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 (!bio_flagged(bio, BIO_CLONED)) {
 324                 *bv = bio->bi_io_vec[bio->bi_vcnt - 1];
 325                 return;
 326         }
 327
 328         if (unlikely(!bio_multiple_segments(bio))) {
 329                 *bv = bio_iovec(bio);
 330                 return;
 331         }
 332
 333         bio_advance_iter(bio, &iter, iter.bi_size);
 334
 335         if (!iter.bi_bvec_done)
 336                 idx = iter.bi_idx - 1;
 337         else    /* in the middle of bvec */
 338                 idx = iter.bi_idx;
 339
 340         *bv = bio->bi_io_vec[idx];
 341
 342         /*
 343          * iter.bi_bvec_done records actual length of the last bvec
 344          * if this bio ends in the middle of one io vector
 345          */
 346         if (iter.bi_bvec_done)
 347                 bv->bv_len = iter.bi_bvec_done;
 348 }
 349
 350 enum bip_flags {
 351         BIP_BLOCK_INTEGRITY     = 1 << 0, /* block layer owns integrity data */
 352         BIP_MAPPED_INTEGRITY    = 1 << 1, /* ref tag has been remapped */
 353         BIP_CTRL_NOCHECK        = 1 << 2, /* disable HBA integrity checking */
 354         BIP_DISK_NOCHECK        = 1 << 3, /* disable disk integrity checking */
 355         BIP_IP_CHECKSUM         = 1 << 4, /* IP checksum */
 356 };
 357
 358 /*
 359  * bio integrity payload
 360  */
 361 struct bio_integrity_payload {
 362         struct bio              *bip_bio;       /* parent bio */
 363
 364         struct bvec_iter        bip_iter;
 365
 366         bio_end_io_t            *bip_end_io;    /* saved I/O completion fn */
 367
 368         unsigned short          bip_slab;       /* slab the bip came from */
 369         unsigned short          bip_vcnt;       /* # of integrity bio_vecs */
 370         unsigned short          bip_max_vcnt;   /* integrity bio_vec slots */
 371         unsigned short          bip_flags;      /* control flags */
 372
 373         struct work_struct      bip_work;       /* I/O completion */
 374
 375         struct bio_vec          *bip_vec;
 376         struct bio_vec          bip_inline_vecs[0];/* embedded bvec array */
 377 };
 378
 379 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 380
 381 static inline struct bio_integrity_payload *bio_integrity(struct bio *bio)
 382 {
 383         if (bio->bi_rw & REQ_INTEGRITY)
 384                 return bio->bi_integrity;
 385
 386         return NULL;
 387 }
 388
 389 static inline bool bio_integrity_flagged(struct bio *bio, enum bip_flags flag)
 390 {
 391         struct bio_integrity_payload *bip = bio_integrity(bio);
 392
 393         if (bip)
 394                 return bip->bip_flags & flag;
 395
 396         return false;
 397 }
 398
 399 static inline sector_t bip_get_seed(struct bio_integrity_payload *bip)
 400 {
 401         return bip->bip_iter.bi_sector;
 402 }
 403
 404 static inline void bip_set_seed(struct bio_integrity_payload *bip,
 405                                 sector_t seed)
 406 {
 407         bip->bip_iter.bi_sector = seed;
 408 }
 409
 410 #endif /* CONFIG_BLK_DEV_INTEGRITY */
 411
 412 extern void bio_trim(struct bio *bio, int offset, int size);
 413 extern struct bio *bio_split(struct bio *bio, int sectors,
 414                              gfp_t gfp, struct bio_set *bs);
 415
 416 /**
 417  * bio_next_split - get next @sectors from a bio, splitting if necessary
 418  * @bio:        bio to split
 419  * @sectors:    number of sectors to split from the front of @bio
 420  * @gfp:        gfp mask
 421  * @bs:         bio set to allocate from
 422  *
 423  * Returns a bio representing the next @sectors of @bio - if the bio is smaller
 424  * than @sectors, returns the original bio unchanged.
 425  */
 426 static inline struct bio *bio_next_split(struct bio *bio, int sectors,
 427                                          gfp_t gfp, struct bio_set *bs)
 428 {
 429         if (sectors >= bio_sectors(bio))
 430                 return bio;
 431
 432         return bio_split(bio, sectors, gfp, bs);
 433 }
 434
 435 extern struct bio_set *bioset_create(unsigned int, unsigned int);
 436 extern struct bio_set *bioset_create_nobvec(unsigned int, unsigned int);
 437 extern void bioset_free(struct bio_set *);
 438 extern mempool_t *biovec_create_pool(int pool_entries);
 439
 440 extern struct bio *bio_alloc_bioset(gfp_t, int, struct bio_set *);
 441 extern void bio_put(struct bio *);
 442
 443 extern void __bio_clone_fast(struct bio *, struct bio *);
 444 extern struct bio *bio_clone_fast(struct bio *, gfp_t, struct bio_set *);
 445 extern struct bio *bio_clone_bioset(struct bio *, gfp_t, struct bio_set *bs);
 446
 447 extern struct bio_set *fs_bio_set;
 448
 449 static inline struct bio *bio_alloc(gfp_t gfp_mask, unsigned int nr_iovecs)
 450 {
 451         return bio_alloc_bioset(gfp_mask, nr_iovecs, fs_bio_set);
 452 }
 453
 454 static inline struct bio *bio_clone(struct bio *bio, gfp_t gfp_mask)
 455 {
 456         return bio_clone_bioset(bio, gfp_mask, fs_bio_set);
 457 }
 458
 459 static inline struct bio *bio_kmalloc(gfp_t gfp_mask, unsigned int nr_iovecs)
 460 {
 461         return bio_alloc_bioset(gfp_mask, nr_iovecs, NULL);
 462 }
 463
 464 static inline struct bio *bio_clone_kmalloc(struct bio *bio, gfp_t gfp_mask)
 465 {
 466         return bio_clone_bioset(bio, gfp_mask, NULL);
 467
 468 }
 469
 470 extern void bio_endio(struct bio *);
 471
 472 static inline void bio_io_error(struct bio *bio)
 473 {
 474         bio->bi_error = -EIO;
 475         bio_endio(bio);
 476 }
 477
 478 struct request_queue;
 479 extern int bio_phys_segments(struct request_queue *, struct bio *);
 480
 481 extern int submit_bio_wait(int rw, struct bio *bio);
 482 extern void bio_advance(struct bio *, unsigned);
 483
 484 extern void bio_init(struct bio *);
 485 extern void bio_reset(struct bio *);
 486 void bio_chain(struct bio *, struct bio *);
 487
 488 extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int);
 489 extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,
 490                            unsigned int, unsigned int);
 491 struct rq_map_data;
 492 extern struct bio *bio_map_user_iov(struct request_queue *,
 493                                     const struct iov_iter *, gfp_t);
 494 extern void bio_unmap_user(struct bio *);
 495 extern struct bio *bio_map_kern(struct request_queue *, void *, unsigned int,
 496                                 gfp_t);
 497 extern struct bio *bio_copy_kern(struct request_queue *, void *, unsigned int,
 498                                  gfp_t, int);
 499 extern void bio_set_pages_dirty(struct bio *bio);
 500 extern void bio_check_pages_dirty(struct bio *bio);
 501
 502 void generic_start_io_acct(int rw, unsigned long sectors,
 503                            struct hd_struct *part);
 504 void generic_end_io_acct(int rw, struct hd_struct *part,
 505                          unsigned long start_time);
 506
 507 #ifndef ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
 508 # error "You should define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE for your platform"
 509 #endif
 510 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
 511 extern void bio_flush_dcache_pages(struct bio *bi);
 512 #else
 513 static inline void bio_flush_dcache_pages(struct bio *bi)
 514 {
 515 }
 516 #endif
 517
 518 extern void bio_copy_data(struct bio *dst, struct bio *src);
 519 extern int bio_alloc_pages(struct bio *bio, gfp_t gfp);
 520
 521 extern struct bio *bio_copy_user_iov(struct request_queue *,
 522                                      struct rq_map_data *,
 523                                      const struct iov_iter *,
 524                                      gfp_t);
 525 extern int bio_uncopy_user(struct bio *);
 526 void zero_fill_bio(struct bio *bio);
 527 extern struct bio_vec *bvec_alloc(gfp_t, int, unsigned long *, mempool_t *);
 528 extern void bvec_free(mempool_t *, struct bio_vec *, unsigned int);
 529 extern unsigned int bvec_nr_vecs(unsigned short idx);
 530
 531 #ifdef CONFIG_BLK_CGROUP
 532 int bio_associate_blkcg(struct bio *bio, struct cgroup_subsys_state *blkcg_css);
 533 int bio_associate_current(struct bio *bio);
 534 void bio_disassociate_task(struct bio *bio);
 535 #else   /* CONFIG_BLK_CGROUP */
 536 static inline int bio_associate_blkcg(struct bio *bio,
 537                         struct cgroup_subsys_state *blkcg_css) { return 0; }
 538 static inline int bio_associate_current(struct bio *bio) { return -ENOENT; }
 539 static inline void bio_disassociate_task(struct bio *bio) { }
 540 #endif  /* CONFIG_BLK_CGROUP */
 541
 542 #ifdef CONFIG_HIGHMEM
 543 /*
 544  * remember never ever reenable interrupts between a bvec_kmap_irq and
 545  * bvec_kunmap_irq!
 546  */
 547 static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
 548 {
 549         unsigned long addr;
 550
 551         /*
 552          * might not be a highmem page, but the preempt/irq count
 553          * balancing is a lot nicer this way
 554          */
 555         local_irq_save(*flags);
 556         addr = (unsigned long) kmap_atomic(bvec->bv_page);
 557
 558         BUG_ON(addr & ~PAGE_MASK);
 559
 560         return (char *) addr + bvec->bv_offset;
 561 }
 562
 563 static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
 564 {
 565         unsigned long ptr = (unsigned long) buffer & PAGE_MASK;
 566
 567         kunmap_atomic((void *) ptr);
 568         local_irq_restore(*flags);
 569 }
 570
 571 #else
 572 static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
 573 {
 574         return page_address(bvec->bv_page) + bvec->bv_offset;
 575 }
 576
 577 static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
 578 {
 579         *flags = 0;
 580 }
 581 #endif
 582
 583 static inline char *__bio_kmap_irq(struct bio *bio, struct bvec_iter iter,
 584                                    unsigned long *flags)
 585 {
 586         return bvec_kmap_irq(&bio_iter_iovec(bio, iter), flags);
 587 }
 588 #define __bio_kunmap_irq(buf, flags)    bvec_kunmap_irq(buf, flags)
 589
 590 #define bio_kmap_irq(bio, flags) \
 591         __bio_kmap_irq((bio), (bio)->bi_iter, (flags))
 592 #define bio_kunmap_irq(buf,flags)       __bio_kunmap_irq(buf, flags)
 593
 594 /*
 595  * BIO list management for use by remapping drivers (e.g. DM or MD) and loop.
 596  *
 597  * A bio_list anchors a singly-linked list of bios chained through the bi_next
 598  * member of the bio.  The bio_list also caches the last list member to allow
 599  * fast access to the tail.
 600  */
 601 struct bio_list {
 602         struct bio *head;
 603         struct bio *tail;
 604 };
 605
 606 static inline int bio_list_empty(const struct bio_list *bl)
 607 {
 608         return bl->head == NULL;
 609 }
 610
 611 static inline void bio_list_init(struct bio_list *bl)
 612 {
 613         bl->head = bl->tail = NULL;
 614 }
 615
 616 #define BIO_EMPTY_LIST  { NULL, NULL }
 617
 618 #define bio_list_for_each(bio, bl) \
 619         for (bio = (bl)->head; bio; bio = bio->bi_next)
 620
 621 static inline unsigned bio_list_size(const struct bio_list *bl)
 622 {
 623         unsigned sz = 0;
 624         struct bio *bio;
 625
 626         bio_list_for_each(bio, bl)
 627                 sz++;
 628
 629         return sz;
 630 }
 631
 632 static inline void bio_list_add(struct bio_list *bl, struct bio *bio)
 633 {
 634         bio->bi_next = NULL;
 635
 636         if (bl->tail)
 637                 bl->tail->bi_next = bio;
 638         else
 639                 bl->head = bio;
 640
 641         bl->tail = bio;
 642 }
 643
 644 static inline void bio_list_add_head(struct bio_list *bl, struct bio *bio)
 645 {
 646         bio->bi_next = bl->head;
 647
 648         bl->head = bio;
 649
 650         if (!bl->tail)
 651                 bl->tail = bio;
 652 }
 653
 654 static inline void bio_list_merge(struct bio_list *bl, struct bio_list *bl2)
 655 {
 656         if (!bl2->head)
 657                 return;
 658
 659         if (bl->tail)
 660                 bl->tail->bi_next = bl2->head;
 661         else
 662                 bl->head = bl2->head;
 663
 664         bl->tail = bl2->tail;
 665 }
 666
 667 static inline void bio_list_merge_head(struct bio_list *bl,
 668                                        struct bio_list *bl2)
 669 {
 670         if (!bl2->head)
 671                 return;
 672
 673         if (bl->head)
 674                 bl2->tail->bi_next = bl->head;
 675         else
 676                 bl->tail = bl2->tail;
 677
 678         bl->head = bl2->head;
 679 }
 680
 681 static inline struct bio *bio_list_peek(struct bio_list *bl)
 682 {
 683         return bl->head;
 684 }
 685
 686 static inline struct bio *bio_list_pop(struct bio_list *bl)
 687 {
 688         struct bio *bio = bl->head;
 689
 690         if (bio) {
 691                 bl->head = bl->head->bi_next;
 692                 if (!bl->head)
 693                         bl->tail = NULL;
 694
 695                 bio->bi_next = NULL;
 696         }
 697
 698         return bio;
 699 }
 700
 701 static inline struct bio *bio_list_get(struct bio_list *bl)
 702 {
 703         struct bio *bio = bl->head;
 704
 705         bl->head = bl->tail = NULL;
 706
 707         return bio;
 708 }
 709
 710 /*
 711  * bio_set is used to allow other portions of the IO system to
 712  * allocate their own private memory pools for bio and iovec structures.
 713  * These memory pools in turn all allocate from the bio_slab
 714  * and the bvec_slabs[].
 715  */
 716 #define BIO_POOL_SIZE 2
 717 #define BIOVEC_NR_POOLS 6
 718 #define BIOVEC_MAX_IDX  (BIOVEC_NR_POOLS - 1)
 719
 720 struct bio_set {
 721         struct kmem_cache *bio_slab;
 722         unsigned int front_pad;
 723
 724         mempool_t *bio_pool;
 725         mempool_t *bvec_pool;
 726 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 727         mempool_t *bio_integrity_pool;
 728         mempool_t *bvec_integrity_pool;
 729 #endif
 730
 731         /*
 732          * Deadlock avoidance for stacking block drivers: see comments in
 733          * bio_alloc_bioset() for details
 734          */
 735         spinlock_t              rescue_lock;
 736         struct bio_list         rescue_list;
 737         struct work_struct      rescue_work;
 738         struct workqueue_struct *rescue_workqueue;
 739 };
 740
 741 struct biovec_slab {
 742         int nr_vecs;
 743         char *name;
 744         struct kmem_cache *slab;
 745 };
 746
 747 /*
 748  * a small number of entries is fine, not going to be performance critical.
 749  * basically we just need to survive
 750  */
 751 #define BIO_SPLIT_ENTRIES 2
 752
 753 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 754
 755 #define bip_for_each_vec(bvl, bip, iter)                                \
 756         for_each_bvec(bvl, (bip)->bip_vec, iter, (bip)->bip_iter)
 757
 758 #define bio_for_each_integrity_vec(_bvl, _bio, _iter)                   \
 759         for_each_bio(_bio)                                              \
 760                 bip_for_each_vec(_bvl, _bio->bi_integrity, _iter)
 761
 762 extern struct bio_integrity_payload *bio_integrity_alloc(struct bio *, gfp_t, unsigned int);
 763 extern void bio_integrity_free(struct bio *);
 764 extern int bio_integrity_add_page(struct bio *, struct page *, unsigned int, unsigned int);
 765 extern bool bio_integrity_enabled(struct bio *bio);
 766 extern int bio_integrity_prep(struct bio *);
 767 extern void bio_integrity_endio(struct bio *);
 768 extern void bio_integrity_advance(struct bio *, unsigned int);
 769 extern void bio_integrity_trim(struct bio *, unsigned int, unsigned int);
 770 extern int bio_integrity_clone(struct bio *, struct bio *, gfp_t);
 771 extern int bioset_integrity_create(struct bio_set *, int);
 772 extern void bioset_integrity_free(struct bio_set *);
 773 extern void bio_integrity_init(void);
 774
 775 #else /* CONFIG_BLK_DEV_INTEGRITY */
 776
 777 static inline void *bio_integrity(struct bio *bio)
 778 {
 779         return NULL;
 780 }
 781
 782 static inline bool bio_integrity_enabled(struct bio *bio)
 783 {
 784         return false;
 785 }
 786
 787 static inline int bioset_integrity_create(struct bio_set *bs, int pool_size)
 788 {
 789         return 0;
 790 }
 791
 792 static inline void bioset_integrity_free (struct bio_set *bs)
 793 {
 794         return;
 795 }
 796
 797 static inline int bio_integrity_prep(struct bio *bio)
 798 {
 799         return 0;
 800 }
 801
 802 static inline void bio_integrity_free(struct bio *bio)
 803 {
 804         return;
 805 }
 806
 807 static inline int bio_integrity_clone(struct bio *bio, struct bio *bio_src,
 808                                       gfp_t gfp_mask)
 809 {
 810         return 0;
 811 }
 812
 813 static inline void bio_integrity_advance(struct bio *bio,
 814                                          unsigned int bytes_done)
 815 {
 816         return;
 817 }
 818
 819 static inline void bio_integrity_trim(struct bio *bio, unsigned int offset,
 820                                       unsigned int sectors)
 821 {
 822         return;
 823 }
 824
 825 static inline void bio_integrity_init(void)
 826 {
 827         return;
 828 }
 829
 830 static inline bool bio_integrity_flagged(struct bio *bio, enum bip_flags flag)
 831 {
 832         return false;
 833 }
 834
 835 static inline void *bio_integrity_alloc(struct bio * bio, gfp_t gfp,
 836                                                                 unsigned int nr)
 837 {
 838         return ERR_PTR(-EINVAL);
 839 }
 840
 841 static inline int bio_integrity_add_page(struct bio *bio, struct page *page,
 842                                         unsigned int len, unsigned int offset)
 843 {
 844         return 0;
 845 }
 846
 847 #endif /* CONFIG_BLK_DEV_INTEGRITY */
 848
 849 #endif /* CONFIG_BLOCK */
 850 #endif /* __LINUX_BIO_H */