fix: do not allow total all kind of snapshots to be bigger than 250

app/cmd/controller.go

@@ -85,7 +85,7 @@ func ControllerCmd() cli.Command {
 			},
 			cli.IntFlag{
 				Name:  "snapshot-max-count",
-				Value: 250,
+				Value: types.MaximumTotalSnapshotCount,
 				Usage: "Maximum number of snapshots to keep",
 			},
 			cli.StringFlag{

app/cmd/replica.go

@@ -76,7 +76,7 @@ func ReplicaCmd() cli.Command {
 			},
 			cli.IntFlag{
 				Name:  "snapshot-max-count",
-				Value: 250,
+				Value: types.MaximumTotalSnapshotCount,
 				Usage: "Maximum number of snapshots to keep",
 			},
 			cli.StringFlag{

go.mod

@@ -4,6 +4,8 @@ go 1.23.0
 
 toolchain go1.23.5
 
+replace github.com/longhorn/types => ../types
+
 require (
 	github.com/docker/go-units v0.5.0
 	github.com/gofrs/flock v0.12.1

go.sum

@@ -84,8 +84,6 @@ github.com/longhorn/go-iscsi-helper v0.0.0-20250111093313-7e1930499625 h1:d39A30
 github.com/longhorn/go-iscsi-helper v0.0.0-20250111093313-7e1930499625/go.mod h1:yIm3sGRuYOw/Y3XzRhG5+3FlZBOfrU5EZOavzwL2jVs=
 github.com/longhorn/sparse-tools v0.0.0-20241216160947-2b328f0fa59c h1:OFz3haCSPdgiiJvXLBeId/4dPu0dxIEqkQkfNMufLwc=
 github.com/longhorn/sparse-tools v0.0.0-20241216160947-2b328f0fa59c/go.mod h1:dfbJqfI8+T9ZCp5zhTYcBi/64hPBNt5/vFF3gTlfMmc=
-github.com/longhorn/types v0.0.0-20241225162202-00d3a5fd7502 h1:jgw7nosooLe1NQEdCGzM/nEOFzPcurNO+0PDsicc5+A=
-github.com/longhorn/types v0.0.0-20241225162202-00d3a5fd7502/go.mod h1:3jHuVDtpkXQzpnp4prguDBskVRric2kmF8aSPkRJ4jw=
 github.com/mattn/go-colorable v0.1.13 h1:fFA4WZxdEF4tXPZVKMLwD8oUnCTTo08duU7wxecdEvA=
 github.com/mattn/go-colorable v0.1.13/go.mod h1:7S9/ev0klgBDR4GtXTXX8a3vIGJpMovkB8vQcUbaXHg=
 github.com/mattn/go-isatty v0.0.16/go.mod h1:kYGgaQfpe5nmfYZH+SKPsOc2e4SrIfOl2e/yFXSvRLM=

pkg/backend/file/file.go

@@ -99,8 +99,8 @@ func (f *Wrapper) SectorSize() (int64, error) {
 	return 4096, nil
 }
 
-func (f *Wrapper) GetSnapshotCountAndSizeUsage() (int, int64, error) {
-	return 1, 0, nil
+func (f *Wrapper) GetSnapshotCountAndSizeUsage() (int, int, int64, error) {
+	return 1, 1, 0, nil
 }
 
 func (f *Wrapper) GetRevisionCounter() (int64, error) {

pkg/backend/remote/remote.go

@@ -222,16 +222,16 @@ func (r *Remote) SectorSize() (int64, error) {
 	return replicaInfo.SectorSize, nil
 }
 
-func (r *Remote) GetSnapshotCountAndSizeUsage() (int, int64, error) {
+func (r *Remote) GetSnapshotCountAndSizeUsage() (int, int, int64, error) {
 	replicaInfo, err := r.info()
 	if err != nil {
-		return 0, 0, err
+		return 0, 0, 0, err
 	}
 	switch replicaInfo.State {
 	case "open", "dirty", "rebuilding":
-		return replicaInfo.SnapshotCountUsage, replicaInfo.SnapshotSizeUsage, nil
+		return replicaInfo.SnapshotCountUsage, replicaInfo.SnapshotCountTotal, replicaInfo.SnapshotSizeUsage, nil
 	}
-	return 0, 0, fmt.Errorf("invalid state %v for counting snapshots", replicaInfo.State)
+	return 0, 0, 0, fmt.Errorf("invalid state %v for counting snapshots", replicaInfo.State)
 }
 
 func (r *Remote) GetRevisionCounter() (int64, error) {

pkg/controller/control.go

@@ -286,13 +286,16 @@ func (c *Controller) Snapshot(inputName string, labels map[string]string, should
 }
 
 func (c *Controller) canDoSnapshot() error {
-	countUsage, sizeUsage, err := c.backend.GetSnapshotCountAndSizeUsage()
+	countUsage, countTotal, sizeUsage, err := c.backend.GetSnapshotCountAndSizeUsage()
 	if err != nil {
 		return err
 	}
 	if countUsage >= c.snapshotMaxCount {
 		return fmt.Errorf("snapshot count usage %d is equal or larger than snapshotMaxCount %d", countUsage, c.snapshotMaxCount)
 	}
+	if countTotal >= types.MaximumTotalSnapshotCount {
+		return fmt.Errorf("snapshot count total is already too big: %v", countTotal)
+	}
 	// if SnapshotMaxSize is 0, it means no limit
 	if c.SnapshotMaxSize == 0 {
 		return nil
@@ -758,7 +761,7 @@ func (c *Controller) SetSnapshotMaxCount(count int) error {
 	c.Lock()
 	defer c.Unlock()
 
-	countUsage, _, err := c.backend.GetSnapshotCountAndSizeUsage()
+	countUsage, _, _, err := c.backend.GetSnapshotCountAndSizeUsage()
 	if err != nil {
 		return err
 	}
@@ -796,7 +799,7 @@ func (c *Controller) SetSnapshotMaxSize(size int64) error {
 	c.Lock()
 	defer c.Unlock()
 
-	_, sizeUsage, err := c.backend.GetSnapshotCountAndSizeUsage()
+	_, _, sizeUsage, err := c.backend.GetSnapshotCountAndSizeUsage()
 	if err != nil {
 		return err
 	}

pkg/controller/replicator.go

@@ -353,35 +353,38 @@ type backendWrapper struct {
 	mode    types.Mode
 }
 
-func (r *replicator) GetSnapshotCountAndSizeUsage() (countUsage int, sizeUsage int64, err error) {
+func (r *replicator) GetSnapshotCountAndSizeUsage() (countUsage, countTotal int, sizeUsage int64, err error) {
 	var (
-		count     int
-		size      int64
-		hasResult bool
+		currentCountUsage, currentCountTotal int
+		size                                 int64
+		hasResult                            bool
 	)
 	for _, backend := range r.backends {
 		if backend.mode == types.ERR {
 			continue
 		}
 		// ignore error and try next one
-		count, size, err = backend.backend.GetSnapshotCountAndSizeUsage()
+		currentCountUsage, currentCountTotal, size, err = backend.backend.GetSnapshotCountAndSizeUsage()
 		if err != nil {
 			logrus.Errorf("Failed to get snapshot count and size usage: %v", err)
 			continue
 		}
 		hasResult = true
-		if countUsage < count {
-			countUsage = count
+		if countUsage < currentCountUsage {
+			countUsage = currentCountUsage
+		}
+		if countTotal < currentCountTotal {
+			countTotal = currentCountTotal
 		}
 		if sizeUsage < size {
 			sizeUsage = size
 		}
 	}
 
 	if !hasResult {
-		return 0, 0, fmt.Errorf("cannot get an valid result for snapshot usage")
+		return 0, 0, 0, fmt.Errorf("cannot get an valid result for snapshot usage")
 	}
-	return countUsage, sizeUsage, nil
+	return countUsage, countTotal, sizeUsage, nil
 }
 
 func (r *replicator) GetHeadFileSize() (int64, error) {

pkg/replica/client/client.go

@@ -168,6 +168,7 @@ func GetReplicaInfo(r *enginerpc.Replica) *types.ReplicaInfo {
 		RevisionCounterDisabled:   r.RevisionCounterDisabled,
 		UnmapMarkDiskChainRemoved: r.UnmapMarkDiskChainRemoved,
 		SnapshotCountUsage:        int(r.SnapshotCountUsage),
+		SnapshotCountTotal:        int(r.SnapshotCountTotal),
 		SnapshotSizeUsage:         r.SnapshotSizeUsage,
 	}
 

pkg/replica/replica.go

@@ -29,8 +29,6 @@ import (
 const (
 	volumeMetaData = "volume.meta"
 
-	maximumChainLength = 250
-
 	tmpFileSuffix = ".tmp"
 
 	// Special indexes inside r.volume.files
@@ -151,7 +149,7 @@ func New(ctx context.Context, size, sectorSize int64, dir string, backingFile *b
 func NewReadOnly(ctx context.Context, dir, head string, backingFile *backingfile.BackingFile) (*Replica, error) {
 	// size and sectorSize don't matter because they will be read from metadata
 	// snapshotMaxCount and SnapshotMaxSize don't matter because readonly replica can't create a new disk
-	return construct(ctx, true, 0, diskutil.ReplicaSectorSize, dir, head, backingFile, false, false, 250, 0)
+	return construct(ctx, true, 0, diskutil.ReplicaSectorSize, dir, head, backingFile, false, false, types.MaximumTotalSnapshotCount, 0)
 }
 
 func construct(ctx context.Context, readonly bool, size, sectorSize int64, dir, head string, backingFile *backingfile.BackingFile, disableRevCounter, unmapMarkDiskChainRemoved bool, snapshotMaxCount int, snapshotMaxSize int64) (*Replica, error) {
@@ -1050,7 +1048,7 @@ func (r *Replica) openLiveChain() error {
 		return err
 	}
 
-	if len(chain) > maximumChainLength {
+	if len(chain) > types.MaximumTotalSnapshotCount {
 		return fmt.Errorf("live chain is too long: %v", len(chain))
 	}
 
@@ -1398,11 +1396,15 @@ func (r *Replica) ListDisks() map[string]DiskInfo {
 	return result
 }
 
-func (r *Replica) GetSnapshotCountUsage() int {
+func (r *Replica) GetSnapshotCount() (int, int) {
 	r.RLock()
 	defer r.RUnlock()
 
-	return r.getSnapshotCountUsage()
+	return r.getSnapshotCountUsage(), r.getSnapshotCountTotal()
+}
+
+func (r *Replica) getSnapshotCountTotal() int {
+	return len(r.diskData)
 }
 
 func (r *Replica) getSnapshotCountUsage() int {

pkg/replica/rpc/server.go

@@ -84,7 +84,9 @@ func (rs *ReplicaServer) getReplica() (replica *enginerpc.Replica) {
 		chain, _ := r.DisplayChain()
 		replica.Chain = chain
 		replica.RemainSnapshots = int32(r.GetRemainSnapshotCounts())
-		replica.SnapshotCountUsage = int32(r.GetSnapshotCountUsage())
+		snapCountUsage, snapCountTotal := r.GetSnapshotCount()
+		replica.SnapshotCountUsage = int32(snapCountUsage)
+		replica.SnapshotCountTotal = int32(snapCountTotal)
 		replica.SnapshotSizeUsage = r.GetSnapshotSizeUsage()
 		if !r.IsRevCounterDisabled() {
 			replica.RevisionCounter = r.GetRevisionCounter()

pkg/types/resource.go

@@ -18,6 +18,7 @@ type ReplicaInfo struct {
 	RevisionCounterDisabled   bool                `json:"revisioncounterdisabled"`
 	UnmapMarkDiskChainRemoved bool                `json:"unmapMarkDiskChainRemoved"`
 	SnapshotCountUsage        int                 `json:"snapshotCountUsage"`
+	SnapshotCountTotal        int                 `json:"snapshotCountTotal"`
 	SnapshotSizeUsage         int64               `json:"snapshotSizeUsage"`
 }
 

pkg/types/types.go

@@ -46,6 +46,8 @@ const (
 	EngineFrontendISCSI    = "tgt-iscsi"
 
 	VolumeHeadName = "volume-head"
+
+	MaximumTotalSnapshotCount = 250
 )
 
 type DataServerProtocol string
@@ -105,7 +107,7 @@ type Backend interface {
 	ResetRebuild() error
 	SetSnapshotMaxCount(count int) error
 	SetSnapshotMaxSize(size int64) error
-	GetSnapshotCountAndSizeUsage() (int, int64, error)
+	GetSnapshotCountAndSizeUsage() (int, int, int64, error)
 }
 
 type BackendFactory interface {