According to man page `man 8 swapon', "Preallocated swap files are
supported on XFS since Linux 4.18". This patch checks for kernel version
before attepting to create swapfile, using dd for XFS only on kernel
versions <= 4.18 or btrfs.

Signed-off-by: Eduardo Otubo <otubo@redhat.com>

Replaced the regex by the os function calls and put it on a separate
function inside util.py module.

Signed-off-by: Eduardo Otubo <otubo@redhat.com>

…g the runtime of cloud-init.

Co-authored-by: Daniel Watkins <daniel@daniel-watkins.co.uk>

Signed-off-by: Eduardo Otubo <otubo@redhat.com>

Signed-off-by: Eduardo Otubo <otubo@redhat.com>

Wrapping test_kernel_version() into class TestKernelVersion() and
adding pytest parametrize decoration. In order to have it working,
the cache decoration would have to be removed, though. Otherwise the
function cache would always return the same value and would fail the
tests.

Signed-off-by: Eduardo Otubo <otubo@redhat.com>

Splitting test_swap_creation_method into 3 different cases for different
filesystems. Leaving the methods way of asserting the test with only
cc_mounts.handle() function. Like test_swap_integrity() does.

Signed-off-by: Eduardo Otubo <otubo@redhat.com>

[0] pytest-dev/pytest#3484

Creating a new class of tests TestSwapFileCreation() for this purpose.
The class still uses test_helpers.FilesystemMockingTestCase to mock
a file system so swap file can be created.

Also added a check on cloudinit/config/cc_mounts.py to make sure the
swap file really exists, which is not the case on unittests. The swap
file is not being created, the test just makes sure if the correct calls
are being done.

Signed-off-by: Eduardo Otubo <otubo@redhat.com>

…blank line added by merge