Line data    Source code

       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         166 : SYSCALL_DEFINE3(msync, unsigned long, start, size_t, len, int, flags)
      33             : {
      34          83 :         unsigned long end;
      35          83 :         struct mm_struct *mm = current->mm;
      36          83 :         struct vm_area_struct *vma;
      37          83 :         int unmapped_error = 0;
      38          83 :         int error = -EINVAL;
      39             : 
      40          83 :         start = untagged_addr(start);
      41             : 
      42          83 :         if (flags & ~(MS_ASYNC | MS_INVALIDATE | MS_SYNC))
      43           0 :                 goto out;
      44          83 :         if (offset_in_page(start))
      45           0 :                 goto out;
      46          83 :         if ((flags & MS_ASYNC) && (flags & MS_SYNC))
      47           0 :                 goto out;
      48          83 :         error = -ENOMEM;
      49          83 :         len = (len + ~PAGE_MASK) & PAGE_MASK;
      50          83 :         end = start + len;
      51          83 :         if (end < start)
      52           0 :                 goto out;
      53          83 :         error = 0;
      54          83 :         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          83 :         mmap_read_lock(mm);
      61          83 :         vma = find_vma(mm, start);
      62          83 :         for (;;) {
      63          83 :                 struct file *file;
      64          83 :                 loff_t fstart, fend;
      65             : 
      66             :                 /* Still start < end. */
      67          83 :                 error = -ENOMEM;
      68          83 :                 if (!vma)
      69           0 :                         goto out_unlock;
      70             :                 /* Here start < vma->vm_end. */
      71          83 :                 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          83 :                 if ((flags & MS_INVALIDATE) &&
      79          81 :                                 (vma->vm_flags & VM_LOCKED)) {
      80           0 :                         error = -EBUSY;
      81           0 :                         goto out_unlock;
      82             :                 }
      83          83 :                 file = vma->vm_file;
      84          83 :                 fstart = (start - vma->vm_start) +
      85          83 :                          ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
      86          83 :                 fend = fstart + (min(end, vma->vm_end) - start) - 1;
      87          83 :                 start = vma->vm_end;
      88          83 :                 if ((flags & MS_SYNC) && file &&
      89          83 :                                 (vma->vm_flags & VM_SHARED)) {
      90          81 :                         get_file(file);
      91          81 :                         mmap_read_unlock(mm);
      92          81 :                         error = vfs_fsync_range(file, fstart, fend, 1);
      93          81 :                         fput(file);
      94          81 :                         if (error || start >= end)
      95          81 :                                 goto out;
      96           0 :                         mmap_read_lock(mm);
      97           0 :                         vma = find_vma(mm, start);
      98             :                 } else {
      99           2 :                         if (start >= end) {
     100           2 :                                 error = 0;
     101           2 :                                 goto out_unlock;
     102             :                         }
     103           0 :                         vma = vma->vm_next;
     104             :                 }
     105             :         }
     106           2 : out_unlock:
     107           2 :         mmap_read_unlock(mm);
     108          83 : out:
     109          83 :         return error ? : unmapped_error;
     110             : }