On Fri, Mar 15, 2013 at 08:15:18AM +0000, James Bottomley wrote: > 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. The trouble with such mechanisms is that they tend to end up depending on fairly non-trivial properties of underlying fs. Try aufs one on btrfs, see how soon you spot the problem. It's nice when a method turns out to be really redundant and implementable in uniform way via other methods present; see fh_to_dentry history for example of situation where it hadn't... -- 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
