rbd: add skipForceFlatten flag

added skipForceFlatten flag to skip
the image deptha and skip image flattening.
This will be very useful if the kernel is
not listed in cephcsi which supports deep
flatten fauture.

Signed-off-by: Madhu Rajanna <madhupr007@gmail.com>

charts/ceph-csi-rbd/templates/provisioner-deployment.yaml

@@ -116,6 +116,9 @@ spec:
             - "--drivername=$(DRIVER_NAME)"
             - "--rbdhardmaxclonedepth={{ .Values.provisioner.hardMaxCloneDepth }}"
             - "--rbdsoftmaxclonedepth={{ .Values.provisioner.softMaxCloneDepth }}"
+            {{- if .Values.provisioner.skipForceFlatten }}
+            - "--skipforceflatten={{ .Values.provisioner.skipForceFlatten }}"
+            {{- end }}
           env:
             - name: POD_IP
               valueFrom:

charts/ceph-csi-rbd/values.yaml

@@ -113,6 +113,9 @@ provisioner:
   # Soft limit for maximum number of nested volume clones that are taken before
   # a flatten occurs
   softMaxCloneDepth: 4
+  # skip image flattening if kernel support mapping of rbd images
+  # which has the deep-flatten feature
+  # skipForceFlatten: false
 
   httpMetrics:
     # Metrics only available for cephcsi/cephcsi => 1.2.0

cmd/cephcsi.go

@@ -79,6 +79,10 @@ func init() {
 
 	flag.UintVar(&conf.RbdHardMaxCloneDepth, "rbdhardmaxclonedepth", 8, "Hard limit for maximum number of nested volume clones that are taken before a flatten occurs")
 	flag.UintVar(&conf.RbdSoftMaxCloneDepth, "rbdsoftmaxclonedepth", 4, "Soft limit for maximum number of nested volume clones that are taken before a flatten occurs")
+
+	flag.BoolVar(&conf.SkipForceFlatten, "skipforceflatten", false,
+		"skip image flattening if kernel support mapping of rbd images which has the deep-flatten feature")
+
 	flag.BoolVar(&conf.Version, "version", false, "Print cephcsi version information")
 
 	klog.InitFlags(nil)

docs/deploy-rbd.md

@@ -44,6 +44,7 @@ make image-cephcsi
 | `--domainlabels`         | _empty_               | Kubernetes node labels to use as CSI domain labels for topology aware provisioning, should be a comma separated value (ex:= "failure-domain/region,failure-domain/zone")                                                                                                             |
 | `--rbdhardmaxclonedepth` | `8`                   | Hard limit for maximum number of nested volume clones that are taken before a flatten occurs                                                                                                                                                                                         |
 | `--rbdsoftmaxclonedepth` | `4`                   | Soft limit for maximum number of nested volume clones that are taken before a flatten occurs                                                                                                                                                                                         |
+| `--skipforceflatten`     | `false`               | skip image flattening on kernel < 5.2 which support mapping of rbd images which has the deep-flatten feature                                                                                                                                                                         |
 
 **Available volume parameters:**
 

internal/rbd/driver.go

@@ -58,6 +58,8 @@ var (
 
 	// rbdSoftMaxCloneDepth is the soft limit for maximum number of nested volume clones that are taken before a flatten occurs
 	rbdSoftMaxCloneDepth uint
+
+	skipForceFlatten bool
 )
 
 // NewDriver returns new rbd driver
@@ -111,6 +113,7 @@ func (r *Driver) Run(conf *util.Config, cachePersister util.CachePersister) {
 	// update clone soft and hard limit
 	rbdHardMaxCloneDepth = conf.RbdHardMaxCloneDepth
 	rbdSoftMaxCloneDepth = conf.RbdSoftMaxCloneDepth
+	skipForceFlatten = conf.SkipForceFlatten
 	// Create instances of the volume and snapshot journal
 	volJournal = journal.NewCSIVolumeJournal(CSIInstanceID)
 	snapJournal = journal.NewCSISnapshotJournal(CSIInstanceID)

internal/rbd/nodeserver.go

@@ -27,6 +27,7 @@ import (
 	"github.com/ceph/ceph-csi/internal/journal"
 	"github.com/ceph/ceph-csi/internal/util"
 
+	librbd "github.com/ceph/go-ceph/rbd"
 	"github.com/container-storage-interface/spec/lib/go/csi"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/status"
@@ -60,6 +61,22 @@ type stageTransaction struct {
 	devicePath string
 }
 
+var (
+	kernelRelease = ""
+	// deepFlattenSupport holds the list of kernel which support mapping rbd
+	// image with deep-flatten image feature
+	deepFlattenSupport = []util.KernelVersion{
+		{
+			Version:      5,
+			PatchLevel:   2,
+			SubLevel:     0,
+			ExtraVersion: 0,
+			Distribution: "",
+			Backport:     false,
+		}, // standard 5.2+ versions
+	}
+)
+
 // NodeStageVolume mounts the volume to a staging path on the node.
 // Implementation notes:
 // - stagingTargetPath is the directory passed in the request where the volume needs to be staged
@@ -205,6 +222,8 @@ func (ns *NodeServer) stageTransaction(ctx context.Context, req *csi.NodeStageVo
 
 	var err error
 	var readOnly bool
+	var feature bool
+
 	var cr *util.Credentials
 	cr, err = util.NewUserCredentials(req.GetSecrets())
 	if err != nil {
@@ -226,6 +245,27 @@ func (ns *NodeServer) stageTransaction(ctx context.Context, req *csi.NodeStageVo
 		volOptions.readOnly = true
 	}
 
+	if kernelRelease == "" {
+		// fetch the current running kernel info
+		kernelRelease, err = util.GetKernelVersion()
+		if err != nil {
+			return transaction, err
+		}
+	}
+	if !util.CheckKernelSupport(kernelRelease, deepFlattenSupport) {
+		if !skipForceFlatten {
+			feature, err = volOptions.checkImageChainHasFeature(ctx, librbd.FeatureDeepFlatten)
+			if err != nil {
+				return transaction, err
+			}
+			if feature {
+				err = volOptions.flattenRbdImage(ctx, cr, true)
+				if err != nil {
+					return transaction, err
+				}
+			}
+		}
+	}
 	// Mapping RBD image
 	var devicePath string
 	devicePath, err = attachRBDImage(ctx, volOptions, cr)

internal/util/util.go

@@ -95,6 +95,10 @@ type Config struct {
 	IsNodeServer       bool // if set to true start node server
 	Version            bool // cephcsi version
 
+	// SkipForceFlatten is set to false if the kernel supports mounting of
+	// rbd image or the image chain has the deep-flatten feature.
+	SkipForceFlatten bool
+
 	// cephfs related flags
 	ForceKernelCephFS bool // force to use the ceph kernel client even if the kernel is < 4.17