Commit | Line | Data |
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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> | |
c22ce143 | 16 | #include <linux/uaccess.h> |
ceffc078 | 17 | |
eb6fe0c3 | 18 | size_t |
01408c49 N |
19 | __filemap_copy_from_user_iovec_inatomic(char *vaddr, |
20 | const struct iovec *iov, | |
21 | size_t base, | |
22 | size_t bytes); | |
ceffc078 CO |
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. | |
01408c49 N |
28 | * |
29 | * NOTE: For this to work reliably we really want copy_from_user_inatomic_nocache | |
30 | * to *NOT* zero any tail of the buffer that it failed to copy. If it does, | |
31 | * and if the following non-atomic copy succeeds, then there is a small window | |
32 | * where the target page contains neither the data before the write, nor the | |
33 | * data after the write (it contains zero). A read at this time will see | |
34 | * data that is inconsistent with any ordering of the read and the write. | |
35 | * (This has been detected in practice). | |
ceffc078 CO |
36 | */ |
37 | static inline size_t | |
38 | filemap_copy_from_user(struct page *page, unsigned long offset, | |
39 | const char __user *buf, unsigned bytes) | |
40 | { | |
41 | char *kaddr; | |
42 | int left; | |
43 | ||
44 | kaddr = kmap_atomic(page, KM_USER0); | |
c22ce143 | 45 | left = __copy_from_user_inatomic_nocache(kaddr + offset, buf, bytes); |
ceffc078 CO |
46 | kunmap_atomic(kaddr, KM_USER0); |
47 | ||
48 | if (left != 0) { | |
49 | /* Do it the slow way */ | |
50 | kaddr = kmap(page); | |
c22ce143 | 51 | left = __copy_from_user_nocache(kaddr + offset, buf, bytes); |
ceffc078 CO |
52 | kunmap(page); |
53 | } | |
54 | return bytes - left; | |
55 | } | |
56 | ||
57 | /* | |
58 | * This has the same sideeffects and return value as filemap_copy_from_user(). | |
59 | * The difference is that on a fault we need to memset the remainder of the | |
60 | * page (out to offset+bytes), to emulate filemap_copy_from_user()'s | |
61 | * single-segment behaviour. | |
62 | */ | |
63 | static inline size_t | |
64 | filemap_copy_from_user_iovec(struct page *page, unsigned long offset, | |
65 | const struct iovec *iov, size_t base, size_t bytes) | |
66 | { | |
67 | char *kaddr; | |
68 | size_t copied; | |
69 | ||
70 | kaddr = kmap_atomic(page, KM_USER0); | |
01408c49 N |
71 | copied = __filemap_copy_from_user_iovec_inatomic(kaddr + offset, iov, |
72 | base, bytes); | |
ceffc078 CO |
73 | kunmap_atomic(kaddr, KM_USER0); |
74 | if (copied != bytes) { | |
75 | kaddr = kmap(page); | |
01408c49 N |
76 | copied = __filemap_copy_from_user_iovec_inatomic(kaddr + offset, iov, |
77 | base, bytes); | |
78 | if (bytes - copied) | |
79 | memset(kaddr + offset + copied, 0, bytes - copied); | |
ceffc078 CO |
80 | kunmap(page); |
81 | } | |
82 | return copied; | |
83 | } | |
84 | ||
85 | static inline void | |
86 | filemap_set_next_iovec(const struct iovec **iovp, size_t *basep, size_t bytes) | |
87 | { | |
88 | const struct iovec *iov = *iovp; | |
89 | size_t base = *basep; | |
90 | ||
91 | while (bytes) { | |
92 | int copy = min(bytes, iov->iov_len - base); | |
93 | ||
94 | bytes -= copy; | |
95 | base += copy; | |
96 | if (iov->iov_len == base) { | |
97 | iov++; | |
98 | base = 0; | |
99 | } | |
100 | } | |
101 | *iovp = iov; | |
102 | *basep = base; | |
103 | } | |
104 | #endif |