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)
reapply Cmd value even if CmdAdd returns early
Docker-DCO-1.1-Signed-off-by: Maximilian Goisser <goisser94@gmail.com> (github: hobofan)
UTIME_OMIT is only available on Linux

Docker-DCO-1.1-Signed-off-by: Kato Kazuyoshi <kato.kazuyoshi@gmail.com> (github: kzys)
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)
modernise the MAINTAINER process documentation to line up with what I understand it to be

Docker-DCO-1.1-Signed-off-by: Sven Dowideit <SvenDowideit@fosiki.com> (github: SvenDowideit)
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)
Add code for Pardot implementation to docs

Docker-DCO-1.1-Signed-off-by: O.S. Tezer <ostezer@gmail.com> (github: ostezer)
registry: adding vbatts to the MAINTAINERS

Docker-DCO-1.1-Signed-off-by: Vincent Batts <vbatts@redhat.com> (github: vbatts)
The Go template is a better pattern for documentation.
Add "Should-Start" cgroupfs-mount and cgroup-lite to sysvinit-debian init script

It's fine to list both here because "Should-Start" is a loose binding (ie, if the listed service exists, it'll be started first, but otherwise, this one will start without it).

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Change owner only on copied content

Fixes #5110
Docker-DCO-1.1-Signed-off-by: Alexandr Morozov <lk4d4math@gmail.com> (github: LK4D4)
move Table to a separate file and add additional unit tests

Docker-DCO-1.1-Signed-off-by: Bryan Murphy <bmurphy1976@gmail.com> (github: bmurphy1976)
Update restrict.Restrict to both show the error message when failing to mount /dev/null over /proc/kcore, and to ignore "not exists" errors while doing so (for when CONFIG_PROC_KCORE=n in the kernel)

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Merge pull request #5659 from ryanaslett/master

Trivial Documentation Change: The Go template is a better pattern for documentation.
Merge pull request #5404 from alexlarsson/dm-new-metadata

Make devicemapper backend able to support multiple processes
Merge pull request #5535 from vmarmol/add-maintainers-cgroup

Adding Rohit Jnagal and Victor Marmol to pkg/cgroups maintainers.