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From: mike@turing.unm.edu (Michael I. Bushnell)
Newsgroups: comp.unix.questions
Subject: Re: Rename bug?
Message-ID: <1106@unmvax.unm.edu>
Date: 15 Jun 88 18:09:56 GMT
References: <9312@eddie.MIT.EDU> <11658@mimsy.UUCP> <1126@mcgill-vision.UUCP> <1132@mcgill-vision.UUCP> <55437@sun.uucp>
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Reply-To: mike@turing.unm.edu.UUCP (Michael I. Bushnell)
Organization: University of New Mexico, Albuquerque
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In article <55437@sun.uucp> guy@gorodish.Sun.COM (Guy Harris) writes:
>> I consider the whole vfs-based filesystem as an NFS thing, since it
>> exists only to support NFS.
>
>Which demonstrates that you *don't* know why the VFS mechanism
>exists.  IT does not "exist only to support NFS."  It exists to
>support *multiple* file systems; in other words, to permit several
>different file system types to share the same system call interface,
>and to permit new file system types to be added without rewhacking
>the system call interface.


And thus, fails.  The discussion is about a manner in which those
different file systems do NOT provide the same system call interface. 
Some of them give an error for rename("foo","foo"), some delete "foo",
some do nothing.  flock(...) works on some, not on others.  And then
there's the celebrated mkdir bug.  If I do 
open(fname, O_RDWR | O_CREAT | O_EXCL, mode), NFS doesn't guarantee
exclusive creation.

NFS and VFS do not guarantee the same semantics for different file
systems.  



-- 
                N u m q u a m   G l o r i a   D e o 

			Michael I. Bushnell
			HASA - "A" division
			mike@turing.unm.edu
	    {ucbvax,gatech}!unmvax!turing.unm.edu!mike