blob: 24e612fefa04dc13eae85af00164d674c0b91940
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 (offset_in_page(start)) |
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 | loff_t fstart, fend; |
62 | |
63 | /* Still start < end. */ |
64 | error = -ENOMEM; |
65 | if (!vma) |
66 | goto out_unlock; |
67 | /* Here start < vma->vm_end. */ |
68 | if (start < vma->vm_start) { |
69 | start = vma->vm_start; |
70 | if (start >= end) |
71 | goto out_unlock; |
72 | unmapped_error = -ENOMEM; |
73 | } |
74 | /* Here vma->vm_start <= start < vma->vm_end. */ |
75 | if ((flags & MS_INVALIDATE) && |
76 | (vma->vm_flags & VM_LOCKED)) { |
77 | error = -EBUSY; |
78 | goto out_unlock; |
79 | } |
80 | file = vma->vm_file; |
81 | fstart = (start - vma->vm_start) + |
82 | ((loff_t)vma->vm_pgoff << PAGE_SHIFT); |
83 | fend = fstart + (min(end, vma->vm_end) - start) - 1; |
84 | start = vma->vm_end; |
85 | if ((flags & MS_SYNC) && file && |
86 | (vma->vm_flags & VM_SHARED)) { |
87 | get_file(file); |
88 | up_read(&mm->mmap_sem); |
89 | error = vfs_fsync_range(file, fstart, fend, 1); |
90 | fput(file); |
91 | if (error || start >= end) |
92 | goto out; |
93 | down_read(&mm->mmap_sem); |
94 | vma = find_vma(mm, start); |
95 | } else { |
96 | if (start >= end) { |
97 | error = 0; |
98 | goto out_unlock; |
99 | } |
100 | vma = vma->vm_next; |
101 | } |
102 | } |
103 | out_unlock: |
104 | up_read(&mm->mmap_sem); |
105 | out: |
106 | return error ? : unmapped_error; |
107 | } |
108 |