From mboxrd@z Thu Jan 1 00:00:00 1970 From: "John Stoffel" Subject: Re: mdadm: Patch to restrict --size when shrinking unless forced Date: Mon, 9 Oct 2017 22:01:24 -0400 Message-ID: <23004.10740.53750.440109@quad.stoffel.home> References: <22997.8664.67459.119616@quad.stoffel.home> <87a81637lq.fsf@notabene.neil.brown.name> <23002.37193.492253.120639@quad.stoffel.home> <87shetz207.fsf@notabene.neil.brown.name> <23002.53075.413063.6948@quad.stoffel.home> <87h8v9yn91.fsf@notabene.neil.brown.name> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Phil Turmel Cc: NeilBrown , John Stoffel , Eli Ben-Shoshan , Jes.Sorensen@gmail.com, linux-raid@vger.kernel.org List-Id: linux-raid.ids >>>>> "Phil" == Phil Turmel writes: Phil> On 10/09/2017 12:10 AM, NeilBrown wrote: >> If there is some action that mdadm can currently be told to perform, and >> when it tries to perform that action it corrupts the array, then >> it is certainly appropriate to teach mdadm not to perform that action. >> It shouldn't even perform that action with --force. I agree that >> changing mdadm like this is complementary to changing the kernel. Both >> are useful. Phil> A certain amount of the trouble with all of this is the english meaning Phil> of "grow" doesn't really match what mdadm allows. Phil> Might it be reasonable to reject "--grow" operations that reduce the Phil> final array size, and introduce the complementary "--reduce" operation Phil> that rejects array size increases? I like this idea! And it wouldn't be hard to implement in mdadm. Phil> Both operations would share the current code, just apply a different Phil> sanity check before proceeding. Phil> mdadm would then at least not violate the rule of least surprise.