Messages in this thread | | | From | "J. R. Okajima" <> | Subject | Re: [PATCH 0/9] overlay filesystem: request for inclusion (v17) | Date | Fri, 15 Mar 2013 14:09:14 +0900 |
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Al Viro: > > +- 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.
"no inodes at all"? Are you assuming the implementation in dcache only (with a new d_type flag)? And it is up to the real fs (layer or branch) whether it consumes inode or not? If so, it has a big disadvantage for the layer-fs (or branch-fs) to have to implement a new method for whiteout.
Overlayfs implements whiteout as symlink+xattr which consumes an inode. And you don't like it, right? What I showed is another generic approach without xattr where the new method to whiteout is unnecessary.
> > +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?
It is the case when find(1) for the layer-fs/branch-fs directly.
J. R. Okajima
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