Date: Wed, 07 Aug 2002 17:42:23 -0700 From: Terry Lambert <tlambert2@mindspring.com> To: Kelly Yancey <kbyanc@posi.net> Cc: "David E. Cross" <crossd@cs.rpi.edu>, fs@FreeBSD.ORG, guptar@cs.rpi.edu Subject: Re: vnodes (UFS journaling)? Message-ID: <3D51BE6F.298F0AF@mindspring.com> References: <20020807170230.Y6264-100000@gateway.posi.net>
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Kelly Yancey wrote: > On Wed, 7 Aug 2002, Terry Lambert wrote: > > "David E. Cross" wrote: > > > Ok, we've noticed an "unfortunate" side-effect of our work. We leak data > > > (part of the journal shows up in other files). I think it is because > > > > What is it that you are trying to do with the vnode? > > > > -- Terry > > > > I believe he is trying to keep a journal, likely as a file on the > filesystem that is being journalled. I don't actually know, but that's > what I would guess. I understand that he's working on a journalling FS. I'm wondering what reaccessing vnodes has to do with journalling? A vnode is an in-core abstract representation of a file in a file system, that has a non-abstract real file association in the FS itself. A vnode doesn't know about the journalling taking place in the underlying FS -- and *shouldn't* know about it. The VFS interface layer is intended as a method of abstracting *exacly* this sort of implementation detail. I'm wondering why journalling would ever be visible via a vnode interaction, as a system artifact, when all the journaling operations are encapsulated in the FS implementation proper, at the non-abstract layer (in FFS terms, journalling would be a per inode operation, not per vnode operation). The *only* place you would really make the underlying structure visible at all, IMO, would be in the addition of VNOPs to add a transactioning interface for user applications. Even then, though, the operations would *still* be abstract. It *seems* like they are trying to implement the journals above the vnode layer, which makes no sense at all... so the question is *why* this is a *vnode* issue at all, ever, under *any* possible interpretation of the problem that's being solved? If they are having data corruption problems, it's lower down. The question, as he asked it, is a total non-sequitur, given his introductory text. It's like asking "Is it shorter to New York, or by bus?". -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message
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