On Thu, Feb 5, 2015 at 11:01 AM, 王旭 <xuw2015@xxxxxxxxx> wrote:
> Hi,
> I read the source code of overlay fs, it's amazing, but a few
> confusion for the rename2 function.
>
> Here is the code:
> 799 if (overwrite) {
>
> 800 if (old_opaque) {
> 801 if (new->d_inode || !new_opaque) {
> 802 /* Whiteout source */
> 803 flags |= RENAME_WHITEOUT;
> 804 } else {
> 805 /* Switch whiteouts */
> 806 flags |= RENAME_EXCHANGE;
> 807 }
> 808 } else if (is_dir && !new->d_inode && new_opaque) {
> 809 flags |= RENAME_EXCHANGE;
> ^^^^^^^^^^Is necessary to use RENAME_EXCHANGE? why
> not let vfs_rename to remove the new(dest) entry?
Source is a directory, dest is a whiteout represented by a chardev.
There's a rule that directory can only overwrite directory and
non-directory can only overwrite non-directory.
Thanks,
Miklos
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