1 files changed, 128 insertions, 0 deletions
diff --git a/libpod/volume_internal_linux.go b/libpod/volume_internal_linux.go
new file mode 100644
index 000000000..68ddb3c0d
--- /dev/null
+++ b/libpod/volume_internal_linux.go
@@ -0,0 +1,128 @@
+// +build linux
+
+package libpod
+
+import (
+	"io/ioutil"
+	"os/exec"
+
+	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
+	"golang.org/x/sys/unix"
+)
+
+// mount mounts the volume if necessary.
+// A mount is necessary if a volume has any options set.
+// If a mount is necessary, v.state.MountCount will be incremented.
+// If it was 0 when the increment occurred, the volume will be mounted on the
+// host. Otherwise, we assume it is already mounted.
+// Must be done while the volume is locked.
+// Is a no-op on volumes that do not require a mount (as defined by
+// volumeNeedsMount())
+func (v *Volume) mount() error {
+	if !v.needsMount() {
+		return nil
+	}
+
+	// Update the volume from the DB to get an accurate mount counter.
+	if err := v.update(); err != nil {
+		return err
+	}
+
+	// If the count is non-zero, the volume is already mounted.
+	// Nothing to do.
+	if v.state.MountCount > 0 {
+		v.state.MountCount = v.state.MountCount + 1
+		logrus.Debugf("Volume %s mount count now at %d", v.Name(), v.state.MountCount)
+		return v.save()
+	}
+
+	volDevice := v.config.Options["device"]
+	volType := v.config.Options["type"]
+	volOptions := v.config.Options["o"]
+
+	// Some filesystems (tmpfs) don't have a device, but we still need to
+	// give the kernel something.
+	if volDevice == "" && volType != "" {
+		volDevice = volType
+	}
+
+	// We need to use the actual mount command.
+	// Convincing unix.Mount to use the same semantics as the mount command
+	// itself seems prohibitively difficult.
+	// TODO: might want to cache this path in the runtime?
+	mountPath, err := exec.LookPath("mount")
+	if err != nil {
+		return errors.Wrapf(err, "error locating 'mount' binary")
+	}
+	mountArgs := []string{}
+	if volOptions != "" {
+		mountArgs = append(mountArgs, "-o", volOptions)
+	}
+	if volType != "" {
+		mountArgs = append(mountArgs, "-t", volType)
+	}
+	mountArgs = append(mountArgs, volDevice, v.config.MountPoint)
+	mountCmd := exec.Command(mountPath, mountArgs...)
+
+	errPipe, err := mountCmd.StderrPipe()
+	if err != nil {
+		return errors.Wrapf(err, "getting stderr pipe")
+	}
+	if err := mountCmd.Start(); err != nil {
+		out, err2 := ioutil.ReadAll(errPipe)
+		if err2 != nil {
+			return errors.Wrapf(err2, "error reading mount STDERR")
+		}
+		return errors.Wrapf(errors.New(string(out)), "error mounting volume %s", v.Name())
+	}
+
+	logrus.Debugf("Mounted volume %s", v.Name())
+
+	// Increment the mount counter
+	v.state.MountCount = v.state.MountCount + 1
+	logrus.Debugf("Volume %s mount count now at %d", v.Name(), v.state.MountCount)
+	return v.save()
+}
+
+// unmount unmounts the volume if necessary.
+// Unmounting a volume that is not mounted is a no-op.
+// Unmounting a volume that does not require a mount is a no-op.
+// The volume must be locked for this to occur.
+// The mount counter will be decremented if non-zero. If the counter reaches 0,
+// the volume will really be unmounted, as no further containers are using the
+// volume.
+// If force is set, the volume will be unmounted regardless of mount counter.
+func (v *Volume) unmount(force bool) error {
+	if !v.needsMount() {
+		return nil
+	}
+
+	// Update the volume from the DB to get an accurate mount counter.
+	if err := v.update(); err != nil {
+		return err
+	}
+
+	if v.state.MountCount == 0 {
+		logrus.Debugf("Volume %s already unmounted", v.Name())
+		return nil
+	}
+
+	if !force {
+		v.state.MountCount = v.state.MountCount - 1
+	} else {
+		v.state.MountCount = 0
+	}
+
+	logrus.Debugf("Volume %s mount count now at %d", v.Name(), v.state.MountCount)
+
+	if v.state.MountCount == 0 {
+		// Unmount the volume
+		if err := unix.Unmount(v.config.MountPoint, unix.MNT_DETACH); err != nil {
+			return errors.Wrapf(err, "error unmounting volume %s", v.Name())
+		}
+		logrus.Debugf("Unmounted volume %s", v.Name())
+	}
+
+	return v.save()
+}