virtiofs: add virtio_fs_shared_versions option

Shared version metadata is managed by the 'ireg' daemon for virtio-fs.
Add an option to enable it.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

Makefile

@@ -166,6 +166,7 @@ DEFVIRTIOFSDAEMON :=
 # Default DAX mapping cache size in GiB
 DEFVIRTIOFSCACHESIZE := 2
 DEFVIRTIOFSCACHE := none
+DEFVIRTIOFSSHAREDVERSIONS := false
 DEFENABLEIOTHREADS := false
 DEFENABLEMEMPREALLOC := false
 DEFENABLEHUGEPAGES := false
@@ -325,6 +326,7 @@ USER_VARS += DEFVIRTIOFS
 USER_VARS += DEFVIRTIOFSDAEMON
 USER_VARS += DEFVIRTIOFSCACHESIZE
 USER_VARS += DEFVIRTIOFSCACHE
+USER_VARS += DEFVIRTIOFSSHAREDVERSIONS
 USER_VARS += DEFENABLEIOTHREADS
 USER_VARS += DEFENABLEMEMPREALLOC
 USER_VARS += DEFENABLEHUGEPAGES
@@ -518,6 +520,7 @@ $(GENERATED_FILES): %: %.in Makefile VERSION
 		-e "s|@DEFVIRTIOFSDAEMON@|$(DEFVIRTIOFSDAEMON)|g" \
 		-e "s|@DEFVIRTIOFSCACHESIZE@|$(DEFVIRTIOFSCACHESIZE)|g" \
 		-e "s|@DEFVIRTIOFSCACHE@|$(DEFVIRTIOFSCACHE)|g" \
+		-e "s|@DEFVIRTIOFSSHAREDVERSIONS@|$(DEFVIRTIOFSSHAREDVERSIONS)|g" \
 		-e "s|@DEFENABLEIOTHREADS@|$(DEFENABLEIOTHREADS)|g" \
 		-e "s|@DEFENABLEMEMPREALLOC@|$(DEFENABLEMEMPREALLOC)|g" \
 		-e "s|@DEFENABLEHUGEPAGES@|$(DEFENABLEHUGEPAGES)|g" \

cli/config/configuration-qemu.toml.in

@@ -121,6 +121,9 @@ virtio_fs_cache_size = @DEFVIRTIOFSCACHESIZE@
 #    Metadata, data, and pathname lookup are cached in guest and never expire.
 virtio_fs_cache = "@DEFVIRTIOFSCACHE@"
 
+# Use shared version metadata
+virtio_fs_shared_versions = @DEFVIRTIOFSSHAREDVERSIONS@
+
 # Block storage driver to be used for the hypervisor in case the container
 # rootfs is backed by a block device. This is virtio-scsi, virtio-blk
 # or nvdimm.

pkg/katautils/config.go

@@ -106,6 +106,7 @@ type hypervisor struct {
 	VirtioFSDaemon          string `toml:"virtio_fs_daemon"`
 	VirtioFSCacheSize       uint32 `toml:"virtio_fs_cache_size"`
 	VirtioFSCache           string `toml:"virtio_fs_cache"`
+	VirtioFSSharedVersions  bool   `toml:"virtio_fs_shared_versions"`
 	MemPrealloc             bool   `toml:"enable_mem_prealloc"`
 	HugePages               bool   `toml:"enable_hugepages"`
 	Swap                    bool   `toml:"enable_swap"`
@@ -542,6 +543,7 @@ func newQemuHypervisorConfig(h hypervisor) (vc.HypervisorConfig, error) {
 		VirtioFSDaemon:          h.VirtioFSDaemon,
 		VirtioFSCacheSize:       h.VirtioFSCacheSize,
 		VirtioFSCache:           h.VirtioFSCache,
+		VirtioFSSharedVersions:  h.VirtioFSSharedVersions,
 		MemPrealloc:             h.MemPrealloc,
 		HugePages:               h.HugePages,
 		Mlock:                   !h.Swap,

virtcontainers/device/config/config.go

@@ -182,6 +182,7 @@ type VhostUserDeviceAttrs struct {
 	Tag string
         CacheSize uint32
 	Cache string
+	SharedVersions bool
 }
 
 // GetHostPathFunc is function pointer used to mock GetHostPath in tests.

virtcontainers/documentation/api/1.0/api.md

@@ -152,6 +152,9 @@ type HypervisorConfig struct {
 	// VirtioFSCache cache mode for fs version cache or "none"
 	VirtioFSCache string
 
+	// VirtioFSSharedVersions enables shared version metadata daemon
+	VirtioFSSharedVersions bool
+
 	// KernelParams are additional guest kernel parameters.
 	KernelParams []Param
 

virtcontainers/hypervisor.go

@@ -250,6 +250,9 @@ type HypervisorConfig struct {
 	// VirtioFSCache cache mode for fs version cache or "none"
 	VirtioFSCache string
 
+	// VirtioFSSharedVersions enables shared version metadata daemon
+	VirtioFSSharedVersions bool
+
 	// EnableIOThreads enables IO to be processed in a separate thread.
 	// Supported currently for virtio-scsi driver.
 	EnableIOThreads bool

virtcontainers/qemu.go

@@ -582,15 +582,21 @@ func (q *qemu) startSandbox(timeout int) error {
 			return err
 		}
 
+		sourcePath := filepath.Join(kataHostSharedDir, q.id)
+
+		var args []string
+		args = append(args, "-o", "virtio_socket=" + sockPath,
+				    "-o", "source=" + sourcePath,
+				    "-o", "cache=" + q.config.VirtioFSCache)
+		if q.config.VirtioFSSharedVersions {
+			args = append(args, "-o", "shared")
+		}
+		args = append(args, "/")
+
 		// The daemon will terminate when the vhost-user socket
 		// connection with QEMU closes.  Therefore we do not keep track
 		// of this child process.
-		sourcePath := filepath.Join(kataHostSharedDir, q.id)
-		cmd = exec.Command(q.config.VirtioFSDaemon,
-				   "-o", "virtio_socket=" + sockPath,
-				   "-o", "source=" + sourcePath,
-				   "-o", "cache=" + q.config.VirtioFSCache,
-				   "/")
+		cmd = exec.Command(q.config.VirtioFSDaemon, args...)
 
 		if err := cmd.Start(); err != nil {
 			return err
@@ -1274,6 +1280,7 @@ func (q *qemu) addDevice(devInfo interface{}, devType deviceType) error {
 				Type: config.VhostUserFS,
 				CacheSize: q.config.VirtioFSCacheSize,
 				Cache: q.config.VirtioFSCache,
+				SharedVersions: q.config.VirtioFSSharedVersions,
 			}
 			vhostDev.SocketPath = sockPath
 			vhostDev.DevID = id

virtcontainers/qemu_arch_base.go

@@ -529,6 +529,7 @@ func (q *qemuArchBase) appendVhostUserDevice(devices []govmmQemu.Device, attr co
 		qemuVhostUserDevice.Tag = attr.Tag
 		qemuVhostUserDevice.CacheSize = attr.CacheSize
 		qemuVhostUserDevice.Cache = attr.Cache
+		qemuVhostUserDevice.SharedVersions = attr.SharedVersions
 	}
 
 	qemuVhostUserDevice.VhostUserType = govmmQemu.DeviceDriver(attr.Type)