Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * bvec iterator
4 *
5 * Copyright (C) 2001 Ming Lei <ming.lei@canonical.com>
6 */
7#ifndef __LINUX_BVEC_H
8#define __LINUX_BVEC_H
9
10#include <linux/highmem.h>
11#include <linux/bug.h>
12#include <linux/errno.h>
13#include <linux/limits.h>
14#include <linux/minmax.h>
15#include <linux/types.h>
16
17struct page;
18
19/**
20 * struct bio_vec - a contiguous range of physical memory addresses
21 * @bv_page: First page associated with the address range.
22 * @bv_len: Number of bytes in the address range.
23 * @bv_offset: Start of the address range relative to the start of @bv_page.
24 *
25 * All pages within a bio_vec starting from @bv_page are contiguous and
26 * can simply be iterated (see bvec_advance()).
27 */
28struct bio_vec {
29 struct page *bv_page;
30 unsigned int bv_len;
31 unsigned int bv_offset;
32};
33
34/**
35 * bvec_set_page - initialize a bvec based off a struct page
36 * @bv: bvec to initialize
37 * @page: page the bvec should point to
38 * @len: length of the bvec
39 * @offset: offset into the page
40 */
41static inline void bvec_set_page(struct bio_vec *bv, struct page *page,
42 unsigned int len, unsigned int offset)
43{
44 bv->bv_page = page;
45 bv->bv_len = len;
46 bv->bv_offset = offset;
47}
48
49/**
50 * bvec_set_folio - initialize a bvec based off a struct folio
51 * @bv: bvec to initialize
52 * @folio: folio the bvec should point to
53 * @len: length of the bvec
54 * @offset: offset into the folio
55 */
56static inline void bvec_set_folio(struct bio_vec *bv, struct folio *folio,
57 size_t len, size_t offset)
58{
59 unsigned long nr = offset / PAGE_SIZE;
60
61 WARN_ON_ONCE(len > UINT_MAX);
62 bvec_set_page(bv, folio_page(folio, nr), len, offset % PAGE_SIZE);
63}
64
65/**
66 * bvec_set_virt - initialize a bvec based on a virtual address
67 * @bv: bvec to initialize
68 * @vaddr: virtual address to set the bvec to
69 * @len: length of the bvec
70 */
71static inline void bvec_set_virt(struct bio_vec *bv, void *vaddr,
72 unsigned int len)
73{
74 bvec_set_page(bv, virt_to_page(vaddr), len, offset_in_page(vaddr));
75}
76
77struct bvec_iter {
78 /*
79 * Current device address in 512 byte sectors. Only updated by the bio
80 * iter wrappers and not the bvec iterator helpers themselves.
81 */
82 sector_t bi_sector;
83
84 /*
85 * Remaining size in bytes.
86 */
87 unsigned int bi_size;
88
89 /*
90 * Current index into the bvec array. This indexes into `bi_io_vec` when
91 * iterating a bvec array that is part of a `bio`.
92 */
93 unsigned int bi_idx;
94
95 /*
96 * Current offset in the bvec entry pointed to by `bi_idx`.
97 */
98 unsigned int bi_bvec_done;
99} __packed __aligned(4);
100
101struct bvec_iter_all {
102 struct bio_vec bv;
103 int idx;
104 unsigned done;
105};
106
107/*
108 * various member access, note that bio_data should of course not be used
109 * on highmem page vectors
110 */
111#define __bvec_iter_bvec(bvec, iter) (&(bvec)[(iter).bi_idx])
112
113/* multi-page (mp_bvec) helpers */
114#define mp_bvec_iter_page(bvec, iter) \
115 (__bvec_iter_bvec((bvec), (iter))->bv_page)
116
117#define mp_bvec_iter_len(bvec, iter) \
118 min((iter).bi_size, \
119 __bvec_iter_bvec((bvec), (iter))->bv_len - (iter).bi_bvec_done)
120
121#define mp_bvec_iter_offset(bvec, iter) \
122 (__bvec_iter_bvec((bvec), (iter))->bv_offset + (iter).bi_bvec_done)
123
124#define mp_bvec_iter_page_idx(bvec, iter) \
125 (mp_bvec_iter_offset((bvec), (iter)) / PAGE_SIZE)
126
127#define mp_bvec_iter_bvec(bvec, iter) \
128((struct bio_vec) { \
129 .bv_page = mp_bvec_iter_page((bvec), (iter)), \
130 .bv_len = mp_bvec_iter_len((bvec), (iter)), \
131 .bv_offset = mp_bvec_iter_offset((bvec), (iter)), \
132})
133
134/* For building single-page bvec in flight */
135 #define bvec_iter_offset(bvec, iter) \
136 (mp_bvec_iter_offset((bvec), (iter)) % PAGE_SIZE)
137
138#define bvec_iter_len(bvec, iter) \
139 min_t(unsigned, mp_bvec_iter_len((bvec), (iter)), \
140 PAGE_SIZE - bvec_iter_offset((bvec), (iter)))
141
142#define bvec_iter_page(bvec, iter) \
143 (mp_bvec_iter_page((bvec), (iter)) + \
144 mp_bvec_iter_page_idx((bvec), (iter)))
145
146#define bvec_iter_bvec(bvec, iter) \
147((struct bio_vec) { \
148 .bv_page = bvec_iter_page((bvec), (iter)), \
149 .bv_len = bvec_iter_len((bvec), (iter)), \
150 .bv_offset = bvec_iter_offset((bvec), (iter)), \
151})
152
153static inline bool bvec_iter_advance(const struct bio_vec *bv,
154 struct bvec_iter *iter, unsigned bytes)
155{
156 unsigned int idx = iter->bi_idx;
157
158 if (WARN_ONCE(bytes > iter->bi_size,
159 "Attempted to advance past end of bvec iter\n")) {
160 iter->bi_size = 0;
161 return false;
162 }
163
164 iter->bi_size -= bytes;
165 bytes += iter->bi_bvec_done;
166
167 while (bytes && bytes >= bv[idx].bv_len) {
168 bytes -= bv[idx].bv_len;
169 idx++;
170 }
171
172 iter->bi_idx = idx;
173 iter->bi_bvec_done = bytes;
174 return true;
175}
176
177/*
178 * A simpler version of bvec_iter_advance(), @bytes should not span
179 * across multiple bvec entries, i.e. bytes <= bv[i->bi_idx].bv_len
180 */
181static inline void bvec_iter_advance_single(const struct bio_vec *bv,
182 struct bvec_iter *iter, unsigned int bytes)
183{
184 unsigned int done = iter->bi_bvec_done + bytes;
185
186 if (done == bv[iter->bi_idx].bv_len) {
187 done = 0;
188 iter->bi_idx++;
189 }
190 iter->bi_bvec_done = done;
191 iter->bi_size -= bytes;
192}
193
194#define for_each_bvec(bvl, bio_vec, iter, start) \
195 for (iter = (start); \
196 (iter).bi_size && \
197 ((bvl = bvec_iter_bvec((bio_vec), (iter))), 1); \
198 bvec_iter_advance_single((bio_vec), &(iter), (bvl).bv_len))
199
200#define for_each_mp_bvec(bvl, bio_vec, iter, start) \
201 for (iter = (start); \
202 (iter).bi_size && \
203 ((bvl = mp_bvec_iter_bvec((bio_vec), (iter))), 1); \
204 bvec_iter_advance_single((bio_vec), &(iter), (bvl).bv_len))
205
206/* for iterating one bio from start to end */
207#define BVEC_ITER_ALL_INIT (struct bvec_iter) \
208{ \
209 .bi_sector = 0, \
210 .bi_size = UINT_MAX, \
211 .bi_idx = 0, \
212 .bi_bvec_done = 0, \
213}
214
215static inline struct bio_vec *bvec_init_iter_all(struct bvec_iter_all *iter_all)
216{
217 iter_all->done = 0;
218 iter_all->idx = 0;
219
220 return &iter_all->bv;
221}
222
223static inline void bvec_advance(const struct bio_vec *bvec,
224 struct bvec_iter_all *iter_all)
225{
226 struct bio_vec *bv = &iter_all->bv;
227
228 if (iter_all->done) {
229 bv->bv_page++;
230 bv->bv_offset = 0;
231 } else {
232 bv->bv_page = bvec->bv_page + (bvec->bv_offset >> PAGE_SHIFT);
233 bv->bv_offset = bvec->bv_offset & ~PAGE_MASK;
234 }
235 bv->bv_len = min_t(unsigned int, PAGE_SIZE - bv->bv_offset,
236 bvec->bv_len - iter_all->done);
237 iter_all->done += bv->bv_len;
238
239 if (iter_all->done == bvec->bv_len) {
240 iter_all->idx++;
241 iter_all->done = 0;
242 }
243}
244
245/**
246 * bvec_kmap_local - map a bvec into the kernel virtual address space
247 * @bvec: bvec to map
248 *
249 * Must be called on single-page bvecs only. Call kunmap_local on the returned
250 * address to unmap.
251 */
252static inline void *bvec_kmap_local(struct bio_vec *bvec)
253{
254 return kmap_local_page(bvec->bv_page) + bvec->bv_offset;
255}
256
257/**
258 * memcpy_from_bvec - copy data from a bvec
259 * @bvec: bvec to copy from
260 *
261 * Must be called on single-page bvecs only.
262 */
263static inline void memcpy_from_bvec(char *to, struct bio_vec *bvec)
264{
265 memcpy_from_page(to, bvec->bv_page, bvec->bv_offset, bvec->bv_len);
266}
267
268/**
269 * memcpy_to_bvec - copy data to a bvec
270 * @bvec: bvec to copy to
271 *
272 * Must be called on single-page bvecs only.
273 */
274static inline void memcpy_to_bvec(struct bio_vec *bvec, const char *from)
275{
276 memcpy_to_page(bvec->bv_page, bvec->bv_offset, from, bvec->bv_len);
277}
278
279/**
280 * memzero_bvec - zero all data in a bvec
281 * @bvec: bvec to zero
282 *
283 * Must be called on single-page bvecs only.
284 */
285static inline void memzero_bvec(struct bio_vec *bvec)
286{
287 memzero_page(bvec->bv_page, bvec->bv_offset, bvec->bv_len);
288}
289
290/**
291 * bvec_virt - return the virtual address for a bvec
292 * @bvec: bvec to return the virtual address for
293 *
294 * Note: the caller must ensure that @bvec->bv_page is not a highmem page.
295 */
296static inline void *bvec_virt(struct bio_vec *bvec)
297{
298 WARN_ON_ONCE(PageHighMem(bvec->bv_page));
299 return page_address(bvec->bv_page) + bvec->bv_offset;
300}
301
302/**
303 * bvec_phys - return the physical address for a bvec
304 * @bvec: bvec to return the physical address for
305 */
306static inline phys_addr_t bvec_phys(const struct bio_vec *bvec)
307{
308 return page_to_phys(bvec->bv_page) + bvec->bv_offset;
309}
310
311#endif /* __LINUX_BVEC_H */