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ceffc078 CO |
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 | ||
eb6fe0c3 | 18 | size_t |
ceffc078 CO |
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 |