If /dev/loop-control exists on the system running the test then
ioctlLoopCtlGetFree() will be called, but if not it won't. It does
not exist in the standard docker build environment, so the tests
currently require this to not be called. This makes it instead
optional, allowing the tests to run on e.g. Fedora.
Docker-DCO-1.1-Signed-off-by: Alexander Larsson <alexl@redhat.com> (github: alexlarsson)
We already have some kind of refcounting in DeviceSet, this fleshes
it out to allow it to completely subsume the refcounting in
devmapper.Driver.
This allows us to drop the double refcounting, and the locking inside
devmapper.Driver. This, in particular the locking simplification will
make it easier in the future to parallelize the device mapper.
Docker-DCO-1.1-Signed-off-by: Alexander Larsson <alexl@redhat.com> (github: alexlarsson)
This works around the fact that deleting a device in a thin pool
doesn't discard the free space. Unfortunately even this is not perfect,
as it seems discards are respected only for blocks that has never been
shared in the thin device code. However, this has been fixed in the
upstream kernel device-mapper tree:
http://git.kernel.org/cgit/linux/kernel/git/device-mapper/linux-dm.git/commit/?h=for-next&id=0ab1c92ff748b745c1ed7cde31bb37ad2c5f901a
When this hits the kernel I belive this will fully return space
for removed images/containers to the host FS. For now it only
helps partially (which is better than nothing).
Docker-DCO-1.1-Signed-off-by: Alexander Larsson <alexl@redhat.com> (github: alexlarsson)
