rump question(s)

[Paul Goyette <paul%whooppee.com@localhost>]

I'm looking to rump-ify the recently added fss(4) atf test, and have 
some questions...

I can easily create a rump.fssconfig utility and use it to create a 
snapshot.  But to be useful, I need to

1. Create two directories, somewhere in the rump-file-system namespace.

2. On one of these, I need to mount a read-write file system.  I can
   create an "image file" for the file system in a number of ways (such
   as creating a file, mapping it on the host with vndconfig, running
   newfs), and then pass the image file to rump with the -d option.  As
   I understand the rump docs, this simply creates a device node to
   map the image file to a disk device, but doesn't actually mount the
   device.  And there doesn't seem to be any rump.mount{,_*fs} utility.

3. After I run my rump.fssconfig utility, I need to mount the newly
   created /dev/fss0 on the other mount-point.  This is needed so I can
   read the snapshot and confirm that it contains original file data,
   even after the file has been modified.  (I plan on creating and
   updating the file using rump.dd utility.)

So, the questions:

* How do I create new directories in the rump file system namespace?

* How do I mount disk devices (either from -d or from rump.fssconfig)
  onto those directories?


PS If I have somehow totally misunderstood rump, please feel free to 
suggest some other mechanism for verifying fss(4) functionality without 
putting the host at risk.  (See my recent PR kern/51377 for one such 
risk!)


+------------------+--------------------------+------------------------+
| Paul Goyette     | PGP Key fingerprint:     | E-mail addresses:      |
| (Retired)        | FA29 0E3B 35AF E8AE 6651 | paul at whooppee.com   |
| Kernel Developer | 0786 F758 55DE 53BA 7731 | pgoyette at netbsd.org |
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