devmapper: Export deferred removal status in status

This will help with debugging as one could just do "docker info" and figure
out of deferred removal is enabled or not.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>

daemon/graphdriver/devmapper/deviceset.go

@@ -115,15 +115,16 @@ type DiskUsage struct {
 }
 
 type Status struct {
-	PoolName          string
-	DataFile          string // actual block device for data
-	DataLoopback      string // loopback file, if used
-	MetadataFile      string // actual block device for metadata
-	MetadataLoopback  string // loopback file, if used
-	Data              DiskUsage
-	Metadata          DiskUsage
-	SectorSize        uint64
-	UdevSyncSupported bool
+	PoolName              string
+	DataFile              string // actual block device for data
+	DataLoopback          string // loopback file, if used
+	MetadataFile          string // actual block device for metadata
+	MetadataLoopback      string // loopback file, if used
+	Data                  DiskUsage
+	Metadata              DiskUsage
+	SectorSize            uint64
+	UdevSyncSupported     bool
+	DeferredRemoveEnabled bool
 }
 
 type DevStatus struct {
@@ -1623,6 +1624,7 @@ func (devices *DeviceSet) Status() *Status {
 	status.MetadataFile = devices.MetadataDevicePath()
 	status.MetadataLoopback = devices.metadataLoopFile
 	status.UdevSyncSupported = devicemapper.UdevSyncSupported()
+	status.DeferredRemoveEnabled = devices.deferredRemove
 
 	totalSizeInSectors, _, dataUsed, dataTotal, metadataUsed, metadataTotal, err := devices.poolStatus()
 	if err == nil {

daemon/graphdriver/devmapper/driver.go

@@ -77,6 +77,7 @@ func (d *Driver) Status() [][2]string {
 		{"Metadata Space Total", fmt.Sprintf("%s", units.HumanSize(float64(s.Metadata.Total)))},
 		{"Metadata Space Available", fmt.Sprintf("%s", units.HumanSize(float64(s.Metadata.Available)))},
 		{"Udev Sync Supported", fmt.Sprintf("%v", s.UdevSyncSupported)},
+		{"Deferred Removal Enabled", fmt.Sprintf("%v", s.DeferredRemoveEnabled)},
 	}
 	if len(s.DataLoopback) > 0 {
 		status = append(status, [2]string{"Data loop file", s.DataLoopback})