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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>
28 * was unsigned short, but we might as well be ready for > 64kB I/O pages
33 unsigned int bv_offset
;
37 sector_t bi_sector
; /* device address in 512 byte
39 unsigned int bi_size
; /* residual I/O count */
41 unsigned int bi_idx
; /* current index into bvl_vec */
43 unsigned int bi_bvec_done
; /* number of bytes completed in
48 * various member access, note that bio_data should of course not be used
49 * on highmem page vectors
51 #define __bvec_iter_bvec(bvec, iter) (&(bvec)[(iter).bi_idx])
53 #define bvec_iter_page(bvec, iter) \
54 (__bvec_iter_bvec((bvec), (iter))->bv_page)
56 #define bvec_iter_len(bvec, iter) \
58 __bvec_iter_bvec((bvec), (iter))->bv_len - (iter).bi_bvec_done)
60 #define bvec_iter_offset(bvec, iter) \
61 (__bvec_iter_bvec((bvec), (iter))->bv_offset + (iter).bi_bvec_done)
63 #define bvec_iter_bvec(bvec, iter) \
65 .bv_page = bvec_iter_page((bvec), (iter)), \
66 .bv_len = bvec_iter_len((bvec), (iter)), \
67 .bv_offset = bvec_iter_offset((bvec), (iter)), \
70 static inline bool bvec_iter_advance(const struct bio_vec
*bv
,
71 struct bvec_iter
*iter
, unsigned bytes
)
73 if (WARN_ONCE(bytes
> iter
->bi_size
,
74 "Attempted to advance past end of bvec iter\n")) {
80 unsigned iter_len
= bvec_iter_len(bv
, *iter
);
81 unsigned len
= min(bytes
, iter_len
);
85 iter
->bi_bvec_done
+= len
;
87 if (iter
->bi_bvec_done
== __bvec_iter_bvec(bv
, *iter
)->bv_len
) {
88 iter
->bi_bvec_done
= 0;
95 static inline bool bvec_iter_rewind(const struct bio_vec
*bv
,
96 struct bvec_iter
*iter
,
100 unsigned len
= min(bytes
, iter
->bi_bvec_done
);
102 if (iter
->bi_bvec_done
== 0) {
103 if (WARN_ONCE(iter
->bi_idx
== 0,
104 "Attempted to rewind iter beyond "
105 "bvec's boundaries\n")) {
109 iter
->bi_bvec_done
= __bvec_iter_bvec(bv
, *iter
)->bv_len
;
113 iter
->bi_size
+= len
;
114 iter
->bi_bvec_done
-= len
;
119 #define for_each_bvec(bvl, bio_vec, iter, start) \
120 for (iter = (start); \
122 ((bvl = bvec_iter_bvec((bio_vec), (iter))), 1); \
123 bvec_iter_advance((bio_vec), &(iter), (bvl).bv_len))
125 /* for iterating one bio from start to end */
126 #define BVEC_ITER_ALL_INIT (struct bvec_iter) \
129 .bi_size = UINT_MAX, \
134 #endif /* __LINUX_BVEC_ITER_H */