Branch data     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                 :          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                 :            : }