Merge branch 'drm-fixes-3.17' of git://people.freedesktop.org/~agd5f/linux into drm...
[sfrench/cifs-2.6.git] / mm / msync.c
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 (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                 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                         if (vma->vm_flags & VM_NONLINEAR)
90                                 error = vfs_fsync(file, 1);
91                         else
92                                 error = vfs_fsync_range(file, fstart, fend, 1);
93                         fput(file);
94                         if (error || start >= end)
95                                 goto out;
96                         down_read(&mm->mmap_sem);
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         up_read(&mm->mmap_sem);
108 out:
109         return error ? : unmapped_error;
110 }