Merge pull request #6109 from unclejack/block_aufs_on_top_of_btrfs

block aufs on incompatible file systems

daemon/graphdriver/aufs/aufs.go

@@ -23,20 +23,23 @@ package aufs
 import (
 	"bufio"
 	"fmt"
-	"github.com/dotcloud/docker/archive"
-	"github.com/dotcloud/docker/daemon/graphdriver"
-	"github.com/dotcloud/docker/pkg/label"
-	mountpk "github.com/dotcloud/docker/pkg/mount"
-	"github.com/dotcloud/docker/utils"
 	"os"
 	"os/exec"
 	"path"
 	"strings"
 	"sync"
+	"syscall"
+
+	"github.com/dotcloud/docker/archive"
+	"github.com/dotcloud/docker/daemon/graphdriver"
+	"github.com/dotcloud/docker/pkg/label"
+	mountpk "github.com/dotcloud/docker/pkg/mount"
+	"github.com/dotcloud/docker/utils"
 )
 
 var (
 	ErrAufsNotSupported = fmt.Errorf("AUFS was not found in /proc/filesystems")
+	IncompatibleFSMagic = []int64{0x9123683E /*btrfs*/, 0x61756673 /*AUFS*/}
 )
 
 func init() {
@@ -56,6 +59,20 @@ func Init(root string) (graphdriver.Driver, error) {
 	if err := supportsAufs(); err != nil {
 		return nil, graphdriver.ErrNotSupported
 	}
+
+	rootdir := path.Dir(root)
+
+	var buf syscall.Statfs_t
+	if err := syscall.Statfs(rootdir, &buf); err != nil {
+		return nil, fmt.Errorf("Couldn't stat the root directory: %s", err)
+	}
+
+	for _, magic := range IncompatibleFSMagic {
+		if int64(buf.Type) == magic {
+			return nil, graphdriver.ErrIncompatibleFS
+		}
+	}
+
 	paths := []string{
 		"mnt",
 		"diff",

daemon/graphdriver/driver.go

@@ -44,8 +44,9 @@ var (
 		"vfs",
 	}
 
-	ErrNotSupported  = errors.New("driver not supported")
-	ErrPrerequisites = errors.New("Prerequisites for driver not satisfied (wrong filesystem?)")
+	ErrNotSupported   = errors.New("driver not supported")
+	ErrPrerequisites  = errors.New("prerequisites for driver not satisfied (wrong filesystem?)")
+	ErrIncompatibleFS = fmt.Errorf("backing file system is unsupported for this graph driver")
 )
 
 func init() {
@@ -79,7 +80,7 @@ func New(root string) (driver Driver, err error) {
 	for _, name := range priority {
 		driver, err = GetDriver(name, root)
 		if err != nil {
-			if err == ErrNotSupported || err == ErrPrerequisites {
+			if err == ErrNotSupported || err == ErrPrerequisites || err == ErrIncompatibleFS {
 				continue
 			}
 			return nil, err
@@ -90,7 +91,7 @@ func New(root string) (driver Driver, err error) {
 	// Check all registered drivers if no priority driver is found
 	for _, initFunc := range drivers {
 		if driver, err = initFunc(root); err != nil {
-			if err == ErrNotSupported || err == ErrPrerequisites {
+			if err == ErrNotSupported || err == ErrPrerequisites || err == ErrIncompatibleFS {
 				continue
 			}
 			return nil, err