From 948e54ac455f88c79524dcf117df80f2d4c3f96c Mon Sep 17 00:00:00 2001
From: Alexander Larsson <alexl@redhat.com>
Date: Thu, 27 Mar 2014 17:45:02 +0100
Subject: [PATCH] devmapper: Fail init with ErrNotSupported if simple devmapper
 call fails

If we can't even get the current device mapper driver version, then
we cleanly fail the devmapper driver as not supported and fall back
on the next one.

Docker-DCO-1.1-Signed-off-by: Alexander Larsson <alexl@redhat.com> (github: alexlarsson)
---
 daemon/graphdriver/devmapper/deviceset.go     |  7 +++
 daemon/graphdriver/devmapper/devmapper.go     | 20 +++++++++
 .../devmapper/devmapper_wrapper.go            | 45 ++++++++++++-------
 3 files changed, 55 insertions(+), 17 deletions(-)

diff --git a/daemon/graphdriver/devmapper/deviceset.go b/daemon/graphdriver/devmapper/deviceset.go
index 4de7858c1..f36faca90 100644
--- a/daemon/graphdriver/devmapper/deviceset.go
+++ b/daemon/graphdriver/devmapper/deviceset.go
@@ -17,6 +17,7 @@ import (
 	"syscall"
 	"time"
 
+	"github.com/dotcloud/docker/daemon/graphdriver"
 	"github.com/dotcloud/docker/pkg/label"
 	"github.com/dotcloud/docker/utils"
 )
@@ -506,6 +507,12 @@ func (devices *DeviceSet) ResizePool(size int64) error {
 func (devices *DeviceSet) initDevmapper(doInit bool) error {
 	logInit(devices)
 
+	_, err := getDriverVersion()
+	if err != nil {
+		// Can't even get driver version, assume not supported
+		return graphdriver.ErrNotSupported
+	}
+
 	if err := os.MkdirAll(devices.metadataDir(), 0700); err != nil && !os.IsExist(err) {
 		return err
 	}
diff --git a/daemon/graphdriver/devmapper/devmapper.go b/daemon/graphdriver/devmapper/devmapper.go
index d78ae1ef8..a6602c276 100644
--- a/daemon/graphdriver/devmapper/devmapper.go
+++ b/daemon/graphdriver/devmapper/devmapper.go
@@ -52,6 +52,7 @@ var (
 	ErrTaskAddTarget          = errors.New("dm_task_add_target failed")
 	ErrTaskSetSector          = errors.New("dm_task_set_sector failed")
 	ErrTaskGetInfo            = errors.New("dm_task_get_info failed")
+	ErrTaskGetDriverVersion   = errors.New("dm_task_get_driver_version failed")
 	ErrTaskSetCookie          = errors.New("dm_task_set_cookie failed")
 	ErrNilCookie              = errors.New("cookie ptr can't be nil")
 	ErrAttachLoopbackDevice   = errors.New("loopback mounting failed")
@@ -178,6 +179,14 @@ func (t *Task) GetInfo() (*Info, error) {
 	return info, nil
 }
 
+func (t *Task) GetDriverVersion() (string, error) {
+	res := DmTaskGetDriverVersion(t.unmanaged)
+	if res == "" {
+		return "", ErrTaskGetDriverVersion
+	}
+	return res, nil
+}
+
 func (t *Task) GetNextTarget(next uintptr) (nextPtr uintptr, start uint64,
 	length uint64, targetType string, params string) {
 
@@ -394,6 +403,17 @@ func getInfo(name string) (*Info, error) {
 	return task.GetInfo()
 }
 
+func getDriverVersion() (string, error) {
+	task := TaskCreate(DeviceVersion)
+	if task == nil {
+		return "", fmt.Errorf("Can't create DeviceVersion task")
+	}
+	if err := task.Run(); err != nil {
+		return "", err
+	}
+	return task.GetDriverVersion()
+}
+
 func getStatus(name string) (uint64, uint64, string, string, error) {
 	task, err := createTask(DeviceStatus, name)
 	if task == nil {
diff --git a/daemon/graphdriver/devmapper/devmapper_wrapper.go b/daemon/graphdriver/devmapper/devmapper_wrapper.go
index bf558affc..9f1b5a605 100644
--- a/daemon/graphdriver/devmapper/devmapper_wrapper.go
+++ b/daemon/graphdriver/devmapper/devmapper_wrapper.go
@@ -85,23 +85,24 @@ const (
 )
 
 var (
-	DmGetLibraryVersion = dmGetLibraryVersionFct
-	DmGetNextTarget     = dmGetNextTargetFct
-	DmLogInitVerbose    = dmLogInitVerboseFct
-	DmSetDevDir         = dmSetDevDirFct
-	DmTaskAddTarget     = dmTaskAddTargetFct
-	DmTaskCreate        = dmTaskCreateFct
-	DmTaskDestroy       = dmTaskDestroyFct
-	DmTaskGetInfo       = dmTaskGetInfoFct
-	DmTaskRun           = dmTaskRunFct
-	DmTaskSetAddNode    = dmTaskSetAddNodeFct
-	DmTaskSetCookie     = dmTaskSetCookieFct
-	DmTaskSetMessage    = dmTaskSetMessageFct
-	DmTaskSetName       = dmTaskSetNameFct
-	DmTaskSetRo         = dmTaskSetRoFct
-	DmTaskSetSector     = dmTaskSetSectorFct
-	DmUdevWait          = dmUdevWaitFct
-	LogWithErrnoInit    = logWithErrnoInitFct
+	DmGetLibraryVersion    = dmGetLibraryVersionFct
+	DmGetNextTarget        = dmGetNextTargetFct
+	DmLogInitVerbose       = dmLogInitVerboseFct
+	DmSetDevDir            = dmSetDevDirFct
+	DmTaskAddTarget        = dmTaskAddTargetFct
+	DmTaskCreate           = dmTaskCreateFct
+	DmTaskDestroy          = dmTaskDestroyFct
+	DmTaskGetInfo          = dmTaskGetInfoFct
+	DmTaskGetDriverVersion = dmTaskGetDriverVersionFct
+	DmTaskRun              = dmTaskRunFct
+	DmTaskSetAddNode       = dmTaskSetAddNodeFct
+	DmTaskSetCookie        = dmTaskSetCookieFct
+	DmTaskSetMessage       = dmTaskSetMessageFct
+	DmTaskSetName          = dmTaskSetNameFct
+	DmTaskSetRo            = dmTaskSetRoFct
+	DmTaskSetSector        = dmTaskSetSectorFct
+	DmUdevWait             = dmUdevWaitFct
+	LogWithErrnoInit       = logWithErrnoInitFct
 )
 
 func free(p *C.char) {
@@ -184,6 +185,16 @@ func dmTaskGetInfoFct(task *CDmTask, info *Info) int {
 	return int(C.dm_task_get_info((*C.struct_dm_task)(task), &Cinfo))
 }
 
+func dmTaskGetDriverVersionFct(task *CDmTask) string {
+	buffer := C.malloc(128)
+	defer C.free(buffer)
+	res := C.dm_task_get_driver_version((*C.struct_dm_task)(task), (*C.char)(buffer), 128)
+	if res == 0 {
+		return ""
+	}
+	return C.GoString((*C.char)(buffer))
+}
+
 func dmGetNextTargetFct(task *CDmTask, next uintptr, start, length *uint64, target, params *string) uintptr {
 	var (
 		Cstart, Clength      C.uint64_t