| 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 | |
| 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 | } |