Date: Thu, 17 Jan 2008 10:58:08 -0700 From: Scott Long <scottl@samsco.org> To: Rick Macklem <rmacklem@uoguelph.ca> Cc: freebsd-fs@freebsd.org, freebsd-afs@freebsd.org, openafs-devel@openafs.org, port-freebsd@openafs.org Subject: Re: VFS KPI was Re: [OpenAFS-devel] Re: AFS ... or equivalent ... Message-ID: <478F9730.7040204@samsco.org> In-Reply-To: <Pine.GSO.4.63.0801171218010.28731@muncher.cs.uoguelph.ca> References: <18CC5A4A2AC36D7FF57615EE@ganymede.hub.org> <478AF6BC.8050604@highperformance.net> <20080114142124.Y55696@fledge.watson.org> <876FB8E38251C27B14CCCA29@atlantis.pc.cs.cmu.edu> <20080116203521.K15541@fledge.watson.org> <Pine.GSO.4.63.0801171120170.18739@muncher.cs.uoguelph.ca> <478F8BF2.4070700@samsco.org> <Pine.GSO.4.63.0801171218010.28731@muncher.cs.uoguelph.ca>
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Rick Macklem wrote: > > > On Thu, 17 Jan 2008, Scott Long wrote: > >> >> Both Solaris and OSX seem to have found the path out of the VFS locking >> woods, and it would indeed be really nice if FreeBSD could follow suit. > Yes, I didn't mention Solaris (because I've never looked at it), but > being able to easily port file system code from OpenSolaris sounds like > it might be a big win. ZFS is an obvious example, but there is also > stuff like pNFS in the pipe that would be nice. (I'm going to try and > get my nfsv4 code into FreeBSD, but it will only be nfsv4.0 and I have > no urge to do 4.1/pNFS.) And others mentioned that there is quite a bit > of momentum w.r.t. OpenAFS in Solaris. > > rick > It's not just about portability, though. I know that some will argue with me on this, but the current VFS API is prohibitively difficult to use properly if you're trying to write, port, or debug a filesystem. You have to worry about interactions between vnode locks, vnode interlocks, and mount locks even before you start locking your own filesystem-private structures. Vectors like VOP_RECLAIM are a delicate and unforgiving minefield. Gaining better portability would of course be a big win, but an even bigger win would be gaining the ability of mere mortal programmers to understand and get involved in filesystems in FreeBSD. Scott
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