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/* Platforms may set this to teach the BIO layer about IOMMU hardware. */ 28#include <asm/io.h> 29 30#if defined(BIO_VMERGE_MAX_SIZE) && defined(BIO_VMERGE_BOUNDARY) 31#define BIOVEC_VIRT_START_SIZE(x) (bvec_to_phys(x) & (BIO_VMERGE_BOUNDARY - 1)) 32#define BIOVEC_VIRT_OVERSIZE(x) ((x) > BIO_VMERGE_MAX_SIZE) 33#else 34#define BIOVEC_VIRT_START_SIZE(x) 0 35#define BIOVEC_VIRT_OVERSIZE(x) 0 36#endif 37 38#ifndef BIO_VMERGE_BOUNDARY 39#define BIO_VMERGE_BOUNDARY 0 40#endif 41 42#define BIO_DEBUG 43 44#ifdef BIO_DEBUG 45#define BIO_BUG_ON BUG_ON 46#else 47#define BIO_BUG_ON 48#endif 49 50#define BIO_MAX_PAGES 256 51#define BIO_MAX_SIZE (BIO_MAX_PAGES << PAGE_CACHE_SHIFT) 52#define BIO_MAX_SECTORS (BIO_MAX_SIZE >> 9) 53 54/* 55 * was unsigned short, but we might as well be ready for > 64kB I/O pages 56 */ 57struct bio_vec { 58 struct page *bv_page; 59 unsigned int bv_len; 60 unsigned int bv_offset; 61}; 62 63struct bio_set; 64struct bio; 65typedef int (bio_end_io_t) (struct bio *, unsigned int, int); 66typedef void (bio_destructor_t) (struct bio *); 67 68/* 69 * main unit of I/O for the block layer and lower layers (ie drivers and 70 * stacking drivers) 71 */ 72struct bio { 73 sector_t bi_sector; 74 struct bio *bi_next; /* request queue link */ 75 struct block_device *bi_bdev; 76 unsigned long bi_flags; /* status, command, etc */ 77 unsigned long bi_rw; /* bottom bits READ/WRITE, 78 * top bits priority 79 */ 80 81 unsigned short bi_vcnt; /* how many bio_vec's */ 82 unsigned short bi_idx; /* current index into bvl_vec */ 83 84 /* Number of segments in this BIO after 85 * physical address coalescing is performed. 86 */ 87 unsigned short bi_phys_segments; 88 89 /* Number of segments after physical and DMA remapping 90 * hardware coalescing is performed. 91 */ 92 unsigned short bi_hw_segments; 93 94 unsigned int bi_size; /* residual I/O count */ 95 96 /* 97 * To keep track of the max hw size, we account for the 98 * sizes of the first and last virtually mergeable segments 99 * in this bio 100 */ 101 unsigned int bi_hw_front_size; 102 unsigned int bi_hw_back_size; 103 104 unsigned int bi_max_vecs; /* max bvl_vecs we can hold */ 105 106 struct bio_vec *bi_io_vec; /* the actual vec list */ 107 108 bio_end_io_t *bi_end_io; 109 atomic_t bi_cnt; /* pin count */ 110 111 void *bi_private; 112 113 bio_destructor_t *bi_destructor; /* destructor */ 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 * upper 16 bits of bi_rw define the io priority of this bio 154 */ 155#define BIO_PRIO_SHIFT (8 * sizeof(unsigned long) - IOPRIO_BITS) 156#define bio_prio(bio) ((bio)->bi_rw >> BIO_PRIO_SHIFT) 157#define bio_prio_valid(bio) ioprio_valid(bio_prio(bio)) 158 159#define bio_set_prio(bio, prio) do { \ 160 WARN_ON(prio >= (1 << IOPRIO_BITS)); \ 161 (bio)->bi_rw &= ((1UL << BIO_PRIO_SHIFT) - 1); \ 162 (bio)->bi_rw |= ((unsigned long) (prio) << BIO_PRIO_SHIFT); \ 163} while (0) 164 165/* 166 * various member access, note that bio_data should of course not be used 167 * on highmem page vectors 168 */ 169#define bio_iovec_idx(bio, idx) (&((bio)->bi_io_vec[(idx)])) 170#define bio_iovec(bio) bio_iovec_idx((bio), (bio)->bi_idx) 171#define bio_page(bio) bio_iovec((bio))->bv_page 172#define bio_offset(bio) bio_iovec((bio))->bv_offset 173#define bio_segments(bio) ((bio)->bi_vcnt - (bio)->bi_idx) 174#define bio_sectors(bio) ((bio)->bi_size >> 9) 175#define bio_cur_sectors(bio) (bio_iovec(bio)->bv_len >> 9) 176#define bio_data(bio) (page_address(bio_page((bio))) + bio_offset((bio))) 177#define bio_barrier(bio) ((bio)->bi_rw & (1 << BIO_RW_BARRIER)) 178#define bio_sync(bio) ((bio)->bi_rw & (1 << BIO_RW_SYNC)) 179#define bio_failfast(bio) ((bio)->bi_rw & (1 << BIO_RW_FAILFAST)) 180#define bio_rw_ahead(bio) ((bio)->bi_rw & (1 << BIO_RW_AHEAD)) 181 182/* 183 * will die 184 */ 185#define bio_to_phys(bio) (page_to_phys(bio_page((bio))) + (unsigned long) bio_offset((bio))) 186#define bvec_to_phys(bv) (page_to_phys((bv)->bv_page) + (unsigned long) (bv)->bv_offset) 187 188/* 189 * queues that have highmem support enabled may still need to revert to 190 * PIO transfers occasionally and thus map high pages temporarily. For 191 * permanent PIO fall back, user is probably better off disabling highmem 192 * I/O completely on that queue (see ide-dma for example) 193 */ 194#define __bio_kmap_atomic(bio, idx, kmtype) \ 195 (kmap_atomic(bio_iovec_idx((bio), (idx))->bv_page, kmtype) + \ 196 bio_iovec_idx((bio), (idx))->bv_offset) 197 198#define __bio_kunmap_atomic(addr, kmtype) kunmap_atomic(addr, kmtype) 199 200/* 201 * merge helpers etc 202 */ 203 204#define __BVEC_END(bio) bio_iovec_idx((bio), (bio)->bi_vcnt - 1) 205#define __BVEC_START(bio) bio_iovec_idx((bio), (bio)->bi_idx) 206 207/* 208 * allow arch override, for eg virtualized architectures (put in asm/io.h) 209 */ 210#ifndef BIOVEC_PHYS_MERGEABLE 211#define BIOVEC_PHYS_MERGEABLE(vec1, vec2) \ 212 ((bvec_to_phys((vec1)) + (vec1)->bv_len) == bvec_to_phys((vec2))) 213#endif 214 215#define BIOVEC_VIRT_MERGEABLE(vec1, vec2) \ 216 ((((bvec_to_phys((vec1)) + (vec1)->bv_len) | bvec_to_phys((vec2))) & (BIO_VMERGE_BOUNDARY - 1)) == 0) 217#define __BIO_SEG_BOUNDARY(addr1, addr2, mask) \ 218 (((addr1) | (mask)) == (((addr2) - 1) | (mask))) 219#define BIOVEC_SEG_BOUNDARY(q, b1, b2) \ 220 __BIO_SEG_BOUNDARY(bvec_to_phys((b1)), bvec_to_phys((b2)) + (b2)->bv_len, (q)->seg_boundary_mask) 221#define BIO_SEG_BOUNDARY(q, b1, b2) \ 222 BIOVEC_SEG_BOUNDARY((q), __BVEC_END((b1)), __BVEC_START((b2))) 223 224#define bio_io_error(bio, bytes) bio_endio((bio), (bytes), -EIO) 225 226/* 227 * drivers should not use the __ version unless they _really_ want to 228 * run through the entire bio and not just pending pieces 229 */ 230#define __bio_for_each_segment(bvl, bio, i, start_idx) \ 231 for (bvl = bio_iovec_idx((bio), (start_idx)), i = (start_idx); \ 232 i < (bio)->bi_vcnt; \ 233 bvl++, i++) 234 235#define bio_for_each_segment(bvl, bio, i) \ 236 __bio_for_each_segment(bvl, bio, i, (bio)->bi_idx) 237 238/* 239 * get a reference to a bio, so it won't disappear. the intended use is 240 * something like: 241 * 242 * bio_get(bio); 243 * submit_bio(rw, bio); 244 * if (bio->bi_flags ...) 245 * do_something 246 * bio_put(bio); 247 * 248 * without the bio_get(), it could potentially complete I/O before submit_bio 249 * returns. and then bio would be freed memory when if (bio->bi_flags ...) 250 * runs 251 */ 252#define bio_get(bio) atomic_inc(&(bio)->bi_cnt) 253 254 255/* 256 * A bio_pair is used when we need to split a bio. 257 * This can only happen for a bio that refers to just one 258 * page of data, and in the unusual situation when the 259 * page crosses a chunk/device boundary 260 * 261 * The address of the master bio is stored in bio1.bi_private 262 * The address of the pool the pair was allocated from is stored 263 * in bio2.bi_private 264 */ 265struct bio_pair { 266 struct bio bio1, bio2; 267 struct bio_vec bv1, bv2; 268 atomic_t cnt; 269 int error; 270}; 271extern struct bio_pair *bio_split(struct bio *bi, mempool_t *pool, 272 int first_sectors); 273extern mempool_t *bio_split_pool; 274extern void bio_pair_release(struct bio_pair *dbio); 275 276extern struct bio_set *bioset_create(int, int, int); 277extern void bioset_free(struct bio_set *); 278 279extern struct bio *bio_alloc(gfp_t, int); 280extern struct bio *bio_alloc_bioset(gfp_t, int, struct bio_set *); 281extern void bio_put(struct bio *); 282extern void bio_free(struct bio *, struct bio_set *); 283 284extern void bio_endio(struct bio *, unsigned int, int); 285struct request_queue; 286extern int bio_phys_segments(struct request_queue *, struct bio *); 287extern int bio_hw_segments(struct request_queue *, struct bio *); 288 289extern void __bio_clone(struct bio *, struct bio *); 290extern struct bio *bio_clone(struct bio *, gfp_t); 291 292extern void bio_init(struct bio *); 293 294extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int); 295extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *, 296 unsigned int, unsigned int); 297extern int bio_get_nr_vecs(struct block_device *); 298extern struct bio *bio_map_user(struct request_queue *, struct block_device *, 299 unsigned long, unsigned int, int); 300struct sg_iovec; 301extern struct bio *bio_map_user_iov(struct request_queue *, 302 struct block_device *, 303 struct sg_iovec *, int, int); 304extern void bio_unmap_user(struct bio *); 305extern struct bio *bio_map_kern(struct request_queue *, void *, unsigned int, 306 gfp_t); 307extern void bio_set_pages_dirty(struct bio *bio); 308extern void bio_check_pages_dirty(struct bio *bio); 309extern struct bio *bio_copy_user(struct request_queue *, unsigned long, unsigned int, int); 310extern int bio_uncopy_user(struct bio *); 311void zero_fill_bio(struct bio *bio); 312 313#ifdef CONFIG_HIGHMEM 314/* 315 * remember to add offset! and never ever reenable interrupts between a 316 * bvec_kmap_irq and bvec_kunmap_irq!! 317 * 318 * This function MUST be inlined - it plays with the CPU interrupt flags. 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, KM_BIO_SRC_IRQ); 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, KM_BIO_SRC_IRQ); 341 local_irq_restore(*flags); 342} 343 344#else 345#define bvec_kmap_irq(bvec, flags) (page_address((bvec)->bv_page) + (bvec)->bv_offset) 346#define bvec_kunmap_irq(buf, flags) do { *(flags) = 0; } while (0) 347#endif 348 349static inline char *__bio_kmap_irq(struct bio *bio, unsigned short idx, 350 unsigned long *flags) 351{ 352 return bvec_kmap_irq(bio_iovec_idx(bio, idx), flags); 353} 354#define __bio_kunmap_irq(buf, flags) bvec_kunmap_irq(buf, flags) 355 356#define bio_kmap_irq(bio, flags) \ 357 __bio_kmap_irq((bio), (bio)->bi_idx, (flags)) 358#define bio_kunmap_irq(buf,flags) __bio_kunmap_irq(buf, flags) 359 360#endif /* __LINUX_BIO_H */ 361