4 * Copyright (C) 2001 Ming Lei <ming.lei@canonical.com>
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.
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
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-
20 #ifndef __LINUX_BVEC_ITER_H
21 #define __LINUX_BVEC_ITER_H
23 #include <linux/kernel.h>
24 #include <linux/bug.h>
25 #include <linux/errno.h>
29 * was unsigned short, but we might as well be ready for > 64kB I/O pages
34 unsigned int bv_offset;
38 sector_t bi_sector; /* device address in 512 byte
40 unsigned int bi_size; /* residual I/O count */
42 unsigned int bi_idx; /* current index into bvl_vec */
44 unsigned int bi_done; /* number of bytes completed */
46 unsigned int bi_bvec_done; /* number of bytes completed in
51 * various member access, note that bio_data should of course not be used
52 * on highmem page vectors
54 #define __bvec_iter_bvec(bvec, iter) (&(bvec)[(iter).bi_idx])
56 /* multi-page (mp_bvec) helpers */
57 #define mp_bvec_iter_page(bvec, iter) \
58 (__bvec_iter_bvec((bvec), (iter))->bv_page)
60 #define mp_bvec_iter_len(bvec, iter) \
62 __bvec_iter_bvec((bvec), (iter))->bv_len - (iter).bi_bvec_done)
64 #define mp_bvec_iter_offset(bvec, iter) \
65 (__bvec_iter_bvec((bvec), (iter))->bv_offset + (iter).bi_bvec_done)
67 #define mp_bvec_iter_page_idx(bvec, iter) \
68 (mp_bvec_iter_offset((bvec), (iter)) / PAGE_SIZE)
70 #define mp_bvec_iter_bvec(bvec, iter) \
72 .bv_page = mp_bvec_iter_page((bvec), (iter)), \
73 .bv_len = mp_bvec_iter_len((bvec), (iter)), \
74 .bv_offset = mp_bvec_iter_offset((bvec), (iter)), \
77 /* For building single-page bvec in flight */
78 #define bvec_iter_offset(bvec, iter) \
79 (mp_bvec_iter_offset((bvec), (iter)) % PAGE_SIZE)
81 #define bvec_iter_len(bvec, iter) \
82 min_t(unsigned, mp_bvec_iter_len((bvec), (iter)), \
83 PAGE_SIZE - bvec_iter_offset((bvec), (iter)))
85 #define bvec_iter_page(bvec, iter) \
86 nth_page(mp_bvec_iter_page((bvec), (iter)), \
87 mp_bvec_iter_page_idx((bvec), (iter)))
89 #define bvec_iter_bvec(bvec, iter) \
91 .bv_page = bvec_iter_page((bvec), (iter)), \
92 .bv_len = bvec_iter_len((bvec), (iter)), \
93 .bv_offset = bvec_iter_offset((bvec), (iter)), \
96 static inline bool bvec_iter_advance(const struct bio_vec *bv,
97 struct bvec_iter *iter, unsigned bytes)
99 if (WARN_ONCE(bytes > iter->bi_size,
100 "Attempted to advance past end of bvec iter\n")) {
106 unsigned iter_len = bvec_iter_len(bv, *iter);
107 unsigned len = min(bytes, iter_len);
110 iter->bi_size -= len;
111 iter->bi_bvec_done += len;
112 iter->bi_done += len;
114 if (iter->bi_bvec_done == __bvec_iter_bvec(bv, *iter)->bv_len) {
115 iter->bi_bvec_done = 0;
122 static inline bool bvec_iter_rewind(const struct bio_vec *bv,
123 struct bvec_iter *iter,
127 unsigned len = min(bytes, iter->bi_bvec_done);
129 if (iter->bi_bvec_done == 0) {
130 if (WARN_ONCE(iter->bi_idx == 0,
131 "Attempted to rewind iter beyond "
132 "bvec's boundaries\n")) {
136 iter->bi_bvec_done = __bvec_iter_bvec(bv, *iter)->bv_len;
140 iter->bi_size += len;
141 iter->bi_bvec_done -= len;
146 static inline void bvec_iter_skip_zero_bvec(struct bvec_iter *iter)
148 iter->bi_bvec_done = 0;
152 #define for_each_bvec(bvl, bio_vec, iter, start) \
153 for (iter = (start); \
155 ((bvl = bvec_iter_bvec((bio_vec), (iter))), 1); \
156 (bvl).bv_len ? (void)bvec_iter_advance((bio_vec), &(iter), \
157 (bvl).bv_len) : bvec_iter_skip_zero_bvec(&(iter)))
159 #endif /* __LINUX_BVEC_ITER_H */