1 /* 2 * 2.5 block I/O model 3 * 4 * Copyright (C) 2001 Jens Axboe <[email protected]> 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 */ 340