| 1 | |
| 2 | * bvec iterator
|
| 3 | *
|
| 4 | * Copyright (C) 2001 Ming Lei <[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_BVEC_ITER_H
|
| 21 | #define __LINUX_BVEC_ITER_H
|
| 22 |
|
| 23 | #include <linux/kernel.h>
|
| 24 | #include <linux/bug.h>
|
| 25 |
|
| 26 | |
| 27 | * was unsigned short, but we might as well be ready for > 64kB I/O pages
|
| 28 |
|
| 29 | struct bio_vec {
|
| 30 | struct page *bv_page;
|
| 31 | unsigned int bv_len;
|
| 32 | unsigned int bv_offset;
|
| 33 | };
|
| 34 |
|
| 35 | struct bvec_iter {
|
| 36 | sector_t bi_sector; |
| 37 | sectors
|
| 38 | unsigned int bi_size;
|
| 39 |
|
| 40 | unsigned int bi_idx;
|
| 41 |
|
| 42 | unsigned int bi_bvec_done; |
| 43 | current bvec
|
| 44 | };
|
| 45 |
|
| 46 | |
| 47 | * various member access, note that bio_data should of course not be used
|
| 48 | * on highmem page vectors
|
| 49 |
|
| 50 | #define __bvec_iter_bvec(bvec, iter) (&(bvec)[(iter).bi_idx])
|
| 51 |
|
| 52 | #define bvec_iter_page(bvec, iter) \
|
| 53 | (__bvec_iter_bvec((bvec), (iter))->bv_page)
|
| 54 |
|
| 55 | #define bvec_iter_len(bvec, iter) \
|
| 56 | min((iter).bi_size, \
|
| 57 | __bvec_iter_bvec((bvec), (iter))->bv_len - (iter).bi_bvec_done)
|
| 58 |
|
| 59 | #define bvec_iter_offset(bvec, iter) \
|
| 60 | (__bvec_iter_bvec((bvec), (iter))->bv_offset + (iter).bi_bvec_done)
|
| 61 |
|
| 62 | #define bvec_iter_bvec(bvec, iter) \
|
| 63 | ((struct bio_vec) { \
|
| 64 | .bv_page = bvec_iter_page((bvec), (iter)), \
|
| 65 | .bv_len = bvec_iter_len((bvec), (iter)), \
|
| 66 | .bv_offset = bvec_iter_offset((bvec), (iter)), \
|
| 67 | })
|
| 68 |
|
| 69 | static inline void bvec_iter_advance(const struct bio_vec *bv,
|
| 70 | struct bvec_iter *iter,
|
| 71 | unsigned bytes)
|
| 72 | {
|
| 73 | WARN_ONCE(bytes > iter->bi_size,
|
| 74 | "Attempted to advance past end of bvec iter\n");
|
| 75 |
|
| 76 | while (bytes) {
|
| 77 | unsigned iter_len = bvec_iter_len(bv, *iter);
|
| 78 | unsigned len = min(bytes, iter_len);
|
| 79 |
|
| 80 | bytes -= len;
|
| 81 | iter->bi_size -= len;
|
| 82 | iter->bi_bvec_done += len;
|
| 83 |
|
| 84 | if (iter->bi_bvec_done == __bvec_iter_bvec(bv, *iter)->bv_len) {
|
| 85 | iter->bi_bvec_done = 0;
|
| 86 | iter->bi_idx++;
|
| 87 | }
|
| 88 | }
|
| 89 | }
|
| 90 |
|
| 91 | #define for_each_bvec(bvl, bio_vec, iter, start) \
|
| 92 | for (iter = (start); \
|
| 93 | (iter).bi_size && \
|
| 94 | ((bvl = bvec_iter_bvec((bio_vec), (iter))), 1); \
|
| 95 | bvec_iter_advance((bio_vec), &(iter), (bvl).bv_len))
|
| 96 |
|
| 97 | #endif
|