From mboxrd@z Thu Jan 1 00:00:00 1970 From: Heinz Mauelshagen Subject: Re: Question about dm target size Date: Wed, 12 Nov 2014 12:15:16 +0100 Message-ID: <54634144.6080004@redhat.com> References: <5462ABD8.1050609@fb.com> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5462ABD8.1050609@fb.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: dm-devel@redhat.com List-Id: dm-devel.ids On 11/12/2014 01:37 AM, Josef Bacik wrote: > Hello, > > I'm creating a dm target to better test power fail situations and I'm > having trouble figuring out how to make the dm device appear as a > different size. So for example you do the normal dm table > > offset size power-fail /dev/whatever args > > I want to use the entire size of /dev/whatever, but I want my dm > device to show up as size/2. So right now I'm doing this in my ->ctr > function > > ti->len /= 2; Passing in "ti->len = 'size of your dev in sectors' / 2" is what you want. Heinz > > Is that acceptable, or will this have some side-effect that's going to > bite me in the ass? I can't see any other target that does something > similar and there appears to be no helper function. This seems to > work as far as blockdev --getsz is concerned, but I'm worried I need > to do more. Thanks, > > Josef > > -- > dm-devel mailing list > dm-devel@redhat.com > https://www.redhat.com/mailman/listinfo/dm-devel