This commit removes some unnecessary custom tmpdir() fixtures
and uses the pytest buildin tmp_path instead.
Some custom tmpdir fixtures are left in place as they configure
the tmp location to be under `/var/tmp` which is not trivial to
do with pytests `tmp_path`. Not sure or not if the is a deep
reason there for using /var/tmp. I assume it's to ensure that
the tests run on a real FS not on a potential tmpfs but I don't
have the full background so didn't want to change anything.
LOOP_CONFIGURE allows to atomically configure the decive when opening
it. This avoid the possibility of a race condition where between set_fd
and set_status some operations are already accepted by the loopback
device. See https://lwn.net/Articles/820408/
This feature was included in the linux kernel 5.8 however it is safe to
not include any kind of fallback to the previous method as @obudai
points out that:
LOOP_CONFIGURE was backported into RHEL 8 kernel in RHEL 8.4 as a part
of https://bugzilla.redhat.com/show_bug.cgi?id=1881760 (block layer:
update to upstream v5.8).
Since RHEL 8.4 is currently the oldest supported release that we support
running osbuild on, it might be just fine implementing this without the
fallback.
From a centos stream 8 container:
kernel-4.18.0-448.el8.x86_64
- loop: Fix missing discard support when using LOOP_CONFIGURE (Ming Lei) [1997338]
- [block] loop: Set correct device size when using LOOP_CONFIGURE (Ming Lei) [1881760]
- [block] loop: unset GENHD_FL_NO_PART_SCAN on LOOP_CONFIGURE (Ming Lei) [1881760]
- [block] loop: Add LOOP_CONFIGURE ioctl (Ming Lei) [1881760]
Introduce a new class to manage devices, `DeviceManger` and move the
code to open devices from the `Device` here. The main insight of why
the logic should be place here is that certain information is needed
to open the devices, independently of specific type: the path to the
device node directory, `devpath`, the actual `tree` and the service
manager instance to start the actual service. Instead of passing all
this information again and again to the `Device` class, we now have
a specialized (service) manager class for devices that has all the
needed information all the time. Additionally, the special handling
of parent devices is moved from the pipeline to the service manager,
which is where it belongs.
This will make even more sense for mounts, where the `DeviceManger`
can then be passed to access the individual devices.
Port the test to use the `DeviceManager`.
