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

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

[Chris Murphy]

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.

-- 
Chris Murphy

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

[Satoru Takeuchi]

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

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

[Chris Murphy]

On Fri, Apr 15, 2016 at 12:51 AM, Satoru Takeuchi
<takeuchi_satoru@jp.fujitsu.com> wrote:

> 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
> ================================================================


Yeah it's a good start. I'm not sure what the UI should be exactly.
Maybe it could be an ro column that's blank for rw and ro if it's ro.
Something that's easy to parse visually? Also have it line up in a
straight column, probably before the path column?

-- 
Chris Murphy

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

[Austin S. Hemmelgarn]

On 2016-04-14 21:55, 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.
If you're just wanting info about one subvolume, just use 'subvol show'. 
  As far as 'subvol list', that was mentioned in discussion on github of 
future changes for btrfs-progs (although I don't think that's gone 
anywhere).

Checking if something is a snapshot is easy though, do 'btrfs subvolume 
show -qt', if the Parent UUID column is a -, it's a regular subvolume, 
if not, it was created as a snapshot.