Merge remote-tracking branch 'stable/linux-5.10.y' into rpi-5.10.y
[platform/kernel/linux-rpi.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         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 }