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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> | |
b1fb2c52 | 25 | #include <linux/errno.h> |
0781e79e ML |
26 | |
27 | /* | |
28 | * was unsigned short, but we might as well be ready for > 64kB I/O pages | |
29 | */ | |
30 | struct bio_vec { | |
31 | struct page *bv_page; | |
32 | unsigned int bv_len; | |
33 | unsigned int bv_offset; | |
34 | }; | |
35 | ||
36 | struct bvec_iter { | |
37 | sector_t bi_sector; /* device address in 512 byte | |
38 | sectors */ | |
39 | unsigned int bi_size; /* residual I/O count */ | |
40 | ||
41 | unsigned int bi_idx; /* current index into bvl_vec */ | |
42 | ||
f9df1cd9 DM |
43 | unsigned int bi_done; /* number of bytes completed */ |
44 | ||
0781e79e ML |
45 | unsigned int bi_bvec_done; /* number of bytes completed in |
46 | current bvec */ | |
47 | }; | |
8fc55455 ML |
48 | |
49 | /* | |
50 | * various member access, note that bio_data should of course not be used | |
51 | * on highmem page vectors | |
52 | */ | |
53 | #define __bvec_iter_bvec(bvec, iter) (&(bvec)[(iter).bi_idx]) | |
54 | ||
55 | #define bvec_iter_page(bvec, iter) \ | |
56 | (__bvec_iter_bvec((bvec), (iter))->bv_page) | |
57 | ||
58 | #define bvec_iter_len(bvec, iter) \ | |
59 | min((iter).bi_size, \ | |
60 | __bvec_iter_bvec((bvec), (iter))->bv_len - (iter).bi_bvec_done) | |
61 | ||
62 | #define bvec_iter_offset(bvec, iter) \ | |
63 | (__bvec_iter_bvec((bvec), (iter))->bv_offset + (iter).bi_bvec_done) | |
64 | ||
65 | #define bvec_iter_bvec(bvec, iter) \ | |
66 | ((struct bio_vec) { \ | |
67 | .bv_page = bvec_iter_page((bvec), (iter)), \ | |
68 | .bv_len = bvec_iter_len((bvec), (iter)), \ | |
69 | .bv_offset = bvec_iter_offset((bvec), (iter)), \ | |
70 | }) | |
71 | ||
b1fb2c52 DM |
72 | static inline bool bvec_iter_advance(const struct bio_vec *bv, |
73 | struct bvec_iter *iter, unsigned bytes) | |
8fc55455 | 74 | { |
b1fb2c52 DM |
75 | if (WARN_ONCE(bytes > iter->bi_size, |
76 | "Attempted to advance past end of bvec iter\n")) { | |
77 | iter->bi_size = 0; | |
78 | return false; | |
79 | } | |
8fc55455 ML |
80 | |
81 | while (bytes) { | |
1ea049b2 JB |
82 | unsigned iter_len = bvec_iter_len(bv, *iter); |
83 | unsigned len = min(bytes, iter_len); | |
8fc55455 ML |
84 | |
85 | bytes -= len; | |
86 | iter->bi_size -= len; | |
87 | iter->bi_bvec_done += len; | |
f9df1cd9 | 88 | iter->bi_done += len; |
8fc55455 ML |
89 | |
90 | if (iter->bi_bvec_done == __bvec_iter_bvec(bv, *iter)->bv_len) { | |
91 | iter->bi_bvec_done = 0; | |
92 | iter->bi_idx++; | |
93 | } | |
94 | } | |
b1fb2c52 | 95 | return true; |
8fc55455 ML |
96 | } |
97 | ||
f9df1cd9 DM |
98 | static inline bool bvec_iter_rewind(const struct bio_vec *bv, |
99 | struct bvec_iter *iter, | |
100 | unsigned int bytes) | |
101 | { | |
102 | while (bytes) { | |
103 | unsigned len = min(bytes, iter->bi_bvec_done); | |
104 | ||
105 | if (iter->bi_bvec_done == 0) { | |
106 | if (WARN_ONCE(iter->bi_idx == 0, | |
107 | "Attempted to rewind iter beyond " | |
108 | "bvec's boundaries\n")) { | |
109 | return false; | |
110 | } | |
111 | iter->bi_idx--; | |
112 | iter->bi_bvec_done = __bvec_iter_bvec(bv, *iter)->bv_len; | |
113 | continue; | |
114 | } | |
115 | bytes -= len; | |
116 | iter->bi_size += len; | |
117 | iter->bi_bvec_done -= len; | |
118 | } | |
119 | return true; | |
120 | } | |
121 | ||
8fc55455 ML |
122 | #define for_each_bvec(bvl, bio_vec, iter, start) \ |
123 | for (iter = (start); \ | |
124 | (iter).bi_size && \ | |
125 | ((bvl = bvec_iter_bvec((bio_vec), (iter))), 1); \ | |
126 | bvec_iter_advance((bio_vec), &(iter), (bvl).bv_len)) | |
127 | ||
128 | #endif /* __LINUX_BVEC_ITER_H */ |