Messages in this thread | | | Date | Fri, 15 Mar 2013 04:44:11 +0000 | From | Al Viro <> | Subject | Re: [PATCH 0/9] overlay filesystem: request for inclusion (v17) |
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On Fri, Mar 15, 2013 at 01:15:36PM +0900, J. R. Okajima wrote:
> +- whiteout is hardlinked in order to reduce the consumption of inodes > + on branch
*blink* Whiteouts have no inodes at all. Filesystem has an additional kind of directory entries, recognizable as whiteouts. How they are done is up to filesystem in question.
> +- kernel thread for removing the dir who has a plenty of whiteouts
Again, implementation detail for individual filesystem.
> +The whiteout in aufs is very similar to Unionfs's. That is represented > +by its filename. UnionMount takes an approach of a file mode, but I am > +afraid several utilities (find(1) or something) will have to support it.
Why the devil should find(1) even see them?
I really don't believe that it's a good idea to try making them fs-agnostic; it's an implementation detail of filesystem, with things like "is this directory empty?" very much belonging to the fs in question...
I don't know; maybe it's my experience of dealing with umsdos that has badly soured me on that kind of approach, but IME this kind of schemes tend to be brittle as hell ;-/
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