On Jan 14, 2015 6:26 PM, "Mike Snitzer" <<a href="mailto:snitzer@redhat.com">snitzer@redhat.com</a>> wrote: > > On Wed, Jan 14 2015 at 7:16pm -0500, > Dan Ehrenberg <<a href="mailto:dehrenberg@chromium.org">dehrenberg@chromium.org</a>> wrote: > > > If a device is used as the root filesystem, it can't be built > > off of devices which are within the root filesystem (just like > > command line arguments to root=). For this reason, Linux has a > > pseudo-filesystem for root= and md initialization based on the > > function name_to_dev_t, which handles different ways of specifying > > devices including PARTUUID and major:minor. > > > > This patch applies name_to_dev_t to dm initialization. Rather > > than assuming that all things which are not major:minor are paths > > in an already-mounted filesystem, this patch first attempts > > name_to_dev_t and tries the filesystem as a fallback. > > What is all this talk of an already-mounted filesystem? > > dm_get_device() currently assumes either a major:minor or path to the > block device is provided. Please be specific about what functionality > this change enables that you cannot do without. I want to run dm-verity on top of an ubiblock device. Ubiblock uses a dynamic major number so I can't just refer to it as a major:minor. Because it is the root filesystem I can't refer to it through the lookup_bdev path. Thanks, Dan