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 */
SYSCALL_DEFINE3(msync,unsigned long,start,size_t,len,int,flags)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 }
104