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1 : : // SPDX-License-Identifier: GPL-2.0 2 : : /* 3 : : * linux/mm/msync.c 4 : : * 5 : : * Copyright (C) 1994-1999 Linus Torvalds 6 : : */ 7 : : 8 : : /* 9 : : * The msync() system call. 10 : : */ 11 : : #include <linux/fs.h> 12 : : #include <linux/mm.h> 13 : : #include <linux/mman.h> 14 : : #include <linux/file.h> 15 : : #include <linux/syscalls.h> 16 : : #include <linux/sched.h> 17 : : 18 : : /* 19 : : * MS_SYNC syncs the entire file - including mappings. 20 : : * 21 : : * MS_ASYNC does not start I/O (it used to, up to 2.5.67). 22 : : * Nor does it marks the relevant pages dirty (it used to up to 2.6.17). 23 : : * Now it doesn't do anything, since dirty pages are properly tracked. 24 : : * 25 : : * The application may now run fsync() to 26 : : * write out the dirty pages and wait on the writeout and check the result. 27 : : * Or the application may run fadvise(FADV_DONTNEED) against the fd to start 28 : : * async writeout immediately. 29 : : * So by _not_ starting I/O in MS_ASYNC we provide complete flexibility to 30 : : * applications. 31 : : */ 32 : 0 : SYSCALL_DEFINE3(msync, unsigned long, start, size_t, len, int, flags) 33 : : { 34 : 0 : unsigned long end; 35 [ # # ]: 0 : struct mm_struct *mm = current->mm; 36 : 0 : struct vm_area_struct *vma; 37 : 0 : int unmapped_error = 0; 38 : 0 : int error = -EINVAL; 39 : : 40 : 0 : start = untagged_addr(start); 41 : : 42 [ # # ]: 0 : if (flags & ~(MS_ASYNC | MS_INVALIDATE | MS_SYNC)) 43 : 0 : goto out; 44 [ # # ]: 0 : if (offset_in_page(start)) 45 : 0 : goto out; 46 [ # # ]: 0 : if ((flags & MS_ASYNC) && (flags & MS_SYNC)) 47 : 0 : goto out; 48 : 0 : error = -ENOMEM; 49 : 0 : len = (len + ~PAGE_MASK) & PAGE_MASK; 50 : 0 : end = start + len; 51 [ # # ]: 0 : if (end < start) 52 : 0 : goto out; 53 : 0 : error = 0; 54 [ # # ]: 0 : if (end == start) 55 : 0 : goto out; 56 : : /* 57 : : * If the interval [start,end) covers some unmapped address ranges, 58 : : * just ignore them, but return -ENOMEM at the end. 59 : : */ 60 : 0 : down_read(&mm->mmap_sem); 61 : 0 : vma = find_vma(mm, start); 62 : 0 : for (;;) { 63 : 0 : struct file *file; 64 : 0 : loff_t fstart, fend; 65 : : 66 : : /* Still start < end. */ 67 : 0 : error = -ENOMEM; 68 [ # # ]: 0 : if (!vma) 69 : 0 : goto out_unlock; 70 : : /* Here start < vma->vm_end. */ 71 [ # # ]: 0 : if (start < vma->vm_start) { 72 : 0 : start = vma->vm_start; 73 [ # # ]: 0 : if (start >= end) 74 : 0 : goto out_unlock; 75 : : unmapped_error = -ENOMEM; 76 : : } 77 : : /* Here vma->vm_start <= start < vma->vm_end. */ 78 [ # # ]: 0 : if ((flags & MS_INVALIDATE) && 79 [ # # ]: 0 : (vma->vm_flags & VM_LOCKED)) { 80 : 0 : error = -EBUSY; 81 : 0 : goto out_unlock; 82 : : } 83 : 0 : file = vma->vm_file; 84 : 0 : fstart = (start - vma->vm_start) + 85 : 0 : ((loff_t)vma->vm_pgoff << PAGE_SHIFT); 86 : 0 : fend = fstart + (min(end, vma->vm_end) - start) - 1; 87 : 0 : start = vma->vm_end; 88 [ # # # # ]: 0 : if ((flags & MS_SYNC) && file && 89 [ # # ]: 0 : (vma->vm_flags & VM_SHARED)) { 90 : 0 : get_file(file); 91 : 0 : up_read(&mm->mmap_sem); 92 : 0 : error = vfs_fsync_range(file, fstart, fend, 1); 93 : 0 : fput(file); 94 [ # # ]: 0 : if (error || start >= end) 95 : 0 : goto out; 96 : 0 : down_read(&mm->mmap_sem); 97 : 0 : vma = find_vma(mm, start); 98 : : } else { 99 [ # # ]: 0 : if (start >= end) { 100 : 0 : error = 0; 101 : 0 : goto out_unlock; 102 : : } 103 : 0 : vma = vma->vm_next; 104 : : } 105 : : } 106 : 0 : out_unlock: 107 : 0 : up_read(&mm->mmap_sem); 108 : 0 : out: 109 [ # # ]: 0 : return error ? : unmapped_error; 110 : : }