[DISK] BTRFS implementation fixes

ingrinder commented 4 years ago

Description

This PR allows the inclusion of btrfs filesystems in the disk space module without root, and fixes the behaviour of the btrfs implementation.

Reason and / or context

Current behaviour is incorrect for btrfs filesystems:-

Usage shown is actually allocated space on disk (this allocated space can be larger than the amount of data stored in it, or can be empty if files have been removed)
Usage and total filesystem space available are counted multiple times for some btrfs configurations, e.g. a RAID-1 setup.
Root is required to use the current btrfs-progs utilities (not ideal!)

How has this been tested ?

Using the python tests.
Using two machines with different btrfs configurations.

Types of changes :

[X] Bug fix (non-breaking change which fixes an issue)
[X] Typo / style fix (non-breaking change which improves readability)
[ ] New feature (non-breaking change which adds functionality)
[X] Breaking change (fix or feature that would cause existing functionality to change)

Checklist :

[X] [IF NEEDED] I have updated the README.md file accordingly ;
[X] [IF NEEDED] I have updated the test cases (which pass) accordingly ;
[X] My changes looks good ;
[X] I agree that my code may be modified in the future ;
[X] My code follows the code style of this project (PEP8).

HorlogeSkynet commented 4 years ago

A few days later... He finally made it. :calendar:

So... Hello @ingrinder ! Thanks for all the work you have done (and are doing) :bow: About this PR, I've just rebased it against master, and taken the freedom to add some changes. If you are :ok: about them, I'd be glad to merge it A.S.A.P. :ok_hand:

PS : I can't officially ask for your review from GitHub (as you are not counted as a collaborator), but we can do something about it in the near future if you are interested too.

Bye, see you on the other sides !

EDIT : and sorry for my first poor BTRFS implementation, I don't know this FS very well :confused:

ingrinder commented 4 years ago

All looks good to me!

Only thing I'd like to ask is about how far back are we aiming for in terms of compatibility? I noticed we have Python 3.4 specified in the CI builds, and given Debian Jessie is still in LTS (at least for a few months) I assumed we were aiming for something around there? Which may mean reversion of 9c859e4368e49d0aaf119a9c91fb41fdcba5f053, since btrfs-progs is only a package in Stretch and later whereas btrfs-tools is supported in Jessie, and later versions as a meta-package for btrfs-progs (meaning btrfs-tools works everywhere in Debian).

Other than that though, feel free to merge 👍

HorlogeSkynet commented 4 years ago

Yes ! It would be very good to keep compatibility down to 3.4, as you said, for Debian Jessie (that's a fact, lots of servers are still running Debian 8).

~~So you are definitely right, I'll partially revert this last commit to restore btrfs-tools for future .DEB generations~~

EDIT @ingrinder : Actually not ! As stated here, .DEB do not work on Jessie, as python3-distro is not packaged in repositories (see #36). So I we may keep btrfs-progs for Stretch and newer :wink:

ingrinder commented 4 years ago

Ahh yeah, okay, we should probably just keep btrfs-progs then 😃

HorlogeSkynet / archey4