Date: Fri, 21 Jan 2000 18:54:15 -0500 (EST) From: Robert Watson <robert@cyrus.watson.org> To: Brian Beattie <beattie@aracnet.com> Cc: fs@freebsd.org Subject: Re: UDF, userfs Message-ID: <Pine.BSF.3.96.1000121184917.66083B-100000@fledge.watson.org> In-Reply-To: <Pine.LNX.4.10.10001211012020.28236-100000@shell1.aracnet.com>
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Brian, Both the Arla and Coda file systems are distributed file systems managed from userland processes. They do this by providing loadable kernel modules (or static compiled in code) to allow userland processes to listen on a device file (/dev/xfsX for Arla, /dev/codaX for Coda) and receive "upcalls" from the kernel. Usually, the userland process is multi-threaded so that it can handle in parallel requests that might involve extensive waiting (for example, transfering a large file using a network file system). Before writing something from scratch, you may want to investigate these and see if they meet your needs. Coda is available in the base FreeBSD distribution, and Arla as a package. I know that the Arla project has put significant work into making their code useful beyond just an AFS client with the intent in mind that other developers could use the module for other file systems. I built a fair portion of a caching file system based on the Arla kernel module at one point. Hope this is helpful, Robert On Fri, 21 Jan 2000, Brian Beattie wrote: > I have made a couple of posts to hackers, that probably should have gone > here to fs. I and thinking about implementing a UDF filesystem. The plan > I am considering, is to implement a "userfs" to allow me to do most of the > work in a user process. > > I have been thinking about the userfs implementation. I will need some > way for the user process to talk the backend of the userfs kernel code. > The two ways I have thought of are I/O,, probably ioctl's or a new system > call. > > I assume that it is possible, using a module to add an entry to the > syscall table, but I lean more towards a new pseudo device to hang the > ioctl's off of. > > I would be ineterested in any comments. I would also like to hear from > anybody who has thought about a userfs implementation for FreeBSD. > > Brian Beattie | The only problem with > beattie@aracnet.com | winning the rat race ... > www.aracnet.com/~beattie | in the end you're still a rat > > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-fs" in the body of the message > Robert N M Watson robert@fledge.watson.org http://www.watson.org/~robert/ PGP key fingerprint: AF B5 5F FF A6 4A 79 37 ED 5F 55 E9 58 04 6A B1 TIS Labs at Network Associates, Safeport Network Services To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message
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