Add 'Available' to storage API.

info/v2/container.go

@@ -151,6 +151,9 @@ type FsInfo struct {
 	// Filesystem usage in bytes.
 	Capacity uint64 `json:"capacity"`
 
+	// Bytes available for non-root use.
+	Available uint64 `json:"available"`
+
 	// Number of bytes used on this filesystem.
 	Usage uint64 `json:"usage"`
 

manager/manager.go

@@ -612,6 +612,7 @@ func (self *manager) GetFsInfo(label string) ([]v2.FsInfo, error) {
 			Mountpoint: mountpoint,
 			Capacity:   fs.Limit,
 			Usage:      fs.Usage,
+			Available:  fs.Available,
 			Labels:     labels,
 		}
 		fsInfo = append(fsInfo, fi)