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 #ifdef CONFIG_THP_SWAP
  42 #if HPAGE_PMD_NR > 256
  43 #define BIO_MAX_PAGES           HPAGE_PMD_NR
  44 #else
  45 #define BIO_MAX_PAGES           256
  46 #endif
  47 #else
  48 #define BIO_MAX_PAGES           256
  49 #endif
  50
  51 #define bio_prio(bio)                   (bio)->bi_ioprio
  52 #define bio_set_prio(bio, prio)         ((bio)->bi_ioprio = prio)
  53
  54 #define bio_iter_iovec(bio, iter)                               \
  55         bvec_iter_bvec((bio)->bi_io_vec, (iter))
  56
  57 #define bio_iter_page(bio, iter)                                \
  58         bvec_iter_page((bio)->bi_io_vec, (iter))
  59 #define bio_iter_len(bio, iter)                                 \
  60         bvec_iter_len((bio)->bi_io_vec, (iter))
  61 #define bio_iter_offset(bio, iter)                              \
  62         bvec_iter_offset((bio)->bi_io_vec, (iter))
  63
  64 #define bio_page(bio)           bio_iter_page((bio), (bio)->bi_iter)
  65 #define bio_offset(bio)         bio_iter_offset((bio), (bio)->bi_iter)
  66 #define bio_iovec(bio)          bio_iter_iovec((bio), (bio)->bi_iter)
  67
  68 #define bio_multiple_segments(bio)                              \
  69         ((bio)->bi_iter.bi_size != bio_iovec(bio).bv_len)
  70
  71 #define bvec_iter_sectors(iter) ((iter).bi_size >> 9)
  72 #define bvec_iter_end_sector(iter) ((iter).bi_sector + bvec_iter_sectors((iter)))
  73
  74 #define bio_sectors(bio)        bvec_iter_sectors((bio)->bi_iter)
  75 #define bio_end_sector(bio)     bvec_iter_end_sector((bio)->bi_iter)
  76
  77 /*
  78  * Return the data direction, READ or WRITE.
  79  */
  80 #define bio_data_dir(bio) \
  81         (op_is_write(bio_op(bio)) ? WRITE : READ)
  82
  83 /*
  84  * Check whether this bio carries any data or not. A NULL bio is allowed.
  85  */
  86 static inline bool bio_has_data(struct bio *bio)
  87 {
  88         if (bio &&
  89             bio->bi_iter.bi_size &&
  90             bio_op(bio) != REQ_OP_DISCARD &&
  91             bio_op(bio) != REQ_OP_SECURE_ERASE &&
  92             bio_op(bio) != REQ_OP_WRITE_ZEROES)
  93                 return true;
  94
  95         return false;
  96 }
  97
  98 static inline bool bio_no_advance_iter(struct bio *bio)
  99 {
 100         return bio_op(bio) == REQ_OP_DISCARD ||
 101                bio_op(bio) == REQ_OP_SECURE_ERASE ||
 102                bio_op(bio) == REQ_OP_WRITE_SAME ||
 103                bio_op(bio) == REQ_OP_WRITE_ZEROES;
 104 }
 105
 106 static inline bool bio_mergeable(struct bio *bio)
 107 {
 108         if (bio->bi_opf & REQ_NOMERGE_FLAGS)
 109                 return false;
 110
 111         return true;
 112 }
 113
 114 static inline unsigned int bio_cur_bytes(struct bio *bio)
 115 {
 116         if (bio_has_data(bio))
 117                 return bio_iovec(bio).bv_len;
 118         else /* dataless requests such as discard */
 119                 return bio->bi_iter.bi_size;
 120 }
 121
 122 static inline void *bio_data(struct bio *bio)
 123 {
 124         if (bio_has_data(bio))
 125                 return page_address(bio_page(bio)) + bio_offset(bio);
 126
 127         return NULL;
 128 }
 129
 130 static inline bool bio_full(struct bio *bio)
 131 {
 132         return bio->bi_vcnt >= bio->bi_max_vecs;
 133 }
 134
 135 /*
 136  * will die
 137  */
 138 #define bvec_to_phys(bv)        (page_to_phys((bv)->bv_page) + (unsigned long) (bv)->bv_offset)
 139
 140 /*
 141  * merge helpers etc
 142  */
 143
 144 /* Default implementation of BIOVEC_PHYS_MERGEABLE */
 145 #define __BIOVEC_PHYS_MERGEABLE(vec1, vec2)     \
 146         ((bvec_to_phys((vec1)) + (vec1)->bv_len) == bvec_to_phys((vec2)))
 147
 148 /*
 149  * allow arch override, for eg virtualized architectures (put in asm/io.h)
 150  */
 151 #ifndef BIOVEC_PHYS_MERGEABLE
 152 #define BIOVEC_PHYS_MERGEABLE(vec1, vec2)       \
 153         __BIOVEC_PHYS_MERGEABLE(vec1, vec2)
 154 #endif
 155
 156 #define __BIO_SEG_BOUNDARY(addr1, addr2, mask) \
 157         (((addr1) | (mask)) == (((addr2) - 1) | (mask)))
 158 #define BIOVEC_SEG_BOUNDARY(q, b1, b2) \
 159         __BIO_SEG_BOUNDARY(bvec_to_phys((b1)), bvec_to_phys((b2)) + (b2)->bv_len, queue_segment_boundary((q)))
 160
 161 /*
 162  * drivers should _never_ use the all version - the bio may have been split
 163  * before it got to the driver and the driver won't own all of it
 164  */
 165 #define bio_for_each_segment_all(bvl, bio, i)                           \
 166         for (i = 0, bvl = (bio)->bi_io_vec; i < (bio)->bi_vcnt; i++, bvl++)
 167
 168 static inline void bio_advance_iter(struct bio *bio, struct bvec_iter *iter,
 169                                     unsigned bytes)
 170 {
 171         iter->bi_sector += bytes >> 9;
 172
 173         if (bio_no_advance_iter(bio)) {
 174                 iter->bi_size -= bytes;
 175                 iter->bi_done += bytes;
 176         } else {
 177                 bvec_iter_advance(bio->bi_io_vec, iter, bytes);
 178                 /* TODO: It is reasonable to complete bio with error here. */
 179         }
 180 }
 181
 182 static inline bool bio_rewind_iter(struct bio *bio, struct bvec_iter *iter,
 183                 unsigned int bytes)
 184 {
 185         iter->bi_sector -= bytes >> 9;
 186
 187         if (bio_no_advance_iter(bio)) {
 188                 iter->bi_size += bytes;
 189                 iter->bi_done -= bytes;
 190                 return true;
 191         }
 192
 193         return bvec_iter_rewind(bio->bi_io_vec, iter, bytes);
 194 }
 195
 196 #define __bio_for_each_segment(bvl, bio, iter, start)                   \
 197         for (iter = (start);                                            \
 198              (iter).bi_size &&                                          \
 199                 ((bvl = bio_iter_iovec((bio), (iter))), 1);             \
 200              bio_advance_iter((bio), &(iter), (bvl).bv_len))
 201
 202 #define bio_for_each_segment(bvl, bio, iter)                            \
 203         __bio_for_each_segment(bvl, bio, iter, (bio)->bi_iter)
 204
 205 #define bio_iter_last(bvec, iter) ((iter).bi_size == (bvec).bv_len)
 206
 207 static inline unsigned bio_segments(struct bio *bio)
 208 {
 209         unsigned segs = 0;
 210         struct bio_vec bv;
 211         struct bvec_iter iter;
 212
 213         /*
 214          * We special case discard/write same/write zeroes, because they
 215          * interpret bi_size differently:
 216          */
 217
 218         switch (bio_op(bio)) {
 219         case REQ_OP_DISCARD:
 220         case REQ_OP_SECURE_ERASE:
 221         case REQ_OP_WRITE_ZEROES:
 222                 return 0;
 223         case REQ_OP_WRITE_SAME:
 224                 return 1;
 225         default:
 226                 break;
 227         }
 228
 229         bio_for_each_segment(bv, bio, iter)
 230                 segs++;
 231
 232         return segs;
 233 }
 234
 235 /*
 236  * get a reference to a bio, so it won't disappear. the intended use is
 237  * something like:
 238  *
 239  * bio_get(bio);
 240  * submit_bio(rw, bio);
 241  * if (bio->bi_flags ...)
 242  *      do_something
 243  * bio_put(bio);
 244  *
 245  * without the bio_get(), it could potentially complete I/O before submit_bio
 246  * returns. and then bio would be freed memory when if (bio->bi_flags ...)
 247  * runs
 248  */
 249 static inline void bio_get(struct bio *bio)
 250 {
 251         bio->bi_flags |= (1 << BIO_REFFED);
 252         smp_mb__before_atomic();
 253         atomic_inc(&bio->__bi_cnt);
 254 }
 255
 256 static inline void bio_cnt_set(struct bio *bio, unsigned int count)
 257 {
 258         if (count != 1) {
 259                 bio->bi_flags |= (1 << BIO_REFFED);
 260                 smp_mb__before_atomic();
 261         }
 262         atomic_set(&bio->__bi_cnt, count);
 263 }
 264
 265 static inline bool bio_flagged(struct bio *bio, unsigned int bit)
 266 {
 267         return (bio->bi_flags & (1U << bit)) != 0;
 268 }
 269
 270 static inline void bio_set_flag(struct bio *bio, unsigned int bit)
 271 {
 272         bio->bi_flags |= (1U << bit);
 273 }
 274
 275 static inline void bio_clear_flag(struct bio *bio, unsigned int bit)
 276 {
 277         bio->bi_flags &= ~(1U << bit);
 278 }
 279
 280 static inline void bio_get_first_bvec(struct bio *bio, struct bio_vec *bv)
 281 {
 282         *bv = bio_iovec(bio);
 283 }
 284
 285 static inline void bio_get_last_bvec(struct bio *bio, struct bio_vec *bv)
 286 {
 287         struct bvec_iter iter = bio->bi_iter;
 288         int idx;
 289
 290         if (unlikely(!bio_multiple_segments(bio))) {
 291                 *bv = bio_iovec(bio);
 292                 return;
 293         }
 294
 295         bio_advance_iter(bio, &iter, iter.bi_size);
 296
 297         if (!iter.bi_bvec_done)
 298                 idx = iter.bi_idx - 1;
 299         else    /* in the middle of bvec */
 300                 idx = iter.bi_idx;
 301
 302         *bv = bio->bi_io_vec[idx];
 303
 304         /*
 305          * iter.bi_bvec_done records actual length of the last bvec
 306          * if this bio ends in the middle of one io vector
 307          */
 308         if (iter.bi_bvec_done)
 309                 bv->bv_len = iter.bi_bvec_done;
 310 }
 311
 312 static inline unsigned bio_pages_all(struct bio *bio)
 313 {
 314         WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED));
 315         return bio->bi_vcnt;
 316 }
 317
 318 static inline struct bio_vec *bio_first_bvec_all(struct bio *bio)
 319 {
 320         WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED));
 321         return bio->bi_io_vec;
 322 }
 323
 324 static inline struct page *bio_first_page_all(struct bio *bio)
 325 {
 326         return bio_first_bvec_all(bio)->bv_page;
 327 }
 328
 329 static inline struct bio_vec *bio_last_bvec_all(struct bio *bio)
 330 {
 331         WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED));
 332         return &bio->bi_io_vec[bio->bi_vcnt - 1];
 333 }
 334
 335 enum bip_flags {
 336         BIP_BLOCK_INTEGRITY     = 1 << 0, /* block layer owns integrity data */
 337         BIP_MAPPED_INTEGRITY    = 1 << 1, /* ref tag has been remapped */
 338         BIP_CTRL_NOCHECK        = 1 << 2, /* disable HBA integrity checking */
 339         BIP_DISK_NOCHECK        = 1 << 3, /* disable disk integrity checking */
 340         BIP_IP_CHECKSUM         = 1 << 4, /* IP checksum */
 341 };
 342
 343 /*
 344  * bio integrity payload
 345  */
 346 struct bio_integrity_payload {
 347         struct bio              *bip_bio;       /* parent bio */
 348
 349         struct bvec_iter        bip_iter;
 350
 351         unsigned short          bip_slab;       /* slab the bip came from */
 352         unsigned short          bip_vcnt;       /* # of integrity bio_vecs */
 353         unsigned short          bip_max_vcnt;   /* integrity bio_vec slots */
 354         unsigned short          bip_flags;      /* control flags */
 355
 356         struct work_struct      bip_work;       /* I/O completion */
 357
 358         struct bio_vec          *bip_vec;
 359         struct bio_vec          bip_inline_vecs[0];/* embedded bvec array */
 360 };
 361
 362 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 363
 364 static inline struct bio_integrity_payload *bio_integrity(struct bio *bio)
 365 {
 366         if (bio->bi_opf & REQ_INTEGRITY)
 367                 return bio->bi_integrity;
 368
 369         return NULL;
 370 }
 371
 372 static inline bool bio_integrity_flagged(struct bio *bio, enum bip_flags flag)
 373 {
 374         struct bio_integrity_payload *bip = bio_integrity(bio);
 375
 376         if (bip)
 377                 return bip->bip_flags & flag;
 378
 379         return false;
 380 }
 381
 382 static inline sector_t bip_get_seed(struct bio_integrity_payload *bip)
 383 {
 384         return bip->bip_iter.bi_sector;
 385 }
 386
 387 static inline void bip_set_seed(struct bio_integrity_payload *bip,
 388                                 sector_t seed)
 389 {
 390         bip->bip_iter.bi_sector = seed;
 391 }
 392
 393 #endif /* CONFIG_BLK_DEV_INTEGRITY */
 394
 395 extern void bio_trim(struct bio *bio, int offset, int size);
 396 extern struct bio *bio_split(struct bio *bio, int sectors,
 397                              gfp_t gfp, struct bio_set *bs);
 398
 399 /**
 400  * bio_next_split - get next @sectors from a bio, splitting if necessary
 401  * @bio:        bio to split
 402  * @sectors:    number of sectors to split from the front of @bio
 403  * @gfp:        gfp mask
 404  * @bs:         bio set to allocate from
 405  *
 406  * Returns a bio representing the next @sectors of @bio - if the bio is smaller
 407  * than @sectors, returns the original bio unchanged.
 408  */
 409 static inline struct bio *bio_next_split(struct bio *bio, int sectors,
 410                                          gfp_t gfp, struct bio_set *bs)
 411 {
 412         if (sectors >= bio_sectors(bio))
 413                 return bio;
 414
 415         return bio_split(bio, sectors, gfp, bs);
 416 }
 417
 418 enum {
 419         BIOSET_NEED_BVECS = BIT(0),
 420         BIOSET_NEED_RESCUER = BIT(1),
 421 };
 422 extern int bioset_init(struct bio_set *, unsigned int, unsigned int, int flags);
 423 extern void bioset_exit(struct bio_set *);
 424 extern int biovec_init_pool(mempool_t *pool, int pool_entries);
 425 extern int bioset_init_from_src(struct bio_set *bs, struct bio_set *src);
 426
 427 extern struct bio *bio_alloc_bioset(gfp_t, unsigned int, struct bio_set *);
 428 extern void bio_put(struct bio *);
 429
 430 extern void __bio_clone_fast(struct bio *, struct bio *);
 431 extern struct bio *bio_clone_fast(struct bio *, gfp_t, struct bio_set *);
 432 extern struct bio *bio_clone_bioset(struct bio *, gfp_t, struct bio_set *bs);
 433
 434 extern struct bio_set fs_bio_set;
 435
 436 static inline struct bio *bio_alloc(gfp_t gfp_mask, unsigned int nr_iovecs)
 437 {
 438         return bio_alloc_bioset(gfp_mask, nr_iovecs, &fs_bio_set);
 439 }
 440
 441 static inline struct bio *bio_kmalloc(gfp_t gfp_mask, unsigned int nr_iovecs)
 442 {
 443         return bio_alloc_bioset(gfp_mask, nr_iovecs, NULL);
 444 }
 445
 446 static inline struct bio *bio_clone_kmalloc(struct bio *bio, gfp_t gfp_mask)
 447 {
 448         return bio_clone_bioset(bio, gfp_mask, NULL);
 449
 450 }
 451
 452 extern blk_qc_t submit_bio(struct bio *);
 453
 454 extern void bio_endio(struct bio *);
 455
 456 static inline void bio_io_error(struct bio *bio)
 457 {
 458         bio->bi_status = BLK_STS_IOERR;
 459         bio_endio(bio);
 460 }
 461
 462 static inline void bio_wouldblock_error(struct bio *bio)
 463 {
 464         bio->bi_status = BLK_STS_AGAIN;
 465         bio_endio(bio);
 466 }
 467
 468 struct request_queue;
 469 extern int bio_phys_segments(struct request_queue *, struct bio *);
 470
 471 extern int submit_bio_wait(struct bio *bio);
 472 extern void bio_advance(struct bio *, unsigned);
 473
 474 extern void bio_init(struct bio *bio, struct bio_vec *table,
 475                      unsigned short max_vecs);
 476 extern void bio_uninit(struct bio *);
 477 extern void bio_reset(struct bio *);
 478 void bio_chain(struct bio *, struct bio *);
 479
 480 extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int);
 481 extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,
 482                            unsigned int, unsigned int);
 483 bool __bio_try_merge_page(struct bio *bio, struct page *page,
 484                 unsigned int len, unsigned int off);
 485 void __bio_add_page(struct bio *bio, struct page *page,
 486                 unsigned int len, unsigned int off);
 487 int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter);
 488 struct rq_map_data;
 489 extern struct bio *bio_map_user_iov(struct request_queue *,
 490                                     struct iov_iter *, gfp_t);
 491 extern void bio_unmap_user(struct bio *);
 492 extern struct bio *bio_map_kern(struct request_queue *, void *, unsigned int,
 493                                 gfp_t);
 494 extern struct bio *bio_copy_kern(struct request_queue *, void *, unsigned int,
 495                                  gfp_t, int);
 496 extern void bio_set_pages_dirty(struct bio *bio);
 497 extern void bio_check_pages_dirty(struct bio *bio);
 498
 499 void generic_start_io_acct(struct request_queue *q, int rw,
 500                                 unsigned long sectors, struct hd_struct *part);
 501 void generic_end_io_acct(struct request_queue *q, int rw,
 502                                 struct hd_struct *part,
 503                                 unsigned long start_time);
 504
 505 #ifndef ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
 506 # error "You should define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE for your platform"
 507 #endif
 508 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
 509 extern void bio_flush_dcache_pages(struct bio *bi);
 510 #else
 511 static inline void bio_flush_dcache_pages(struct bio *bi)
 512 {
 513 }
 514 #endif
 515
 516 extern void bio_copy_data_iter(struct bio *dst, struct bvec_iter *dst_iter,
 517                                struct bio *src, struct bvec_iter *src_iter);
 518 extern void bio_copy_data(struct bio *dst, struct bio *src);
 519 extern void bio_list_copy_data(struct bio *dst, struct bio *src);
 520 extern void bio_free_pages(struct bio *bio);
 521
 522 extern struct bio *bio_copy_user_iov(struct request_queue *,
 523                                      struct rq_map_data *,
 524                                      struct iov_iter *,
 525                                      gfp_t);
 526 extern int bio_uncopy_user(struct bio *);
 527 void zero_fill_bio_iter(struct bio *bio, struct bvec_iter iter);
 528
 529 static inline void zero_fill_bio(struct bio *bio)
 530 {
 531         zero_fill_bio_iter(bio, bio->bi_iter);
 532 }
 533
 534 extern struct bio_vec *bvec_alloc(gfp_t, int, unsigned long *, mempool_t *);
 535 extern void bvec_free(mempool_t *, struct bio_vec *, unsigned int);
 536 extern unsigned int bvec_nr_vecs(unsigned short idx);
 537 extern const char *bio_devname(struct bio *bio, char *buffer);
 538
 539 #define bio_set_dev(bio, bdev)                  \
 540 do {                                            \
 541         if ((bio)->bi_disk != (bdev)->bd_disk)  \
 542                 bio_clear_flag(bio, BIO_THROTTLED);\
 543         (bio)->bi_disk = (bdev)->bd_disk;       \
 544         (bio)->bi_partno = (bdev)->bd_partno;   \
 545 } while (0)
 546
 547 #define bio_copy_dev(dst, src)                  \
 548 do {                                            \
 549         (dst)->bi_disk = (src)->bi_disk;        \
 550         (dst)->bi_partno = (src)->bi_partno;    \
 551 } while (0)
 552
 553 #define bio_dev(bio) \
 554         disk_devt((bio)->bi_disk)
 555
 556 #ifdef CONFIG_BLK_CGROUP
 557 int bio_associate_blkcg(struct bio *bio, struct cgroup_subsys_state *blkcg_css);
 558 void bio_disassociate_task(struct bio *bio);
 559 void bio_clone_blkcg_association(struct bio *dst, struct bio *src);
 560 #else   /* CONFIG_BLK_CGROUP */
 561 static inline int bio_associate_blkcg(struct bio *bio,
 562                         struct cgroup_subsys_state *blkcg_css) { return 0; }
 563 static inline void bio_disassociate_task(struct bio *bio) { }
 564 static inline void bio_clone_blkcg_association(struct bio *dst,
 565                         struct bio *src) { }
 566 #endif  /* CONFIG_BLK_CGROUP */
 567
 568 #ifdef CONFIG_HIGHMEM
 569 /*
 570  * remember never ever reenable interrupts between a bvec_kmap_irq and
 571  * bvec_kunmap_irq!
 572  */
 573 static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
 574 {
 575         unsigned long addr;
 576
 577         /*
 578          * might not be a highmem page, but the preempt/irq count
 579          * balancing is a lot nicer this way
 580          */
 581         local_irq_save(*flags);
 582         addr = (unsigned long) kmap_atomic(bvec->bv_page);
 583
 584         BUG_ON(addr & ~PAGE_MASK);
 585
 586         return (char *) addr + bvec->bv_offset;
 587 }
 588
 589 static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
 590 {
 591         unsigned long ptr = (unsigned long) buffer & PAGE_MASK;
 592
 593         kunmap_atomic((void *) ptr);
 594         local_irq_restore(*flags);
 595 }
 596
 597 #else
 598 static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
 599 {
 600         return page_address(bvec->bv_page) + bvec->bv_offset;
 601 }
 602
 603 static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
 604 {
 605         *flags = 0;
 606 }
 607 #endif
 608
 609 /*
 610  * BIO list management for use by remapping drivers (e.g. DM or MD) and loop.
 611  *
 612  * A bio_list anchors a singly-linked list of bios chained through the bi_next
 613  * member of the bio.  The bio_list also caches the last list member to allow
 614  * fast access to the tail.
 615  */
 616 struct bio_list {
 617         struct bio *head;
 618         struct bio *tail;
 619 };
 620
 621 static inline int bio_list_empty(const struct bio_list *bl)
 622 {
 623         return bl->head == NULL;
 624 }
 625
 626 static inline void bio_list_init(struct bio_list *bl)
 627 {
 628         bl->head = bl->tail = NULL;
 629 }
 630
 631 #define BIO_EMPTY_LIST  { NULL, NULL }
 632
 633 #define bio_list_for_each(bio, bl) \
 634         for (bio = (bl)->head; bio; bio = bio->bi_next)
 635
 636 static inline unsigned bio_list_size(const struct bio_list *bl)
 637 {
 638         unsigned sz = 0;
 639         struct bio *bio;
 640
 641         bio_list_for_each(bio, bl)
 642                 sz++;
 643
 644         return sz;
 645 }
 646
 647 static inline void bio_list_add(struct bio_list *bl, struct bio *bio)
 648 {
 649         bio->bi_next = NULL;
 650
 651         if (bl->tail)
 652                 bl->tail->bi_next = bio;
 653         else
 654                 bl->head = bio;
 655
 656         bl->tail = bio;
 657 }
 658
 659 static inline void bio_list_add_head(struct bio_list *bl, struct bio *bio)
 660 {
 661         bio->bi_next = bl->head;
 662
 663         bl->head = bio;
 664
 665         if (!bl->tail)
 666                 bl->tail = bio;
 667 }
 668
 669 static inline void bio_list_merge(struct bio_list *bl, struct bio_list *bl2)
 670 {
 671         if (!bl2->head)
 672                 return;
 673
 674         if (bl->tail)
 675                 bl->tail->bi_next = bl2->head;
 676         else
 677                 bl->head = bl2->head;
 678
 679         bl->tail = bl2->tail;
 680 }
 681
 682 static inline void bio_list_merge_head(struct bio_list *bl,
 683                                        struct bio_list *bl2)
 684 {
 685         if (!bl2->head)
 686                 return;
 687
 688         if (bl->head)
 689                 bl2->tail->bi_next = bl->head;
 690         else
 691                 bl->tail = bl2->tail;
 692
 693         bl->head = bl2->head;
 694 }
 695
 696 static inline struct bio *bio_list_peek(struct bio_list *bl)
 697 {
 698         return bl->head;
 699 }
 700
 701 static inline struct bio *bio_list_pop(struct bio_list *bl)
 702 {
 703         struct bio *bio = bl->head;
 704
 705         if (bio) {
 706                 bl->head = bl->head->bi_next;
 707                 if (!bl->head)
 708                         bl->tail = NULL;
 709
 710                 bio->bi_next = NULL;
 711         }
 712
 713         return bio;
 714 }
 715
 716 static inline struct bio *bio_list_get(struct bio_list *bl)
 717 {
 718         struct bio *bio = bl->head;
 719
 720         bl->head = bl->tail = NULL;
 721
 722         return bio;
 723 }
 724
 725 /*
 726  * Increment chain count for the bio. Make sure the CHAIN flag update
 727  * is visible before the raised count.
 728  */
 729 static inline void bio_inc_remaining(struct bio *bio)
 730 {
 731         bio_set_flag(bio, BIO_CHAIN);
 732         smp_mb__before_atomic();
 733         atomic_inc(&bio->__bi_remaining);
 734 }
 735
 736 /*
 737  * bio_set is used to allow other portions of the IO system to
 738  * allocate their own private memory pools for bio and iovec structures.
 739  * These memory pools in turn all allocate from the bio_slab
 740  * and the bvec_slabs[].
 741  */
 742 #define BIO_POOL_SIZE 2
 743
 744 struct bio_set {
 745         struct kmem_cache *bio_slab;
 746         unsigned int front_pad;
 747
 748         mempool_t bio_pool;
 749         mempool_t bvec_pool;
 750 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 751         mempool_t bio_integrity_pool;
 752         mempool_t bvec_integrity_pool;
 753 #endif
 754
 755         /*
 756          * Deadlock avoidance for stacking block drivers: see comments in
 757          * bio_alloc_bioset() for details
 758          */
 759         spinlock_t              rescue_lock;
 760         struct bio_list         rescue_list;
 761         struct work_struct      rescue_work;
 762         struct workqueue_struct *rescue_workqueue;
 763 };
 764
 765 struct biovec_slab {
 766         int nr_vecs;
 767         char *name;
 768         struct kmem_cache *slab;
 769 };
 770
 771 static inline bool bioset_initialized(struct bio_set *bs)
 772 {
 773         return bs->bio_slab != NULL;
 774 }
 775
 776 /*
 777  * a small number of entries is fine, not going to be performance critical.
 778  * basically we just need to survive
 779  */
 780 #define BIO_SPLIT_ENTRIES 2
 781
 782 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 783
 784 #define bip_for_each_vec(bvl, bip, iter)                                \
 785         for_each_bvec(bvl, (bip)->bip_vec, iter, (bip)->bip_iter)
 786
 787 #define bio_for_each_integrity_vec(_bvl, _bio, _iter)                   \
 788         for_each_bio(_bio)                                              \
 789                 bip_for_each_vec(_bvl, _bio->bi_integrity, _iter)
 790
 791 extern struct bio_integrity_payload *bio_integrity_alloc(struct bio *, gfp_t, unsigned int);
 792 extern int bio_integrity_add_page(struct bio *, struct page *, unsigned int, unsigned int);
 793 extern bool bio_integrity_prep(struct bio *);
 794 extern void bio_integrity_advance(struct bio *, unsigned int);
 795 extern void bio_integrity_trim(struct bio *);
 796 extern int bio_integrity_clone(struct bio *, struct bio *, gfp_t);
 797 extern int bioset_integrity_create(struct bio_set *, int);
 798 extern void bioset_integrity_free(struct bio_set *);
 799 extern void bio_integrity_init(void);
 800
 801 #else /* CONFIG_BLK_DEV_INTEGRITY */
 802
 803 static inline void *bio_integrity(struct bio *bio)
 804 {
 805         return NULL;
 806 }
 807
 808 static inline int bioset_integrity_create(struct bio_set *bs, int pool_size)
 809 {
 810         return 0;
 811 }
 812
 813 static inline void bioset_integrity_free (struct bio_set *bs)
 814 {
 815         return;
 816 }
 817
 818 static inline bool bio_integrity_prep(struct bio *bio)
 819 {
 820         return true;
 821 }
 822
 823 static inline int bio_integrity_clone(struct bio *bio, struct bio *bio_src,
 824                                       gfp_t gfp_mask)
 825 {
 826         return 0;
 827 }
 828
 829 static inline void bio_integrity_advance(struct bio *bio,
 830                                          unsigned int bytes_done)
 831 {
 832         return;
 833 }
 834
 835 static inline void bio_integrity_trim(struct bio *bio)
 836 {
 837         return;
 838 }
 839
 840 static inline void bio_integrity_init(void)
 841 {
 842         return;
 843 }
 844
 845 static inline bool bio_integrity_flagged(struct bio *bio, enum bip_flags flag)
 846 {
 847         return false;
 848 }
 849
 850 static inline void *bio_integrity_alloc(struct bio * bio, gfp_t gfp,
 851                                                                 unsigned int nr)
 852 {
 853         return ERR_PTR(-EINVAL);
 854 }
 855
 856 static inline int bio_integrity_add_page(struct bio *bio, struct page *page,
 857                                         unsigned int len, unsigned int offset)
 858 {
 859         return 0;
 860 }
 861
 862 #endif /* CONFIG_BLK_DEV_INTEGRITY */
 863
 864 #endif /* CONFIG_BLOCK */
 865 #endif /* __LINUX_BIO_H */