fi resize: rework output

[kdave]

The current output of the resize command is practically useless.

$ btrfs fi resize 2:-10G /path
Resize '.' of '2:-10G'

The operation and end result should be described better possibly in human readable text and expected device state after the operation.

[adam900710]

For the readability part, 2 and -10G should definite changed to something like resize device 2 to <new_size> (diff -10G)

But for the . part, should we just output the original path like resize the btrfs mounted at '/path' .... or with more details like UUID?

[kdave]

I think more information in this case is desirable so we can put them on separate lines. Also as we have the global verbose options we can do two modes:

• one line summary

Resize device id 1 (/dev/path) from 100G to 90G

• multiple 'key: value' lines with further details

Resize device on /path
Device id: 1
Device path: /dev/path
Old size: 100G
New size: 90G
Difference: -10G

That's for starters.

[realwakka]

@kdave , If there is no one that handle this, is it okay to handle it? Is it right format like you write above?

[kdave]

The one line summary has been added to devel. The long output as described could be also useful and we now have all the information parsed so it's just a matter of formatting. One line is missing in the proposed format Device size: with the block device size. The long format goes with the verbosity level at least 1.

[cmurf]

I'm seeing this with btrfs-progs v5.11.1 and kernel 5.12-rc6

# btrfs fi show
Label: 'OWC300G'  uuid: ab845dd9-63b5-4459-b98b-06ed92398247
Total devices 1 FS bytes used 160.00KiB
devid    1 size 298.09GiB used 3.06GiB path /dev/sdb1
         
# btrfs fi resize 1:150g /srv/extra
Resize device id 1 (/dev/sdb1) from 298.09GiB to 0.00B

# btrfs fi show
Label: 'OWC300G'  uuid: ab845dd9-63b5-4459-b98b-06ed92398247
Total devices 1 FS bytes used 160.00KiB
devid    1 size 150.00GiB used 3.06GiB path /dev/sdb1

from 298.09GiB to 0.00B? That's wrong. At least it did the resize correctly.

[kdave]

Fix pushed to devel. I'm leaving this open until the verbose version of resize output is done.

[kdave]

I find the one line summary sufficient, if somebody wants to add extended info, please open a new issue with suggested output.