Date: Sat, 24 Jun 2000 12:00:26 -0700 From: Kirk McKusick <mckusick@mckusick.com> To: Adrian Chadd <adrian@freebsd.org> Cc: Stefan Esser <se@freebsd.org>, freebsd-current@freebsd.org Subject: Re: cvs commit: src/sys/contrib/softupdates softdep.h ffs_softdep.c Message-ID: <200006241900.MAA04365@beastie.mckusick.com> In-Reply-To: Your message of "Thu, 22 Jun 2000 11:54:26 %2B0200." <20000622115426.H29036@zoe.bastard.co.uk>
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Date: Thu, 22 Jun 2000 11:54:26 +0200 From: Adrian Chadd <adrian@freebsd.org> To: mckusick@mckusick.com Cc: freebsd-current@freebsd.org Subject: Re: cvs commit: src/sys/contrib/softupdates softdep.h ffs_softdep.c On Thu, Jun 22, 2000, Brad Knowles wrote: > At 10:30 AM +0200 2000/6/22, Adrian Chadd wrote: > > > I like this. Would anyone object if this was brought over > > from NetBSD ? > > If you're asking for a vote, you've got mine. Hmm, Kirk has valid points for leaving a softupdates filesystem identified by tunefs and not a mount option. Kirk, do you still want to keep things that way ? Adrian Yes, I do want it kept as a yunefs option. Date: Thu, 22 Jun 2000 13:31:29 +0200 From: Stefan Esser <se@freebsd.org> To: Adrian Chadd <adrian@freebsd.org> Cc: mckusick@mckusick.com, freebsd-current@freebsd.org, Stefan Esser <se@freebsd.org> Subject: Re: cvs commit: src/sys/contrib/softupdates softdep.h ffs_softdep.c ... I do remember the discussion that lead to the requirement to enable soft-updates with tunefs -n. But I do not remember, why the soft-updates state could not be just set in the local copy of the super-block and flushed to disk when the file system is marked dirty ? Just before a clean file system is to be mounted R/W, it is obviously safe to modify the soft-updates state. The file system must have been cleaned before, or the R/W mount will not be possible (extra logic can prevent the modification of the MNT_SOFTDEP bit if a mount of a non-clean partition is forced, in order to preserve the soft-updates state for the next fsck run). If the kernel was compiled without soft-updates, it may be the right thing to keep MNT_SOFTDEP cleared, to not mislead FSCK ... Did I miss something obvious ? Regards, STefan Your above proposal would work, though that is not how NetBSD implemented it. I feel that it is a lot of extra mechanism for very little gain. Administrators generally make a one-time decision to run soft updates on a filesystem. It is not the sort of thing that they want to change on a regular basis. It is possible to run tunefs on a filesystem that is mounted read-only, so it no more difficult to use tunefs than it is to make it a mount-time option (i.e., they still have to down-grade to read-only, set the option, then upgrade). Finally, I expect that soft updates will eventually just be defaulted to `on' when a filesystem is built, and in a few rare instances an administrator will want to turn it off. I do not want to have an option that needs to be added to nearly every fstab entry to get the default behavior. Plus it is just one more bit of trivia that new system administrators need to learn to make their systems run well. The more of those details that need not be learned because they just do the right thing, the better. Kirk McKusick To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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