On Tue, Nov 11, 2014 at 07:37:44PM -0500, 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 Just make the size argument in your table be equal to dev_size / 2. This is where ti->len comes from and it's the correct way to tell device-mapper how big your mapped device should be. Your ctr can then parse out /dev/whatever from its args, open it and do whatever it likes with it. Access to that device by your target code is in no way constrained by the offset/size params used in the table. E.g.: # dmsetup create pf0 --table="0 2048 power-fail /dev/whatever foo bar" Would create a 1M device named pf0. The power-fail target could still access the whole of /dev/whatever if it wants to. within the Regards, Bryn. -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
