From caaee11b33930dd2ef73ef5578f3727d80219c60 Mon Sep 17 00:00:00 2001
From: Ivan Shvedunov <ishvedunov@mirantis.com>
Date: Sat, 9 Feb 2019 21:22:55 +0300
Subject: [PATCH] Fix 9pfs mounts of hostPath volumes

hostPath was only working for the host paths that are mounted inside
the virtlet container.
---
 pkg/fs/fs.go       |  3 ++-
 pkg/fs/fs_linux.go | 22 +++++++++++++++++-----
 2 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/pkg/fs/fs.go b/pkg/fs/fs.go
index cf2fa21e1..c41b92dbd 100644
--- a/pkg/fs/fs.go
+++ b/pkg/fs/fs.go
@@ -51,7 +51,8 @@ type DelimitedReader interface {
 // FileSystem defines a filesystem interface interface
 type FileSystem interface {
 	// Mount mounts the specified source under the target path.
-	// For bind mounts, bind must be true.
+	// For bind mounts, bind must be true. The bind mounts will
+	// happen in the host mount namespace (that of PID 1).
 	Mount(source string, target string, fstype string, bind bool) error
 	// Unmount unmounts the specified target directory. If detach
 	// is true, MNT_DETACH option is used (disconnect the
diff --git a/pkg/fs/fs_linux.go b/pkg/fs/fs_linux.go
index 5636a238c..74f2ba880 100644
--- a/pkg/fs/fs_linux.go
+++ b/pkg/fs/fs_linux.go
@@ -18,15 +18,27 @@ limitations under the License.
 
 package fs
 
-import "syscall"
+import (
+	"fmt"
+	"os/exec"
+	"syscall"
+)
 
 // Mount inplements Mount method of FileSystem interface.
 func (fs *realFileSystem) Mount(source string, target string, fstype string, bind bool) error {
-	flags := uintptr(0)
-	if bind {
-		flags = syscall.MS_BIND | syscall.MS_REC
+	if !bind {
+		return syscall.Mount(source, target, fstype, uintptr(0), "")
 	}
-	return syscall.Mount(source, target, fstype, flags, "")
+
+	// In case of bind mounts, we want to do it in the outer mount namespace.
+	// This is used for hostPath volumes, for example.
+	args := []string{"/usr/bin/nsenter", "-t", "1", "-m", "/bin/mount", "--bind", source, target}
+	if out, err := exec.Command(args[0], args[1:]...).CombinedOutput(); err != nil {
+		return fmt.Errorf("mount %v: %v; output: %v", args, err, string(out))
+	}
+
+	return nil
+
 }
 
 // Unmount inplements Unmount method of FileSystem interface.