Hi all, I'm planning for a python-btrfs release to happen in a about week.
All new changes are in the develop branch: https://github.com/knorrie/python-btrfs/commits/develop tl;dr: check out the two new examples added in the latest git commits and see if they provide correct info! ## Detailed usage reporting The new FsUsage object provides information on different levels (physical allocated bytes on devices, virtual space usage, etc) and also contains code to estimate how much space is still actually really available before ENOSPC happens. (e.g. the values that would ideally show up in df output). It works for all allocation profiles! Two examples have been added, which use the new code. I would appreciate extra testing. Please try them and see if the reported numbers make sense: space_calculator.py ------------------- Best to be initially described as a CLI version of the well-known webbased btrfs space calculator by Hugo. ;] Throw a few disk sizes at it, choose data and metadata profile and see how much space you would get to store actual data. See commit message "Add example to calculate usable and wasted space" for example output. show_usage.py ------------- The contents of the old show_usage.py example that simply showed a list of block groups are replaced with a detailed usage report of an existing filesystem. See commit message "A new show usage example!" for example output. ## A btrfs tutorial! A while ago I started creating documentation for python-btrfs in tutorial style. By playing around with an example filesystem we learn where btrfs puts our data on the disks, what a chunk, block group and an extent is, how we can quickly look up interesting things in metadata and how cows climb trees, moo. https://github.com/knorrie/python-btrfs/issues/11 https://github.com/knorrie/python-btrfs/blob/tutorial/tutorial/README.md I'm not sure yet if I'm going to 'ship' the first few pages already, since it's still very much a work in progress, but in any case feedback / ideas are welcome. Have a look! ## Other changes Other changes are the addition of the sync, fideduperange and get_features ioctl calls and a workaround for python 3.7 which breaks the struct module api. ## P.S. And finally, when doing the above, I discovered a few extra unintended features and bugs in the btrfs chunk allocator (Did you know RAID10 block groups are limited to 5GiB in size? Did you know that when the last chunk added on a disk is of DUP type, it could end up having an end beyond the limit of a device?). I still have to actually test the second one, causing it to happen. If anyone is interested to help with that, please ask about it. The bugs are all related to repeated kernel code all over the place containing a lot of if statements dealing with different kind of allocation profiles and their exceptions. What I ended up doing is making a few helper functions instead, see the commit "Add volumes.py, handling device / chunk logic". It would probably be nice to do the same in the kernel code, which would also solve the mentioned bugs and prevent new similar ones from happening. Have fun, -- Hans van Kranenburg
