From 6ddf98addf1ce54c69719187a7edcf7fbdd8586c Mon Sep 17 00:00:00 2001
From: gman <robert.vasek@cern.ch>
Date: Tue, 14 Aug 2018 16:48:30 +0200
Subject: [PATCH] cephfs: cache available volume mounters

---
 pkg/cephfs/driver.go        |  12 ++--
 pkg/cephfs/volumemounter.go | 123 ++++++++++++++++++------------------
 2 files changed, 70 insertions(+), 65 deletions(-)

diff --git a/pkg/cephfs/driver.go b/pkg/cephfs/driver.go
index 785f62d04..b73f602b0 100644
--- a/pkg/cephfs/driver.go
+++ b/pkg/cephfs/driver.go
@@ -82,6 +82,10 @@ func (fs *cephfsDriver) Run(driverName, nodeId, endpoint, volumeMounter string)
 		glog.Errorf("cephfs: failed to read volume cache: %v", err)
 	}
 
+	if err := loadAvailableMounters(); err != nil {
+		glog.Fatalf("cephfs: failed to load ceph mounters: %v", err)
+	}
+
 	if volumeMounter != "" {
 		if err := validateMounter(volumeMounter); err != nil {
 			glog.Fatalln(err)
@@ -89,11 +93,9 @@ func (fs *cephfsDriver) Run(driverName, nodeId, endpoint, volumeMounter string)
 			DefaultVolumeMounter = volumeMounter
 		}
 	} else {
-		availableMounters := getAvailableMounters()
-		if len(availableMounters) == 0 {
-			glog.Fatal("no ceph mounters found on system")
-		}
-
+		// Pick the first available mounter as the default one.
+		// The choice is biased towards "fuse" in case both
+		// ceph fuse and kernel mounters are available.
 		DefaultVolumeMounter = availableMounters[0]
 	}
 
diff --git a/pkg/cephfs/volumemounter.go b/pkg/cephfs/volumemounter.go
index 3451bf154..efc5aa334 100644
--- a/pkg/cephfs/volumemounter.go
+++ b/pkg/cephfs/volumemounter.go
@@ -28,11 +28,74 @@ const (
 	volumeMounter_kernel = "kernel"
 )
 
+var (
+	availableMounters []string
+)
+
+// Load available ceph mounters installed on system into availableMounters
+// Called from driver.go's Run()
+func loadAvailableMounters() error {
+	fuseMounterProbe := exec.Command("ceph-fuse", "--version")
+	kernelMounterProbe := exec.Command("mount.ceph")
+
+	if fuseMounterProbe.Run() == nil {
+		availableMounters = append(availableMounters, volumeMounter_fuse)
+	}
+
+	if kernelMounterProbe.Run() == nil {
+		availableMounters = append(availableMounters, volumeMounter_kernel)
+	}
+
+	if len(availableMounters) == 0 {
+		return fmt.Errorf("no ceph mounters found on system")
+	}
+
+	return nil
+}
+
 type volumeMounter interface {
 	mount(mountPoint string, cr *credentials, volOptions *volumeOptions, volId volumeID) error
 	name() string
 }
 
+func newMounter(volOptions *volumeOptions) (volumeMounter, error) {
+	// Get the mounter from the configuration
+
+	wantMounter := volOptions.Mounter
+
+	if wantMounter == "" {
+		wantMounter = DefaultVolumeMounter
+	}
+
+	// Verify that it's available
+
+	var chosenMounter string
+
+	for _, availMounter := range availableMounters {
+		if chosenMounter == "" {
+			if availMounter == wantMounter {
+				chosenMounter = wantMounter
+			}
+		}
+	}
+
+	if chosenMounter == "" {
+		// Otherwise pick whatever is left
+		chosenMounter = availableMounters[0]
+	}
+
+	// Create the mounter
+
+	switch chosenMounter {
+	case volumeMounter_fuse:
+		return &fuseMounter{}, nil
+	case volumeMounter_kernel:
+		return &kernelMounter{}, nil
+	}
+
+	return nil, fmt.Errorf("unknown mounter '%s'", chosenMounter)
+}
+
 type fuseMounter struct{}
 
 func mountFuse(mountPoint string, cr *credentials, volOptions *volumeOptions, volId volumeID) error {
@@ -114,63 +177,3 @@ func unmountVolume(mountPoint string) error {
 func createMountPoint(root string) error {
 	return os.MkdirAll(root, 0750)
 }
-
-func getAvailableMounters() []string {
-	var ms []string
-
-	fuseMounterProbe := exec.Command("ceph-fuse", "--version")
-	kernelMounterProbe := exec.Command("mount.ceph")
-
-	if fuseMounterProbe.Run() == nil {
-		ms = append(ms, volumeMounter_fuse)
-	}
-
-	if kernelMounterProbe.Run() == nil {
-		ms = append(ms, volumeMounter_kernel)
-	}
-
-	return ms
-}
-
-func newMounter(volOptions *volumeOptions) (volumeMounter, error) {
-	// Get the mounter from the configuration
-
-	wantMounter := volOptions.Mounter
-
-	if wantMounter == "" {
-		wantMounter = DefaultVolumeMounter
-	}
-
-	// Verify that it's available
-
-	availableMounters := getAvailableMounters()
-	if len(availableMounters) == 0 {
-		return nil, fmt.Errorf("no ceph mounters found on system")
-	}
-
-	var chosenMounter string
-
-	for _, availMounter := range getAvailableMounters() {
-		if chosenMounter == "" {
-			if availMounter == wantMounter {
-				chosenMounter = wantMounter
-			}
-		}
-	}
-
-	if chosenMounter == "" {
-		// Otherwise pick whatever is left
-		chosenMounter = availableMounters[0]
-	}
-
-	// Create the mounter
-
-	switch chosenMounter {
-	case volumeMounter_fuse:
-		return &fuseMounter{}, nil
-	case volumeMounter_kernel:
-		return &kernelMounter{}, nil
-	}
-
-	return nil, fmt.Errorf("unknown mounter '%s'", chosenMounter)
-}