Date: Tue, 14 May 2002 23:15:26 -0700 From: Terry Lambert <tlambert2@mindspring.com> To: Robert Watson <rwatson@FreeBSD.org> Cc: Julian Elischer <julian@elischer.org>, arch@FreeBSD.org Subject: Re: Future of IFS Message-ID: <3CE1FCFE.A2602D49@mindspring.com> References: <Pine.NEB.3.96L.1020514132531.72699A-100000@fledge.watson.org>
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Robert Watson wrote: > My impression from my conversation with him was that if he did start > maintaining IFS again, it would be a re-implementation for 5.0. I'm > concerned that in its current state, we will be unable to make progress on > UFS2. At first glance, I find this answer surprising. I would think that the problems of externalizing UFS2 through the existing system call interface (a VFS consumer limited to 32 bits for everything but file offsets) would be exactly analogous to externalizing it via NFSv3 (a VFS consumer limited to 32 bits for almost everything, except the things where it's limited to 16 bits). The IFS code conversion of inode numbers into files isn't, to my mind, so significantly different from the conversion of NFS handles into files, that I could see how you could fundamentally break one without at least causing a lot of problems for the other. In fact, since the on disk dirent and the system call exposed dirent are only intentionally "coincidentally" equal... the same for the stuctures used by getattr/setattr/stat... it should be possible to implement a UFS2 in FreeBSD without really changing *any* of the exposed interfaces seen by user space, except later, to get at UFS2 specific features, so the work could even be staged to reduce overall risk. Every FS that isn't FFS (and therefore doesn't "coincidently" luck out) already does explicit conversions. Breaking the historical "coincidence" for a new FS seems to be a logical way of achieving ABI/API compatability. Please correct me if my logic is way off base. -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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