Add --force to podman umount to force the unmounting of the rootfs

podman umount will currently only unmount file system if not other
process is using it, otherwise the umount decrements the container
storage to indicate that the caller is no longer using the mount
point, once the count gets to 0, the file system is actually unmounted.

Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>

Closes: #1184
Approved by: TomSweeneyRedHat

1 files changed, 19 insertions, 3 deletions

diff --git a/cmd/podman/umount.go b/cmd/podman/umount.go
index 1a2cf22c6..1e364b48f 100644
--- a/cmd/podman/umount.go
+++ b/cmd/podman/umount.go
@@ -3,6 +3,7 @@ package main
 import (
 	"fmt"
 
+	"github.com/containers/storage"
 	"github.com/pkg/errors"
 	"github.com/projectatomic/libpod/cmd/podman/libpodruntime"
 	"github.com/projectatomic/libpod/libpod"
@@ -16,13 +17,24 @@ var (
 			Name:  "all, a",
 			Usage: "umount all of the currently mounted containers",
 		},
+		cli.BoolFlag{
+			Name:  "force, f",
+			Usage: "force the complete umount all of the currently mounted containers",
+		},
 	}
 
+	description = `
+Container storage increments a mount counter each time a container is mounted.
+When a container is unmounted, the mount counter is decremented and the
+container's root filesystem is physically unmounted only when the mount
+counter reaches zero indicating no other processes are using the mount.
+An unmount can be forced with the --force flag.
+`
 	umountCommand = cli.Command{
 		Name:        "umount",
 		Aliases:     []string{"unmount"},
 		Usage:       "Unmounts working container's root filesystem",
-		Description: "Unmounts working container's root filesystem",
+		Description: description,
 		Flags:       umountFlags,
 		Action:      umountCmd,
 		ArgsUsage:   "CONTAINER-NAME-OR-ID",
@@ -36,6 +48,7 @@ func umountCmd(c *cli.Context) error {
 	}
 	defer runtime.Shutdown(false)
 
+	force := c.Bool("force")
 	umountAll := c.Bool("all")
 	args := c.Args()
 	if len(args) == 0 && !umountAll {
@@ -58,7 +71,7 @@ func umountCmd(c *cli.Context) error {
 				continue
 			}
 
-			if err = ctr.Unmount(); err != nil {
+			if err = ctr.Unmount(force); err != nil {
 				if lastError != nil {
 					logrus.Error(lastError)
 				}
@@ -78,7 +91,10 @@ func umountCmd(c *cli.Context) error {
 				continue
 			}
 
-			if err = ctr.Unmount(); err != nil {
+			if err = ctr.Unmount(force); err != nil {
+				if umountAll && errors.Cause(err) == storage.ErrLayerNotMounted {
+					continue
+				}
 				if lastError != nil {
 					logrus.Error(lastError)
 				}