Problems

At this point we know what the kernel expect from the file system, and we have a pretty good idea of what a metadata file system is, so some of you might predict some problems by implementing a metadata file system in the Linux kernel. The kernel expect something which fit into the VFS API, and it expect something based on regular files and folders. A metadata file system is based on meta data and queries.

One option would off cause be to simply change the VFS API and change the system call the kernel provides. But doing this will create a new set of problems, it would break compability with almost every program which exits. This means that would have to adjust every program we would like to work on the file system, which would prevent the file system in ever be spread to a lot of people.

An other option would be to instead of change the current interfaces in the kernel and in VFS, to extends the interface with some extra functions. But this would result in the same problem, the applications would still have to be adjusted to benefit from the metadata file system.

So what we need is something in between, at least in the intermediate stage until the world have been convinced of using my file system ;)