LXR linux/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/* Platforms may set this to teach the BIO layer about IOMMU hardware. */
  30#include <asm/io.h>
  31
  32#if defined(BIO_VMERGE_MAX_SIZE) && defined(BIO_VMERGE_BOUNDARY)
  33#define BIOVEC_VIRT_START_SIZE(x) (bvec_to_phys(x) & (BIO_VMERGE_BOUNDARY - 1))
  34#define BIOVEC_VIRT_OVERSIZE(x) ((x) > BIO_VMERGE_MAX_SIZE)
  35#else
  36#define BIOVEC_VIRT_START_SIZE(x)       0
  37#define BIOVEC_VIRT_OVERSIZE(x)         0
  38#endif
  39
  40#ifndef BIO_VMERGE_BOUNDARY
  41#define BIO_VMERGE_BOUNDARY     0
  42#endif
  43
  44#define BIO_DEBUG
  45
  46#ifdef BIO_DEBUG
  47#define BIO_BUG_ON      BUG_ON
  48#else
  49#define BIO_BUG_ON
  50#endif
  51
  52#define BIO_MAX_PAGES           256
  53#define BIO_MAX_SIZE            (BIO_MAX_PAGES << PAGE_CACHE_SHIFT)
  54#define BIO_MAX_SECTORS         (BIO_MAX_SIZE >> 9)
  55
  56/*
  57 * was unsigned short, but we might as well be ready for > 64kB I/O pages
  58 */
  59struct bio_vec {
  60        struct page     *bv_page;
  61        unsigned int    bv_len;
  62        unsigned int    bv_offset;
  63};
  64
  65struct bio_set;
  66struct bio;
  67typedef void (bio_end_io_t) (struct bio *, int);
  68typedef void (bio_destructor_t) (struct bio *);
  69
  70/*
  71 * main unit of I/O for the block layer and lower layers (ie drivers and
  72 * stacking drivers)
  73 */
  74struct bio {
  75        sector_t                bi_sector;      /* device address in 512 byte
  76                                                   sectors */
  77        struct bio              *bi_next;       /* request queue link */
  78        struct block_device     *bi_bdev;
  79        unsigned long           bi_flags;       /* status, command, etc */
  80        unsigned long           bi_rw;          /* bottom bits READ/WRITE,
  81                                                 * top bits priority
  82                                                 */
  83
  84        unsigned short          bi_vcnt;        /* how many bio_vec's */
  85        unsigned short          bi_idx;         /* current index into bvl_vec */
  86
  87        /* Number of segments in this BIO after
  88         * physical address coalescing is performed.
  89         */
  90        unsigned short          bi_phys_segments;
  91
  92        /* Number of segments after physical and DMA remapping
  93         * hardware coalescing is performed.
  94         */
  95        unsigned short          bi_hw_segments;
  96
  97        unsigned int            bi_size;        /* residual I/O count */
  98
  99        /*
 100         * To keep track of the max hw size, we account for the
 101         * sizes of the first and last virtually mergeable segments
 102         * in this bio
 103         */
 104        unsigned int            bi_hw_front_size;
 105        unsigned int            bi_hw_back_size;
 106
 107        unsigned int            bi_max_vecs;    /* max bvl_vecs we can hold */
 108
 109        struct bio_vec          *bi_io_vec;     /* the actual vec list */
 110
 111        bio_end_io_t            *bi_end_io;
 112        atomic_t                bi_cnt;         /* pin count */
 113
 114        void                    *bi_private;
 115
 116        bio_destructor_t        *bi_destructor; /* destructor */
 117};
 118
 119/*
 120 * bio flags
 121 */
 122#define BIO_UPTODATE    0       /* ok after I/O completion */
 123#define BIO_RW_BLOCK    1       /* RW_AHEAD set, and read/write would block */
 124#define BIO_EOF         2       /* out-out-bounds error */
 125#define BIO_SEG_VALID   3       /* nr_hw_seg valid */
 126#define BIO_CLONED      4       /* doesn't own data */
 127#define BIO_BOUNCED     5       /* bio is a bounce bio */
 128#define BIO_USER_MAPPED 6       /* contains user pages */
 129#define BIO_EOPNOTSUPP  7       /* not supported */
 130#define bio_flagged(bio, flag)  ((bio)->bi_flags & (1 << (flag)))
 131
 132/*
 133 * top 4 bits of bio flags indicate the pool this bio came from
 134 */
 135#define BIO_POOL_BITS           (4)
 136#define BIO_POOL_OFFSET         (BITS_PER_LONG - BIO_POOL_BITS)
 137#define BIO_POOL_MASK           (1UL << BIO_POOL_OFFSET)
 138#define BIO_POOL_IDX(bio)       ((bio)->bi_flags >> BIO_POOL_OFFSET)    
 139
 140/*
 141 * bio bi_rw flags
 142 *
 143 * bit 0 -- read (not set) or write (set)
 144 * bit 1 -- rw-ahead when set
 145 * bit 2 -- barrier
 146 * bit 3 -- fail fast, don't want low level driver retries
 147 * bit 4 -- synchronous I/O hint: the block layer will unplug immediately
 148 */
 149#define BIO_RW          0
 150#define BIO_RW_AHEAD    1
 151#define BIO_RW_BARRIER  2
 152#define BIO_RW_FAILFAST 3
 153#define BIO_RW_SYNC     4
 154#define BIO_RW_META     5
 155
 156/*
 157 * upper 16 bits of bi_rw define the io priority of this bio
 158 */
 159#define BIO_PRIO_SHIFT  (8 * sizeof(unsigned long) - IOPRIO_BITS)
 160#define bio_prio(bio)   ((bio)->bi_rw >> BIO_PRIO_SHIFT)
 161#define bio_prio_valid(bio)     ioprio_valid(bio_prio(bio))
 162
 163#define bio_set_prio(bio, prio)         do {                    \
 164        WARN_ON(prio >= (1 << IOPRIO_BITS));                    \
 165        (bio)->bi_rw &= ((1UL << BIO_PRIO_SHIFT) - 1);          \
 166        (bio)->bi_rw |= ((unsigned long) (prio) << BIO_PRIO_SHIFT);     \
 167} while (0)
 168
 169/*
 170 * various member access, note that bio_data should of course not be used
 171 * on highmem page vectors
 172 */
 173#define bio_iovec_idx(bio, idx) (&((bio)->bi_io_vec[(idx)]))
 174#define bio_iovec(bio)          bio_iovec_idx((bio), (bio)->bi_idx)
 175#define bio_page(bio)           bio_iovec((bio))->bv_page
 176#define bio_offset(bio)         bio_iovec((bio))->bv_offset
 177#define bio_segments(bio)       ((bio)->bi_vcnt - (bio)->bi_idx)
 178#define bio_sectors(bio)        ((bio)->bi_size >> 9)
 179#define bio_barrier(bio)        ((bio)->bi_rw & (1 << BIO_RW_BARRIER))
 180#define bio_sync(bio)           ((bio)->bi_rw & (1 << BIO_RW_SYNC))
 181#define bio_failfast(bio)       ((bio)->bi_rw & (1 << BIO_RW_FAILFAST))
 182#define bio_rw_ahead(bio)       ((bio)->bi_rw & (1 << BIO_RW_AHEAD))
 183#define bio_rw_meta(bio)        ((bio)->bi_rw & (1 << BIO_RW_META))
 184#define bio_empty_barrier(bio)  (bio_barrier(bio) && !(bio)->bi_size)
 185
 186static inline unsigned int bio_cur_sectors(struct bio *bio)
 187{
 188        if (bio->bi_vcnt)
 189                return bio_iovec(bio)->bv_len >> 9;
 190
 191        return 0;
 192}
 193
 194static inline void *bio_data(struct bio *bio)
 195{
 196        if (bio->bi_vcnt)
 197                return page_address(bio_page(bio)) + bio_offset(bio);
 198
 199        return NULL;
 200}
 201
 202/*
 203 * will die
 204 */
 205#define bio_to_phys(bio)        (page_to_phys(bio_page((bio))) + (unsigned long) bio_offset((bio)))
 206#define bvec_to_phys(bv)        (page_to_phys((bv)->bv_page) + (unsigned long) (bv)->bv_offset)
 207
 208/*
 209 * queues that have highmem support enabled may still need to revert to
 210 * PIO transfers occasionally and thus map high pages temporarily. For
 211 * permanent PIO fall back, user is probably better off disabling highmem
 212 * I/O completely on that queue (see ide-dma for example)
 213 */
 214#define __bio_kmap_atomic(bio, idx, kmtype)                             \
 215        (kmap_atomic(bio_iovec_idx((bio), (idx))->bv_page, kmtype) +    \
 216                bio_iovec_idx((bio), (idx))->bv_offset)
 217
 218#define __bio_kunmap_atomic(addr, kmtype) kunmap_atomic(addr, kmtype)
 219
 220/*
 221 * merge helpers etc
 222 */
 223
 224#define __BVEC_END(bio)         bio_iovec_idx((bio), (bio)->bi_vcnt - 1)
 225#define __BVEC_START(bio)       bio_iovec_idx((bio), (bio)->bi_idx)
 226
 227/*
 228 * allow arch override, for eg virtualized architectures (put in asm/io.h)
 229 */
 230#ifndef BIOVEC_PHYS_MERGEABLE
 231#define BIOVEC_PHYS_MERGEABLE(vec1, vec2)       \
 232        ((bvec_to_phys((vec1)) + (vec1)->bv_len) == bvec_to_phys((vec2)))
 233#endif
 234
 235#define BIOVEC_VIRT_MERGEABLE(vec1, vec2)       \
 236        ((((bvec_to_phys((vec1)) + (vec1)->bv_len) | bvec_to_phys((vec2))) & (BIO_VMERGE_BOUNDARY - 1)) == 0)
 237#define __BIO_SEG_BOUNDARY(addr1, addr2, mask) \
 238        (((addr1) | (mask)) == (((addr2) - 1) | (mask)))
 239#define BIOVEC_SEG_BOUNDARY(q, b1, b2) \
 240        __BIO_SEG_BOUNDARY(bvec_to_phys((b1)), bvec_to_phys((b2)) + (b2)->bv_len, (q)->seg_boundary_mask)
 241#define BIO_SEG_BOUNDARY(q, b1, b2) \
 242        BIOVEC_SEG_BOUNDARY((q), __BVEC_END((b1)), __BVEC_START((b2)))
 243
 244#define bio_io_error(bio) bio_endio((bio), -EIO)
 245
 246/*
 247 * drivers should not use the __ version unless they _really_ want to
 248 * run through the entire bio and not just pending pieces
 249 */
 250#define __bio_for_each_segment(bvl, bio, i, start_idx)                  \
 251        for (bvl = bio_iovec_idx((bio), (start_idx)), i = (start_idx);  \
 252             i < (bio)->bi_vcnt;                                        \
 253             bvl++, i++)
 254
 255#define bio_for_each_segment(bvl, bio, i)                               \
 256        __bio_for_each_segment(bvl, bio, i, (bio)->bi_idx)
 257
 258/*
 259 * get a reference to a bio, so it won't disappear. the intended use is
 260 * something like:
 261 *
 262 * bio_get(bio);
 263 * submit_bio(rw, bio);
 264 * if (bio->bi_flags ...)
 265 *      do_something
 266 * bio_put(bio);
 267 *
 268 * without the bio_get(), it could potentially complete I/O before submit_bio
 269 * returns. and then bio would be freed memory when if (bio->bi_flags ...)
 270 * runs
 271 */
 272#define bio_get(bio)    atomic_inc(&(bio)->bi_cnt)
 273
 274
 275/*
 276 * A bio_pair is used when we need to split a bio.
 277 * This can only happen for a bio that refers to just one
 278 * page of data, and in the unusual situation when the
 279 * page crosses a chunk/device boundary
 280 *
 281 * The address of the master bio is stored in bio1.bi_private
 282 * The address of the pool the pair was allocated from is stored
 283 *   in bio2.bi_private
 284 */
 285struct bio_pair {
 286        struct bio      bio1, bio2;
 287        struct bio_vec  bv1, bv2;
 288        atomic_t        cnt;
 289        int             error;
 290};
 291extern struct bio_pair *bio_split(struct bio *bi, mempool_t *pool,
 292                                  int first_sectors);
 293extern mempool_t *bio_split_pool;
 294extern void bio_pair_release(struct bio_pair *dbio);
 295
 296extern struct bio_set *bioset_create(int, int);
 297extern void bioset_free(struct bio_set *);
 298
 299extern struct bio *bio_alloc(gfp_t, int);
 300extern struct bio *bio_alloc_bioset(gfp_t, int, struct bio_set *);
 301extern void bio_put(struct bio *);
 302extern void bio_free(struct bio *, struct bio_set *);
 303
 304extern void bio_endio(struct bio *, int);
 305struct request_queue;
 306extern int bio_phys_segments(struct request_queue *, struct bio *);
 307extern int bio_hw_segments(struct request_queue *, struct bio *);
 308
 309extern void __bio_clone(struct bio *, struct bio *);
 310extern struct bio *bio_clone(struct bio *, gfp_t);
 311
 312extern void bio_init(struct bio *);
 313
 314extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int);
 315extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,
 316                           unsigned int, unsigned int);
 317extern int bio_get_nr_vecs(struct block_device *);
 318extern struct bio *bio_map_user(struct request_queue *, struct block_device *,
 319                                unsigned long, unsigned int, int);
 320struct sg_iovec;
 321extern struct bio *bio_map_user_iov(struct request_queue *,
 322                                    struct block_device *,
 323                                    struct sg_iovec *, int, int);
 324extern void bio_unmap_user(struct bio *);
 325extern struct bio *bio_map_kern(struct request_queue *, void *, unsigned int,
 326                                gfp_t);
 327extern void bio_set_pages_dirty(struct bio *bio);
 328extern void bio_check_pages_dirty(struct bio *bio);
 329extern struct bio *bio_copy_user(struct request_queue *, unsigned long, unsigned int, int);
 330extern int bio_uncopy_user(struct bio *);
 331void zero_fill_bio(struct bio *bio);
 332
 333#ifdef CONFIG_HIGHMEM
 334/*
 335 * remember to add offset! and never ever reenable interrupts between a
 336 * bvec_kmap_irq and bvec_kunmap_irq!!
 337 *
 338 * This function MUST be inlined - it plays with the CPU interrupt flags.
 339 */
 340static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
 341{
 342        unsigned long addr;
 343
 344        /*
 345         * might not be a highmem page, but the preempt/irq count
 346         * balancing is a lot nicer this way
 347         */
 348        local_irq_save(*flags);
 349        addr = (unsigned long) kmap_atomic(bvec->bv_page, KM_BIO_SRC_IRQ);
 350
 351        BUG_ON(addr & ~PAGE_MASK);
 352
 353        return (char *) addr + bvec->bv_offset;
 354}
 355
 356static inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
 357{
 358        unsigned long ptr = (unsigned long) buffer & PAGE_MASK;
 359
 360        kunmap_atomic((void *) ptr, KM_BIO_SRC_IRQ);
 361        local_irq_restore(*flags);
 362}
 363
 364#else
 365#define bvec_kmap_irq(bvec, flags)      (page_address((bvec)->bv_page) + (bvec)->bv_offset)
 366#define bvec_kunmap_irq(buf, flags)     do { *(flags) = 0; } while (0)
 367#endif
 368
 369static inline char *__bio_kmap_irq(struct bio *bio, unsigned short idx,
 370                                   unsigned long *flags)
 371{
 372        return bvec_kmap_irq(bio_iovec_idx(bio, idx), flags);
 373}
 374#define __bio_kunmap_irq(buf, flags)    bvec_kunmap_irq(buf, flags)
 375
 376#define bio_kmap_irq(bio, flags) \
 377        __bio_kmap_irq((bio), (bio)->bi_idx, (flags))
 378#define bio_kunmap_irq(buf,flags)       __bio_kunmap_irq(buf, flags)
 379
 380#endif /* CONFIG_BLOCK */
 381#endif /* __LINUX_BIO_H */
 382