Commit | Line | Data |
---|---|---|
8fc55455 ML |
1 | /* |
2 | * bvec iterator | |
3 | * | |
4 | * Copyright (C) 2001 Ming Lei <ming.lei@canonical.com> | |
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 | ||
0781e79e ML |
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; /* device address in 512 byte | |
37 | sectors */ | |
38 | unsigned int bi_size; /* residual I/O count */ | |
39 | ||
40 | unsigned int bi_idx; /* current index into bvl_vec */ | |
41 | ||
42 | unsigned int bi_bvec_done; /* number of bytes completed in | |
43 | current bvec */ | |
44 | }; | |
8fc55455 ML |
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 | ||
80f162ff ML |
69 | static inline void bvec_iter_advance(const struct bio_vec *bv, |
70 | struct bvec_iter *iter, | |
8fc55455 ML |
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) { | |
1ea049b2 JB |
77 | unsigned iter_len = bvec_iter_len(bv, *iter); |
78 | unsigned len = min(bytes, iter_len); | |
8fc55455 ML |
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 /* __LINUX_BVEC_ITER_H */ |