This is a contunuation of thread: "lxc: truncate LOOP_GET_STATUS64.lo_file_name for long loop backing paths" https://lists.libvirt.org/archives/list/[email protected]/thread/NSOQDVNLF4XP34KBOGEACJYBVRGDXHQD/ with updated and more relevant subject.
This patch fixes problem reported as https://gitlab.com/libvirt/libvirt/-/work_items/63 but before it could be posted, it required fixing or rather implementing aliase for block devices and file systems on LXC domains, commit 065337dd2c1b120be92a4960d0566eb745e8e350 and the patch posted here: https://lists.libvirt.org/archives/list/[email protected]/thread/RWKBBQHE377G55CKFEX6DNZUXO6OJXAA/ Now, with the working aliases for for block devices and file systems, this change implement the this naming pattern "libvirt-$UUID-$DEVALIAS" for LOOP_GET_STATUS64.lo_file_name which is shown in output of the losetup. Example, for domain with these file systems attached, where the second one is backed by path with long file name: <filesystem type='file' accessmode='passthrough'> <driver type='loop' format='raw'/> <source file='/var/tmp/short.raw'/> <target dir='/short'/> <alias name='fs1'/> </filesystem> <filesystem type='file' accessmode='passthrough'> <driver type='loop' format='raw'/> <source file='/var/tmp/looooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong.raw'/> <target dir='/long'/> <alias name='fs2'/> </filesystem> The losetup output looks like below: [root@rvm08m-3 ]# losetup -l -O +REF NAME SIZELIMIT OFFSET AUTOCLEAR RO BACK-FILE DIO LOG-SEC REF /dev/loop1 0 0 1 0 /var/tmp/looooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong.raw 0 512 libvirt-942c6580-8c49-4b8d-8e79-bba79e9709fd-fs2 /dev/loop0 0 0 1 0 /var/tmp/short.raw 0 512 libvirt-942c6580-8c49-4b8d-8e79-bba79e9709fd-fs1 The last column is where the LOOP_GET_STATUS64.lo_file_name can be seen. This patch does not add support for custom, user specified aliases because: 1. At the start of the domain, user aliases are silently dropped during XML parsing and are auto-generated as fs0, fs1, ... VIR_DOMAIN_DEF_FEATURE_USER_ALIAS is not set for LXC domains. 2. Attaching, hot-plug of a file system to live LXC domain is not supported: "error: unsupported configuration: device type 'filesystem' cannot be attached"
