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  * Check if adding a bio_vec after bprv with offset would create a gap in
 191  * the SG list. Most drivers don't care about this, but some do.
 192  */
 193 static inline bool bvec_gap_to_prev(struct bio_vec *bprv, unsigned int offset)
 194 {
 195         return offset || ((bprv->bv_offset + bprv->bv_len) & (PAGE_SIZE - 1));
 196 }
 197
 198 #define bio_io_error(bio) bio_endio((bio), -EIO)
 199
 200 /*
 201  * drivers should _never_ use the all version - the bio may have been split
 202  * before it got to the driver and the driver won't own all of it
 203  */
 204 #define bio_for_each_segment_all(bvl, bio, i)                           \
 205         for (i = 0, bvl = (bio)->bi_io_vec; i < (bio)->bi_vcnt; i++, bvl++)
 206
 207 static inline void bvec_iter_advance(struct bio_vec *bv, struct bvec_iter *iter,
 208                                      unsigned bytes)
 209 {
 210         WARN_ONCE(bytes > iter->bi_size,
 211                   "Attempted to advance past end of bvec iter\n");
 212
 213         while (bytes) {
 214                 unsigned len = min(bytes, bvec_iter_len(bv, *iter));
 215
 216                 bytes -= len;
 217                 iter->bi_size -= len;
 218                 iter->bi_bvec_done += len;
 219
 220                 if (iter->bi_bvec_done == __bvec_iter_bvec(bv, *iter)->bv_len) {
 221                         iter->bi_bvec_done = 0;
 222                         iter->bi_idx++;
 223                 }
 224         }
 225 }
 226
 227 #define for_each_bvec(bvl, bio_vec, iter, start)                        \
 228         for (iter = (start);                                            \
 229              (iter).bi_size &&                                          \
 230                 ((bvl = bvec_iter_bvec((bio_vec), (iter))), 1); \
 231              bvec_iter_advance((bio_vec), &(iter), (bvl).bv_len))
 232
 233
 234 static inline void bio_advance_iter(struct bio *bio, struct bvec_iter *iter,
 235                                     unsigned bytes)
 236 {
 237         iter->bi_sector += bytes >> 9;
 238
 239         if (bio->bi_rw & BIO_NO_ADVANCE_ITER_MASK)
 240                 iter->bi_size -= bytes;
 241         else
 242                 bvec_iter_advance(bio->bi_io_vec, iter, bytes);
 243 }
 244
 245 #define __bio_for_each_segment(bvl, bio, iter, start)                   \
 246         for (iter = (start);                                            \
 247              (iter).bi_size &&                                          \
 248                 ((bvl = bio_iter_iovec((bio), (iter))), 1);             \
 249              bio_advance_iter((bio), &(iter), (bvl).bv_len))
 250
 251 #define bio_for_each_segment(bvl, bio, iter)                            \
 252         __bio_for_each_segment(bvl, bio, iter, (bio)->bi_iter)
 253
 254 #define bio_iter_last(bvec, iter) ((iter).bi_size == (bvec).bv_len)
 255
 256 static inline unsigned bio_segments(struct bio *bio)
 257 {
 258         unsigned segs = 0;
 259         struct bio_vec bv;
 260         struct bvec_iter iter;
 261
 262         /*
 263          * We special case discard/write same, because they interpret bi_size
 264          * differently:
 265          */
 266
 267         if (bio->bi_rw & REQ_DISCARD)
 268                 return 1;
 269
 270         if (bio->bi_rw & REQ_WRITE_SAME)
 271                 return 1;
 272
 273         bio_for_each_segment(bv, bio, iter)
 274                 segs++;
 275
 276         return segs;
 277 }
 278
 279 /*
 280  * get a reference to a bio, so it won't disappear. the intended use is
 281  * something like:
 282  *
 283  * bio_get(bio);
 284  * submit_bio(rw, bio);
 285  * if (bio->bi_flags ...)
 286  *      do_something
 287  * bio_put(bio);
 288  *
 289  * without the bio_get(), it could potentially complete I/O before submit_bio
 290  * returns. and then bio would be freed memory when if (bio->bi_flags ...)
 291  * runs
 292  */
 293 #define bio_get(bio)    atomic_inc(&(bio)->bi_cnt)
 294
 295 enum bip_flags {
 296         BIP_BLOCK_INTEGRITY     = 1 << 0, /* block layer owns integrity data */
 297         BIP_MAPPED_INTEGRITY    = 1 << 1, /* ref tag has been remapped */
 298         BIP_CTRL_NOCHECK        = 1 << 2, /* disable HBA integrity checking */
 299         BIP_DISK_NOCHECK        = 1 << 3, /* disable disk integrity checking */
 300         BIP_IP_CHECKSUM         = 1 << 4, /* IP checksum */
 301 };
 302
 303 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 304
 305 static inline struct bio_integrity_payload *bio_integrity(struct bio *bio)
 306 {
 307         if (bio->bi_rw & REQ_INTEGRITY)
 308                 return bio->bi_integrity;
 309
 310         return NULL;
 311 }
 312
 313 /*
 314  * bio integrity payload
 315  */
 316 struct bio_integrity_payload {
 317         struct bio              *bip_bio;       /* parent bio */
 318
 319         struct bvec_iter        bip_iter;
 320
 321         bio_end_io_t            *bip_end_io;    /* saved I/O completion fn */
 322
 323         unsigned short          bip_slab;       /* slab the bip came from */
 324         unsigned short          bip_vcnt;       /* # of integrity bio_vecs */
 325         unsigned short          bip_max_vcnt;   /* integrity bio_vec slots */
 326         unsigned short          bip_flags;      /* control flags */
 327
 328         struct work_struct      bip_work;       /* I/O completion */
 329
 330         struct bio_vec          *bip_vec;
 331         struct bio_vec          bip_inline_vecs[0];/* embedded bvec array */
 332 };
 333
 334 static inline bool bio_integrity_flagged(struct bio *bio, enum bip_flags flag)
 335 {
 336         struct bio_integrity_payload *bip = bio_integrity(bio);
 337
 338         if (bip)
 339                 return bip->bip_flags & flag;
 340
 341         return false;
 342 }
 343
 344 static inline sector_t bip_get_seed(struct bio_integrity_payload *bip)
 345 {
 346         return bip->bip_iter.bi_sector;
 347 }
 348
 349 static inline void bip_set_seed(struct bio_integrity_payload *bip,
 350                                 sector_t seed)
 351 {
 352         bip->bip_iter.bi_sector = seed;
 353 }
 354
 355 #endif /* CONFIG_BLK_DEV_INTEGRITY */
 356
 357 extern void bio_trim(struct bio *bio, int offset, int size);
 358 extern struct bio *bio_split(struct bio *bio, int sectors,
 359                              gfp_t gfp, struct bio_set *bs);
 360
 361 /**
 362  * bio_next_split - get next @sectors from a bio, splitting if necessary
 363  * @bio:        bio to split
 364  * @sectors:    number of sectors to split from the front of @bio
 365  * @gfp:        gfp mask
 366  * @bs:         bio set to allocate from
 367  *
 368  * Returns a bio representing the next @sectors of @bio - if the bio is smaller
 369  * than @sectors, returns the original bio unchanged.
 370  */
 371 static inline struct bio *bio_next_split(struct bio *bio, int sectors,
 372                                          gfp_t gfp, struct bio_set *bs)
 373 {
 374         if (sectors >= bio_sectors(bio))
 375                 return bio;
 376
 377         return bio_split(bio, sectors, gfp, bs);
 378 }
 379
 380 extern struct bio_set *bioset_create(unsigned int, unsigned int);
 381 extern struct bio_set *bioset_create_nobvec(unsigned int, unsigned int);
 382 extern void bioset_free(struct bio_set *);
 383 extern mempool_t *biovec_create_pool(int pool_entries);
 384
 385 extern struct bio *bio_alloc_bioset(gfp_t, int, struct bio_set *);
 386 extern void bio_put(struct bio *);
 387
 388 extern void __bio_clone_fast(struct bio *, struct bio *);
 389 extern struct bio *bio_clone_fast(struct bio *, gfp_t, struct bio_set *);
 390 extern struct bio *bio_clone_bioset(struct bio *, gfp_t, struct bio_set *bs);
 391
 392 extern struct bio_set *fs_bio_set;
 393
 394 static inline struct bio *bio_alloc(gfp_t gfp_mask, unsigned int nr_iovecs)
 395 {
 396         return bio_alloc_bioset(gfp_mask, nr_iovecs, fs_bio_set);
 397 }
 398
 399 static inline struct bio *bio_clone(struct bio *bio, gfp_t gfp_mask)
 400 {
 401         return bio_clone_bioset(bio, gfp_mask, fs_bio_set);
 402 }
 403
 404 static inline struct bio *bio_kmalloc(gfp_t gfp_mask, unsigned int nr_iovecs)
 405 {
 406         return bio_alloc_bioset(gfp_mask, nr_iovecs, NULL);
 407 }
 408
 409 static inline struct bio *bio_clone_kmalloc(struct bio *bio, gfp_t gfp_mask)
 410 {
 411         return bio_clone_bioset(bio, gfp_mask, NULL);
 412
 413 }
 414
 415 extern void bio_endio(struct bio *, int);
 416 extern void bio_endio_nodec(struct bio *, int);
 417 struct request_queue;
 418 extern int bio_phys_segments(struct request_queue *, struct bio *);
 419
 420 extern int submit_bio_wait(int rw, struct bio *bio);
 421 extern void bio_advance(struct bio *, unsigned);
 422
 423 extern void bio_init(struct bio *);
 424 extern void bio_reset(struct bio *);
 425 void bio_chain(struct bio *, struct bio *);
 426
 427 extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int);
 428 extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,
 429                            unsigned int, unsigned int);
 430 extern int bio_get_nr_vecs(struct block_device *);
 431 struct rq_map_data;
 432 extern struct bio *bio_map_user_iov(struct request_queue *,
 433                                     const struct iov_iter *, gfp_t);
 434 extern void bio_unmap_user(struct bio *);
 435 extern struct bio *bio_map_kern(struct request_queue *, void *, unsigned int,
 436                                 gfp_t);
 437 extern struct bio *bio_copy_kern(struct request_queue *, void *, unsigned int,
 438                                  gfp_t, int);
 439 extern void bio_set_pages_dirty(struct bio *bio);
 440 extern void bio_check_pages_dirty(struct bio *bio);
 441
 442 void generic_start_io_acct(int rw, unsigned long sectors,
 443                            struct hd_struct *part);
 444 void generic_end_io_acct(int rw, struct hd_struct *part,
 445                          unsigned long start_time);
 446
 447 #ifndef ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
 448 # error "You should define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE for your platform"
 449 #endif
 450 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
 451 extern void bio_flush_dcache_pages(struct bio *bi);
 452 #else
 453 static inline void bio_flush_dcache_pages(struct bio *bi)
 454 {
 455 }
 456 #endif
 457
 458 extern void bio_copy_data(struct bio *dst, struct bio *src);
 459 extern int bio_alloc_pages(struct bio *bio, gfp_t gfp);
 460
 461 extern struct bio *bio_copy_user_iov(struct request_queue *,
 462                                      struct rq_map_data *,
 463                                      const struct iov_iter *,
 464                                      gfp_t);
 465 extern int bio_uncopy_user(struct bio *);
 466 void zero_fill_bio(struct bio *bio);
 467 extern struct bio_vec *bvec_alloc(gfp_t, int, unsigned long *, mempool_t *);
 468 extern void bvec_free(mempool_t *, struct bio_vec *, unsigned int);
 469 extern unsigned int bvec_nr_vecs(unsigned short idx);
 470
 471 #ifdef CONFIG_BLK_CGROUP
 472 int bio_associate_current(struct bio *bio);
 473 void bio_disassociate_task(struct bio *bio);
 474 #else   /* CONFIG_BLK_CGROUP */
 475 static inline int bio_associate_current(struct bio *bio) { return -ENOENT; }
 476 static inline void bio_disassociate_task(struct bio *bio) { }
 477 #endif  /* CONFIG_BLK_CGROUP */
 478
 479 #ifdef CONFIG_HIGHMEM
 480 /*
 481  * remember never ever reenable interrupts between a bvec_kmap_irq and
 482  * bvec_kunmap_irq!
 483  */
 484 static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
 485 {
 486         unsigned long addr;
 487
 488         /*
 489          * might not be a highmem page, but the preempt/irq count
 490          * balancing is a lot nicer this way
 491          */
 492         local_irq_save(*flags);
 493         addr = (unsigned long) kmap_atomic(bvec->bv_page);
 494
 495         BUG_ON(addr & ~PAGE_MASK);
 496
 497         return (char *) addr + bvec->bv_offset;
 498 }
 499
 500 static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
 501 {
 502         unsigned long ptr = (unsigned long) buffer & PAGE_MASK;
 503
 504         kunmap_atomic((void *) ptr);
 505         local_irq_restore(*flags);
 506 }
 507
 508 #else
 509 static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
 510 {
 511         return page_address(bvec->bv_page) + bvec->bv_offset;
 512 }
 513
 514 static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
 515 {
 516         *flags = 0;
 517 }
 518 #endif
 519
 520 static inline char *__bio_kmap_irq(struct bio *bio, struct bvec_iter iter,
 521                                    unsigned long *flags)
 522 {
 523         return bvec_kmap_irq(&bio_iter_iovec(bio, iter), flags);
 524 }
 525 #define __bio_kunmap_irq(buf, flags)    bvec_kunmap_irq(buf, flags)
 526
 527 #define bio_kmap_irq(bio, flags) \
 528         __bio_kmap_irq((bio), (bio)->bi_iter, (flags))
 529 #define bio_kunmap_irq(buf,flags)       __bio_kunmap_irq(buf, flags)
 530
 531 /*
 532  * BIO list management for use by remapping drivers (e.g. DM or MD) and loop.
 533  *
 534  * A bio_list anchors a singly-linked list of bios chained through the bi_next
 535  * member of the bio.  The bio_list also caches the last list member to allow
 536  * fast access to the tail.
 537  */
 538 struct bio_list {
 539         struct bio *head;
 540         struct bio *tail;
 541 };
 542
 543 static inline int bio_list_empty(const struct bio_list *bl)
 544 {
 545         return bl->head == NULL;
 546 }
 547
 548 static inline void bio_list_init(struct bio_list *bl)
 549 {
 550         bl->head = bl->tail = NULL;
 551 }
 552
 553 #define BIO_EMPTY_LIST  { NULL, NULL }
 554
 555 #define bio_list_for_each(bio, bl) \
 556         for (bio = (bl)->head; bio; bio = bio->bi_next)
 557
 558 static inline unsigned bio_list_size(const struct bio_list *bl)
 559 {
 560         unsigned sz = 0;
 561         struct bio *bio;
 562
 563         bio_list_for_each(bio, bl)
 564                 sz++;
 565
 566         return sz;
 567 }
 568
 569 static inline void bio_list_add(struct bio_list *bl, struct bio *bio)
 570 {
 571         bio->bi_next = NULL;
 572
 573         if (bl->tail)
 574                 bl->tail->bi_next = bio;
 575         else
 576                 bl->head = bio;
 577
 578         bl->tail = bio;
 579 }
 580
 581 static inline void bio_list_add_head(struct bio_list *bl, struct bio *bio)
 582 {
 583         bio->bi_next = bl->head;
 584
 585         bl->head = bio;
 586
 587         if (!bl->tail)
 588                 bl->tail = bio;
 589 }
 590
 591 static inline void bio_list_merge(struct bio_list *bl, struct bio_list *bl2)
 592 {
 593         if (!bl2->head)
 594                 return;
 595
 596         if (bl->tail)
 597                 bl->tail->bi_next = bl2->head;
 598         else
 599                 bl->head = bl2->head;
 600
 601         bl->tail = bl2->tail;
 602 }
 603
 604 static inline void bio_list_merge_head(struct bio_list *bl,
 605                                        struct bio_list *bl2)
 606 {
 607         if (!bl2->head)
 608                 return;
 609
 610         if (bl->head)
 611                 bl2->tail->bi_next = bl->head;
 612         else
 613                 bl->tail = bl2->tail;
 614
 615         bl->head = bl2->head;
 616 }
 617
 618 static inline struct bio *bio_list_peek(struct bio_list *bl)
 619 {
 620         return bl->head;
 621 }
 622
 623 static inline struct bio *bio_list_pop(struct bio_list *bl)
 624 {
 625         struct bio *bio = bl->head;
 626
 627         if (bio) {
 628                 bl->head = bl->head->bi_next;
 629                 if (!bl->head)
 630                         bl->tail = NULL;
 631
 632                 bio->bi_next = NULL;
 633         }
 634
 635         return bio;
 636 }
 637
 638 static inline struct bio *bio_list_get(struct bio_list *bl)
 639 {
 640         struct bio *bio = bl->head;
 641
 642         bl->head = bl->tail = NULL;
 643
 644         return bio;
 645 }
 646
 647 /*
 648  * bio_set is used to allow other portions of the IO system to
 649  * allocate their own private memory pools for bio and iovec structures.
 650  * These memory pools in turn all allocate from the bio_slab
 651  * and the bvec_slabs[].
 652  */
 653 #define BIO_POOL_SIZE 2
 654 #define BIOVEC_NR_POOLS 6
 655 #define BIOVEC_MAX_IDX  (BIOVEC_NR_POOLS - 1)
 656
 657 struct bio_set {
 658         struct kmem_cache *bio_slab;
 659         unsigned int front_pad;
 660
 661         mempool_t *bio_pool;
 662         mempool_t *bvec_pool;
 663 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 664         mempool_t *bio_integrity_pool;
 665         mempool_t *bvec_integrity_pool;
 666 #endif
 667
 668         /*
 669          * Deadlock avoidance for stacking block drivers: see comments in
 670          * bio_alloc_bioset() for details
 671          */
 672         spinlock_t              rescue_lock;
 673         struct bio_list         rescue_list;
 674         struct work_struct      rescue_work;
 675         struct workqueue_struct *rescue_workqueue;
 676 };
 677
 678 struct biovec_slab {
 679         int nr_vecs;
 680         char *name;
 681         struct kmem_cache *slab;
 682 };
 683
 684 /*
 685  * a small number of entries is fine, not going to be performance critical.
 686  * basically we just need to survive
 687  */
 688 #define BIO_SPLIT_ENTRIES 2
 689
 690 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 691
 692 #define bip_for_each_vec(bvl, bip, iter)                                \
 693         for_each_bvec(bvl, (bip)->bip_vec, iter, (bip)->bip_iter)
 694
 695 #define bio_for_each_integrity_vec(_bvl, _bio, _iter)                   \
 696         for_each_bio(_bio)                                              \
 697                 bip_for_each_vec(_bvl, _bio->bi_integrity, _iter)
 698
 699 extern struct bio_integrity_payload *bio_integrity_alloc(struct bio *, gfp_t, unsigned int);
 700 extern void bio_integrity_free(struct bio *);
 701 extern int bio_integrity_add_page(struct bio *, struct page *, unsigned int, unsigned int);
 702 extern bool bio_integrity_enabled(struct bio *bio);
 703 extern int bio_integrity_prep(struct bio *);
 704 extern void bio_integrity_endio(struct bio *, int);
 705 extern void bio_integrity_advance(struct bio *, unsigned int);
 706 extern void bio_integrity_trim(struct bio *, unsigned int, unsigned int);
 707 extern int bio_integrity_clone(struct bio *, struct bio *, gfp_t);
 708 extern int bioset_integrity_create(struct bio_set *, int);
 709 extern void bioset_integrity_free(struct bio_set *);
 710 extern void bio_integrity_init(void);
 711
 712 #else /* CONFIG_BLK_DEV_INTEGRITY */
 713
 714 static inline void *bio_integrity(struct bio *bio)
 715 {
 716         return NULL;
 717 }
 718
 719 static inline bool bio_integrity_enabled(struct bio *bio)
 720 {
 721         return false;
 722 }
 723
 724 static inline int bioset_integrity_create(struct bio_set *bs, int pool_size)
 725 {
 726         return 0;
 727 }
 728
 729 static inline void bioset_integrity_free (struct bio_set *bs)
 730 {
 731         return;
 732 }
 733
 734 static inline int bio_integrity_prep(struct bio *bio)
 735 {
 736         return 0;
 737 }
 738
 739 static inline void bio_integrity_free(struct bio *bio)
 740 {
 741         return;
 742 }
 743
 744 static inline int bio_integrity_clone(struct bio *bio, struct bio *bio_src,
 745                                       gfp_t gfp_mask)
 746 {
 747         return 0;
 748 }
 749
 750 static inline void bio_integrity_advance(struct bio *bio,
 751                                          unsigned int bytes_done)
 752 {
 753         return;
 754 }
 755
 756 static inline void bio_integrity_trim(struct bio *bio, unsigned int offset,
 757                                       unsigned int sectors)
 758 {
 759         return;
 760 }
 761
 762 static inline void bio_integrity_init(void)
 763 {
 764         return;
 765 }
 766
 767 static inline bool bio_integrity_flagged(struct bio *bio, enum bip_flags flag)
 768 {
 769         return false;
 770 }
 771
 772 #endif /* CONFIG_BLK_DEV_INTEGRITY */
 773
 774 #endif /* CONFIG_BLOCK */
 775 #endif /* __LINUX_BIO_H */