Re: CVS commit: src/sbin/umount

[David Holland <dholland-tech%netbsd.org@localhost>]

On Thu, Mar 27, 2025 at 05:42:03AM +0700, Robert Elz wrote:
 >   | Because vnds are specifically configured for mounts; the only thing
 >   | they're useful for is mounting a fs image that lives in a regular
 >   | file.
 > 
 > No they're not, they can be used for playing with newfs variants,
 > fsdb, fsck, resize_ffs, ...   Nothing requires they be mounted.

Those will all run on regular files. The only thing that requires a
device for a fs image is mount.

But that's a backwards argument anyway. The point is that a vnd is a
shim whose purpose is to work around a weakness in the system
interfaces. (Namely, that you can't mount a fs image in a regular
file.) It has no state, and no semantics of its own either; it's just
a plug.

It is perfectly reasonable for mount to create a vnd automatically
when you ask it to mount an image that's a regular file, and dispose
of it equally automatically later.

This is not true of, and doesn't make sense for, raid, ccd, cgd, or
any of your other examples.

-- 
David A. Holland
dholland%netbsd.org@localhost