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
  26 /* Platforms may set this to teach the BIO layer about IOMMU hardware. */
  27 #include <asm/io.h>
  28
  29 #if defined(BIO_VMERGE_MAX_SIZE) && defined(BIO_VMERGE_BOUNDARY)
  30 #define BIOVEC_VIRT_START_SIZE(x) (bvec_to_phys(x) & (BIO_VMERGE_BOUNDARY - 1))
  31 #define BIOVEC_VIRT_OVERSIZE(x) ((x) > BIO_VMERGE_MAX_SIZE)
  32 #else
  33 #define BIOVEC_VIRT_START_SIZE(x)       0
  34 #define BIOVEC_VIRT_OVERSIZE(x)         0
  35 #endif
  36
  37 #ifndef BIO_VMERGE_BOUNDARY
  38 #define BIO_VMERGE_BOUNDARY     0
  39 #endif
  40
  41 #define BIO_DEBUG
  42
  43 #ifdef BIO_DEBUG
  44 #define BIO_BUG_ON      BUG_ON
  45 #else
  46 #define BIO_BUG_ON
  47 #endif
  48
  49 #define BIO_MAX_PAGES           (256)
  50 #define BIO_MAX_SIZE            (BIO_MAX_PAGES << PAGE_CACHE_SHIFT)
  51 #define BIO_MAX_SECTORS         (BIO_MAX_SIZE >> 9)
  52
  53 /*
  54  * was unsigned short, but we might as well be ready for > 64kB I/O pages
  55  */
  56 struct bio_vec {
  57         struct page     *bv_page;
  58         unsigned int    bv_len;
  59         unsigned int    bv_offset;
  60 };
  61
  62 struct bio_set;
  63 struct bio;
  64 typedef int (bio_end_io_t) (struct bio *, unsigned int, int);
  65 typedef void (bio_destructor_t) (struct bio *);
  66
  67 /*
  68  * main unit of I/O for the block layer and lower layers (ie drivers and
  69  * stacking drivers)
  70  */
  71 struct bio {
  72         sector_t                bi_sector;
  73         struct bio              *bi_next;       /* request queue link */
  74         struct block_device     *bi_bdev;
  75         unsigned long           bi_flags;       /* status, command, etc */
  76         unsigned long           bi_rw;          /* bottom bits READ/WRITE,
  77                                                  * top bits priority
  78                                                  */
  79
  80         unsigned short          bi_vcnt;        /* how many bio_vec's */
  81         unsigned short          bi_idx;         /* current index into bvl_vec */
  82
  83         /* Number of segments in this BIO after
  84          * physical address coalescing is performed.
  85          */
  86         unsigned short          bi_phys_segments;
  87
  88         /* Number of segments after physical and DMA remapping
  89          * hardware coalescing is performed.
  90          */
  91         unsigned short          bi_hw_segments;
  92
  93         unsigned int            bi_size;        /* residual I/O count */
  94
  95         /*
  96          * To keep track of the max hw size, we account for the
  97          * sizes of the first and last virtually mergeable segments
  98          * in this bio
  99          */
 100         unsigned int            bi_hw_front_size;
 101         unsigned int            bi_hw_back_size;
 102
 103         unsigned int            bi_max_vecs;    /* max bvl_vecs we can hold */
 104
 105         struct bio_vec          *bi_io_vec;     /* the actual vec list */
 106
 107         bio_end_io_t            *bi_end_io;
 108         atomic_t                bi_cnt;         /* pin count */
 109
 110         void                    *bi_private;
 111
 112         bio_destructor_t        *bi_destructor; /* destructor */
 113         struct bio_set          *bi_set;        /* memory pools set */
 114 };
 115
 116 /*
 117  * bio flags
 118  */
 119 #define BIO_UPTODATE    0       /* ok after I/O completion */
 120 #define BIO_RW_BLOCK    1       /* RW_AHEAD set, and read/write would block */
 121 #define BIO_EOF         2       /* out-out-bounds error */
 122 #define BIO_SEG_VALID   3       /* nr_hw_seg valid */
 123 #define BIO_CLONED      4       /* doesn't own data */
 124 #define BIO_BOUNCED     5       /* bio is a bounce bio */
 125 #define BIO_USER_MAPPED 6       /* contains user pages */
 126 #define BIO_EOPNOTSUPP  7       /* not supported */
 127 #define bio_flagged(bio, flag)  ((bio)->bi_flags & (1 << (flag)))
 128
 129 /*
 130  * top 4 bits of bio flags indicate the pool this bio came from
 131  */
 132 #define BIO_POOL_BITS           (4)
 133 #define BIO_POOL_OFFSET         (BITS_PER_LONG - BIO_POOL_BITS)
 134 #define BIO_POOL_MASK           (1UL << BIO_POOL_OFFSET)
 135 #define BIO_POOL_IDX(bio)       ((bio)->bi_flags >> BIO_POOL_OFFSET)
 136
 137 /*
 138  * bio bi_rw flags
 139  *
 140  * bit 0 -- read (not set) or write (set)
 141  * bit 1 -- rw-ahead when set
 142  * bit 2 -- barrier
 143  * bit 3 -- fail fast, don't want low level driver retries
 144  * bit 4 -- synchronous I/O hint: the block layer will unplug immediately
 145  */
 146 #define BIO_RW          0
 147 #define BIO_RW_AHEAD    1
 148 #define BIO_RW_BARRIER  2
 149 #define BIO_RW_FAILFAST 3
 150 #define BIO_RW_SYNC     4
 151
 152 /*
 153  * various member access, note that bio_data should of course not be used
 154  * on highmem page vectors
 155  */
 156 #define bio_iovec_idx(bio, idx) (&((bio)->bi_io_vec[(idx)]))
 157 #define bio_iovec(bio)          bio_iovec_idx((bio), (bio)->bi_idx)
 158 #define bio_page(bio)           bio_iovec((bio))->bv_page
 159 #define bio_offset(bio)         bio_iovec((bio))->bv_offset
 160 #define bio_segments(bio)       ((bio)->bi_vcnt - (bio)->bi_idx)
 161 #define bio_sectors(bio)        ((bio)->bi_size >> 9)
 162 #define bio_cur_sectors(bio)    (bio_iovec(bio)->bv_len >> 9)
 163 #define bio_data(bio)           (page_address(bio_page((bio))) + bio_offset((bio)))
 164 #define bio_barrier(bio)        ((bio)->bi_rw & (1 << BIO_RW_BARRIER))
 165 #define bio_sync(bio)           ((bio)->bi_rw & (1 << BIO_RW_SYNC))
 166 #define bio_failfast(bio)       ((bio)->bi_rw & (1 << BIO_RW_FAILFAST))
 167 #define bio_rw_ahead(bio)       ((bio)->bi_rw & (1 << BIO_RW_AHEAD))
 168
 169 /*
 170  * will die
 171  */
 172 #define bio_to_phys(bio)        (page_to_phys(bio_page((bio))) + (unsigned long) bio_offset((bio)))
 173 #define bvec_to_phys(bv)        (page_to_phys((bv)->bv_page) + (unsigned long) (bv)->bv_offset)
 174
 175 /*
 176  * queues that have highmem support enabled may still need to revert to
 177  * PIO transfers occasionally and thus map high pages temporarily. For
 178  * permanent PIO fall back, user is probably better off disabling highmem
 179  * I/O completely on that queue (see ide-dma for example)
 180  */
 181 #define __bio_kmap_atomic(bio, idx, kmtype)                             \
 182         (kmap_atomic(bio_iovec_idx((bio), (idx))->bv_page, kmtype) +    \
 183                 bio_iovec_idx((bio), (idx))->bv_offset)
 184
 185 #define __bio_kunmap_atomic(addr, kmtype) kunmap_atomic(addr, kmtype)
 186
 187 /*
 188  * merge helpers etc
 189  */
 190
 191 #define __BVEC_END(bio)         bio_iovec_idx((bio), (bio)->bi_vcnt - 1)
 192 #define __BVEC_START(bio)       bio_iovec_idx((bio), (bio)->bi_idx)
 193
 194 /*
 195  * allow arch override, for eg virtualized architectures (put in asm/io.h)
 196  */
 197 #ifndef BIOVEC_PHYS_MERGEABLE
 198 #define BIOVEC_PHYS_MERGEABLE(vec1, vec2)       \
 199         ((bvec_to_phys((vec1)) + (vec1)->bv_len) == bvec_to_phys((vec2)))
 200 #endif
 201
 202 #define BIOVEC_VIRT_MERGEABLE(vec1, vec2)       \
 203         ((((bvec_to_phys((vec1)) + (vec1)->bv_len) | bvec_to_phys((vec2))) & (BIO_VMERGE_BOUNDARY - 1)) == 0)
 204 #define __BIO_SEG_BOUNDARY(addr1, addr2, mask) \
 205         (((addr1) | (mask)) == (((addr2) - 1) | (mask)))
 206 #define BIOVEC_SEG_BOUNDARY(q, b1, b2) \
 207         __BIO_SEG_BOUNDARY(bvec_to_phys((b1)), bvec_to_phys((b2)) + (b2)->bv_len, (q)->seg_boundary_mask)
 208 #define BIO_SEG_BOUNDARY(q, b1, b2) \
 209         BIOVEC_SEG_BOUNDARY((q), __BVEC_END((b1)), __BVEC_START((b2)))
 210
 211 #define bio_io_error(bio, bytes) bio_endio((bio), (bytes), -EIO)
 212
 213 /*
 214  * drivers should not use the __ version unless they _really_ want to
 215  * run through the entire bio and not just pending pieces
 216  */
 217 #define __bio_for_each_segment(bvl, bio, i, start_idx)                  \
 218         for (bvl = bio_iovec_idx((bio), (start_idx)), i = (start_idx);  \
 219              i < (bio)->bi_vcnt;                                        \
 220              bvl++, i++)
 221
 222 #define bio_for_each_segment(bvl, bio, i)                               \
 223         __bio_for_each_segment(bvl, bio, i, (bio)->bi_idx)
 224
 225 /*
 226  * get a reference to a bio, so it won't disappear. the intended use is
 227  * something like:
 228  *
 229  * bio_get(bio);
 230  * submit_bio(rw, bio);
 231  * if (bio->bi_flags ...)
 232  *      do_something
 233  * bio_put(bio);
 234  *
 235  * without the bio_get(), it could potentially complete I/O before submit_bio
 236  * returns. and then bio would be freed memory when if (bio->bi_flags ...)
 237  * runs
 238  */
 239 #define bio_get(bio)    atomic_inc(&(bio)->bi_cnt)
 240
 241
 242 /*
 243  * A bio_pair is used when we need to split a bio.
 244  * This can only happen for a bio that refers to just one
 245  * page of data, and in the unusual situation when the
 246  * page crosses a chunk/device boundary
 247  *
 248  * The address of the master bio is stored in bio1.bi_private
 249  * The address of the pool the pair was allocated from is stored
 250  *   in bio2.bi_private
 251  */
 252 struct bio_pair {
 253         struct bio      bio1, bio2;
 254         struct bio_vec  bv1, bv2;
 255         atomic_t        cnt;
 256         int             error;
 257 };
 258 extern struct bio_pair *bio_split(struct bio *bi, mempool_t *pool,
 259                                   int first_sectors);
 260 extern mempool_t *bio_split_pool;
 261 extern void bio_pair_release(struct bio_pair *dbio);
 262
 263 extern struct bio_set *bioset_create(int, int, int);
 264 extern void bioset_free(struct bio_set *);
 265
 266 extern struct bio *bio_alloc(unsigned int __nocast, int);
 267 extern struct bio *bio_alloc_bioset(unsigned int __nocast, int, struct bio_set *);
 268 extern void bio_put(struct bio *);
 269
 270 extern void bio_endio(struct bio *, unsigned int, int);
 271 struct request_queue;
 272 extern int bio_phys_segments(struct request_queue *, struct bio *);
 273 extern int bio_hw_segments(struct request_queue *, struct bio *);
 274
 275 extern void __bio_clone(struct bio *, struct bio *);
 276 extern struct bio *bio_clone(struct bio *, unsigned int __nocast);
 277
 278 extern void bio_init(struct bio *);
 279
 280 extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int);
 281 extern int bio_get_nr_vecs(struct block_device *);
 282 extern struct bio *bio_map_user(struct request_queue *, struct block_device *,
 283                                 unsigned long, unsigned int, int);
 284 extern void bio_unmap_user(struct bio *);
 285 extern void bio_set_pages_dirty(struct bio *bio);
 286 extern void bio_check_pages_dirty(struct bio *bio);
 287 extern struct bio *bio_copy_user(struct request_queue *, unsigned long, unsigned int, int);
 288 extern int bio_uncopy_user(struct bio *);
 289 void zero_fill_bio(struct bio *bio);
 290
 291 #ifdef CONFIG_HIGHMEM
 292 /*
 293  * remember to add offset! and never ever reenable interrupts between a
 294  * bvec_kmap_irq and bvec_kunmap_irq!!
 295  *
 296  * This function MUST be inlined - it plays with the CPU interrupt flags.
 297  * Hence the `extern inline'.
 298  */
 299 extern inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
 300 {
 301         unsigned long addr;
 302
 303         /*
 304          * might not be a highmem page, but the preempt/irq count
 305          * balancing is a lot nicer this way
 306          */
 307         local_irq_save(*flags);
 308         addr = (unsigned long) kmap_atomic(bvec->bv_page, KM_BIO_SRC_IRQ);
 309
 310         BUG_ON(addr & ~PAGE_MASK);
 311
 312         return (char *) addr + bvec->bv_offset;
 313 }
 314
 315 extern inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
 316 {
 317         unsigned long ptr = (unsigned long) buffer & PAGE_MASK;
 318
 319         kunmap_atomic((void *) ptr, KM_BIO_SRC_IRQ);
 320         local_irq_restore(*flags);
 321 }
 322
 323 #else
 324 #define bvec_kmap_irq(bvec, flags)      (page_address((bvec)->bv_page) + (bvec)->bv_offset)
 325 #define bvec_kunmap_irq(buf, flags)     do { *(flags) = 0; } while (0)
 326 #endif
 327
 328 extern inline char *__bio_kmap_irq(struct bio *bio, unsigned short idx,
 329                                    unsigned long *flags)
 330 {
 331         return bvec_kmap_irq(bio_iovec_idx(bio, idx), flags);
 332 }
 333 #define __bio_kunmap_irq(buf, flags)    bvec_kunmap_irq(buf, flags)
 334
 335 #define bio_kmap_irq(bio, flags) \
 336         __bio_kmap_irq((bio), (bio)->bi_idx, (flags))
 337 #define bio_kunmap_irq(buf,flags)       __bio_kunmap_irq(buf, flags)
 338
 339 #endif /* __LINUX_BIO_H */