Re: Multiplexing filesystem

Helge Hafting
2001-11-27T10:28:47Z

Mark Richards wrote:
>
> Quick question, which I suspect has a long answer.
>
> I would like to write a multiplexing filesystem. The idea is as follows:
>
> The filesystem would ideally wrap another filesystem, such as nfs or smbfs or
> ext2. Most operations would just be passed to the native fs call. However, for
> some files, selectable at run time by some control singal, would actually reside
> on another file system. The other filesystem would have to be mounted.
>
> The idea is for a version controlling filesystem. The server would be a network
> server (hence the desire to wrap nfs) which presents a 'view' of the source
> code. When the user reserves a file for editing, the file is copied to the
> local disk. From that point on, the local file is referred to until the user
> commits the change or unreserves the file. Ideally, the local copy of the file
> could be on any file system, not one that is necessarily local. And this has to
> be totally transparent to the user, except for the step where the user
> 'reserves' the file.

Coda already do what you want:
Files are kept on a server, and copied to your local disk when
you use it. You may even disconnect when working on the local
copy - your changes will be propagated back to the server
whenever you reconnect to the network.
The copying is indeed completely transparent.

If you need reservation - use the permission system.
A suid program simply makes _you_ owner, and only
the owner gets write permission. This is your check-out
program. Check-in consists of changing ownership
back to root (or some userid allocated to the versioning system)

Helge Hafting