Messages in this thread | | | Date | Wed, 13 Apr 2005 16:58:52 +0100 | From | Jamie Lokier <> | Subject | Re: [RFC] FUSE permission modell (Was: fuse review bits) |
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> > > A nice implemention of it in FUSE could push it along a bit :) > > > > Aren't there some assumptions in VFS that currently make this > > impossible? > > I believe it's OK with VFS, but applications would be confused to death. > Well, there really is one issue -- dentries have exactly one parent, so > what do you do when opening a file with hardlinks as a directory? (In > fact IIRC that is what lead to all the funny talk about mountpoints, > since they don't have this limitation)
Hardlinks aren't a problem when entering a file as if it's a directory, provided the directory does not contain any hard links to a parent in the hierarchy. In other words, as long as it's a directed acyclic graph.
This is trivially always true for virtual directories such as entering an archive file. And detachable/movable mountpoints are a nice and sensible way to implement it. Some work has actually been done on this.
Experiments with the reiserfs file-as-directory extension showed that applications are generally ok with it. It looks like a file, but you can cd into it or follow a path lookup into it.
Linus had some good ideas on the exact semantics to implement when doing path lookup on these objects.
-- Jamie - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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