Date: Sun, 31 Oct 1999 17:11:20 -0500 (EST) From: Erez Zadok <ezk@cs.columbia.edu> To: Mats Lofkvist <mal@algonet.se> Cc: freebsd-fs@FreeBSD.org, ezk@cs.columbia.edu (Erez Zadok) Subject: Re: stupidfs - easily extensible test file systems? Message-ID: <199910312211.RAA00014@shekel.mcl.cs.columbia.edu> In-Reply-To: Your message of "31 Oct 1999 19:53:43 %2B0100." <y2qk8o35pl4.fsf@kairos.algonet.se>
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In message <y2qk8o35pl4.fsf@kairos.algonet.se>, Mats Lofkvist writes: > ezk@cs.columbia.edu (Erez Zadok) writes: > > > Robert, it's been done. To some degree that's nullfs (if nullfs had been > > working; the VFS is broken). I've written stackable f/s templates exactly > > for the purpose of developers using them to build other f/s w/o having the > > many hassles of writing a full f/s. My wrapper templates, called wrapfs, > > work on freebsd, linux, and solaris. You can build all kinds of f/s using > > them, including f/s that do not require persistent storage. > > > > See > > http://www.cs.columbia.edu/~ezk/research > > for papers, and > > http://www.cs.columbia.edu/~ezk/research/software > > for tarballs. > > Is wrapfs/fist actively updated for FreeBSD? (I noted that the > latest FreeBSD version is almost a year old and for 3.0 only.) I will be updating this port for 3.3 and 4.0 in the two weeks following LISA, i.e. by end of November. > And does anyone know if this has a chance being a standard part > of FreeBSD, and how it relates to the general cleanup of the > stacking fs code that seem to be on the "todo sometime in the > future" list for FreeBSD? What do you mean by "this"? My code will be fixed soon. The problem is that I'm forced to use synchronous writes to work around the VFS problems. I don't expect the VFS to be fixed any time soon. It's been broken for a long time and there aren't too many "customers" complaining about it, or it would have been fixed by now. It just doesn't appear to be a high priority for the freebsd developers. I think it's too late for 3.x, but now would be a good time for freebsd to put those fixes into 4.0, before it becomes the default stable version. Many people on this list understand the problems and know how to fix them. There are even some experimental patches made by Eivind Eklund, but those patches aren't part of the kernel. Eivind's patches used to be in http://www.freebsd.org/~eivind/VOP_GETBACKINGOBJECT.patch and now they appear to be in http://www.freebsd.org/~eivind/FixNULL.patch (Eivind, can you confirm the new URL? FixNull.patch seems to include stuff unrelated to the VFS, such as scsi driver fixes. Thanks.) There's also been talk about some people (McKusick et al) rewriting the whole VFS. While I think that's a great idea, it's a large undertaking and will take a long while for busy people like McKusick to complete. I think a complete rewrite, if any, should be scheduled for 5.x. I would therefore suggest that a simpler fix such as Eivind's be incorporated into a 4.0 so people can use stackable f/s (unionfs, nulls, and my wrapfs/cryptfs, etc.) in the more immediate future. > Mats Lofkvist > mal@algonet.se I'd like to mention that I understand the pressures the freebsd developers are under. From a support perspective, you have to prioritize your human resources based on customer needs. There are, however, enough people (myself included) who are willing to work together and come up with a design and an implementation of the VFS fixes, and we are willing to spend our personal (i.e., free) time to do so. All we ask is commitment on the part of the management to include such patches in a none-too-distant future release. BTW, if there's enough momentum and FreeBSD developers/hackers attending LISA, we can have a brainstorming meeting in Seattle... Thanks, Erez Zadok. --- Columbia University Department of Computer Science. EMail: ezk@cs.columbia.edu Web: http://www.cs.columbia.edu/~ezk To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message
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