feat(CSI-247): implement InterfaceGroup.GetRandomIpAddress() (#319)

### TL;DR

Implemented random IP selection for NFS mounts and simplified mount reference counting.

### What changed?

- Added a new `GetRandomIpAddress` method to the `InterfaceGroup` struct, which selects a random IP address from the available IPs.
- Modified `GetNfsMountIp` to use the new `GetRandomIpAddress` method instead of `GetIpAddress`.
- Removed reference counting logic from the `nfsMount` struct, including the `refCount` field and associated `lock`.
- Simplified `incRef` and `decRef` methods to always perform mount and unmount operations, respectively.

### How to test?

1. Test the new `GetRandomIpAddress` method by calling it multiple times and verifying that different IPs are returned.
2. Verify that NFS mounts now use randomly selected IP addresses.
3. Test mounting and unmounting operations to ensure they work correctly without reference counting.
4. Check that concurrent mount operations are handled properly.

### Why make this change?

- Random IP selection for NFS mounts improves load balancing across available IPs.
- Simplifying the mount reference counting reduces complexity and potential race conditions.
- These changes aim to enhance the reliability and performance of NFS mount operations in the system.

---

feat(CSI-247): implement InterfaceGroup.GetRandomIpAddress()

feat(CSI-247): optimize NFS by utilizing multiple targets

pkg/wekafs/apiclient/interfacegroup.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"github.com/google/uuid"
 	"github.com/rs/zerolog/log"
+	"k8s.io/apimachinery/pkg/util/rand"
 	"k8s.io/helm/pkg/urlutil"
 	"os"
 	"sort"
@@ -93,6 +94,20 @@ func (i *InterfaceGroup) GetIpAddress(ctx context.Context) (string, error) {
 	return i.Ips[idx], nil
 }
 
+func (i *InterfaceGroup) GetRandomIpAddress(ctx context.Context) (string, error) {
+	logger := log.Ctx(ctx)
+	if i == nil {
+		return "", errors.New("interface group is nil")
+	}
+	if len(i.Ips) == 0 {
+		return "", errors.New("no IP addresses found for interface group")
+	}
+	idx := rand.Intn(len(i.Ips))
+	ip := i.Ips[idx]
+	logger.Debug().Str("ip", ip).Msg("Selected random IP address")
+	return ip, nil
+}
+
 func (a *ApiClient) GetInterfaceGroups(ctx context.Context, interfaceGroups *[]InterfaceGroup) error {
 	ig := &InterfaceGroup{}
 
@@ -191,5 +206,5 @@ func (a *ApiClient) GetNfsMountIp(ctx context.Context, interfaceGroupName *strin
 		return "", errors.New("no IP addresses found for NFS interface group")
 	}
 
-	return ig.GetIpAddress(ctx)
+	return ig.GetRandomIpAddress(ctx)
 }

pkg/wekafs/nfsmount.go

@@ -10,15 +10,12 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
-	"sync"
 	"time"
 )
 
 type nfsMount struct {
 	fsName             string
 	mountPoint         string
-	refCount           int
-	lock               sync.Mutex
 	kMounter           mount.Interface
 	debugPath          string
 	mountOptions       MountOptions
@@ -33,7 +30,7 @@ func (m *nfsMount) getMountPoint() string {
 }
 
 func (m *nfsMount) getRefCount() int {
-	return m.refCount
+	return 0
 }
 
 func (m *nfsMount) getMountOptions() MountOptions {
@@ -53,44 +50,15 @@ func (m *nfsMount) isMounted() bool {
 }
 
 func (m *nfsMount) incRef(ctx context.Context, apiClient *apiclient.ApiClient) error {
-	logger := log.Ctx(ctx)
-	m.lock.Lock()
-	defer m.lock.Unlock()
-	if m.refCount < 0 {
-		logger.Error().Str("mount_point", m.mountPoint).Int("refcount", m.refCount).Msg("During incRef negative refcount encountered")
-		m.refCount = 0 // to make sure that we don't have negative refcount later
-	}
-	if m.refCount == 0 {
-		if err := m.doMount(ctx, apiClient, m.mountOptions); err != nil {
-			return err
-		}
-	} else if !m.isMounted() {
-		logger.Warn().Str("mount_point", m.mountPoint).Int("refcount", m.refCount).Msg("Mount not exists although should!")
-		if err := m.doMount(ctx, apiClient, m.mountOptions); err != nil {
-			return err
-		}
-
+	if err := m.doMount(ctx, apiClient, m.mountOptions); err != nil {
+		return err
 	}
-	m.refCount++
-	logger.Trace().Int("refcount", m.refCount).Strs("mount_options", m.mountOptions.Strings()).Str("filesystem_name", m.fsName).Msg("RefCount increased")
 	return nil
 }
 
 func (m *nfsMount) decRef(ctx context.Context) error {
-	logger := log.Ctx(ctx)
-	m.lock.Lock()
-	defer m.lock.Unlock()
-	m.refCount--
-	m.lastUsed = time.Now()
-	logger.Trace().Int("refcount", m.refCount).Strs("mount_options", m.mountOptions.Strings()).Str("filesystem_name", m.fsName).Msg("RefCount decreased")
-	if m.refCount < 0 {
-		logger.Error().Int("refcount", m.refCount).Msg("During decRef negative refcount encountered")
-		m.refCount = 0 // to make sure that we don't have negative refcount later
-	}
-	if m.refCount == 0 {
-		if err := m.doUnmount(ctx); err != nil {
-			return err
-		}
+	if err := m.doUnmount(ctx); err != nil {
+		return err
 	}
 	return nil
 }