[lkml]   [2014]   [Feb]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH 00/13] cross rename v4
On Thu, Feb 13, 2014 at 9:28 AM, Miklos Szeredi <> wrote:
> On Thu, Feb 13, 2014 at 5:42 PM, David Howells <> wrote:
>> Miklos Szeredi <> 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).

Are there any users of unions / overlays who will want to modify the
bottom layer after creating the top layer? I'm starting to think that
changing the bottom layer should require userspace to do a three-way
merge or something and explicitly decide what it wants to do.


 \ /
  Last update: 2014-02-13 20:01    [W:0.054 / U:3.584 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site