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From: Matthias Andree <matthias.andree@gmx.de>
To: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: <64074.1125994865@phk.freebsd.dk> (Poul-Henning Kamp's message of
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Date: Tue, 06 Sep 2005 11:01:30 +0200
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Cc: Don Lewis <truckman@FreeBSD.org>, current@FreeBSD.org
Subject: Re: patch for ext2fs unmount problem at shutdown
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"Poul-Henning Kamp" <phk@phk.freebsd.dk> writes:

> PS: Considering power management, sleep/suspend modes etc, it would
> make sense to add a "MNT_CLEAN" flag to pass to VOP_FSYNC which
> instructed the filesystem to flush everything to disk, and reset
> any "dirty" flags on the disk to "clean" but leave the filesystem
> mounted.  (On subsequent I/O the first thing the filesystem must
> do is set the dirty flag again.  That way it would be as safe (as
> possible) to power a sleeping/suspend machine off.

If you have proper cache flushing/synchronization semantics (such as
putting an ATA disk to sleep), go right ahead - but woe betide the user
whose disk choses to reorder writes and sleep before flushing the whole
cache.

-- 
Matthias Andree