vc: Utilize map for newMounts to speed up replaceOCIMountSource

Fixes kata-containers#2212

Signed-off-by: Ted Yu <yuzhihong@gmail.com>

virtcontainers/container.go

@@ -533,8 +533,8 @@ func (c *Container) shareFiles(m Mount, idx int, hostSharedDir, guestSharedDir s
 // It also updates the container mount list with the HostPath info, and store
 // container mounts to the storage. This way, we will have the HostPath info
 // available when we will need to unmount those mounts.
-func (c *Container) mountSharedDirMounts(hostSharedDir, guestSharedDir string) ([]Mount, []Mount, error) {
-	var sharedDirMounts []Mount
+func (c *Container) mountSharedDirMounts(hostSharedDir, guestSharedDir string) (map[string]Mount, []Mount, error) {
+	sharedDirMounts := make(map[string]Mount)
 	var ignoredMounts []Mount
 	for idx, m := range c.mounts {
 		// Skip mounting certain system paths from the source on the host side
@@ -607,7 +607,7 @@ func (c *Container) mountSharedDirMounts(hostSharedDir, guestSharedDir string) (
 			ReadOnly:    readonly,
 		}
 
-		sharedDirMounts = append(sharedDirMounts, sharedDirMount)
+		sharedDirMounts[sharedDirMount.Destination] = sharedDirMount
 	}
 
 	if !c.sandbox.supportNewStore() {

virtcontainers/kata_agent.go

@@ -962,15 +962,11 @@ func (k *kataAgent) stopSandbox(sandbox *Sandbox) error {
 	return nil
 }
 
-func (k *kataAgent) replaceOCIMountSource(spec *specs.Spec, guestMounts []Mount) error {
+func (k *kataAgent) replaceOCIMountSource(spec *specs.Spec, guestMounts map[string]Mount) error {
 	ociMounts := spec.Mounts
 
 	for index, m := range ociMounts {
-		for _, guestMount := range guestMounts {
-			if guestMount.Destination != m.Destination {
-				continue
-			}
-
+		if guestMount, ok := guestMounts[m.Destination]; ok {
 			k.Logger().Debugf("Replacing OCI mount (%s) source %s with %s", m.Destination, m.Source, guestMount.Source)
 			ociMounts[index].Source = guestMount.Source
 		}