From owner-svn-src-head@FreeBSD.ORG Tue Nov 18 14:44:00 2014 Return-Path: Delivered-To: svn-src-head@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id AECCA2A1 for ; Tue, 18 Nov 2014 14:44:00 +0000 (UTC) Received: from out4-smtp.messagingengine.com (out4-smtp.messagingengine.com [66.111.4.28]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 7EA48F15 for ; Tue, 18 Nov 2014 14:44:00 +0000 (UTC) Received: from compute4.internal (compute4.nyi.internal [10.202.2.44]) by mailout.nyi.internal (Postfix) with ESMTP id 8515020A08 for ; Tue, 18 Nov 2014 09:43:59 -0500 (EST) Received: from web3 ([10.202.2.213]) by compute4.internal (MEProxy); Tue, 18 Nov 2014 09:43:59 -0500 DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; d= messagingengine.com; h=message-id:x-sasl-enc:from:to :mime-version:content-transfer-encoding:content-type:subject :date:in-reply-to:references; s=smtpout; bh=lq3iXhaA54zEW0mVYYq7 K0l147s=; b=jJYwf0QMLKyaixvkGkEa+KG1GpZuzttctSggOfnUPi9Nv8MThUjd deJ4NpvL4El5c3fXjz1/HHyxoTp6moO8Dy6L8dPgXle12Dt8N4+BvGy3Zeb7cS9k +5nQ+4IqAZ4UkguZhXw1mO4tWB9mH6r85op9cZlbWG4gxSn7dOXfnlg= Received: by web3.nyi.internal (Postfix, from userid 99) id 5784110C4AA; Tue, 18 Nov 2014 09:43:59 -0500 (EST) Message-Id: <1416321839.350194.192432157.42AB6F37@webmail.messagingengine.com> X-Sasl-Enc: /lH2plczP6GnX3iv8GvAc7DZsNqMlRDbsgi7xzmjdhNn 1416321839 From: Mark Felder To: svn-src-head@freebsd.org, Ian Lepore , kostikbel@gmail.com, cperciva@freebsd.org MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain X-Mailer: MessagingEngine.com Webmail Interface - ajax-9183bd94 Subject: Re: svn commit: r274653 - head/usr.sbin/freebsd-update Date: Tue, 18 Nov 2014 08:43:59 -0600 In-Reply-To: <20141118142449.GW17068@kib.kiev.ua> References: <201411181338.sAIDc9U3051869@svn.freebsd.org> <20141118142449.GW17068@kib.kiev.ua> X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 18 Nov 2014 14:44:00 -0000 On Tue, Nov 18, 2014, at 08:24, Konstantin Belousov wrote: > Why do you suppose that md-backed volumes are not persistent ? > vnode-backed devices are stable. > You're right, a vnode-backed filesystem would definitely be persistent. Clearly I've done a poor job of researching this thoroughly. I've now read md(4) in its entirety and remember mounting disk images like Linux's "mount -o loop" in the past. I don't see a way to reliably detect an mfs filesystem because it uses md and masquerades as ufs in df's output. Do you have any suggestions on how to detect this reliably? On the other hand, anyone could write a filesystem we aren't blacklisting and fall into the same trap. I thought this was going to help a few people since Oliver reported it and seemed to have a valid use-case for a tmpfs mounted /var but still wanted to use freebsd-update. Instead I'm beginning to think we should just throw this away and add an entry into BUGS in the man page and call it a day. We can't keep everyone from shooting their feet off and we probably shouldn't waste our time trying. Thoughts?