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
  27 #ifdef CONFIG_BLOCK
  28
  29 #include <asm/io.h>
  30
  31 /* struct bio, bio_vec and BIO_* flags are defined in blk_types.h */
  32 #include <linux/blk_types.h>
  33
  34 #define BIO_DEBUG
  35
  36 #ifdef BIO_DEBUG
  37 #define BIO_BUG_ON      BUG_ON
  38 #else
  39 #define BIO_BUG_ON
  40 #endif
  41
  42 #define BIO_MAX_PAGES           256
  43 #define BIO_MAX_SIZE            (BIO_MAX_PAGES << PAGE_CACHE_SHIFT)
  44 #define BIO_MAX_SECTORS         (BIO_MAX_SIZE >> 9)
  45
  46 /*
  47  * upper 16 bits of bi_rw define the io priority of this bio
  48  */
  49 #define BIO_PRIO_SHIFT  (8 * sizeof(unsigned long) - IOPRIO_BITS)
  50 #define bio_prio(bio)   ((bio)->bi_rw >> BIO_PRIO_SHIFT)
  51 #define bio_prio_valid(bio)     ioprio_valid(bio_prio(bio))
  52
  53 #define bio_set_prio(bio, prio)         do {                    \
  54         WARN_ON(prio >= (1 << IOPRIO_BITS));                    \
  55         (bio)->bi_rw &= ((1UL << BIO_PRIO_SHIFT) - 1);          \
  56         (bio)->bi_rw |= ((unsigned long) (prio) << BIO_PRIO_SHIFT);     \
  57 } while (0)
  58
  59 /*
  60  * various member access, note that bio_data should of course not be used
  61  * on highmem page vectors
  62  */
  63 #define bio_iovec_idx(bio, idx) (&((bio)->bi_io_vec[(idx)]))
  64 #define bio_iovec(bio)          bio_iovec_idx((bio), (bio)->bi_idx)
  65 #define bio_page(bio)           bio_iovec((bio))->bv_page
  66 #define bio_offset(bio)         bio_iovec((bio))->bv_offset
  67 #define bio_segments(bio)       ((bio)->bi_vcnt - (bio)->bi_idx)
  68 #define bio_sectors(bio)        ((bio)->bi_size >> 9)
  69 #define bio_empty_barrier(bio) \
  70         ((bio->bi_rw & REQ_HARDBARRIER) && \
  71          !bio_has_data(bio) && \
  72          !(bio->bi_rw & REQ_DISCARD))
  73
  74 static inline unsigned int bio_cur_bytes(struct bio *bio)
  75 {
  76         if (bio->bi_vcnt)
  77                 return bio_iovec(bio)->bv_len;
  78         else /* dataless requests such as discard */
  79                 return bio->bi_size;
  80 }
  81
  82 static inline void *bio_data(struct bio *bio)
  83 {
  84         if (bio->bi_vcnt)
  85                 return page_address(bio_page(bio)) + bio_offset(bio);
  86
  87         return NULL;
  88 }
  89
  90 static inline int bio_has_allocated_vec(struct bio *bio)
  91 {
  92         return bio->bi_io_vec && bio->bi_io_vec != bio->bi_inline_vecs;
  93 }
  94
  95 /*
  96  * will die
  97  */
  98 #define bio_to_phys(bio)        (page_to_phys(bio_page((bio))) + (unsigned long) bio_offset((bio)))
  99 #define bvec_to_phys(bv)        (page_to_phys((bv)->bv_page) + (unsigned long) (bv)->bv_offset)
 100
 101 /*
 102  * queues that have highmem support enabled may still need to revert to
 103  * PIO transfers occasionally and thus map high pages temporarily. For
 104  * permanent PIO fall back, user is probably better off disabling highmem
 105  * I/O completely on that queue (see ide-dma for example)
 106  */
 107 #define __bio_kmap_atomic(bio, idx, kmtype)                             \
 108         (kmap_atomic(bio_iovec_idx((bio), (idx))->bv_page, kmtype) +    \
 109                 bio_iovec_idx((bio), (idx))->bv_offset)
 110
 111 #define __bio_kunmap_atomic(addr, kmtype) kunmap_atomic(addr, kmtype)
 112
 113 /*
 114  * merge helpers etc
 115  */
 116
 117 #define __BVEC_END(bio)         bio_iovec_idx((bio), (bio)->bi_vcnt - 1)
 118 #define __BVEC_START(bio)       bio_iovec_idx((bio), (bio)->bi_idx)
 119
 120 /* Default implementation of BIOVEC_PHYS_MERGEABLE */
 121 #define __BIOVEC_PHYS_MERGEABLE(vec1, vec2)     \
 122         ((bvec_to_phys((vec1)) + (vec1)->bv_len) == bvec_to_phys((vec2)))
 123
 124 /*
 125  * allow arch override, for eg virtualized architectures (put in asm/io.h)
 126  */
 127 #ifndef BIOVEC_PHYS_MERGEABLE
 128 #define BIOVEC_PHYS_MERGEABLE(vec1, vec2)       \
 129         __BIOVEC_PHYS_MERGEABLE(vec1, vec2)
 130 #endif
 131
 132 #define __BIO_SEG_BOUNDARY(addr1, addr2, mask) \
 133         (((addr1) | (mask)) == (((addr2) - 1) | (mask)))
 134 #define BIOVEC_SEG_BOUNDARY(q, b1, b2) \
 135         __BIO_SEG_BOUNDARY(bvec_to_phys((b1)), bvec_to_phys((b2)) + (b2)->bv_len, queue_segment_boundary((q)))
 136 #define BIO_SEG_BOUNDARY(q, b1, b2) \
 137         BIOVEC_SEG_BOUNDARY((q), __BVEC_END((b1)), __BVEC_START((b2)))
 138
 139 #define bio_io_error(bio) bio_endio((bio), -EIO)
 140
 141 /*
 142  * drivers should not use the __ version unless they _really_ want to
 143  * run through the entire bio and not just pending pieces
 144  */
 145 #define __bio_for_each_segment(bvl, bio, i, start_idx)                  \
 146         for (bvl = bio_iovec_idx((bio), (start_idx)), i = (start_idx);  \
 147              i < (bio)->bi_vcnt;                                        \
 148              bvl++, i++)
 149
 150 #define bio_for_each_segment(bvl, bio, i)                               \
 151         __bio_for_each_segment(bvl, bio, i, (bio)->bi_idx)
 152
 153 /*
 154  * get a reference to a bio, so it won't disappear. the intended use is
 155  * something like:
 156  *
 157  * bio_get(bio);
 158  * submit_bio(rw, bio);
 159  * if (bio->bi_flags ...)
 160  *      do_something
 161  * bio_put(bio);
 162  *
 163  * without the bio_get(), it could potentially complete I/O before submit_bio
 164  * returns. and then bio would be freed memory when if (bio->bi_flags ...)
 165  * runs
 166  */
 167 #define bio_get(bio)    atomic_inc(&(bio)->bi_cnt)
 168
 169 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 170 /*
 171  * bio integrity payload
 172  */
 173 struct bio_integrity_payload {
 174         struct bio              *bip_bio;       /* parent bio */
 175
 176         sector_t                bip_sector;     /* virtual start sector */
 177
 178         void                    *bip_buf;       /* generated integrity data */
 179         bio_end_io_t            *bip_end_io;    /* saved I/O completion fn */
 180
 181         unsigned int            bip_size;
 182
 183         unsigned short          bip_slab;       /* slab the bip came from */
 184         unsigned short          bip_vcnt;       /* # of integrity bio_vecs */
 185         unsigned short          bip_idx;        /* current bip_vec index */
 186
 187         struct work_struct      bip_work;       /* I/O completion */
 188         struct bio_vec          bip_vec[0];     /* embedded bvec array */
 189 };
 190 #endif /* CONFIG_BLK_DEV_INTEGRITY */
 191
 192 /*
 193  * A bio_pair is used when we need to split a bio.
 194  * This can only happen for a bio that refers to just one
 195  * page of data, and in the unusual situation when the
 196  * page crosses a chunk/device boundary
 197  *
 198  * The address of the master bio is stored in bio1.bi_private
 199  * The address of the pool the pair was allocated from is stored
 200  *   in bio2.bi_private
 201  */
 202 struct bio_pair {
 203         struct bio                      bio1, bio2;
 204         struct bio_vec                  bv1, bv2;
 205 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 206         struct bio_integrity_payload    bip1, bip2;
 207         struct bio_vec                  iv1, iv2;
 208 #endif
 209         atomic_t                        cnt;
 210         int                             error;
 211 };
 212 extern struct bio_pair *bio_split(struct bio *bi, int first_sectors);
 213 extern void bio_pair_release(struct bio_pair *dbio);
 214
 215 extern struct bio_set *bioset_create(unsigned int, unsigned int);
 216 extern void bioset_free(struct bio_set *);
 217
 218 extern struct bio *bio_alloc(gfp_t, int);
 219 extern struct bio *bio_kmalloc(gfp_t, int);
 220 extern struct bio *bio_alloc_bioset(gfp_t, int, struct bio_set *);
 221 extern void bio_put(struct bio *);
 222 extern void bio_free(struct bio *, struct bio_set *);
 223
 224 extern void bio_endio(struct bio *, int);
 225 struct request_queue;
 226 extern int bio_phys_segments(struct request_queue *, struct bio *);
 227
 228 extern void __bio_clone(struct bio *, struct bio *);
 229 extern struct bio *bio_clone(struct bio *, gfp_t);
 230
 231 extern void bio_init(struct bio *);
 232
 233 extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int);
 234 extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,
 235                            unsigned int, unsigned int);
 236 extern int bio_get_nr_vecs(struct block_device *);
 237 extern sector_t bio_sector_offset(struct bio *, unsigned short, unsigned int);
 238 extern struct bio *bio_map_user(struct request_queue *, struct block_device *,
 239                                 unsigned long, unsigned int, int, gfp_t);
 240 struct sg_iovec;
 241 struct rq_map_data;
 242 extern struct bio *bio_map_user_iov(struct request_queue *,
 243                                     struct block_device *,
 244                                     struct sg_iovec *, int, int, gfp_t);
 245 extern void bio_unmap_user(struct bio *);
 246 extern struct bio *bio_map_kern(struct request_queue *, void *, unsigned int,
 247                                 gfp_t);
 248 extern struct bio *bio_copy_kern(struct request_queue *, void *, unsigned int,
 249                                  gfp_t, int);
 250 extern void bio_set_pages_dirty(struct bio *bio);
 251 extern void bio_check_pages_dirty(struct bio *bio);
 252
 253 #ifndef ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
 254 # error "You should define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE for your platform"
 255 #endif
 256 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
 257 extern void bio_flush_dcache_pages(struct bio *bi);
 258 #else
 259 static inline void bio_flush_dcache_pages(struct bio *bi)
 260 {
 261 }
 262 #endif
 263
 264 extern struct bio *bio_copy_user(struct request_queue *, struct rq_map_data *,
 265                                  unsigned long, unsigned int, int, gfp_t);
 266 extern struct bio *bio_copy_user_iov(struct request_queue *,
 267                                      struct rq_map_data *, struct sg_iovec *,
 268                                      int, int, gfp_t);
 269 extern int bio_uncopy_user(struct bio *);
 270 void zero_fill_bio(struct bio *bio);
 271 extern struct bio_vec *bvec_alloc_bs(gfp_t, int, unsigned long *, struct bio_set *);
 272 extern void bvec_free_bs(struct bio_set *, struct bio_vec *, unsigned int);
 273 extern unsigned int bvec_nr_vecs(unsigned short idx);
 274
 275 /*
 276  * Allow queuer to specify a completion CPU for this bio
 277  */
 278 static inline void bio_set_completion_cpu(struct bio *bio, unsigned int cpu)
 279 {
 280         bio->bi_comp_cpu = cpu;
 281 }
 282
 283 /*
 284  * bio_set is used to allow other portions of the IO system to
 285  * allocate their own private memory pools for bio and iovec structures.
 286  * These memory pools in turn all allocate from the bio_slab
 287  * and the bvec_slabs[].
 288  */
 289 #define BIO_POOL_SIZE 2
 290 #define BIOVEC_NR_POOLS 6
 291 #define BIOVEC_MAX_IDX  (BIOVEC_NR_POOLS - 1)
 292
 293 struct bio_set {
 294         struct kmem_cache *bio_slab;
 295         unsigned int front_pad;
 296
 297         mempool_t *bio_pool;
 298 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 299         mempool_t *bio_integrity_pool;
 300 #endif
 301         mempool_t *bvec_pool;
 302 };
 303
 304 struct biovec_slab {
 305         int nr_vecs;
 306         char *name;
 307         struct kmem_cache *slab;
 308 };
 309
 310 extern struct bio_set *fs_bio_set;
 311 extern struct biovec_slab bvec_slabs[BIOVEC_NR_POOLS] __read_mostly;
 312
 313 /*
 314  * a small number of entries is fine, not going to be performance critical.
 315  * basically we just need to survive
 316  */
 317 #define BIO_SPLIT_ENTRIES 2
 318
 319 #ifdef CONFIG_HIGHMEM
 320 /*
 321  * remember never ever reenable interrupts between a bvec_kmap_irq and
 322  * bvec_kunmap_irq!
 323  */
 324 static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
 325 {
 326         unsigned long addr;
 327
 328         /*
 329          * might not be a highmem page, but the preempt/irq count
 330          * balancing is a lot nicer this way
 331          */
 332         local_irq_save(*flags);
 333         addr = (unsigned long) kmap_atomic(bvec->bv_page, KM_BIO_SRC_IRQ);
 334
 335         BUG_ON(addr & ~PAGE_MASK);
 336
 337         return (char *) addr + bvec->bv_offset;
 338 }
 339
 340 static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
 341 {
 342         unsigned long ptr = (unsigned long) buffer & PAGE_MASK;
 343
 344         kunmap_atomic((void *) ptr, KM_BIO_SRC_IRQ);
 345         local_irq_restore(*flags);
 346 }
 347
 348 #else
 349 #define bvec_kmap_irq(bvec, flags)      (page_address((bvec)->bv_page) + (bvec)->bv_offset)
 350 #define bvec_kunmap_irq(buf, flags)     do { *(flags) = 0; } while (0)
 351 #endif
 352
 353 static inline char *__bio_kmap_irq(struct bio *bio, unsigned short idx,
 354                                    unsigned long *flags)
 355 {
 356         return bvec_kmap_irq(bio_iovec_idx(bio, idx), flags);
 357 }
 358 #define __bio_kunmap_irq(buf, flags)    bvec_kunmap_irq(buf, flags)
 359
 360 #define bio_kmap_irq(bio, flags) \
 361         __bio_kmap_irq((bio), (bio)->bi_idx, (flags))
 362 #define bio_kunmap_irq(buf,flags)       __bio_kunmap_irq(buf, flags)
 363
 364 /*
 365  * Check whether this bio carries any data or not. A NULL bio is allowed.
 366  */
 367 static inline int bio_has_data(struct bio *bio)
 368 {
 369         return bio && bio->bi_io_vec != NULL;
 370 }
 371
 372 /*
 373  * BIO list management for use by remapping drivers (e.g. DM or MD) and loop.
 374  *
 375  * A bio_list anchors a singly-linked list of bios chained through the bi_next
 376  * member of the bio.  The bio_list also caches the last list member to allow
 377  * fast access to the tail.
 378  */
 379 struct bio_list {
 380         struct bio *head;
 381         struct bio *tail;
 382 };
 383
 384 static inline int bio_list_empty(const struct bio_list *bl)
 385 {
 386         return bl->head == NULL;
 387 }
 388
 389 static inline void bio_list_init(struct bio_list *bl)
 390 {
 391         bl->head = bl->tail = NULL;
 392 }
 393
 394 #define bio_list_for_each(bio, bl) \
 395         for (bio = (bl)->head; bio; bio = bio->bi_next)
 396
 397 static inline unsigned bio_list_size(const struct bio_list *bl)
 398 {
 399         unsigned sz = 0;
 400         struct bio *bio;
 401
 402         bio_list_for_each(bio, bl)
 403                 sz++;
 404
 405         return sz;
 406 }
 407
 408 static inline void bio_list_add(struct bio_list *bl, struct bio *bio)
 409 {
 410         bio->bi_next = NULL;
 411
 412         if (bl->tail)
 413                 bl->tail->bi_next = bio;
 414         else
 415                 bl->head = bio;
 416
 417         bl->tail = bio;
 418 }
 419
 420 static inline void bio_list_add_head(struct bio_list *bl, struct bio *bio)
 421 {
 422         bio->bi_next = bl->head;
 423
 424         bl->head = bio;
 425
 426         if (!bl->tail)
 427                 bl->tail = bio;
 428 }
 429
 430 static inline void bio_list_merge(struct bio_list *bl, struct bio_list *bl2)
 431 {
 432         if (!bl2->head)
 433                 return;
 434
 435         if (bl->tail)
 436                 bl->tail->bi_next = bl2->head;
 437         else
 438                 bl->head = bl2->head;
 439
 440         bl->tail = bl2->tail;
 441 }
 442
 443 static inline void bio_list_merge_head(struct bio_list *bl,
 444                                        struct bio_list *bl2)
 445 {
 446         if (!bl2->head)
 447                 return;
 448
 449         if (bl->head)
 450                 bl2->tail->bi_next = bl->head;
 451         else
 452                 bl->tail = bl2->tail;
 453
 454         bl->head = bl2->head;
 455 }
 456
 457 static inline struct bio *bio_list_peek(struct bio_list *bl)
 458 {
 459         return bl->head;
 460 }
 461
 462 static inline struct bio *bio_list_pop(struct bio_list *bl)
 463 {
 464         struct bio *bio = bl->head;
 465
 466         if (bio) {
 467                 bl->head = bl->head->bi_next;
 468                 if (!bl->head)
 469                         bl->tail = NULL;
 470
 471                 bio->bi_next = NULL;
 472         }
 473
 474         return bio;
 475 }
 476
 477 static inline struct bio *bio_list_get(struct bio_list *bl)
 478 {
 479         struct bio *bio = bl->head;
 480
 481         bl->head = bl->tail = NULL;
 482
 483         return bio;
 484 }
 485
 486 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 487
 488 #define bip_vec_idx(bip, idx)   (&(bip->bip_vec[(idx)]))
 489 #define bip_vec(bip)            bip_vec_idx(bip, 0)
 490
 491 #define __bip_for_each_vec(bvl, bip, i, start_idx)                      \
 492         for (bvl = bip_vec_idx((bip), (start_idx)), i = (start_idx);    \
 493              i < (bip)->bip_vcnt;                                       \
 494              bvl++, i++)
 495
 496 #define bip_for_each_vec(bvl, bip, i)                                   \
 497         __bip_for_each_vec(bvl, bip, i, (bip)->bip_idx)
 498
 499 #define bio_integrity(bio) (bio->bi_integrity != NULL)
 500
 501 extern struct bio_integrity_payload *bio_integrity_alloc_bioset(struct bio *, gfp_t, unsigned int, struct bio_set *);
 502 extern struct bio_integrity_payload *bio_integrity_alloc(struct bio *, gfp_t, unsigned int);
 503 extern void bio_integrity_free(struct bio *, struct bio_set *);
 504 extern int bio_integrity_add_page(struct bio *, struct page *, unsigned int, unsigned int);
 505 extern int bio_integrity_enabled(struct bio *bio);
 506 extern int bio_integrity_set_tag(struct bio *, void *, unsigned int);
 507 extern int bio_integrity_get_tag(struct bio *, void *, unsigned int);
 508 extern int bio_integrity_prep(struct bio *);
 509 extern void bio_integrity_endio(struct bio *, int);
 510 extern void bio_integrity_advance(struct bio *, unsigned int);
 511 extern void bio_integrity_trim(struct bio *, unsigned int, unsigned int);
 512 extern void bio_integrity_split(struct bio *, struct bio_pair *, int);
 513 extern int bio_integrity_clone(struct bio *, struct bio *, gfp_t, struct bio_set *);
 514 extern int bioset_integrity_create(struct bio_set *, int);
 515 extern void bioset_integrity_free(struct bio_set *);
 516 extern void bio_integrity_init(void);
 517
 518 #else /* CONFIG_BLK_DEV_INTEGRITY */
 519
 520 #define bio_integrity(a)                (0)
 521 #define bioset_integrity_create(a, b)   (0)
 522 #define bio_integrity_prep(a)           (0)
 523 #define bio_integrity_enabled(a)        (0)
 524 #define bio_integrity_clone(a, b, c, d) (0)
 525 #define bioset_integrity_free(a)        do { } while (0)
 526 #define bio_integrity_free(a, b)        do { } while (0)
 527 #define bio_integrity_endio(a, b)       do { } while (0)
 528 #define bio_integrity_advance(a, b)     do { } while (0)
 529 #define bio_integrity_trim(a, b, c)     do { } while (0)
 530 #define bio_integrity_split(a, b, c)    do { } while (0)
 531 #define bio_integrity_set_tag(a, b, c)  do { } while (0)
 532 #define bio_integrity_get_tag(a, b, c)  do { } while (0)
 533 #define bio_integrity_init(a)           do { } while (0)
 534
 535 #endif /* CONFIG_BLK_DEV_INTEGRITY */
 536
 537 #endif /* CONFIG_BLOCK */
 538 #endif /* __LINUX_BIO_H */