Include xfsprogs in build environment.
devmapper uses xfs by default now. So include xfsprogs in build
environment. Also update docs to reflect the new default.
@@ -260,11 +260,11 @@ options for `zfs` start with `zfs`.
* `dm.fs`
Specifies the filesystem type to use for the base device. The supported
- options are "ext4" and "xfs". The default is "ext4"
+ options are "ext4" and "xfs". The default is "xfs"
Example use:
- $ docker daemon --storage-opt dm.fs=xfs
+ $ docker daemon --storage-opt dm.fs=ext4
* `dm.mkfsarg`
