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1 | /* | |
2 | * linux/mm/msync.c | |
3 | * | |
4 | * Copyright (C) 1994-1999 Linus Torvalds | |
5 | */ | |
6 | ||
7 | /* | |
8 | * The msync() system call. | |
9 | */ | |
10 | #include <linux/fs.h> | |
11 | #include <linux/mm.h> | |
12 | #include <linux/mman.h> | |
13 | #include <linux/file.h> | |
14 | #include <linux/syscalls.h> | |
15 | #include <linux/sched.h> | |
16 | ||
17 | /* | |
18 | * MS_SYNC syncs the entire file - including mappings. | |
19 | * | |
20 | * MS_ASYNC does not start I/O (it used to, up to 2.5.67). | |
21 | * Nor does it marks the relevant pages dirty (it used to up to 2.6.17). | |
22 | * Now it doesn't do anything, since dirty pages are properly tracked. | |
23 | * | |
24 | * The application may now run fsync() to | |
25 | * write out the dirty pages and wait on the writeout and check the result. | |
26 | * Or the application may run fadvise(FADV_DONTNEED) against the fd to start | |
27 | * async writeout immediately. | |
28 | * So by _not_ starting I/O in MS_ASYNC we provide complete flexibility to | |
29 | * applications. | |
30 | */ | |
31 | SYSCALL_DEFINE3(msync, unsigned long, start, size_t, len, int, flags) | |
32 | { | |
33 | unsigned long end; | |
34 | struct mm_struct *mm = current->mm; | |
35 | struct vm_area_struct *vma; | |
36 | int unmapped_error = 0; | |
37 | int error = -EINVAL; | |
38 | ||
39 | if (flags & ~(MS_ASYNC | MS_INVALIDATE | MS_SYNC)) | |
40 | goto out; | |
41 | if (start & ~PAGE_MASK) | |
42 | goto out; | |
43 | if ((flags & MS_ASYNC) && (flags & MS_SYNC)) | |
44 | goto out; | |
45 | error = -ENOMEM; | |
46 | len = (len + ~PAGE_MASK) & PAGE_MASK; | |
47 | end = start + len; | |
48 | if (end < start) | |
49 | goto out; | |
50 | error = 0; | |
51 | if (end == start) | |
52 | goto out; | |
53 | /* | |
54 | * If the interval [start,end) covers some unmapped address ranges, | |
55 | * just ignore them, but return -ENOMEM at the end. | |
56 | */ | |
57 | down_read(&mm->mmap_sem); | |
58 | vma = find_vma(mm, start); | |
59 | for (;;) { | |
60 | struct file *file; | |
61 | ||
62 | /* Still start < end. */ | |
63 | error = -ENOMEM; | |
64 | if (!vma) | |
65 | goto out_unlock; | |
66 | /* Here start < vma->vm_end. */ | |
67 | if (start < vma->vm_start) { | |
68 | start = vma->vm_start; | |
69 | if (start >= end) | |
70 | goto out_unlock; | |
71 | unmapped_error = -ENOMEM; | |
72 | } | |
73 | /* Here vma->vm_start <= start < vma->vm_end. */ | |
74 | if ((flags & MS_INVALIDATE) && | |
75 | (vma->vm_flags & VM_LOCKED)) { | |
76 | error = -EBUSY; | |
77 | goto out_unlock; | |
78 | } | |
79 | file = vma->vm_file; | |
80 | start = vma->vm_end; | |
81 | if ((flags & MS_SYNC) && file && | |
82 | (vma->vm_flags & VM_SHARED)) { | |
83 | get_file(file); | |
84 | up_read(&mm->mmap_sem); | |
85 | error = vfs_fsync(file, 0); | |
86 | fput(file); | |
87 | if (error || start >= end) | |
88 | goto out; | |
89 | down_read(&mm->mmap_sem); | |
90 | vma = find_vma(mm, start); | |
91 | } else { | |
92 | if (start >= end) { | |
93 | error = 0; | |
94 | goto out_unlock; | |
95 | } | |
96 | vma = vma->vm_next; | |
97 | } | |
98 | } | |
99 | out_unlock: | |
100 | up_read(&mm->mmap_sem); | |
101 | out: | |
102 | return error ? : unmapped_error; | |
103 | } |