Re: [Libguestfs] [PATCH v5 REBASE 0/4] virt-resize: add support for resizing logical

On Wed, Jan 28, 2015 at 03:43:19PM +0000, Richard W.M. Jones wrote: > On Wed, Jan 28, 2015 at 02:24:15PM +0800, Hu Tao wrote: > > On Wed, Dec 17, 2014 at 03:07:11PM +0800, Hu Tao wrote: > > > On Thu, Oct 30, 2014 at 10:46:52AM +0800, Hu Tao wrote: > > > > Hi Rich, > > > > > > > > This is rebase of v5 series. Meanwhile, I found a bug when shrinking > > > > partitions, and the fix is incuded in this version (patch 2). > > > > > > Hi, > > > > > > When support to resizing logical partitions is enabled, there is a > > > problem about resizing the extended partition: whether the extended > > > partition is automatically resized (expanded or shrunk) by virt-resize > > > based on the resizing of logical partitions? > > > > > > All the cases can be categorized as these two: > > > > > > 1. user doesn't explictly resize the extended partition. In this case it > > > seems reasonable to automatically expand the extended partition as well. > > > > > > 2. user explictly resizes the extended partition. If the extended > > > partition is resized as user requested, then we should deal with the > > > conflicts about resizing extended partition and logical partitions, > > > this is somewhat tricky in the current implementation; But if the > > > extended partition is automatically resized, user will be confused as > > > the resulting size may be what he/she expects. > > > > s/may be/may not be/ > > > > I think the best choice is: > > > > 1. If user doesn't explictly resize the extended partition, then any > > resizing (expanding or shrinking) of logical partitions will cause > > the automatical resizing of the extended partition. > > > > 2. If user explictly resize the extended partition, then any confliction > > between resizing of the extended partition and logical partitions > > will raise an error. > > > > To achieve this, the patchset needs to be refactored heavily. So I'd > > like to hear suggestions before starting refactor. > > Part of the problem I have with the original patch set is really > nothing to do with this user input question. It's that the patches > don't model properly how the extended partition and logical partitions > actually work. There is one partition which is nominated as the > extended partition (EP), and then logical partitions (LP) live inside > that EP. At the moment we just have a list of partitions and list of > LPs. Do you have any idea about modelling EP and LPs? What I can think of is adding a type extended_partition which is similar to type partition, except that it has a member partitions of type partition list to hold logical partitions.