tree-wide: remove Emacs lines from all files This should be handled fine now by .dir-locals.el, so need to carry that stuff in every file.

basic: include only what we use This is a cleaned up result of running iwyu but without forward declarations on src/basic.

tmpfiles: create subvolumes for "v", "q", and "Q" only if / is a subvolume It's not a good idea to create subvolumes for parts of the OS tree (such as /home, or /var) if the root directory is not a subvolume too. We shouldn't assume control of "heavier" objects such as subvolumes, if the originating object (the root directory) is a "light-weight" object, i.e. a plain directory. Effectively this means that chroot() environments that are run on a plain directory do not have to deal with problems around systemd creating subvolumes that cannot be removed with a simple "rm" anymore. However, if the chroot manager creates a proper subvolume for such an environment it will also get further subvolumes placed in there, under the assumption that the manager understands the concept of subvolumes in that case.

btrfs: beef-up btrfs support with a limited understanding of quota With this change we understand more than just leaf quota groups for btrfs file systems. Specifically: - When we create a subvolume we can now optionally add the new subvolume to all qgroups its parent subvolume was member of too. Alternatively it is also possible to insert an intermediary quota group between the parent's qgroups and the subvolume's leaf qgroup, which is useful for a concept of "subtree" qgroups, that contain a subvolume and all its children. - The remove logic for subvolumes has been updated to optionally remove any leaf qgroups or "subtree" qgroups, following the logic above. - The snapshot logic for subvolumes has been updated to replicate the original qgroup setup of the source, if it follows the "subtree" design described above. It will not cover qgroup setups that introduce arbitrary qgroups, especially those orthogonal to the subvolume hierarchy. This also tries to be more graceful when setting up /var/lib/machines as btrfs. For example, if mkfs.btrfs is missing we don't even try to set it up as loopback device. Fixes #1559 Fixes #1129

btrfs: always remove the per-subvol qgroup when removing a subvol btrfs doesn't do that automatically, hence let's do that explicitly each time.

btrfs-util: when snapshotting make sure we don't descent into subvolumes we just created We already had a safety check in place that we don't end up descending to the original subvolume again, but we also should avoid descending in the newly created one. This is particularly important if we make a snapshot below its source, like we do in "systemd-nspawn --ephemeral -D /". Closes https://bugs.freedesktop.org/show_bug.cgi?id=90803

build-sys: split internal basic/ library from shared/ basic/ can be used by everything cannot use anything outside of basic/ libsystemd/ can use basic/ cannot use shared/ shared/ can use libsystemd/