Date: Fri, 17 Jun 2005 16:02:10 -0400 From: Erez Zadok <ezk@cs.sunysb.edu> To: Allan Fields <bsd@afields.ca> Cc: freebsd-fs@freebsd.org, jwd@freebsd.org Subject: Re: Summer of Code: Magic Links, FiST/vnode stacking?, ReiserFS Message-ID: <200506172002.j5HK2AVS016366@agora.fsl.cs.sunysb.edu> In-Reply-To: Your message of "Thu, 16 Jun 2005 22:08:03 EDT." <20050617020803.GC95979@afields.ca>
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In message <20050617020803.GC95979@afields.ca>, Allan Fields writes: > * FiST / vnode stacking (Coordinating w/ Erez Zadok?): > > This is one I wanted to see move forward on *BSD. What FiST offers > is a unified approach for template file systems which can aid in > cross-platform development of filesystem code (potentially) saving > a significant amount of developer effort and duplication. It's > been around for a number of years now and FreeBSD templates do > exist. Good timing: we just released fistgen-0.1.2, which contains updated ports to FreeBSD-5.x. You may get it from ftp://ftp.filesystems.org/pub/fist/fistgen-0.1.2.tar.gz > The Size-Changing Algorithm (SCA) code is Linux specific, > so I'm not certain of the status. The SCA code is indeed only in the Linux templates and hasn't been ported to the FreeBSD ones. There are also several SCA-related bugs in our bugzilla server, yet to be fixed. > Areas left to address: FreeBSD Templates (remaining build issues, > keep templates up to date, etc.), SCA: Size-Changing-Algorithm (some > work on this internally w/ the Stony Brook team?), Our group would love to work with anyone in the freebsd community to get more and stable stackable file systems into freebsd. > Cache Coherency issues, etc. Cache coherency has always been an issue with stackable file systems. What OSs need is something like Heindeman did in his SOSP 1995 paper. > [http://www.fsl.cs.sunysb.edu , http://www.filesystems.org ] > > Desirable/Related File System Ports: ncryptfs and/or ecryptfs, > gzipfs, unionfs [ne]cryptfs would indeed be very nice to have, but I thought that freebsd already had some pretty powerful crypto device-level support, no? gzipfs will "just work" once the SCA code is ported to freebsd. Unionfs is another story. We've developed and released a unioning f/s for Linux, and in the 6+ months since it's been released, we've had many downloads and users -- and consequenetly many bugs reported and mostly fixed. We've found out that doing namespace unification properly (i.e., unix semeantics compliant) is much harder than it initially seems. We've written a detailed tech report on it. If anyone is going to tackle fixing the freebsd unionfs, you should read our tech-report first. Cheers, Erez.
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