Date: Sun, 29 Oct 2017 12:25:37 +0100 From: Stefan Esser <se@freebsd.org> To: Kirk McKusick <mckusick@mckusick.com>, Mark Johnston <markj@FreeBSD.org> Cc: freebsd-fs@FreeBSD.org Subject: Re: softdep as a mount(8) option Message-ID: <659abe72-69f9-8e89-24ba-36a9fdfb3fd5@freebsd.org> In-Reply-To: <201710282225.v9SMPDCZ074228@chez.mckusick.com> References: <201710282225.v9SMPDCZ074228@chez.mckusick.com>
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Am 29.10.17 um 00:25 schrieb Kirk McKusick: >> Date: Fri, 27 Oct 2017 11:39:00 -0400 >> From: Mark Johnston <markj@FreeBSD.org> >> To: freebsd-fs@FreeBSD.org >> Subject: softdep as a mount(8) option >> >> Hi, >> >> I'd like to finally enable the use of SU (not SU+J) on some small UFS >> filesystems. The fact that SU is enabled using a flag in the superblock >> poses a problem for me, however: the systems containing these >> filesystems may at any time be repurposed to run a kernel that supports >> SU but contains bugs[*] that render it unusable. I therefore can't >> persistently enable SU in these systems. >> >> I'm wondering if it would be possible to enable SU using a mount >> option rather than with a persistent flag. fsck_ffs conditionalizes some >> of its logic on whether SU is configured - is this necessary for >> correctness? That is, if I run fsck on an unclean filesystem that had >> been mounted with SU, and fsck runs as though SU hadn't been configured, >> what problems might arise? >> >> [*] These bugs are a result of local modifications and aren't in >> FreeBSD. > > While it is safe and possible to add soft-updates (but not journalled > soft updates) as a mount option, it means that fsck will not know that > soft updates were in use, so it will always run in full (slow) mode at > boot time. This is why I have not added it as an option. Hi Kirk, this is a link to the message where you agreed to make SU a mount option: http://docs.freebsd.org/cgi/mid.cgi?200006282051.NAA05776 Seems you were (rightly) not too worried about FSCK, back then ;-) Regards, STefan
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