4 * Copyright (C) 1994-1999 Linus Torvalds
8 * The msync() system call.
12 #include <linux/mman.h>
13 #include <linux/file.h>
14 #include <linux/syscalls.h>
17 * MS_SYNC syncs the entire file - including mappings.
19 * MS_ASYNC does not start I/O (it used to, up to 2.5.67).
20 * Nor does it marks the relevant pages dirty (it used to up to 2.6.17).
21 * Now it doesn't do anything, since dirty pages are properly tracked.
23 * The application may now run fsync() to
24 * write out the dirty pages and wait on the writeout and check the result.
25 * Or the application may run fadvise(FADV_DONTNEED) against the fd to start
26 * async writeout immediately.
27 * So by _not_ starting I/O in MS_ASYNC we provide complete flexibility to
30 asmlinkage
long sys_msync(unsigned long start
, size_t len
, int flags
)
33 struct mm_struct
*mm
= current
->mm
;
34 struct vm_area_struct
*vma
;
35 int unmapped_error
= 0;
38 if (flags
& ~(MS_ASYNC
| MS_INVALIDATE
| MS_SYNC
))
40 if (start
& ~PAGE_MASK
)
42 if ((flags
& MS_ASYNC
) && (flags
& MS_SYNC
))
45 len
= (len
+ ~PAGE_MASK
) & PAGE_MASK
;
53 * If the interval [start,end) covers some unmapped address ranges,
54 * just ignore them, but return -ENOMEM at the end.
56 down_read(&mm
->mmap_sem
);
57 vma
= find_vma(mm
, start
);
61 /* Still start < end. */
65 /* Here start < vma->vm_end. */
66 if (start
< vma
->vm_start
) {
67 start
= vma
->vm_start
;
70 unmapped_error
= -ENOMEM
;
72 /* Here vma->vm_start <= start < vma->vm_end. */
73 if ((flags
& MS_INVALIDATE
) &&
74 (vma
->vm_flags
& VM_LOCKED
)) {
80 if ((flags
& MS_SYNC
) && file
&&
81 (vma
->vm_flags
& VM_SHARED
)) {
83 up_read(&mm
->mmap_sem
);
84 error
= do_fsync(file
, 0);
86 if (error
|| start
>= end
)
88 down_read(&mm
->mmap_sem
);
89 vma
= find_vma(mm
, start
);
99 up_read(&mm
->mmap_sem
);
101 return error
? : unmapped_error
;
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