]>
Commit | Line | Data |
---|---|---|
1 | // SPDX-License-Identifier: GPL-2.0 | |
2 | /* | |
3 | * linux/mm/msync.c | |
4 | * | |
5 | * Copyright (C) 1994-1999 Linus Torvalds | |
6 | */ | |
7 | ||
8 | /* | |
9 | * The msync() system call. | |
10 | */ | |
11 | #include <linux/fs.h> | |
12 | #include <linux/mm.h> | |
13 | #include <linux/mman.h> | |
14 | #include <linux/file.h> | |
15 | #include <linux/syscalls.h> | |
16 | #include <linux/sched.h> | |
17 | ||
18 | /* | |
19 | * MS_SYNC syncs the entire file - including mappings. | |
20 | * | |
21 | * MS_ASYNC does not start I/O (it used to, up to 2.5.67). | |
22 | * Nor does it marks the relevant pages dirty (it used to up to 2.6.17). | |
23 | * Now it doesn't do anything, since dirty pages are properly tracked. | |
24 | * | |
25 | * The application may now run fsync() to | |
26 | * write out the dirty pages and wait on the writeout and check the result. | |
27 | * Or the application may run fadvise(FADV_DONTNEED) against the fd to start | |
28 | * async writeout immediately. | |
29 | * So by _not_ starting I/O in MS_ASYNC we provide complete flexibility to | |
30 | * applications. | |
31 | */ | |
32 | SYSCALL_DEFINE3(msync, unsigned long, start, size_t, len, int, flags) | |
33 | { | |
34 | unsigned long end; | |
35 | struct mm_struct *mm = current->mm; | |
36 | struct vm_area_struct *vma; | |
37 | int unmapped_error = 0; | |
38 | int error = -EINVAL; | |
39 | ||
40 | start = untagged_addr(start); | |
41 | ||
42 | if (flags & ~(MS_ASYNC | MS_INVALIDATE | MS_SYNC)) | |
43 | goto out; | |
44 | if (offset_in_page(start)) | |
45 | goto out; | |
46 | if ((flags & MS_ASYNC) && (flags & MS_SYNC)) | |
47 | goto out; | |
48 | error = -ENOMEM; | |
49 | len = (len + ~PAGE_MASK) & PAGE_MASK; | |
50 | end = start + len; | |
51 | if (end < start) | |
52 | goto out; | |
53 | error = 0; | |
54 | if (end == start) | |
55 | goto out; | |
56 | /* | |
57 | * If the interval [start,end) covers some unmapped address ranges, | |
58 | * just ignore them, but return -ENOMEM at the end. | |
59 | */ | |
60 | mmap_read_lock(mm); | |
61 | vma = find_vma(mm, start); | |
62 | for (;;) { | |
63 | struct file *file; | |
64 | loff_t fstart, fend; | |
65 | ||
66 | /* Still start < end. */ | |
67 | error = -ENOMEM; | |
68 | if (!vma) | |
69 | goto out_unlock; | |
70 | /* Here start < vma->vm_end. */ | |
71 | if (start < vma->vm_start) { | |
72 | start = vma->vm_start; | |
73 | if (start >= end) | |
74 | goto out_unlock; | |
75 | unmapped_error = -ENOMEM; | |
76 | } | |
77 | /* Here vma->vm_start <= start < vma->vm_end. */ | |
78 | if ((flags & MS_INVALIDATE) && | |
79 | (vma->vm_flags & VM_LOCKED)) { | |
80 | error = -EBUSY; | |
81 | goto out_unlock; | |
82 | } | |
83 | file = vma->vm_file; | |
84 | fstart = (start - vma->vm_start) + | |
85 | ((loff_t)vma->vm_pgoff << PAGE_SHIFT); | |
86 | fend = fstart + (min(end, vma->vm_end) - start) - 1; | |
87 | start = vma->vm_end; | |
88 | if ((flags & MS_SYNC) && file && | |
89 | (vma->vm_flags & VM_SHARED)) { | |
90 | get_file(file); | |
91 | mmap_read_unlock(mm); | |
92 | error = vfs_fsync_range(file, fstart, fend, 1); | |
93 | fput(file); | |
94 | if (error || start >= end) | |
95 | goto out; | |
96 | mmap_read_lock(mm); | |
97 | vma = find_vma(mm, start); | |
98 | } else { | |
99 | if (start >= end) { | |
100 | error = 0; | |
101 | goto out_unlock; | |
102 | } | |
103 | vma = vma->vm_next; | |
104 | } | |
105 | } | |
106 | out_unlock: | |
107 | mmap_read_unlock(mm); | |
108 | out: | |
109 | return error ? : unmapped_error; | |
110 | } |