[libvirt] virsh blockresize syntax is inconsistent with vol-resize and somewhat dangerous

Hello, virsh has two commands which can be used to resize block devices - "blockresize" for volumes in use by and active guest, and "vol-resize" for volumes which are not in use. The vol-resize syntax allows to specify the size as a delta (increase or decrease vs. the current size), and also refuses to shrink a volume unless the "--shrink" argument is also passed. Most other tools which can be used for block device resizing (outside of libvirt) also have similar "--shrink" argument requirements when reducing the size of an existing block device. e.g. ceph requires "--allow-shrink" when using the "rbd resize" command. The lack of such a safety device makes "blockresize" a foot-gun (which I recently found to great effect when I typoed the domain name to another valid domain). It seems I am not alone in making this error e.g. https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=902171 One possible solution would be to make a new command e.g. "domblkresize" or perhaps "live-resize", which implement the "--shrink" and "--delta" behaviour to make it consistent with "vol-resize" syntax, and mark the "blockresize" command as deprecated in the documentation and help (so that existing automation which depends on the current behaviour doesn't break). Any thoughts? Should I open this as an RFE? Thanks, Tim. -- South East Open Source Solutions Limited Registered in England and Wales with company number 06134732. Registered Office: 2 Powell Gardens, Redhill, Surrey, RH1 1TQ VAT number: 900 6633 53 http://seoss.co.uk/ +44-(0)1273-808309