treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 110
[sfrench/cifs-2.6.git] / mm / msync.c
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         if (flags & ~(MS_ASYNC | MS_INVALIDATE | MS_SYNC))
41                 goto out;
42         if (offset_in_page(start))
43                 goto out;
44         if ((flags & MS_ASYNC) && (flags & MS_SYNC))
45                 goto out;
46         error = -ENOMEM;
47         len = (len + ~PAGE_MASK) & PAGE_MASK;
48         end = start + len;
49         if (end < start)
50                 goto out;
51         error = 0;
52         if (end == start)
53                 goto out;
54         /*
55          * If the interval [start,end) covers some unmapped address ranges,
56          * just ignore them, but return -ENOMEM at the end.
57          */
58         down_read(&mm->mmap_sem);
59         vma = find_vma(mm, start);
60         for (;;) {
61                 struct file *file;
62                 loff_t fstart, fend;
63
64                 /* Still start < end. */
65                 error = -ENOMEM;
66                 if (!vma)
67                         goto out_unlock;
68                 /* Here start < vma->vm_end. */
69                 if (start < vma->vm_start) {
70                         start = vma->vm_start;
71                         if (start >= end)
72                                 goto out_unlock;
73                         unmapped_error = -ENOMEM;
74                 }
75                 /* Here vma->vm_start <= start < vma->vm_end. */
76                 if ((flags & MS_INVALIDATE) &&
77                                 (vma->vm_flags & VM_LOCKED)) {
78                         error = -EBUSY;
79                         goto out_unlock;
80                 }
81                 file = vma->vm_file;
82                 fstart = (start - vma->vm_start) +
83                          ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
84                 fend = fstart + (min(end, vma->vm_end) - start) - 1;
85                 start = vma->vm_end;
86                 if ((flags & MS_SYNC) && file &&
87                                 (vma->vm_flags & VM_SHARED)) {
88                         get_file(file);
89                         up_read(&mm->mmap_sem);
90                         error = vfs_fsync_range(file, fstart, fend, 1);
91                         fput(file);
92                         if (error || start >= end)
93                                 goto out;
94                         down_read(&mm->mmap_sem);
95                         vma = find_vma(mm, start);
96                 } else {
97                         if (start >= end) {
98                                 error = 0;
99                                 goto out_unlock;
100                         }
101                         vma = vma->vm_next;
102                 }
103         }
104 out_unlock:
105         up_read(&mm->mmap_sem);
106 out:
107         return error ? : unmapped_error;
108 }