1 /*
2 * linux/mm/filemap.h
3 *
4 * Copyright (C) 1994-1999 Linus Torvalds
5 */
6
7 #ifndef __FILEMAP_H
8 #define __FILEMAP_H
9
10 #include <linux/types.h>
11 #include <linux/fs.h>
12 #include <linux/mm.h>
13 #include <linux/highmem.h>
14 #include <linux/uio.h>
15 #include <linux/config.h>
16 #include <asm/uaccess.h>
17
18 size_t
19 __filemap_copy_from_user_iovec(char *vaddr,
20 const struct iovec *iov,
21 size_t base,
22 size_t bytes);
23
24 /*
25 * Copy as much as we can into the page and return the number of bytes which
26 * were sucessfully copied. If a fault is encountered then clear the page
27 * out to (offset+bytes) and return the number of bytes which were copied.
28 */
29 static inline size_t
30 filemap_copy_from_user(struct page *page, unsigned long offset,
31 const char __user *buf, unsigned bytes)
32 {
33 char *kaddr;
34 int left;
35
36 kaddr = kmap_atomic(page, KM_USER0);
37 left = __copy_from_user_inatomic(kaddr + offset, buf, bytes);
38 kunmap_atomic(kaddr, KM_USER0);
39
40 if (left != 0) {
41 /* Do it the slow way */
42 kaddr = kmap(page);
43 left = __copy_from_user(kaddr + offset, buf, bytes);
44 kunmap(page);
45 }
46 return bytes - left;
47 }
48
49 /*
50 * This has the same sideeffects and return value as filemap_copy_from_user().
51 * The difference is that on a fault we need to memset the remainder of the
52 * page (out to offset+bytes), to emulate filemap_copy_from_user()'s
53 * single-segment behaviour.
54 */
55 static inline size_t
56 filemap_copy_from_user_iovec(struct page *page, unsigned long offset,
57 const struct iovec *iov, size_t base, size_t bytes)
58 {
59 char *kaddr;
60 size_t copied;
61
62 kaddr = kmap_atomic(page, KM_USER0);
63 copied = __filemap_copy_from_user_iovec(kaddr + offset, iov,
64 base, bytes);
65 kunmap_atomic(kaddr, KM_USER0);
66 if (copied != bytes) {
67 kaddr = kmap(page);
68 copied = __filemap_copy_from_user_iovec(kaddr + offset, iov,
69 base, bytes);
70 kunmap(page);
71 }
72 return copied;
73 }
74
75 static inline void
76 filemap_set_next_iovec(const struct iovec **iovp, size_t *basep, size_t bytes)
77 {
78 const struct iovec *iov = *iovp;
79 size_t base = *basep;
80
81 while (bytes) {
82 int copy = min(bytes, iov->iov_len - base);
83
84 bytes -= copy;
85 base += copy;
86 if (iov->iov_len == base) {
87 iov++;
88 base = 0;
89 }
90 }
91 *iovp = iov;
92 *basep = base;
93 }
94 #endif
95
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