Re: [PATCH v3] ovl: Check link ability between upperdir and workdir

[Vivek Goyal <vgoyal@redhat.com>]

On Tue, Dec 19, 2017 at 04:11:13PM +0200, Amir Goldstein wrote:
[..]
> With non-indexed copy up (of regular file, when O_TMPFILE supported)
> tmpfile is created in upperdir and linked to upper dir, which allows for
> concurrent copy up of two files within different parent dirs.

Is it correct. I am looking at the code and we always seem to get tmpfile
in work/work.

ovl_copy_up_locked()
  ovl_get_tmpfile()
      ovl_do_tmpfile(c->workdir, c->stat.mode)

I was hoping that for a regular file copy up, we could create tmpfile in
upper/ so that we don't have the requirement of allowing linking between
work/ and upper/ as long as upper supported tmpfile. But given that index 
will require linking with alias in upper, we can't get rid of this
requirement completely.

Vivek