linux/include/linux/bio.h
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   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 bio_iovec_idx(bio, idx) (&((bio)->bi_io_vec[(idx)]))
  65#define bio_iovec(bio)          bio_iovec_idx((bio), (bio)->bi_idx)
  66#define bio_page(bio)           bio_iovec((bio))->bv_page
  67#define bio_offset(bio)         bio_iovec((bio))->bv_offset
  68#define bio_segments(bio)       ((bio)->bi_vcnt - (bio)->bi_idx)
  69#define bio_sectors(bio)        ((bio)->bi_size >> 9)
  70
  71static inline unsigned int bio_cur_bytes(struct bio *bio)
  72{
  73        if (bio->bi_vcnt)
  74                return bio_iovec(bio)->bv_len;
  75        else /* dataless requests such as discard */
  76                return bio->bi_size;
  77}
  78
  79static inline void *bio_data(struct bio *bio)
  80{
  81        if (bio->bi_vcnt)
  82                return page_address(bio_page(bio)) + bio_offset(bio);
  83
  84        return NULL;
  85}
  86
  87static inline int bio_has_allocated_vec(struct bio *bio)
  88{
  89        return bio->bi_io_vec && bio->bi_io_vec != bio->bi_inline_vecs;
  90}
  91
  92/*
  93 * will die
  94 */
  95#define bio_to_phys(bio)        (page_to_phys(bio_page((bio))) + (unsigned long) bio_offset((bio)))
  96#define bvec_to_phys(bv)        (page_to_phys((bv)->bv_page) + (unsigned long) (bv)->bv_offset)
  97
  98/*
  99 * queues that have highmem support enabled may still need to revert to
 100 * PIO transfers occasionally and thus map high pages temporarily. For
 101 * permanent PIO fall back, user is probably better off disabling highmem
 102 * I/O completely on that queue (see ide-dma for example)
 103 */
 104#define __bio_kmap_atomic(bio, idx, kmtype)                             \
 105        (kmap_atomic(bio_iovec_idx((bio), (idx))->bv_page) +    \
 106                bio_iovec_idx((bio), (idx))->bv_offset)
 107
 108#define __bio_kunmap_atomic(addr, kmtype) kunmap_atomic(addr)
 109
 110/*
 111 * merge helpers etc
 112 */
 113
 114#define __BVEC_END(bio)         bio_iovec_idx((bio), (bio)->bi_vcnt - 1)
 115#define __BVEC_START(bio)       bio_iovec_idx((bio), (bio)->bi_idx)
 116
 117/* Default implementation of BIOVEC_PHYS_MERGEABLE */
 118#define __BIOVEC_PHYS_MERGEABLE(vec1, vec2)     \
 119        ((bvec_to_phys((vec1)) + (vec1)->bv_len) == bvec_to_phys((vec2)))
 120
 121/*
 122 * allow arch override, for eg virtualized architectures (put in asm/io.h)
 123 */
 124#ifndef BIOVEC_PHYS_MERGEABLE
 125#define BIOVEC_PHYS_MERGEABLE(vec1, vec2)       \
 126        __BIOVEC_PHYS_MERGEABLE(vec1, vec2)
 127#endif
 128
 129#define __BIO_SEG_BOUNDARY(addr1, addr2, mask) \
 130        (((addr1) | (mask)) == (((addr2) - 1) | (mask)))
 131#define BIOVEC_SEG_BOUNDARY(q, b1, b2) \
 132        __BIO_SEG_BOUNDARY(bvec_to_phys((b1)), bvec_to_phys((b2)) + (b2)->bv_len, queue_segment_boundary((q)))
 133#define BIO_SEG_BOUNDARY(q, b1, b2) \
 134        BIOVEC_SEG_BOUNDARY((q), __BVEC_END((b1)), __BVEC_START((b2)))
 135
 136#define bio_io_error(bio) bio_endio((bio), -EIO)
 137
 138/*
 139 * drivers should not use the __ version unless they _really_ want to
 140 * run through the entire bio and not just pending pieces
 141 */
 142#define __bio_for_each_segment(bvl, bio, i, start_idx)                  \
 143        for (bvl = bio_iovec_idx((bio), (start_idx)), i = (start_idx);  \
 144             i < (bio)->bi_vcnt;                                        \
 145             bvl++, i++)
 146
 147#define bio_for_each_segment(bvl, bio, i)                               \
 148        __bio_for_each_segment(bvl, bio, i, (bio)->bi_idx)
 149
 150/*
 151 * get a reference to a bio, so it won't disappear. the intended use is
 152 * something like:
 153 *
 154 * bio_get(bio);
 155 * submit_bio(rw, bio);
 156 * if (bio->bi_flags ...)
 157 *      do_something
 158 * bio_put(bio);
 159 *
 160 * without the bio_get(), it could potentially complete I/O before submit_bio
 161 * returns. and then bio would be freed memory when if (bio->bi_flags ...)
 162 * runs
 163 */
 164#define bio_get(bio)    atomic_inc(&(bio)->bi_cnt)
 165
 166#if defined(CONFIG_BLK_DEV_INTEGRITY)
 167/*
 168 * bio integrity payload
 169 */
 170struct bio_integrity_payload {
 171        struct bio              *bip_bio;       /* parent bio */
 172
 173        sector_t                bip_sector;     /* virtual start sector */
 174
 175        void                    *bip_buf;       /* generated integrity data */
 176        bio_end_io_t            *bip_end_io;    /* saved I/O completion fn */
 177
 178        unsigned int            bip_size;
 179
 180        unsigned short          bip_slab;       /* slab the bip came from */
 181        unsigned short          bip_vcnt;       /* # of integrity bio_vecs */
 182        unsigned short          bip_idx;        /* current bip_vec index */
 183
 184        struct work_struct      bip_work;       /* I/O completion */
 185        struct bio_vec          bip_vec[0];     /* embedded bvec array */
 186};
 187#endif /* CONFIG_BLK_DEV_INTEGRITY */
 188
 189/*
 190 * A bio_pair is used when we need to split a bio.
 191 * This can only happen for a bio that refers to just one
 192 * page of data, and in the unusual situation when the
 193 * page crosses a chunk/device boundary
 194 *
 195 * The address of the master bio is stored in bio1.bi_private
 196 * The address of the pool the pair was allocated from is stored
 197 *   in bio2.bi_private
 198 */
 199struct bio_pair {
 200        struct bio                      bio1, bio2;
 201        struct bio_vec                  bv1, bv2;
 202#if defined(CONFIG_BLK_DEV_INTEGRITY)
 203        struct bio_integrity_payload    bip1, bip2;
 204        struct bio_vec                  iv1, iv2;
 205#endif
 206        atomic_t                        cnt;
 207        int                             error;
 208};
 209extern struct bio_pair *bio_split(struct bio *bi, int first_sectors);
 210extern void bio_pair_release(struct bio_pair *dbio);
 211
 212extern struct bio_set *bioset_create(unsigned int, unsigned int);
 213extern void bioset_free(struct bio_set *);
 214
 215extern struct bio *bio_alloc(gfp_t, unsigned int);
 216extern struct bio *bio_kmalloc(gfp_t, unsigned int);
 217extern struct bio *bio_alloc_bioset(gfp_t, int, struct bio_set *);
 218extern void bio_put(struct bio *);
 219extern void bio_free(struct bio *, struct bio_set *);
 220
 221extern void bio_endio(struct bio *, int);
 222struct request_queue;
 223extern int bio_phys_segments(struct request_queue *, struct bio *);
 224
 225extern void __bio_clone(struct bio *, struct bio *);
 226extern struct bio *bio_clone(struct bio *, gfp_t);
 227
 228extern void bio_init(struct bio *);
 229
 230extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int);
 231extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,
 232                           unsigned int, unsigned int);
 233extern int bio_get_nr_vecs(struct block_device *);
 234extern sector_t bio_sector_offset(struct bio *, unsigned short, unsigned int);
 235extern struct bio *bio_map_user(struct request_queue *, struct block_device *,
 236                                unsigned long, unsigned int, int, gfp_t);
 237struct sg_iovec;
 238struct rq_map_data;
 239extern struct bio *bio_map_user_iov(struct request_queue *,
 240                                    struct block_device *,
 241                                    struct sg_iovec *, int, int, gfp_t);
 242extern void bio_unmap_user(struct bio *);
 243extern struct bio *bio_map_kern(struct request_queue *, void *, unsigned int,
 244                                gfp_t);
 245extern struct bio *bio_copy_kern(struct request_queue *, void *, unsigned int,
 246                                 gfp_t, int);
 247extern void bio_set_pages_dirty(struct bio *bio);
 248extern void bio_check_pages_dirty(struct bio *bio);
 249
 250#ifndef ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
 251# error "You should define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE for your platform"
 252#endif
 253#if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
 254extern void bio_flush_dcache_pages(struct bio *bi);
 255#else
 256static inline void bio_flush_dcache_pages(struct bio *bi)
 257{
 258}
 259#endif
 260
 261extern struct bio *bio_copy_user(struct request_queue *, struct rq_map_data *,
 262                                 unsigned long, unsigned int, int, gfp_t);
 263extern struct bio *bio_copy_user_iov(struct request_queue *,
 264                                     struct rq_map_data *, struct sg_iovec *,
 265                                     int, int, gfp_t);
 266extern int bio_uncopy_user(struct bio *);
 267void zero_fill_bio(struct bio *bio);
 268extern struct bio_vec *bvec_alloc_bs(gfp_t, int, unsigned long *, struct bio_set *);
 269extern void bvec_free_bs(struct bio_set *, struct bio_vec *, unsigned int);
 270extern unsigned int bvec_nr_vecs(unsigned short idx);
 271
 272#ifdef CONFIG_BLK_CGROUP
 273int bio_associate_current(struct bio *bio);
 274void bio_disassociate_task(struct bio *bio);
 275#else   /* CONFIG_BLK_CGROUP */
 276static inline int bio_associate_current(struct bio *bio) { return -ENOENT; }
 277static inline void bio_disassociate_task(struct bio *bio) { }
 278#endif  /* CONFIG_BLK_CGROUP */
 279
 280/*
 281 * bio_set is used to allow other portions of the IO system to
 282 * allocate their own private memory pools for bio and iovec structures.
 283 * These memory pools in turn all allocate from the bio_slab
 284 * and the bvec_slabs[].
 285 */
 286#define BIO_POOL_SIZE 2
 287#define BIOVEC_NR_POOLS 6
 288#define BIOVEC_MAX_IDX  (BIOVEC_NR_POOLS - 1)
 289
 290struct bio_set {
 291        struct kmem_cache *bio_slab;
 292        unsigned int front_pad;
 293
 294        mempool_t *bio_pool;
 295#if defined(CONFIG_BLK_DEV_INTEGRITY)
 296        mempool_t *bio_integrity_pool;
 297#endif
 298        mempool_t *bvec_pool;
 299};
 300
 301struct biovec_slab {
 302        int nr_vecs;
 303        char *name;
 304        struct kmem_cache *slab;
 305};
 306
 307extern struct bio_set *fs_bio_set;
 308
 309/*
 310 * a small number of entries is fine, not going to be performance critical.
 311 * basically we just need to survive
 312 */
 313#define BIO_SPLIT_ENTRIES 2
 314
 315#ifdef CONFIG_HIGHMEM
 316/*
 317 * remember never ever reenable interrupts between a bvec_kmap_irq and
 318 * bvec_kunmap_irq!
 319 */
 320static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
 321{
 322        unsigned long addr;
 323
 324        /*
 325         * might not be a highmem page, but the preempt/irq count
 326         * balancing is a lot nicer this way
 327         */
 328        local_irq_save(*flags);
 329        addr = (unsigned long) kmap_atomic(bvec->bv_page);
 330
 331        BUG_ON(addr & ~PAGE_MASK);
 332
 333        return (char *) addr + bvec->bv_offset;
 334}
 335
 336static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
 337{
 338        unsigned long ptr = (unsigned long) buffer & PAGE_MASK;
 339
 340        kunmap_atomic((void *) ptr);
 341        local_irq_restore(*flags);
 342}
 343
 344#else
 345static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
 346{
 347        return page_address(bvec->bv_page) + bvec->bv_offset;
 348}
 349
 350static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
 351{
 352        *flags = 0;
 353}
 354#endif
 355
 356static inline char *__bio_kmap_irq(struct bio *bio, unsigned short idx,
 357                                   unsigned long *flags)
 358{
 359        return bvec_kmap_irq(bio_iovec_idx(bio, idx), flags);
 360}
 361#define __bio_kunmap_irq(buf, flags)    bvec_kunmap_irq(buf, flags)
 362
 363#define bio_kmap_irq(bio, flags) \
 364        __bio_kmap_irq((bio), (bio)->bi_idx, (flags))
 365#define bio_kunmap_irq(buf,flags)       __bio_kunmap_irq(buf, flags)
 366
 367/*
 368 * Check whether this bio carries any data or not. A NULL bio is allowed.
 369 */
 370static inline int bio_has_data(struct bio *bio)
 371{
 372        return bio && bio->bi_io_vec != NULL;
 373}
 374
 375/*
 376 * BIO list management for use by remapping drivers (e.g. DM or MD) and loop.
 377 *
 378 * A bio_list anchors a singly-linked list of bios chained through the bi_next
 379 * member of the bio.  The bio_list also caches the last list member to allow
 380 * fast access to the tail.
 381 */
 382struct bio_list {
 383        struct bio *head;
 384        struct bio *tail;
 385};
 386
 387static inline int bio_list_empty(const struct bio_list *bl)
 388{
 389        return bl->head == NULL;
 390}
 391
 392static inline void bio_list_init(struct bio_list *bl)
 393{
 394        bl->head = bl->tail = NULL;
 395}
 396
 397#define bio_list_for_each(bio, bl) \
 398        for (bio = (bl)->head; bio; bio = bio->bi_next)
 399
 400static inline unsigned bio_list_size(const struct bio_list *bl)
 401{
 402        unsigned sz = 0;
 403        struct bio *bio;
 404
 405        bio_list_for_each(bio, bl)
 406                sz++;
 407
 408        return sz;
 409}
 410
 411static inline void bio_list_add(struct bio_list *bl, struct bio *bio)
 412{
 413        bio->bi_next = NULL;
 414
 415        if (bl->tail)
 416                bl->tail->bi_next = bio;
 417        else
 418                bl->head = bio;
 419
 420        bl->tail = bio;
 421}
 422
 423static inline void bio_list_add_head(struct bio_list *bl, struct bio *bio)
 424{
 425        bio->bi_next = bl->head;
 426
 427        bl->head = bio;
 428
 429        if (!bl->tail)
 430                bl->tail = bio;
 431}
 432
 433static inline void bio_list_merge(struct bio_list *bl, struct bio_list *bl2)
 434{
 435        if (!bl2->head)
 436                return;
 437
 438        if (bl->tail)
 439                bl->tail->bi_next = bl2->head;
 440        else
 441                bl->head = bl2->head;
 442
 443        bl->tail = bl2->tail;
 444}
 445
 446static inline void bio_list_merge_head(struct bio_list *bl,
 447                                       struct bio_list *bl2)
 448{
 449        if (!bl2->head)
 450                return;
 451
 452        if (bl->head)
 453                bl2->tail->bi_next = bl->head;
 454        else
 455                bl->tail = bl2->tail;
 456
 457        bl->head = bl2->head;
 458}
 459
 460static inline struct bio *bio_list_peek(struct bio_list *bl)
 461{
 462        return bl->head;
 463}
 464
 465static inline struct bio *bio_list_pop(struct bio_list *bl)
 466{
 467        struct bio *bio = bl->head;
 468
 469        if (bio) {
 470                bl->head = bl->head->bi_next;
 471                if (!bl->head)
 472                        bl->tail = NULL;
 473
 474                bio->bi_next = NULL;
 475        }
 476
 477        return bio;
 478}
 479
 480static inline struct bio *bio_list_get(struct bio_list *bl)
 481{
 482        struct bio *bio = bl->head;
 483
 484        bl->head = bl->tail = NULL;
 485
 486        return bio;
 487}
 488
 489#if defined(CONFIG_BLK_DEV_INTEGRITY)
 490
 491#define bip_vec_idx(bip, idx)   (&(bip->bip_vec[(idx)]))
 492#define bip_vec(bip)            bip_vec_idx(bip, 0)
 493
 494#define __bip_for_each_vec(bvl, bip, i, start_idx)                      \
 495        for (bvl = bip_vec_idx((bip), (start_idx)), i = (start_idx);    \
 496             i < (bip)->bip_vcnt;                                       \
 497             bvl++, i++)
 498
 499#define bip_for_each_vec(bvl, bip, i)                                   \
 500        __bip_for_each_vec(bvl, bip, i, (bip)->bip_idx)
 501
 502#define bio_for_each_integrity_vec(_bvl, _bio, _iter)                   \
 503        for_each_bio(_bio)                                              \
 504                bip_for_each_vec(_bvl, _bio->bi_integrity, _iter)
 505
 506#define bio_integrity(bio) (bio->bi_integrity != NULL)
 507
 508extern struct bio_integrity_payload *bio_integrity_alloc_bioset(struct bio *, gfp_t, unsigned int, struct bio_set *);
 509extern struct bio_integrity_payload *bio_integrity_alloc(struct bio *, gfp_t, unsigned int);
 510extern void bio_integrity_free(struct bio *, struct bio_set *);
 511extern int bio_integrity_add_page(struct bio *, struct page *, unsigned int, unsigned int);
 512extern int bio_integrity_enabled(struct bio *bio);
 513extern int bio_integrity_set_tag(struct bio *, void *, unsigned int);
 514extern int bio_integrity_get_tag(struct bio *, void *, unsigned int);
 515extern int bio_integrity_prep(struct bio *);
 516extern void bio_integrity_endio(struct bio *, int);
 517extern void bio_integrity_advance(struct bio *, unsigned int);
 518extern void bio_integrity_trim(struct bio *, unsigned int, unsigned int);
 519extern void bio_integrity_split(struct bio *, struct bio_pair *, int);
 520extern int bio_integrity_clone(struct bio *, struct bio *, gfp_t, struct bio_set *);
 521extern int bioset_integrity_create(struct bio_set *, int);
 522extern void bioset_integrity_free(struct bio_set *);
 523extern void bio_integrity_init(void);
 524
 525#else /* CONFIG_BLK_DEV_INTEGRITY */
 526
 527static inline int bio_integrity(struct bio *bio)
 528{
 529        return 0;
 530}
 531
 532static inline int bio_integrity_enabled(struct bio *bio)
 533{
 534        return 0;
 535}
 536
 537static inline int bioset_integrity_create(struct bio_set *bs, int pool_size)
 538{
 539        return 0;
 540}
 541
 542static inline void bioset_integrity_free (struct bio_set *bs)
 543{
 544        return;
 545}
 546
 547static inline int bio_integrity_prep(struct bio *bio)
 548{
 549        return 0;
 550}
 551
 552static inline void bio_integrity_free(struct bio *bio, struct bio_set *bs)
 553{
 554        return;
 555}
 556
 557static inline int bio_integrity_clone(struct bio *bio, struct bio *bio_src,
 558                                      gfp_t gfp_mask, struct bio_set *bs)
 559{
 560        return 0;
 561}
 562
 563static inline void bio_integrity_split(struct bio *bio, struct bio_pair *bp,
 564                                       int sectors)
 565{
 566        return;
 567}
 568
 569static inline void bio_integrity_advance(struct bio *bio,
 570                                         unsigned int bytes_done)
 571{
 572        return;
 573}
 574
 575static inline void bio_integrity_trim(struct bio *bio, unsigned int offset,
 576                                      unsigned int sectors)
 577{
 578        return;
 579}
 580
 581static inline void bio_integrity_init(void)
 582{
 583        return;
 584}
 585
 586#endif /* CONFIG_BLK_DEV_INTEGRITY */
 587
 588#endif /* CONFIG_BLOCK */
 589#endif /* __LINUX_BIO_H */
 590
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