msync.c

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    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 }

Cache object: 332299b19050b82564f351fbcd5e6c93

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FreeBSD/Linux Kernel Cross Reference sys/mm/msync.c

FreeBSD/Linux Kernel Cross Reference
sys/mm/msync.c