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Christoph Hellwig8c165672019-04-30 14:42:39 -04001/* SPDX-License-Identifier: GPL-2.0 */
Ming Lei8fc55452016-06-09 10:00:58 -06002/*
3 * bvec iterator
4 *
5 * Copyright (C) 2001 Ming Lei <ming.lei@canonical.com>
Ming Lei8fc55452016-06-09 10:00:58 -06006 */
7#ifndef __LINUX_BVEC_ITER_H
8#define __LINUX_BVEC_ITER_H
9
Ming Lei0781e792016-05-30 21:34:30 +080010#include <linux/kernel.h>
11#include <linux/bug.h>
Dmitry Monakhovb1fb2c52017-06-29 11:31:13 -070012#include <linux/errno.h>
Ming Lei3d75ca02019-02-15 19:13:10 +080013#include <linux/mm.h>
Ming Lei0781e792016-05-30 21:34:30 +080014
15/*
16 * was unsigned short, but we might as well be ready for > 64kB I/O pages
17 */
18struct bio_vec {
19 struct page *bv_page;
20 unsigned int bv_len;
21 unsigned int bv_offset;
22};
23
24struct bvec_iter {
25 sector_t bi_sector; /* device address in 512 byte
26 sectors */
27 unsigned int bi_size; /* residual I/O count */
28
29 unsigned int bi_idx; /* current index into bvl_vec */
30
31 unsigned int bi_bvec_done; /* number of bytes completed in
32 current bvec */
33};
Ming Lei8fc55452016-06-09 10:00:58 -060034
Ming Lei6dc4f102019-02-15 19:13:19 +080035struct bvec_iter_all {
36 struct bio_vec bv;
37 int idx;
38 unsigned done;
39};
40
Ming Lei8fc55452016-06-09 10:00:58 -060041/*
42 * various member access, note that bio_data should of course not be used
43 * on highmem page vectors
44 */
45#define __bvec_iter_bvec(bvec, iter) (&(bvec)[(iter).bi_idx])
46
Ming Lei3d75ca02019-02-15 19:13:10 +080047/* multi-page (mp_bvec) helpers */
48#define mp_bvec_iter_page(bvec, iter) \
Ming Lei8fc55452016-06-09 10:00:58 -060049 (__bvec_iter_bvec((bvec), (iter))->bv_page)
50
Ming Lei3d75ca02019-02-15 19:13:10 +080051#define mp_bvec_iter_len(bvec, iter) \
Ming Lei8fc55452016-06-09 10:00:58 -060052 min((iter).bi_size, \
53 __bvec_iter_bvec((bvec), (iter))->bv_len - (iter).bi_bvec_done)
54
Ming Lei3d75ca02019-02-15 19:13:10 +080055#define mp_bvec_iter_offset(bvec, iter) \
Ming Lei8fc55452016-06-09 10:00:58 -060056 (__bvec_iter_bvec((bvec), (iter))->bv_offset + (iter).bi_bvec_done)
57
Ming Lei3d75ca02019-02-15 19:13:10 +080058#define mp_bvec_iter_page_idx(bvec, iter) \
59 (mp_bvec_iter_offset((bvec), (iter)) / PAGE_SIZE)
60
61#define mp_bvec_iter_bvec(bvec, iter) \
62((struct bio_vec) { \
63 .bv_page = mp_bvec_iter_page((bvec), (iter)), \
64 .bv_len = mp_bvec_iter_len((bvec), (iter)), \
65 .bv_offset = mp_bvec_iter_offset((bvec), (iter)), \
66})
67
68/* For building single-page bvec in flight */
69 #define bvec_iter_offset(bvec, iter) \
70 (mp_bvec_iter_offset((bvec), (iter)) % PAGE_SIZE)
71
72#define bvec_iter_len(bvec, iter) \
73 min_t(unsigned, mp_bvec_iter_len((bvec), (iter)), \
74 PAGE_SIZE - bvec_iter_offset((bvec), (iter)))
75
76#define bvec_iter_page(bvec, iter) \
Christoph Hellwig52d52d12019-04-11 08:23:31 +020077 (mp_bvec_iter_page((bvec), (iter)) + \
78 mp_bvec_iter_page_idx((bvec), (iter)))
Ming Lei3d75ca02019-02-15 19:13:10 +080079
Ming Lei8fc55452016-06-09 10:00:58 -060080#define bvec_iter_bvec(bvec, iter) \
81((struct bio_vec) { \
82 .bv_page = bvec_iter_page((bvec), (iter)), \
83 .bv_len = bvec_iter_len((bvec), (iter)), \
84 .bv_offset = bvec_iter_offset((bvec), (iter)), \
85})
86
Dmitry Monakhovb1fb2c52017-06-29 11:31:13 -070087static inline bool bvec_iter_advance(const struct bio_vec *bv,
88 struct bvec_iter *iter, unsigned bytes)
Ming Lei8fc55452016-06-09 10:00:58 -060089{
Dmitry Monakhovb1fb2c52017-06-29 11:31:13 -070090 if (WARN_ONCE(bytes > iter->bi_size,
91 "Attempted to advance past end of bvec iter\n")) {
92 iter->bi_size = 0;
93 return false;
94 }
Ming Lei8fc55452016-06-09 10:00:58 -060095
96 while (bytes) {
Christoph Hellwig5b88a172019-02-28 11:00:18 -050097 const struct bio_vec *cur = bv + iter->bi_idx;
98 unsigned len = min3(bytes, iter->bi_size,
99 cur->bv_len - iter->bi_bvec_done);
Ming Lei8fc55452016-06-09 10:00:58 -0600100
101 bytes -= len;
102 iter->bi_size -= len;
103 iter->bi_bvec_done += len;
104
Christoph Hellwig5b88a172019-02-28 11:00:18 -0500105 if (iter->bi_bvec_done == cur->bv_len) {
Ming Lei8fc55452016-06-09 10:00:58 -0600106 iter->bi_bvec_done = 0;
107 iter->bi_idx++;
108 }
109 }
Dmitry Monakhovb1fb2c52017-06-29 11:31:13 -0700110 return true;
Ming Lei8fc55452016-06-09 10:00:58 -0600111}
112
Ming Lei8fc55452016-06-09 10:00:58 -0600113#define for_each_bvec(bvl, bio_vec, iter, start) \
114 for (iter = (start); \
115 (iter).bi_size && \
116 ((bvl = bvec_iter_bvec((bio_vec), (iter))), 1); \
117 bvec_iter_advance((bio_vec), &(iter), (bvl).bv_len))
118
Ming Lei3c892a02017-12-18 20:22:07 +0800119/* for iterating one bio from start to end */
120#define BVEC_ITER_ALL_INIT (struct bvec_iter) \
121{ \
122 .bi_sector = 0, \
123 .bi_size = UINT_MAX, \
124 .bi_idx = 0, \
125 .bi_bvec_done = 0, \
126}
127
Ming Lei6dc4f102019-02-15 19:13:19 +0800128static inline struct bio_vec *bvec_init_iter_all(struct bvec_iter_all *iter_all)
129{
Ming Lei6dc4f102019-02-15 19:13:19 +0800130 iter_all->done = 0;
Ming Lei1200e07f2019-04-08 19:02:38 +0800131 iter_all->idx = 0;
Ming Lei6dc4f102019-02-15 19:13:19 +0800132
133 return &iter_all->bv;
134}
135
Ming Lei1200e07f2019-04-08 19:02:38 +0800136static inline void bvec_advance(const struct bio_vec *bvec,
137 struct bvec_iter_all *iter_all)
Ming Lei6dc4f102019-02-15 19:13:19 +0800138{
139 struct bio_vec *bv = &iter_all->bv;
140
Ming Lei1200e07f2019-04-08 19:02:38 +0800141 if (iter_all->done) {
Christoph Hellwig52d52d12019-04-11 08:23:31 +0200142 bv->bv_page++;
Ming Lei6dc4f102019-02-15 19:13:19 +0800143 bv->bv_offset = 0;
144 } else {
Christoph Hellwigb8753432019-05-07 08:53:35 +0200145 bv->bv_page = bvec->bv_page + (bvec->bv_offset >> PAGE_SHIFT);
Ming Lei6bedf002019-04-17 09:11:26 +0800146 bv->bv_offset = bvec->bv_offset & ~PAGE_MASK;
Ming Lei6dc4f102019-02-15 19:13:19 +0800147 }
148 bv->bv_len = min_t(unsigned int, PAGE_SIZE - bv->bv_offset,
149 bvec->bv_len - iter_all->done);
Ming Lei1200e07f2019-04-08 19:02:38 +0800150 iter_all->done += bv->bv_len;
151
152 if (iter_all->done == bvec->bv_len) {
153 iter_all->idx++;
154 iter_all->done = 0;
155 }
Ming Lei6dc4f102019-02-15 19:13:19 +0800156}
157
Ming Lei45a3fb92019-02-15 19:13:14 +0800158/*
159 * Get the last single-page segment from the multi-page bvec and store it
160 * in @seg
161 */
162static inline void mp_bvec_last_segment(const struct bio_vec *bvec,
163 struct bio_vec *seg)
164{
165 unsigned total = bvec->bv_offset + bvec->bv_len;
166 unsigned last_page = (total - 1) / PAGE_SIZE;
167
Christoph Hellwig52d52d12019-04-11 08:23:31 +0200168 seg->bv_page = bvec->bv_page + last_page;
Ming Lei45a3fb92019-02-15 19:13:14 +0800169
170 /* the whole segment is inside the last page */
171 if (bvec->bv_offset >= last_page * PAGE_SIZE) {
172 seg->bv_offset = bvec->bv_offset % PAGE_SIZE;
173 seg->bv_len = bvec->bv_len;
174 } else {
175 seg->bv_offset = 0;
176 seg->bv_len = total - last_page * PAGE_SIZE;
177 }
178}
179
Ming Lei8fc55452016-06-09 10:00:58 -0600180#endif /* __LINUX_BVEC_ITER_H */