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Date: Mon, 30 May 2011 15:26:33 -0400 (EDT)
From: Rick Macklem <rmacklem@uoguelph.ca>
To: Robert Watson <rwatson@FreeBSD.org>
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Cc: svn-src-head@freebsd.org, Rick Macklem <rmacklem@freebsd.org>,
	svn-src-all@freebsd.org, src-committers@freebsd.org,
	Kostik Belousov <kostikbel@gmail.com>
Subject: Re: svn commit: r222466 - head/sbin/umount
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> 
> No doubt. :-)
> 
> If the sync(2) has actual consistency and reliability benefits, it
> should
> probably be done by the umount(2) system call, so that other future
> auto-mounters, etc, also get the same result, rather than having to
> encode it
> in every application. If it's done on blind faith, perhaps it
> shouldn't be
> done at all.
> 
I wouldn't say it's necessary, but if you look at dounmount() in
vfs_mount.c, it does a VFS_SYNC() before VFS_UNMOUNT(). I needed to
fix nfs_sync() for forced dismounts to work because of this.

rick