Re: RFE: btrfs subvolume list -t, include marker for snapshots, and whether they are ro

[Satoru Takeuchi <takeuchi_satoru@jp.fujitsu.com>]

On 2016/04/15 10:55, Chris Murphy wrote:
> Hi,
>
> I'm realizing instead of doing 'btrfs subvolume -t' and then 'btrfs
> subvolume -tr' and comparing, it would be better if -t just had a
> column for whether a subvolume is ro. And maybe it's useful to know if
> a subvolume is a snapshot or not (?). I'm not super picky about the
> last one. But being able to see if it's ro or not is a nice to have.
>
> In particular on openSUSE with snapper where there's a prolific amount
> of snapshots, and the naming convention doesn't indicate whether
> something is ro or not.
>

Although I'm not sure whether such changes is acceptable or not,
just FYI, you can list subvols with ro flags by the following script.

================================================================
#!/bin/ruby

IO.popen("btrfs sub list -t " + ARGV[0]) {|p_list|
   puts p_list.gets.chomp + "ro"
   puts p_list.gets.chomp + "--"
   ro = ''
   p_list.each { |l|
     l.chomp!
     path = l.split[3]
     IO.popen("btrfs property get #{ARGV[0]+path} | sed -nre 's/^ro=(true|false)$/\\1/p'") { |p_prop|
       ro = p_prop.gets
       ro = "false" if ro.nil?
     }

     puts l + "\t" + ro
   }
}
================================================================

# NOTE: It's not well tested.

sample output:
================================================================
# ./sub-list-with-ro.rb /
ID      gen     top level       path    ro
--      ---     ---------       ----    --
257     48672   5               root    false
259     48623   257             var/lib/machines        false
452     36540   257             root/snaps/root-2016-03-18      true
457     45676   257             root/snaps/root-2016-04-08      true
================================================================

Thanks,
Satoru