Date: Tue, 20 Jul 1999 15:01:18 -0700 (PDT) From: Matthew Dillon <dillon@apollo.backplane.com> To: "Ronald G. Minnich" <rminnich@acl.lanl.gov> Cc: John Milford <jwm@CSUA.Berkeley.EDU>, "David E. Cross" <crossd@cs.rpi.edu>, freebsd-hackers@FreeBSD.ORG Subject: Re: USFS (User Space File System) Message-ID: <199907202201.PAA07726@apollo.backplane.com> References: <Pine.SGI.4.10.9907201540340.60018-100000@acl.lanl.gov>
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:On Mon, 19 Jul 1999, John Milford wrote:
:
:> Unless I am misunderstanding you, mfs does what you are
:> describing.
:
:I'm pretty sure you're misunderstanding him. MFS is not even close.
:
:ron
You know, none of us are being clear :-)
The basic problem is that MFS is not a filesystem device. What you say?
It looks like a filesystem device to you!
Well, no. MFS is actually a *block* device that UFS runs on top of. When
you create an MFS filesystem you are actually creating a UFS filesystem
and running all the UFS filesystem device code, except the backing store
is being implemented by MFS as a dummy block device. MFS simply copies
the data to and from the VM space of the mfs process.
-Matt
Matthew Dillon
<dillon@backplane.com>
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