Re: [RFC][PATCH 0/15] VFS based Union Mount

[Shaya Potter <spotter@cs.columbia.edu>]

Bharata B Rao wrote:
> Hi,
> 
> Here is an attempt towards vfs based union mount implementation.
> Union mount provides the filesytem namespace unification feature.
> Unlike the traditional mounts which hide the contents of the mount point,
> the union mount presents the merged view of the mount point and the
> mounted filesytem.

does this approach allow one to add directories to the union and have it 
behave normally.  namely when imagine one has the situation

dir-b
dir-a/ (contains file foo)


if one unions this and deletes foo, that will create a whiteout entry in 
dir-a

now, what happens if one does

dir-c
dir-b (now contains whiteout, from previous union).
dir-a (contains file foo)

will one see foo or not. i.e. are whiteouts only looked for in the 
topmost dir, or in every dir?