fix: add lock ownership to expire locks (#10571)

- Add owner information for expiry, locking, unlocking a resource
- TopLocks returns now locks in quorum by default, provides
  a way to capture stale locks as well with `?stale=true`
- Simplify the quorum handling for locks to avoid from storage
  class, because there were challenges to make it consistent
  across all situations.
- And other tiny simplifications to reset locks.

cmd/admin-handlers.go

@@ -336,23 +336,26 @@ func (a adminAPIHandlers) DataUsageInfoHandler(w http.ResponseWriter, r *http.Re
 	writeSuccessResponseJSON(w, dataUsageInfoJSON)
 }
 
-func lriToLockEntry(l lockRequesterInfo, resource, server string) *madmin.LockEntry {
+func lriToLockEntry(l lockRequesterInfo, resource, server string, rquorum, wquorum int) *madmin.LockEntry {
 	entry := &madmin.LockEntry{
 		Timestamp:  l.Timestamp,
 		Resource:   resource,
 		ServerList: []string{server},
 		Source:     l.Source,
+		Owner:      l.Owner,
 		ID:         l.UID,
 	}
 	if l.Writer {
 		entry.Type = "WRITE"
+		entry.Quorum = wquorum
 	} else {
 		entry.Type = "READ"
+		entry.Quorum = rquorum
 	}
 	return entry
 }
 
-func topLockEntries(peerLocks []*PeerLocks, count int) madmin.LockEntries {
+func topLockEntries(peerLocks []*PeerLocks, count int, rquorum, wquorum int, stale bool) madmin.LockEntries {
 	entryMap := make(map[string]*madmin.LockEntry)
 	for _, peerLock := range peerLocks {
 		if peerLock == nil {
@@ -364,20 +367,26 @@ func topLockEntries(peerLocks []*PeerLocks, count int) madmin.LockEntries {
 					if val, ok := entryMap[lockReqInfo.UID]; ok {
 						val.ServerList = append(val.ServerList, peerLock.Addr)
 					} else {
-						entryMap[lockReqInfo.UID] = lriToLockEntry(lockReqInfo, k, peerLock.Addr)
+						entryMap[lockReqInfo.UID] = lriToLockEntry(lockReqInfo, k, peerLock.Addr, rquorum, wquorum)
 					}
 				}
 			}
 		}
 	}
-	var lockEntries = make(madmin.LockEntries, 0, len(entryMap))
+	var lockEntries madmin.LockEntries
 	for _, v := range entryMap {
+		if len(lockEntries) == count {
+			break
+		}
+		if stale {
+			lockEntries = append(lockEntries, *v)
+			continue
+		}
+		if len(v.ServerList) >= v.Quorum {
 			lockEntries = append(lockEntries, *v)
 		}
-	sort.Sort(lockEntries)
-	if len(lockEntries) > count {
-		lockEntries = lockEntries[:count]
 	}
+	sort.Sort(lockEntries)
 	return lockEntries
 }
 
@@ -407,21 +416,14 @@ func (a adminAPIHandlers) TopLocksHandler(w http.ResponseWriter, r *http.Request
 			return
 		}
 	}
+	stale := r.URL.Query().Get("stale") == "true" // list also stale locks
 
-	peerLocks := globalNotificationSys.GetLocks(ctx)
+	peerLocks := globalNotificationSys.GetLocks(ctx, r)
-	// Once we have received all the locks currently used from peers
-	// add the local peer locks list as well.
-	var getRespLocks GetLocksResp
-	for _, llocker := range globalLockServers {
-		getRespLocks = append(getRespLocks, llocker.DupLockMap())
-	}
 
-	peerLocks = append(peerLocks, &PeerLocks{
+	rquorum := getReadQuorum(objectAPI.SetDriveCount())
-		Addr:  getHostName(r),
+	wquorum := getWriteQuorum(objectAPI.SetDriveCount())
-		Locks: getRespLocks,
-	})
 
-	topLocks := topLockEntries(peerLocks, count)
+	topLocks := topLockEntries(peerLocks, count, rquorum, wquorum, stale)
 
 	// Marshal API response
 	jsonBytes, err := json.Marshal(topLocks)

cmd/data-crawler.go

@@ -21,6 +21,7 @@ import (
 	"context"
 	"encoding/binary"
 	"errors"
+	"math/rand"
 	"os"
 	"path"
 	"strconv"
@@ -49,10 +50,6 @@ const (
 	healDeleteDangling    = true
 	healFolderIncludeProb = 32  // Include a clean folder one in n cycles.
 	healObjectSelectProb  = 512 // Overall probability of a file being scanned; one in n.
-
-	// sleep for an hour after a lock timeout
-	// before retrying to acquire lock again.
-	dataCrawlerLeaderLockTimeoutSleepInterval = time.Hour
 )
 
 var (
@@ -73,10 +70,11 @@ func initDataCrawler(ctx context.Context, objAPI ObjectLayer) {
 func runDataCrawler(ctx context.Context, objAPI ObjectLayer) {
 	// Make sure only 1 crawler is running on the cluster.
 	locker := objAPI.NewNSLock(ctx, minioMetaBucket, "runDataCrawler.lock")
+	r := rand.New(rand.NewSource(time.Now().UnixNano()))
 	for {
 		err := locker.GetLock(dataCrawlerLeaderLockTimeout)
 		if err != nil {
-			time.Sleep(dataCrawlerLeaderLockTimeoutSleepInterval)
+			time.Sleep(time.Duration(r.Float64() * float64(dataCrawlStartDelay)))
 			continue
 		}
 		break

cmd/erasure-sets.go

@@ -66,6 +66,9 @@ type erasureSets struct {
 	// Distributed locker clients.
 	erasureLockers setsDsyncLockers
 
+	// Distributed lock owner (constant per running instance).
+	erasureLockOwner string
+
 	// List of endpoints provided on the command line.
 	endpoints Endpoints
 
@@ -261,11 +264,11 @@ func (s *erasureSets) monitorAndConnectEndpoints(ctx context.Context, monitorInt
 	}
 }
 
-func (s *erasureSets) GetLockers(setIndex int) func() []dsync.NetLocker {
+func (s *erasureSets) GetLockers(setIndex int) func() ([]dsync.NetLocker, string) {
-	return func() []dsync.NetLocker {
+	return func() ([]dsync.NetLocker, string) {
 		lockers := make([]dsync.NetLocker, s.setDriveCount)
 		copy(lockers, s.erasureLockers[setIndex])
-		return lockers
+		return lockers, s.erasureLockOwner
 	}
 }
 
@@ -308,6 +311,7 @@ func newErasureSets(ctx context.Context, endpoints Endpoints, storageDisks []Sto
 		sets:                make([]*erasureObjects, setCount),
 		erasureDisks:        make([][]StorageAPI, setCount),
 		erasureLockers:      make([][]dsync.NetLocker, setCount),
+		erasureLockOwner:    mustGetUUID(),
 		endpoints:           endpoints,
 		endpointStrings:     endpointStrings,
 		setCount:            setCount,

cmd/erasure.go

@@ -52,7 +52,7 @@ type erasureObjects struct {
 	getDisks func() []StorageAPI
 
 	// getLockers returns list of remote and local lockers.
-	getLockers func() []dsync.NetLocker
+	getLockers func() ([]dsync.NetLocker, string)
 
 	// getEndpoints returns list of endpoint strings belonging this set.
 	// some may be local and some remote.

cmd/local-locker.go

@@ -32,6 +32,9 @@ type lockRequesterInfo struct {
 	Timestamp     time.Time // Timestamp set at the time of initialization.
 	TimeLastCheck time.Time // Timestamp for last check of validity of lock.
 	Source        string    // Contains line, function and filename reqesting the lock.
+	// Owner represents the UUID of the owner who originally requested the lock
+	// useful in expiry.
+	Owner string
 }
 
 // isWriteLock returns whether the lock is a write or read lock.
@@ -73,10 +76,6 @@ func (l *localLocker) canTakeLock(resources ...string) bool {
 }
 
 func (l *localLocker) Lock(ctx context.Context, args dsync.LockArgs) (reply bool, err error) {
-	select {
-	case <-ctx.Done():
-		return false, ctx.Err()
-	default:
 	l.mutex.Lock()
 	defer l.mutex.Unlock()
 
@@ -93,6 +92,7 @@ func (l *localLocker) Lock(ctx context.Context, args dsync.LockArgs) (reply bool
 			{
 				Writer:        true,
 				Source:        args.Source,
+				Owner:         args.Owner,
 				UID:           args.UID,
 				Timestamp:     UTCNow(),
 				TimeLastCheck: UTCNow(),
@@ -100,7 +100,6 @@ func (l *localLocker) Lock(ctx context.Context, args dsync.LockArgs) (reply bool
 		}
 	}
 	return true, nil
-	}
 }
 
 func (l *localLocker) Unlock(args dsync.LockArgs) (reply bool, err error) {
@@ -113,7 +112,7 @@ func (l *localLocker) Unlock(args dsync.LockArgs) (reply bool, err error) {
 	}
 	for _, resource := range args.Resources {
 		lri := l.lockMap[resource]
-		if !l.removeEntry(resource, args.UID, &lri) {
+		if !l.removeEntry(resource, args, &lri) {
 			return false, fmt.Errorf("Unlock unable to find corresponding lock for uid: %s on resource %s", args.UID, resource)
 		}
 	}
@@ -124,10 +123,10 @@ func (l *localLocker) Unlock(args dsync.LockArgs) (reply bool, err error) {
 // removeEntry based on the uid of the lock message, removes a single entry from the
 // lockRequesterInfo array or the whole array from the map (in case of a write lock
 // or last read lock)
-func (l *localLocker) removeEntry(name, uid string, lri *[]lockRequesterInfo) bool {
+func (l *localLocker) removeEntry(name string, args dsync.LockArgs, lri *[]lockRequesterInfo) bool {
 	// Find correct entry to remove based on uid.
 	for index, entry := range *lri {
-		if entry.UID == uid {
+		if entry.UID == args.UID && entry.Owner == args.Owner {
 			if len(*lri) == 1 {
 				// Remove the write lock.
 				delete(l.lockMap, name)
@@ -145,15 +144,12 @@ func (l *localLocker) removeEntry(name, uid string, lri *[]lockRequesterInfo) bo
 }
 
 func (l *localLocker) RLock(ctx context.Context, args dsync.LockArgs) (reply bool, err error) {
-	select {
-	case <-ctx.Done():
-		return false, ctx.Err()
-	default:
 	l.mutex.Lock()
 	defer l.mutex.Unlock()
 	lrInfo := lockRequesterInfo{
 		Writer:        false,
 		Source:        args.Source,
+		Owner:         args.Owner,
 		UID:           args.UID,
 		Timestamp:     UTCNow(),
 		TimeLastCheck: UTCNow(),
@@ -170,7 +166,6 @@ func (l *localLocker) RLock(ctx context.Context, args dsync.LockArgs) (reply boo
 		reply = true
 	}
 	return reply, nil
-	}
 }
 
 func (l *localLocker) RUnlock(args dsync.LockArgs) (reply bool, err error) {
@@ -187,7 +182,7 @@ func (l *localLocker) RUnlock(args dsync.LockArgs) (reply bool, err error) {
 		// A write-lock is held, cannot release a read lock
 		return reply, fmt.Errorf("RUnlock attempted on a write locked entity: %s", resource)
 	}
-	if !l.removeEntry(resource, args.UID, &lri) {
+	if !l.removeEntry(resource, args, &lri) {
 		return false, fmt.Errorf("RUnlock unable to find corresponding read lock for uid: %s", args.UID)
 	}
 	return reply, nil
@@ -226,7 +221,7 @@ func (l *localLocker) Expired(ctx context.Context, args dsync.LockArgs) (expired
 			if lri, ok := l.lockMap[resource]; ok {
 				// Check whether uid is still active
 				for _, entry := range lri {
-					if entry.UID == args.UID {
+					if entry.UID == args.UID && entry.Owner == args.Owner {
 						return false, nil
 					}
 				}
@@ -244,7 +239,7 @@ func (l *localLocker) removeEntryIfExists(nlrip nameLockRequesterInfoPair) {
 		// Even if the entry exists, it may not be the same entry which was
 		// considered as expired, so we simply an attempt to remove it if its
 		// not possible there is nothing we need to do.
-		l.removeEntry(nlrip.name, nlrip.lri.UID, &lri)
+		l.removeEntry(nlrip.name, dsync.LockArgs{Owner: nlrip.lri.Owner, UID: nlrip.lri.UID}, &lri)
 	}
 }
 

cmd/lock-rest-client.go

@@ -87,6 +87,7 @@ func (client *lockRESTClient) Close() error {
 func (client *lockRESTClient) restCall(ctx context.Context, call string, args dsync.LockArgs) (reply bool, err error) {
 	values := url.Values{}
 	values.Set(lockRESTUID, args.UID)
+	values.Set(lockRESTOwner, args.Owner)
 	values.Set(lockRESTSource, args.Source)
 	var buffer bytes.Buffer
 	for _, resource := range args.Resources {

cmd/lock-rest-server-common.go

@@ -34,8 +34,12 @@ const (
 	lockRESTMethodRUnlock = "/runlock"
 	lockRESTMethodExpired = "/expired"
 
+	// lockRESTOwner represents owner UUID
+	lockRESTOwner = "owner"
+
 	// Unique ID of lock/unlock request.
 	lockRESTUID = "uid"
+
 	// Source contains the line number, function and file name of the code
 	// on the client node that requested the lock.
 	lockRESTSource = "source"

cmd/lock-rest-server-common_test.go

@@ -21,6 +21,8 @@ import (
 	"reflect"
 	"sync"
 	"testing"
+
+	"github.com/minio/minio/pkg/dsync"
 )
 
 // Helper function to create a lock server for testing
@@ -53,12 +55,14 @@ func TestLockRpcServerRemoveEntry(t *testing.T) {
 	defer os.RemoveAll(testPath)
 
 	lockRequesterInfo1 := lockRequesterInfo{
+		Owner:         "owner",
 		Writer:        true,
 		UID:           "0123-4567",
 		Timestamp:     UTCNow(),
 		TimeLastCheck: UTCNow(),
 	}
 	lockRequesterInfo2 := lockRequesterInfo{
+		Owner:         "owner",
 		Writer:        true,
 		UID:           "89ab-cdef",
 		Timestamp:     UTCNow(),
@@ -73,11 +77,17 @@ func TestLockRpcServerRemoveEntry(t *testing.T) {
 	lri := locker.ll.lockMap["name"]
 
 	// test unknown uid
-	if locker.ll.removeEntry("name", "unknown-uid", &lri) {
+	if locker.ll.removeEntry("name", dsync.LockArgs{
+		Owner: "owner",
+		UID:   "unknown-uid",
+	}, &lri) {
 		t.Errorf("Expected %#v, got %#v", false, true)
 	}
 
-	if !locker.ll.removeEntry("name", "0123-4567", &lri) {
+	if !locker.ll.removeEntry("name", dsync.LockArgs{
+		Owner: "owner",
+		UID:   "0123-4567",
+	}, &lri) {
 		t.Errorf("Expected %#v, got %#v", true, false)
 	} else {
 		gotLri := locker.ll.lockMap["name"]
@@ -87,7 +97,10 @@ func TestLockRpcServerRemoveEntry(t *testing.T) {
 		}
 	}
 
-	if !locker.ll.removeEntry("name", "89ab-cdef", &lri) {
+	if !locker.ll.removeEntry("name", dsync.LockArgs{
+		Owner: "owner",
+		UID:   "89ab-cdef",
+	}, &lri) {
 		t.Errorf("Expected %#v, got %#v", true, false)
 	} else {
 		gotLri := locker.ll.lockMap["name"]

cmd/lock-rest-server.go

@@ -32,7 +32,7 @@ import (
 
 const (
 	// Lock maintenance interval.
-	lockMaintenanceInterval = 1 * time.Minute
+	lockMaintenanceInterval = 30 * time.Second
 
 	// Lock validity check interval.
 	lockValidityCheckInterval = 2 * time.Minute
@@ -64,6 +64,7 @@ func (l *lockRESTServer) IsValid(w http.ResponseWriter, r *http.Request) bool {
 
 func getLockArgs(r *http.Request) (args dsync.LockArgs, err error) {
 	args = dsync.LockArgs{
+		Owner:  r.URL.Query().Get(lockRESTOwner),
 		UID:    r.URL.Query().Get(lockRESTUID),
 		Source: r.URL.Query().Get(lockRESTSource),
 	}
@@ -246,10 +247,28 @@ func lockMaintenance(ctx context.Context, interval time.Duration) error {
 		return nil
 	}
 
+	type nlock struct {
+		locks  int
+		writer bool
+	}
+
+	updateNlocks := func(nlripsMap map[string]nlock, name string, writer bool) {
+		nlk, ok := nlripsMap[name]
+		if !ok {
+			nlripsMap[name] = nlock{
+				locks:  1,
+				writer: writer,
+			}
+		} else {
+			nlk.locks++
+			nlripsMap[name] = nlk
+		}
+	}
+
 	// Validate if long lived locks are indeed clean.
 	// Get list of long lived locks to check for staleness.
 	for lendpoint, nlrips := range getLongLivedLocks(interval) {
-		nlripsMap := make(map[string]int, len(nlrips))
+		nlripsMap := make(map[string]nlock, len(nlrips))
 		for _, nlrip := range nlrips {
 			// Locks are only held on first zone, make sure that
 			// we only look for ownership of locks from endpoints
@@ -257,7 +276,7 @@ func lockMaintenance(ctx context.Context, interval time.Duration) error {
 			for _, endpoint := range globalEndpoints[0].Endpoints {
 				c := newLockAPI(endpoint)
 				if !c.IsOnline() {
-					nlripsMap[nlrip.name]++
+					updateNlocks(nlripsMap, nlrip.name, nlrip.lri.Writer)
 					continue
 				}
 
@@ -266,18 +285,19 @@ func lockMaintenance(ctx context.Context, interval time.Duration) error {
 				// Call back to original server verify whether the lock is
 				// still active (based on name & uid)
 				expired, err := c.Expired(ctx, dsync.LockArgs{
+					Owner:     nlrip.lri.Owner,
 					UID:       nlrip.lri.UID,
 					Resources: []string{nlrip.name},
 				})
 				cancel()
 				if err != nil {
-					nlripsMap[nlrip.name]++
+					updateNlocks(nlripsMap, nlrip.name, nlrip.lri.Writer)
 					c.Close()
 					continue
 				}
 
 				if !expired {
-					nlripsMap[nlrip.name]++
+					updateNlocks(nlripsMap, nlrip.name, nlrip.lri.Writer)
 				}
 
 				// Close the connection regardless of the call response.
@@ -285,14 +305,13 @@ func lockMaintenance(ctx context.Context, interval time.Duration) error {
 			}
 
 			// Read locks we assume quorum for be N/2 success
-			quorum := objAPI.SetDriveCount() / 2
+			quorum := getReadQuorum(objAPI.SetDriveCount())
 			if nlrip.lri.Writer {
-				// For write locks we need N/2+1 success
+				quorum = getWriteQuorum(objAPI.SetDriveCount())
-				quorum = objAPI.SetDriveCount()/2 + 1
 			}
 
 			// less than the quorum, we have locks expired.
-			if nlripsMap[nlrip.name] < quorum {
+			if nlripsMap[nlrip.name].locks < quorum {
 				// The lock is no longer active at server that originated
 				// the lock, attempt to remove the lock.
 				globalLockServers[lendpoint].mutex.Lock()
@@ -348,7 +367,6 @@ func startLockMaintenance(ctx context.Context) {
 
 // registerLockRESTHandlers - register lock rest router.
 func registerLockRESTHandlers(router *mux.Router, endpointZones EndpointZones) {
-	queries := restQueries(lockRESTUID, lockRESTSource)
 	for _, ep := range endpointZones {
 		for _, endpoint := range ep.Endpoints {
 			if !endpoint.IsLocal {
@@ -361,11 +379,11 @@ func registerLockRESTHandlers(router *mux.Router, endpointZones EndpointZones) {
 
 			subrouter := router.PathPrefix(path.Join(lockRESTPrefix, endpoint.Path)).Subrouter()
 			subrouter.Methods(http.MethodPost).Path(lockRESTVersionPrefix + lockRESTMethodHealth).HandlerFunc(httpTraceHdrs(lockServer.HealthHandler))
-			subrouter.Methods(http.MethodPost).Path(lockRESTVersionPrefix + lockRESTMethodLock).HandlerFunc(httpTraceHdrs(lockServer.LockHandler)).Queries(queries...)
+			subrouter.Methods(http.MethodPost).Path(lockRESTVersionPrefix + lockRESTMethodLock).HandlerFunc(httpTraceHdrs(lockServer.LockHandler))
-			subrouter.Methods(http.MethodPost).Path(lockRESTVersionPrefix + lockRESTMethodRLock).HandlerFunc(httpTraceHdrs(lockServer.RLockHandler)).Queries(queries...)
+			subrouter.Methods(http.MethodPost).Path(lockRESTVersionPrefix + lockRESTMethodRLock).HandlerFunc(httpTraceHdrs(lockServer.RLockHandler))
-			subrouter.Methods(http.MethodPost).Path(lockRESTVersionPrefix + lockRESTMethodUnlock).HandlerFunc(httpTraceHdrs(lockServer.UnlockHandler)).Queries(queries...)
+			subrouter.Methods(http.MethodPost).Path(lockRESTVersionPrefix + lockRESTMethodUnlock).HandlerFunc(httpTraceHdrs(lockServer.UnlockHandler))
-			subrouter.Methods(http.MethodPost).Path(lockRESTVersionPrefix + lockRESTMethodRUnlock).HandlerFunc(httpTraceHdrs(lockServer.RUnlockHandler)).Queries(queries...)
+			subrouter.Methods(http.MethodPost).Path(lockRESTVersionPrefix + lockRESTMethodRUnlock).HandlerFunc(httpTraceHdrs(lockServer.RUnlockHandler))
-			subrouter.Methods(http.MethodPost).Path(lockRESTVersionPrefix + lockRESTMethodExpired).HandlerFunc(httpTraceAll(lockServer.ExpiredHandler)).Queries(queries...)
+			subrouter.Methods(http.MethodPost).Path(lockRESTVersionPrefix + lockRESTMethodExpired).HandlerFunc(httpTraceAll(lockServer.ExpiredHandler))
 
 			globalLockServers[endpoint] = lockServer.ll
 		}

cmd/namespace-lock.go

@@ -28,7 +28,6 @@ import (
 	"fmt"
 	"time"
 
-	"github.com/minio/minio/cmd/config/storageclass"
 	"github.com/minio/minio/cmd/logger"
 	"github.com/minio/minio/pkg/dsync"
 	"github.com/minio/minio/pkg/lsync"
@@ -148,17 +147,8 @@ func (di *distLockInstance) GetLock(timeout *dynamicTimeout) (timedOutErr error)
 	lockSource := getSource(2)
 	start := UTCNow()
 
-	// Lockers default to standard storage class always, why because
-	// we always dictate storage tolerance in terms of standard
-	// storage class be it number of drives or a multiplicative
-	// of number of nodes, defaulting lockers to this value
-	// simply means that locking is always similar in behavior
-	// and effect with erasure coded drive tolerance.
-	tolerance := globalStorageClass.GetParityForSC(storageclass.STANDARD)
-
 	if !di.rwMutex.GetLock(di.ctx, di.opsID, lockSource, dsync.Options{
 		Timeout: timeout.Timeout(),
-		Tolerance: tolerance,
 	}) {
 		timeout.LogFailure()
 		return OperationTimedOut{}
@@ -177,12 +167,8 @@ func (di *distLockInstance) GetRLock(timeout *dynamicTimeout) (timedOutErr error
 	lockSource := getSource(2)
 	start := UTCNow()
 
-	// Lockers default to standard storage class always.
-	tolerance := globalStorageClass.GetParityForSC(storageclass.STANDARD)
-
 	if !di.rwMutex.GetRLock(di.ctx, di.opsID, lockSource, dsync.Options{
 		Timeout: timeout.Timeout(),
-		Tolerance: tolerance,
 	}) {
 		timeout.LogFailure()
 		return OperationTimedOut{}
@@ -208,11 +194,11 @@ type localLockInstance struct {
 // NewNSLock - returns a lock instance for a given volume and
 // path. The returned lockInstance object encapsulates the nsLockMap,
 // volume, path and operation ID.
-func (n *nsLockMap) NewNSLock(ctx context.Context, lockersFn func() []dsync.NetLocker, volume string, paths ...string) RWLocker {
+func (n *nsLockMap) NewNSLock(ctx context.Context, lockers func() ([]dsync.NetLocker, string), volume string, paths ...string) RWLocker {
 	opsID := mustGetUUID()
 	if n.isDistErasure {
 		drwmutex := dsync.NewDRWMutex(&dsync.Dsync{
-			GetLockersFn: lockersFn,
+			GetLockers: lockers,
 		}, pathsJoinPrefix(volume, paths...)...)
 		return &distLockInstance{drwmutex, opsID, ctx}
 	}

cmd/notification.go

@@ -22,6 +22,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
+	"net/http"
 	"net/url"
 	"sort"
 	"strings"
@@ -505,36 +506,24 @@ func (sys *NotificationSys) updateBloomFilter(ctx context.Context, current uint6
 }
 
 // GetLocks - makes GetLocks RPC call on all peers.
-func (sys *NotificationSys) GetLocks(ctx context.Context) []*PeerLocks {
+func (sys *NotificationSys) GetLocks(ctx context.Context, r *http.Request) []*PeerLocks {
 	locksResp := make([]*PeerLocks, len(sys.peerClients))
 	g := errgroup.WithNErrs(len(sys.peerClients))
 	for index, client := range sys.peerClients {
-		if client == nil {
-			continue
-		}
 		index := index
 		g.Go(func() error {
-			// Try to fetch serverInfo remotely in three attempts.
+			if client == nil {
-			for i := 0; i < 3; i++ {
+				return nil
+			}
 			serverLocksResp, err := sys.peerClients[index].GetLocks()
-				if err == nil {
+			if err != nil {
+				return err
+			}
 			locksResp[index] = &PeerLocks{
 				Addr:  sys.peerClients[index].host.String(),
 				Locks: serverLocksResp,
 			}
 			return nil
-				}
-
-				// Last iteration log the error.
-				if i == 2 {
-					return err
-				}
-				// Wait for one second and no need wait after last attempt.
-				if i < 2 {
-					time.Sleep(1 * time.Second)
-				}
-			}
-			return nil
 		}, index)
 	}
 	for index, err := range g.Wait() {
@@ -543,6 +532,16 @@ func (sys *NotificationSys) GetLocks(ctx context.Context) []*PeerLocks {
 		ctx := logger.SetReqInfo(ctx, reqInfo)
 		logger.LogOnceIf(ctx, err, sys.peerClients[index].host.String())
 	}
+	// Once we have received all the locks currently used from peers
+	// add the local peer locks list as well.
+	var getRespLocks GetLocksResp
+	for _, llocker := range globalLockServers {
+		getRespLocks = append(getRespLocks, llocker.DupLockMap())
+	}
+	locksResp = append(locksResp, &PeerLocks{
+		Addr:  getHostName(r),
+		Locks: getRespLocks,
+	})
 	return locksResp
 }
 

pkg/dsync/drwmutex.go

@@ -71,8 +71,9 @@ func isLocked(uid string) bool {
 
 // NewDRWMutex - initializes a new dsync RW mutex.
 func NewDRWMutex(clnt *Dsync, names ...string) *DRWMutex {
+	restClnts, _ := clnt.GetLockers()
 	return &DRWMutex{
-		writeLocks: make([]string, len(clnt.GetLockersFn())),
+		writeLocks: make([]string, len(restClnts)),
 		Names:      names,
 		clnt:       clnt,
 	}
@@ -141,28 +142,19 @@ const (
 // algorithm until either the lock is acquired successfully or more
 // time has elapsed than the timeout value.
 func (dm *DRWMutex) lockBlocking(ctx context.Context, id, source string, isReadLock bool, opts Options) (locked bool) {
-	restClnts := dm.clnt.GetLockersFn()
+	restClnts, _ := dm.clnt.GetLockers()
 
 	r := rand.New(rand.NewSource(time.Now().UnixNano()))
 
 	// Create lock array to capture the successful lockers
 	locks := make([]string, len(restClnts))
 
-	cleanLocks := func(locks []string) {
-		for i := range locks {
-			locks[i] = ""
-		}
-	}
-
 	log("lockBlocking %s/%s for %#v: lockType readLock(%t), additional opts: %#v\n", id, source, dm.Names, isReadLock, opts)
 	retryCtx, cancel := context.WithTimeout(ctx, opts.Timeout)
 
 	defer cancel()
 
 	for {
-		// cleanup any older state, re-use the lock slice.
-		cleanLocks(locks)
-
 		select {
 		case <-retryCtx.Done():
 			log("lockBlocking canceled %s/%s for %#v: lockType readLock(%t), additional opts: %#v\n", id, source, dm.Names, isReadLock, opts)
@@ -195,8 +187,11 @@ func (dm *DRWMutex) lockBlocking(ctx context.Context, id, source string, isReadL
 
 // lock tries to acquire the distributed lock, returning true or false.
 func lock(ctx context.Context, ds *Dsync, locks *[]string, id, source string, isReadLock bool, tolerance int, lockNames ...string) bool {
+	for i := range *locks {
+		(*locks)[i] = ""
+	}
 
-	restClnts := ds.GetLockersFn()
+	restClnts, owner := ds.GetLockers()
 
 	// Tolerance is not set, defaults to half of the locker clients.
 	if tolerance == 0 {
@@ -237,6 +232,7 @@ func lock(ctx context.Context, ds *Dsync, locks *[]string, id, source string, is
 			}
 
 			args := LockArgs{
+				Owner:     owner,
 				UID:       id,
 				Resources: lockNames,
 				Source:    source,
@@ -293,7 +289,7 @@ func lock(ctx context.Context, ds *Dsync, locks *[]string, id, source string, is
 						done = true
 						// Increment the number of grants received from the buffered channel.
 						i++
-						releaseAll(ds, locks, isReadLock, restClnts, lockNames...)
+						releaseAll(ds, owner, locks, isReadLock, restClnts, lockNames...)
 					}
 				}
 			case <-timeout:
@@ -302,7 +298,7 @@ func lock(ctx context.Context, ds *Dsync, locks *[]string, id, source string, is
 				// number of locks to check whether we have quorum or not
 				if !checkQuorumMet(locks, quorum) {
 					log("Quorum not met after timeout\n")
-					releaseAll(ds, locks, isReadLock, restClnts, lockNames...)
+					releaseAll(ds, owner, locks, isReadLock, restClnts, lockNames...)
 				} else {
 					log("Quorum met after timeout\n")
 				}
@@ -327,6 +323,7 @@ func lock(ctx context.Context, ds *Dsync, locks *[]string, id, source string, is
 			if grantToBeReleased.isLocked() {
 				// release lock
 				sendRelease(ds, restClnts[grantToBeReleased.index],
+					owner,
 					grantToBeReleased.lockUID, isReadLock, lockNames...)
 			}
 		}
@@ -350,10 +347,10 @@ func checkQuorumMet(locks *[]string, quorum int) bool {
 }
 
 // releaseAll releases all locks that are marked as locked
-func releaseAll(ds *Dsync, locks *[]string, isReadLock bool, restClnts []NetLocker, lockNames ...string) {
+func releaseAll(ds *Dsync, owner string, locks *[]string, isReadLock bool, restClnts []NetLocker, lockNames ...string) {
 	for lock := range restClnts {
 		if isLocked((*locks)[lock]) {
-			sendRelease(ds, restClnts[lock], (*locks)[lock], isReadLock, lockNames...)
+			sendRelease(ds, restClnts[lock], owner, (*locks)[lock], isReadLock, lockNames...)
 			(*locks)[lock] = ""
 		}
 	}
@@ -364,7 +361,7 @@ func releaseAll(ds *Dsync, locks *[]string, isReadLock bool, restClnts []NetLock
 // It is a run-time error if dm is not locked on entry to Unlock.
 func (dm *DRWMutex) Unlock() {
 
-	restClnts := dm.clnt.GetLockersFn()
+	restClnts, owner := dm.clnt.GetLockers()
 	// create temp array on stack
 	locks := make([]string, len(restClnts))
 
@@ -391,7 +388,7 @@ func (dm *DRWMutex) Unlock() {
 	}
 
 	isReadLock := false
-	unlock(dm.clnt, locks, isReadLock, restClnts, dm.Names...)
+	unlock(dm.clnt, owner, locks, isReadLock, restClnts, dm.Names...)
 }
 
 // RUnlock releases a read lock held on dm.
@@ -400,7 +397,7 @@ func (dm *DRWMutex) Unlock() {
 func (dm *DRWMutex) RUnlock() {
 
 	// create temp array on stack
-	restClnts := dm.clnt.GetLockersFn()
+	restClnts, owner := dm.clnt.GetLockers()
 
 	locks := make([]string, len(restClnts))
 	{
@@ -416,10 +413,10 @@ func (dm *DRWMutex) RUnlock() {
 	}
 
 	isReadLock := true
-	unlock(dm.clnt, locks, isReadLock, restClnts, dm.Names...)
+	unlock(dm.clnt, owner, locks, isReadLock, restClnts, dm.Names...)
 }
 
-func unlock(ds *Dsync, locks []string, isReadLock bool, restClnts []NetLocker, names ...string) {
+func unlock(ds *Dsync, owner string, locks []string, isReadLock bool, restClnts []NetLocker, names ...string) {
 
 	// We don't need to synchronously wait until we have released all the locks (or the quorum)
 	// (a subsequent lock will retry automatically in case it would fail to get quorum)
@@ -428,19 +425,20 @@ func unlock(ds *Dsync, locks []string, isReadLock bool, restClnts []NetLocker, n
 
 		if isLocked(locks[index]) {
 			// broadcast lock release to all nodes that granted the lock
-			sendRelease(ds, c, locks[index], isReadLock, names...)
+			sendRelease(ds, c, owner, locks[index], isReadLock, names...)
 		}
 	}
 }
 
 // sendRelease sends a release message to a node that previously granted a lock
-func sendRelease(ds *Dsync, c NetLocker, uid string, isReadLock bool, names ...string) {
+func sendRelease(ds *Dsync, c NetLocker, owner string, uid string, isReadLock bool, names ...string) {
 	if c == nil {
 		log("Unable to call RUnlock failed with %s\n", errors.New("netLocker is offline"))
 		return
 	}
 
 	args := LockArgs{
+		Owner:     owner,
 		UID:       uid,
 		Resources: names,
 	}

pkg/dsync/dsync.go

@@ -20,5 +20,5 @@ package dsync
 // authenticated clients, used to initiate lock REST calls.
 type Dsync struct {
 	// List of rest client objects, one per lock server.
-	GetLockersFn func() []NetLocker
+	GetLockers func() ([]NetLocker, string)
 }

pkg/dsync/dsync_test.go

@@ -31,6 +31,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/google/uuid"
 	. "github.com/minio/minio/pkg/dsync"
 )
 
@@ -78,7 +79,7 @@ func TestMain(m *testing.M) {
 	}
 
 	ds = &Dsync{
-		GetLockersFn: func() []NetLocker { return clnts },
+		GetLockers: func() ([]NetLocker, string) { return clnts, uuid.New().String() },
 	}
 
 	startRPCServers(nodes)

pkg/dsync/rpc-client-interface.go

@@ -29,6 +29,10 @@ type LockArgs struct {
 	// Source contains the line number, function and file name of the code
 	// on the client node that requested the lock.
 	Source string
+
+	// Owner represents unique ID for this instance, an owner who originally requested
+	// the locked resource, useful primarily in figuring our stale locks.
+	Owner string
 }
 
 // NetLocker is dsync compatible locker interface.

pkg/madmin/top-commands.go

@@ -36,7 +36,9 @@ type LockEntry struct {
 	Type       string    `json:"type"`       // Type indicates if 'Write' or 'Read' lock
 	Source     string    `json:"source"`     // Source at which lock was granted
 	ServerList []string  `json:"serverlist"` // List of servers participating in the lock.
+	Owner      string    `json:"owner"`      // Owner UUID indicates server owns the lock.
 	ID         string    `json:"id"`         // UID to uniquely identify request of client.
+	Quorum     int       `json:"quorum"`     // represents quorum number of servers required to hold this lock, used to look for stale locks.
 }
 
 // LockEntries - To sort the locks
@@ -54,13 +56,21 @@ func (l LockEntries) Swap(i, j int) {
 	l[i], l[j] = l[j], l[i]
 }
 
-// TopNLocks - returns the count number of oldest locks currently active on the server.
+// TopLockOpts top lock options
-func (adm *AdminClient) TopNLocks(ctx context.Context, count int) (LockEntries, error) {
+type TopLockOpts struct {
+	Count int
+	Stale bool
+}
+
+// TopLocksWithOpts - returns the count number of oldest locks currently active on the server.
+// additionally we can also enable `stale` to get stale locks currently present on server.
+func (adm *AdminClient) TopLocksWithOpts(ctx context.Context, opts TopLockOpts) (LockEntries, error) {
 	// Execute GET on /minio/admin/v3/top/locks?count=10
 	// to get the 'count' number of oldest locks currently
 	// active on the server.
 	queryVals := make(url.Values)
-	queryVals.Set("count", strconv.Itoa(count))
+	queryVals.Set("count", strconv.Itoa(opts.Count))
+	queryVals.Set("stale", strconv.FormatBool(opts.Stale))
 	resp, err := adm.executeMethod(ctx,
 		http.MethodGet,
 		requestData{
@@ -89,5 +99,5 @@ func (adm *AdminClient) TopNLocks(ctx context.Context, count int) (LockEntries,
 
 // TopLocks - returns top '10' oldest locks currently active on the server.
 func (adm *AdminClient) TopLocks(ctx context.Context) (LockEntries, error) {
-	return adm.TopNLocks(ctx, 10)
+	return adm.TopLocksWithOpts(ctx, TopLockOpts{Count: 10})
 }