Add dmcache input plugin (#1667)

plugins/inputs/dmcache/dmcache.go

@@ -0,0 +1,33 @@
+package dmcache
+
+import (
+	"github.com/influxdata/telegraf"
+	"github.com/influxdata/telegraf/plugins/inputs"
+)
+
+type DMCache struct {
+	PerDevice        bool `toml:"per_device"`
+	getCurrentStatus func() ([]string, error)
+}
+
+var sampleConfig = `
+  ## Whether to report per-device stats or not
+  per_device = true
+`
+
+func (c *DMCache) SampleConfig() string {
+	return sampleConfig
+}
+
+func (c *DMCache) Description() string {
+	return "Provide a native collection for dmsetup based statistics for dm-cache"
+}
+
+func init() {
+	inputs.Add("dmcache", func() telegraf.Input {
+		return &DMCache{
+			PerDevice:        true,
+			getCurrentStatus: dmSetupStatus,
+		}
+	})
+}