On Fri, 2013-03-15 at 05:13 +0000, Al Viro wrote: > On Fri, Mar 15, 2013 at 02:09:14PM +0900, J. R. Okajima wrote: > > > 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. > > I'm yet to see the reason that would make implementing that method a big > disadvantage, TBH... It's the fact that a directory entry based whiteout limits the amount of change to the VFS, but has to be supported by underlying filesystems. The generic_dirent_fallthrough() mechanism is a nice way of hiding it, but there are still quite a few fs specific mods in the union mount tree because of this. Having to modify filesystems to me indicates the mechanism is a bit fragile. If we could do whiteouts purely in the VFS, so it would work for any filesystem (without needing filesystem modifications) that would seem to be a more robust approach. I'm not saying we can definitely do this in an elegant way ... I'm just saying that if someone comes up with it, it's obviously preferable. James -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
