devmapper: Maks createSnapDevice a function, not a method

No idea why this was a method. Maybe a cut and paste bug.

Docker-DCO-1.1-Signed-off-by: Alexander Larsson <alexl@redhat.com> (github: alexlarsson)
devmapper: Move error detection to devmapper.go

This moves the EBUSY detection to devmapper.go, and then returns
a real ErrBusy that deviceset uses.

Docker-DCO-1.1-Signed-off-by: Alexander Larsson <alexl@redhat.com> (github: alexlarsson)
devmapper: Simplify thin pool device id allocation

Instead of globally keeping track of the free device ids we just
start from 0 each run and handle EEXIST error and try the next one.

This way we don't need any global state for the device ids, which
means we can read device metadata lazily. This is important for
multi-process use of the backend.

Docker-DCO-1.1-Signed-off-by: Alexander Larsson <alexl@redhat.com> (github: alexlarsson)
devmapper: Store metadata in one file per device

This allows multiple instances of the backend in different containers
to access devices (although generally only one can modify/create them).

Any old metadata is converted on the first run.

Docker-DCO-1.1-Signed-off-by: Alexander Larsson <alexl@redhat.com> (github: alexlarsson)
Update hack/dind to mount cgroups on "/cgroup" instead of "/sys/fs/cgroup" for better compatibility

Fixes #5122

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Adding Rohit Jnagal and Victor Marmol to pkg/cgroups maintainers.

Docker-DCO-1.1-Signed-off-by: Victor Marmol <vmarmol@google.com> (github: vmarmol)
Introduce x-axe scrolling to code-blocks.

This improvement introduces x-axe scrolling to code-blocks by
overriding certain default bootstrap word-wrapping constraints.

This PR closes: https://github.com/dotcloud/docker/issues/5279

Docker-DCO-1.1-Signed-off-by: O.S. Tezer <ostezer@gmail.com> (github: ostezer)
Fixed the horrible OSX installation docs

Docker-DCO-1.1-Signed-off-by: James Turnbull <james@lovedthanlost.net> (github: jamtur01)
Add alex as devmapper and btrfs maintainer
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
cgroups: Update systemd to match fs backend

This updates systemd.Apply to match the fs backend by:
* Always join blockio controller (for stats)
* Support CpusetCpus
* Support MemorySwap

Also, it removes the generic UnitProperties in favour of a single
option to set the slice.

Docker-DCO-1.1-Signed-off-by: Alexander Larsson <alexl@redhat.com> (github: alexlarsson)
Check supplied hostname before using it.

Docker-DCO-1.1-Signed-off-by: Rohit Jnagal <jnagal@google.com> (github: rjnagal)
Merge pull request #5597 from jamtur01/docs-simplify-osx-install

Fixed the horrible OSX installation docs
Merge pull request #5354 from alexlarsson/cgroups-systemd-fixes

cgroups: Update systemd to match fs backend
propagate errors write

Docker-DCO-1.1-Signed-off-by: Victor Vieux <vieux@docker.com> (github: vieux)
Merge pull request #5613 from vieux/better_error_handling

propagate errors write
Move Attach from container to daemon

This moves the Attach method from the container to the daemon.  This
method mostly supports the http attach logic and does not have anything
to do with the running of a container.
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Merge pull request #5614 from crosbymichael/move-attach-to-daemon

Move Attach from container to daemon
Use the correct "it's."
Merge pull request #5601 from crosbymichael/alex-maintainer

Add alex as devmapper and btrfs maintainer
Add alex as devmapper and btrfs maintainer
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)