Messages in this thread | | | Date | Thu, 13 Jan 2000 00:19:17 +0100 (CET) | From | Mikulas Patocka <> | Subject | Re: Suggestion: a garbage-collected file system |
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> Number two, how do we implement this as a traditional filesystem? The > first question to be answered is whether the Linux VFS layer makes few > enough assumptions on the semantics of filesystems so that a gcfs is > possible. For example, it must not make the assumption anywhere that > to rmdir() a directory the directory must be empty. It must not make > the assumption that reference-counting is effectively used in the > filesystem. It must not make the assumption that the .. entry in a > directory points to the ``parent'' directory (something which is > rather meaningless in a gcfs). And so on. Or, if it makes these > assumptions, it must make them in a benign way, that is, it need can > be fooled into thinking that the filesystem has Unix semantics. > > This is where I have insufficient knowledge of the kernel internals to > answer all these questions: can someone fill me up on this? It would > be a shame to start worrying about all the gc details only to discover > that the gcfs cannot be implemented under Linux because the VFS makes > some faulty assumptions about filesystem semantics.
It won't work. dentry cache expects directory structure as tree. A lot of lockups or hanging references will happen when you create directory loop.
You can try implementing it for 2.0 kernels - there is no dcache, and so directory anomalies shouldn't cause much trouble.
Mikulas
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