Re: [Libguestfs] list-filesystems and btrfs snapshots

Hello everyone! I have an issue with OpenSUSE-42.1 (I guess this is the only distro with btrfs snapshots by default). As we remember, list_filesystems returns btrfs snapshots along with devices. ><fs> list-filesystems /dev/sda1: swap btrfsvol:/dev/sda2/@: btrfs btrfsvol:/dev/sda2/@/.snapshots: btrfs btrfsvol:/dev/sda2/@/.snapshots/1/snapshot: btrfs btrfsvol:/dev/sda2/@/.snapshots/2/snapshot: btrfs ... btrfsvol:/dev/sda2/@/.snapshots/16/snapshot: btrfs /dev/sda2: btrfs The btrfs snapshots are not block devices, so an error is thrown by RESOLVE_DEVICE macro in stubs.c. That means we will get an error trying to call blockdev - oriented functions at these devices. ========================= After grepping "list_filesystems" issues were found in: - virt-sparsify (in-place and copying): is_lv - virt-filesystems: blockdev_getsize64 - virt-cat (inspect_os) treats this as multiboot system and refuses to proceed - virt-rescue --suggest suggests all snapshots (maybe this is correct) - virt-sysprep --operation fs-uuids goes into infinite loop [ 144.2] Performing "fs-uuids" ... virt-sysprep: warning: cannot set random UUID on filesystem btrfsvol:/dev/sda2/@/.snapshots/16/snapshot type btrfs: set_uuid: set_uuid_stub: btrfsvol:/dev/sda2/@/.snapshots/16/snapshot: expecting a device name

virt-sysprep: warning: cannot set random UUID on filesystem btrfsvol:/dev/sda2/@/.snapshots/1/snapshot type btrfs: set_uuid: set_uuid_stub: btrfsvol:/dev/sda2/@/.snapshots/1/snapshot: expecting a device name virt-sysprep: warning: cannot set random UUID on filesystem btrfsvol:/dev/sda2/@/.snapshots type btrfs: set_uuid: set_uuid_stub: btrfsvol:/dev/sda2/@/.snapshots: expecting a device name virt-sysprep: warning: cannot set random UUID on filesystem btrfsvol:/dev/sda2/@ type btrfs: set_uuid: set_uuid_stub: btrfsvol:/dev/sda2/@: expecting a device name [ 154.4] Performing "fs-uuids" ... ========================= I'd like to ask for your comments on fixing this. Should we 1. add a new command (guestfs_list_filesystems_devices) to return only device-like filesystems? 2. add something like guestfs_is_device which handles subvolumes on host side? NB: guestfs_is_blockdev also fails on stub 3. allow guestfs_is_(blockdev|chardev|...) to check subvolumes on host side? (maybe together with 2?) 4. anything else?