Re: EXT2_UNRM_FL

Albert D. Cahalan (acahalan@cs.uml.edu)
Thu, 4 Mar 1999 11:00:45 -0500 (EST)


Richard Gooch writes:

> There is simply no need for an undelete/move-to-garbage-area feature
> in the kernel. It can all be done perfectly fine in userspace.

This is wrong. Userspace should not need to be aware of mount point
crossings. You need one trashcan for each mounted filesystem.
(it is not "perfectly fine" for libc to read /proc/mounts every time
you want to unlink something)

Think about what happens when you delete a 2 GB file. You want that
to happen quickly, with a simple rename. You definitely don't want
to read 2 GB and write 2 GB.

There is another unrelated reason why the kernel must be involved.
You need to really delete files as the disk gets full. Polling is
just total crap, with race conditions and extra system load. You can
run out of disk space between two polls. That is not allowed.

Undelete isn't such a weird concept. Novell has it. Currently we have
to unmount the partition (I hope!) and hack it, just like DOS users.
People actually do this. I think the Novell way is better.

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