Date: Thu, 28 Mar 2002 17:51:46 -0800 From: Terry Lambert <tlambert2@mindspring.com> To: Garance A Drosihn <drosih@rpi.edu> Cc: "Brian F. Feldman" <green@FreeBSD.ORG>, Kirk McKusick <mckusick@beastie.mckusick.com>, arch@FreeBSD.ORG Subject: Re: vnode::v_op bugfix / PERFORCE change 8574 for review (fwd) Message-ID: <3CA3C8B2.D9E15AFF@mindspring.com> References: <200203282327.g2SNRog05733@green.bikeshed.org> <p0510152eb8c96b7c9b78@[128.113.24.47]>
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Garance A Drosihn wrote: > A previous message said new vnode-ops are very rare. I > do not know what would trigger them, but I will note that > one of the things I can brag about with freebsd is that > I have a freebsd machine running a production service > here which has now been up for 437 consecutive days. Are > these events rare enough that I would never have to worry > about ending an uptime-streak because of too many of them? That was my claim. How often do you load FS's that support operations and additional system calls that reference those operations, that weren't there before you loaded the FS? The specific problem is adding non-existant VOP placeholders to existing VOP lists for FS's that don't support them anyway, so that when they are bogusly dereferenced out, they don't end up being a derference of whatever-happens-to-be-there-in-memory after thenend of the table. The "fix" is to replace the VOP list on all existing vnodes, but doing that screws up operations in progress, since there is no draining barrier. Actually, there's a really ugly hack you could do as well, which is the same ugly hack that would allow you to enable soft updates as a mount option, rather than having to use tunefs, but I really hesitate to suggest it, because it is truly incredibly ugly, since it simulates an unmount and a mount, without invalidating any open vnodes. Conversion of read-only to R/W and vice versa do it today; the ugly part is that you have to break the routine out, add a VFSOP for it, and then pass a function to it to call in the middle of the operation. I wouldn't recommend it, unless you cleared the boards on the mount code and really worked it over (again; several of us have had our noses in there in the past, myself included). -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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