio_set;
 443
 444 static inline struct bio *bio_alloc(gfp_t gfp_mask, unsigned int nr_iovecs)
 445 {
 446         return bio_alloc_bioset(gfp_mask, nr_iovecs, fs_bio_set);
 447 }
 448
 449 static inline struct bio *bio_clone(struct bio *bio, gfp_t gfp_mask)
 450 {
 451         return bio_clone_bioset(bio, gfp_mask, fs_bio_set);
 452 }
 453
 454 static inline struct bio *bio_kmalloc(gfp_t gfp_mask, unsigned int nr_iovecs)
 455 {
 456         return bio_alloc_bioset(gfp_mask, nr_iovecs, NULL);
 457 }
 458
 459 static inline struct bio *bio_clone_kmalloc(struct bio *bio, gfp_t gfp_mask)
 460 {
 461         return bio_clone_bioset(bio, gfp_mask, NULL);
 462
 463 }
 464
 465 extern void bio_endio(struct bio *);
 466
 467 static inline void bio_io_error(struct bio *bio)
 468 {
 469         bio->bi_error = -EIO;
 470         bio_endio(bio);
 471 }
 472
 473 struct request_queue;
 474 extern int bio_phys_segments(struct request_queue *, struct bio *);
 475
 476 extern int submit_bio_wait(int rw, struct bio *bio);
 477 extern void bio_advance(struct bio *, unsigned);
 478
 479 extern void bio_init(struct bio *);
 480 extern void bio_reset(struct bio *);
 481 void bio_chain(struct bio *, struct bio *);
 482
 483 extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int);
 484 extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,
 485                            unsigned int, unsigned int);
 486 struct rq_map_data;
 487 extern struct bio *bio_map_user_iov(struct request_queue *,
 488                                     const struct iov_iter *, gfp_t);
 489 extern void bio_unmap_user(struct bio *);
 490 extern struct bio *bio_map_kern(struct request_queue *, void *, unsigned int,
 491                                 gfp_t);
 492 extern struct bio *bio_copy_kern(struct request_queue *, void *, unsigned int,
 493                                  gfp_t, int);
 494 extern void bio_set_pages_dirty(struct bio *bio);
 495 extern void bio_check_pages_dirty(struct bio *bio);
 496
 497 void generic_start_io_acct(int rw, unsigned long sectors,
 498                            struct hd_struct *part);
 499 void generic_end_io_acct(int rw, struct hd_struct *part,
 500                          unsigned long start_time);
 501
 502 #ifndef ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
 503 # error "You should define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE for your platform"
 504 #endif
 505 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
 506 extern void bio_flush_dcache_pages(struct bio *bi);
 507 #else
 508 static inline void bio_flush_dcache_pages(struct bio *bi)
 509 {
 510 }
 511 #endif
 512
 513 extern void bio_copy_data(struct bio *dst, struct bio *src);
 514 extern int bio_alloc_pages(struct bio *bio, gfp_t gfp);
 515
 516 extern struct bio *bio_copy_user_iov(struct request_queue *,
 517                                      struct rq_map_data *,
 518                                      const struct iov_iter *,
 519                                      gfp_t);
 520 extern int bio_uncopy_user(struct bio *);
 521 void zero_fill_bio(struct bio *bio);
 522 extern struct bio_vec *bvec_alloc(gfp_t, int, unsigned long *, mempool_t *);
 523 extern void bvec_free(mempool_t *, struct bio_vec *, unsigned int);
 524 extern unsigned int bvec_nr_vecs(unsigned short idx);
 525
 526 #ifdef CONFIG_BLK_CGROUP
 527 int bio_associate_blkcg(struct bio *bio, struct cgroup_subsys_state *blkcg_css);
 528 int bio_associate_current(struct bio *bio);
 529 void bio_disassociate_task(struct bio *bio);
 530 #else   /* CONFIG_BLK_CGROUP */
 531 static inline int bio_associate_blkcg(struct bio *bio,
 532                         struct cgroup_subsys_state *blkcg_css) { return 0; }
 533 static inline int bio_associate_current(struct bio *bio) { return -ENOENT; }
 534 static inline void bio_disassociate_task(struct bio *bio) { }
 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 static inline char *__bio_kmap_irq(struct bio *bio, struct bvec_iter iter,
 579                                    unsigned long *flags)
 580 {
 581         return bvec_kmap_irq(&bio_iter_iovec(bio, iter), flags);
 582 }
 583 #define __bio_kunmap_irq(buf, flags)    bvec_kunmap_irq(buf, flags)
 584
 585 #define bio_kmap_irq(bio, flags) \
 586         __bio_kmap_irq((bio), (bio)->bi_iter, (flags))
 587 #define bio_kunmap_irq(buf,flags)       __bio_kunmap_irq(buf, flags)
 588
 589 /*
 590  * BIO list management for use by remapping drivers (e.g. DM or MD) and loop.
 591  *
 592  * A bio_list anchors a singly-linked list of bios chained through the bi_next
 593  * member of the bio.  The bio_list also caches the last list member to allow
 594  * fast access to the tail.
 595  */
 596 struct bio_list {
 597         struct bio *head;
 598         struct bio *tail;
 599 };
 600
 601 static inline int bio_list_empty(const struct bio_list *bl)
 602 {
 603         return bl->head == NULL;
 604 }
 605
 606 static inline void bio_list_init(struct bio_list *bl)
 607 {
 608         bl->head = bl->tail = NULL;
 609 }
 610
 611 #define BIO_EMPTY_LIST  { NULL, NULL }
 612
 613 #define bio_list_for_each(bio, bl) \
 614         for (bio = (bl)->head; bio; bio = bio->bi_next)
 615
 616 static inline unsigned bio_list_size(const struct bio_list *bl)
 617 {
 618         unsigned sz = 0;
 619         struct bio *bio;
 620
 621         bio_list_for_each(bio, bl)
 622                 sz++;
 623
 624         return sz;
 625 }
 626
 627 static inline void bio_list_add(struct bio_list *bl, struct bio *bio)
 628 {
 629         bio->bi_next = NULL;
 630
 631         if (bl->tail)
 632                 bl->tail->bi_next = bio;
 633         else
 634                 bl->head = bio;
 635
 636         bl->tail = bio;
 637 }
 638
 639 static inline void bio_list_add_head(struct bio_list *bl, struct bio *bio)
 640 {
 641         bio->bi_next = bl->head;
 642
 643         bl->head = bio;
 644
 645         if (!bl->tail)
 646                 bl->tail = bio;
 647 }
 648
 649 static inline void bio_list_merge(struct bio_list *bl, struct bio_list *bl2)
 650 {
 651         if (!bl2->head)
 652                 return;
 653
 654         if (bl->tail)
 655                 bl->tail->bi_next = bl2->head;
 656         else
 657                 bl->head = bl2->head;
 658
 659         bl->tail = bl2->tail;
 660 }
 661
 662 static inline void bio_list_merge_head(struct bio_list *bl,
 663                                        struct bio_list *bl2)
 664 {
 665         if (!bl2->head)
 666                 return;
 667
 668         if (bl->head)
 669                 bl2->tail->bi_next = bl->head;
 670         else
 671                 bl->tail = bl2->tail;
 672
 673         bl->head = bl2->head;
 674 }
 675
 676 static inline struct bio *bio_list_peek(struct bio_list *bl)
 677 {
 678         return bl->head;
 679 }
 680
 681 static inline struct bio *bio_list_pop(struct bio_list *bl)
 682 {
 683         struct bio *bio = bl->head;
 684
 685         if (bio) {
 686                 bl->head = bl->head->bi_next;
 687                 if (!bl->head)
 688                         bl->tail = NULL;
 689
 690                 bio->bi_next = NULL;
 691         }
 692
 693         return bio;
 694 }
 695
 696 static inline struct bio *bio_list_get(struct bio_list *bl)
 697 {
 698         struct bio *bio = bl->head;
 699
 700         bl->head = bl->tail = NULL;
 701
 702         return bio;
 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 #define BIOVEC_NR_POOLS 6
 713 #define BIOVEC_MAX_IDX  (BIOVEC_NR_POOLS - 1)
 714
 715 struct bio_set {
 716         struct kmem_cache *bio_slab;
 717         unsigned int front_pad;
 718
 719         mempool_t *bio_pool;
 720         mempool_t *bvec_pool;
 721 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 722         mempool_t *bio_integrity_pool;
 723         mempool_t *bvec_integrity_pool;
 724 #endif
 725
 726         /*
 727          * Deadlock avoidance for stacking block drivers: see comments in
 728          * bio_alloc_bioset() for details
 729          */
 730         spinlock_t              rescue_lock;
 731         struct bio_list         rescue_list;
 732         struct work_struct      rescue_work;
 733         struct workqueue_struct *rescue_workqueue;
 734 };
 735
 736 struct biovec_slab {
 737         int nr_vecs;
 738         char *name;
 739         struct kmem_cache *slab;
 740 };
 741
 742 /*
 743  * a small number of entries is fine, not going to be performance critical.
 744  * basically we just need to survive
 745  */
 746 #define BIO_SPLIT_ENTRIES 2
 747
 748 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 749
 750 #define bip_for_each_vec(bvl, bip, iter)                                \
 751         for_each_bvec(bvl, (bip)->bip_vec, iter, (bip)->bip_iter)
 752
 753 #define bio_for_each_integrity_vec(_bvl, _bio, _iter)                   \
 754         for_each_bio(_bio)                                              \
 755                 bip_for_each_vec(_bvl, _bio->bi_integrity, _iter)
 756
 757 extern struct bio_integrity_payload *bio_integrity_alloc(struct bio *, gfp_t, unsigned int);
 758 extern void bio_integrity_free(struct bio *);
 759 extern int bio_integrity_add_page(struct bio *, struct page *, unsigned int, unsigned int);
 760 extern bool bio_integrity_enabled(struct bio *bio);
 761 extern int bio_integrity_prep(struct bio *);
 762 extern void bio_integrity_endio(struct bio *);
 763 extern void bio_integrity_advance(struct bio *, unsigned int);
 764 extern void bio_integrity_trim(struct bio *, unsigned int, unsigned int);
 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 bool bio_integrity_enabled(struct bio *bio)
 778 {
 779         return false;
 780 }
 781
 782 static inline int bioset_integrity_create(struct bio_set *bs, int pool_size)
 783 {
 784         return 0;
 785 }
 786
 787 static inline void bioset_integrity_free (struct bio_set *bs)
 788 {
 789         return;
 790 }
 791
 792 static inline int bio_integrity_prep(struct bio *bio)
 793 {
 794         return 0;
 795 }
 796
 797 static inline void bio_integrity_free(struct bio *bio)
 798 {
 799         return;
 800 }
 801
 802 static inline int bio_integrity_clone(struct bio *bio, struct bio *bio_src,
 803                                       gfp_t gfp_mask)
 804 {
 805         return 0;
 806 }
 807
 808 static inline void bio_integrity_advance(struct bio *bio,
 809                                          unsigned int bytes_done)
 810 {
 811         return;
 812 }
 813
 814 static inline void bio_integrity_trim(struct bio *bio, unsigned int offset,
 815                                       unsigned int sectors)
 816 {
 817         return;
 818 }
 819
 820 static inline void bio_integrity_init(void)
 821 {
 822         return;
 823 }
 824
 825 static inline bool bio_integrity_flagged(struct bio *bio, enum bip_flags flag)
 826 {
 827         return false;
 828 }
 829
 830 static inline void *bio_integrity_alloc(struct bio * bio, gfp_t gfp,
 831                                                                 unsigned int nr)
 832 {
 833         return ERR_PTR(-EINVAL);
 834 }
 835
 836 static inline int bio_integrity_add_page(struct bio *bio, struct page *page,
 837                                         unsigned int len, unsigned int offset)
 838 {
 839         return 0;
 840 }
 841
 842 #endif /* CONFIG_BLK_DEV_INTEGRITY */
 843
 844 #endif /* CONFIG_BLOCK */
 845 #endif /* __LINUX_BIO_H */