Messages in this thread |  | | Date | Thu, 13 Feb 2014 18:28:35 +0100 | Subject | Re: [PATCH 00/13] cross rename v4 | From | Miklos Szeredi <> |
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On Thu, Feb 13, 2014 at 5:42 PM, David Howells <dhowells@redhat.com> wrote: > Miklos Szeredi <miklos@szeredi.hu> wrote: > >> Regarding whiteouts, I raised a couple of questions that nobody answered >> yet, so let me ask again. >> >> - If a filesystem containing whiteouts (fallthroughs, etc...) is mounted as >> not part of a union, how are these special entities represented to >> userspace? > > I would suggest that whiteouts appear as otherwise negative dentries and that > they don't appear in getdents().
I'd argue that this is an administration nightmare. E.g. what if the a backup needs to be made of the rw layer?
Will rmdir work normally in a directory containing whiteouts? Will the VFS take care of that, just like if it was part of a union? Or will it fail with ENOTEMPTY despite *appearing* empty?
And zillion other problems related to the fact that things happen to a filesystem even when they do not appear to happen ("mv foo bar; mv bar foo" has side effects).
Thanks, Miklos
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