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 asmlinkage long sys_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 = do_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