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refactor: remove r.ChainLength for simplicity
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Signed-off-by: Shuo Wu <[email protected]>
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@shuo-wu
shuo-wu committed Oct 23, 2024
1 parent 3d621bb commit 7306f70
Showing 1 changed file with 28 additions and 40 deletions.
68 changes: 28 additions & 40 deletions pkg/spdk/replica.go
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Original file line number Diff line number Diff line change
Expand Up @@ -48,10 +48,6 @@ type Replica struct {
// If a replica does not contain a backing image, the first entry will be nil.
// The last entry of the chain should the head lvol if it exists.
ActiveChain []*Lvol
// ChainLength typically has length no less than 2.
// Since the first and last entries of ActiveChain are the backing image and the head, respectively.
// If the head does not exist, the last entry of ActiveChain will be a snapshot or the backing image.
ChainLength int
// SnapshotLvolMap map[<snapshot lvol name>]. <snapshot lvol name> consists of `<replica name>-snap-<snapshot name>`
SnapshotLvolMap map[string]*Lvol

Expand Down Expand Up @@ -164,7 +160,6 @@ func NewReplica(ctx context.Context, replicaName, lvsName, lvsUUID string, specS
ActiveChain: []*Lvol{
nil,
},
ChainLength: 2,
SnapshotLvolMap: map[string]*Lvol{},
Name: replicaName,
Alias: spdktypes.GetLvolAlias(lvsName, replicaName),
Expand Down Expand Up @@ -258,7 +253,6 @@ func (r *Replica) construct(bdevLvolMap map[string]*spdktypes.BdevInfo) (err err

r.Head = newChain[len(newChain)-1]
r.ActiveChain = newChain
r.ChainLength = len(r.ActiveChain)
r.SnapshotLvolMap = newSnapshotLvolMap

if r.State == types.InstanceStatePending {
Expand Down Expand Up @@ -343,7 +337,7 @@ func (r *Replica) validateAndUpdate(bdevLvolMap map[string]*spdktypes.BdevInfo,
}
}

replicaActualSize := newChain[r.ChainLength-1].ActualSize
replicaActualSize := newChain[len(newChain)-1].ActualSize
for _, snapLvol := range newSnapshotLvolMap {
replicaActualSize += snapLvol.ActualSize
}
Expand Down Expand Up @@ -599,8 +593,8 @@ func (r *Replica) Create(spdkClient *spdkclient.Client, portCount int32, superio

// Create bdev lvol if the replica is the new one
if r.State == types.InstanceStatePending {
if r.ChainLength != 1 {
return nil, fmt.Errorf("invalid chain length %d for new replica creation", r.ChainLength)
if len(r.ActiveChain) != 1 {
return nil, fmt.Errorf("invalid chain length %d for new replica creation", len(r.ActiveChain))
}
}

Expand Down Expand Up @@ -663,7 +657,7 @@ func (r *Replica) Create(spdkClient *spdkclient.Client, portCount int32, superio

func (r *Replica) prepareHead(spdkClient *spdkclient.Client) (err error) {
requireHead := false
if r.ChainLength < 2 {
if len(r.ActiveChain) < 2 {
requireHead = true
} else {
bdevLvolList, err := spdkClient.BdevLvolGet(r.Alias, 0)
Expand All @@ -673,20 +667,19 @@ func (r *Replica) prepareHead(spdkClient *spdkclient.Client) (err error) {
if len(bdevLvolList) < 1 {
requireHead = true
r.Head = nil
if r.ActiveChain[r.ChainLength-1] != nil && r.ActiveChain[r.ChainLength-1].Name == r.Name {
r.ChainLength--
r.ActiveChain = r.ActiveChain[:r.ChainLength]
if r.ActiveChain[len(r.ActiveChain)-1] != nil && r.ActiveChain[len(r.ActiveChain)-1].Name == r.Name {
r.ActiveChain = r.ActiveChain[:len(r.ActiveChain)-1]
}
}
}

if requireHead {
r.log.Info("Creating a lvol bdev as replica Head")
if r.ActiveChain[r.ChainLength-1] != nil { // The replica has a backing image or somehow there are already snapshots in the chain
if _, err := spdkClient.BdevLvolClone(r.ActiveChain[r.ChainLength-2].UUID, r.Name); err != nil {
if r.ActiveChain[len(r.ActiveChain)-1] != nil { // The replica has a backing image or somehow there are already snapshots in the chain
if _, err := spdkClient.BdevLvolClone(r.ActiveChain[len(r.ActiveChain)-1].UUID, r.Name); err != nil {
return err
}
if r.ActiveChain[r.ChainLength-1].SpecSize != r.SpecSize {
if r.ActiveChain[len(r.ActiveChain)-1].SpecSize != r.SpecSize {
if _, err := spdkClient.BdevLvolResize(r.Alias, r.SpecSize); err != nil {
return err
}
Expand All @@ -707,17 +700,16 @@ func (r *Replica) prepareHead(spdkClient *spdkclient.Client) (err error) {

r.Head = BdevLvolInfoToServiceLvol(&bdevLvolList[0])

if r.ActiveChain[r.ChainLength-1] != nil && r.ActiveChain[r.ChainLength-1].Name != r.Name {
r.ChainLength++
if len(r.ActiveChain) == 1 || (r.ActiveChain[len(r.ActiveChain)-1] != nil && r.ActiveChain[len(r.ActiveChain)-1].Name != r.Name) {
r.ActiveChain = append(r.ActiveChain, r.Head)
} else {
r.ActiveChain[r.ChainLength-1] = r.Head
r.ActiveChain[len(r.ActiveChain)-1] = r.Head
}
if r.ActiveChain[r.ChainLength-2] != nil {
if r.ActiveChain[r.ChainLength-2].Name != r.Head.Parent {
return fmt.Errorf("found the last entry of the active chain %v is not the head parent %v", r.ActiveChain[r.ChainLength-2].Name, r.Head.Parent)
if r.ActiveChain[len(r.ActiveChain)-2] != nil {
if r.ActiveChain[len(r.ActiveChain)-2].Name != r.Head.Parent {
return fmt.Errorf("found the last entry of the active chain %v is not the head parent %v", r.ActiveChain[len(r.ActiveChain)-2].Name, r.Head.Parent)
}
r.ActiveChain[r.ChainLength-2].Children[r.Head.Name] = r.Head
r.ActiveChain[len(r.ActiveChain)-2].Children[r.Head.Name] = r.Head
}

return nil
Expand Down Expand Up @@ -922,9 +914,8 @@ func (r *Replica) SnapshotCreate(spdkClient *spdkclient.Client, snapshotName str
delete(prevSvcLvol.Children, r.Head.Name)
prevSvcLvol.Children[snapSvcLvol.Name] = snapSvcLvol
}
r.ActiveChain[r.ChainLength-1] = snapSvcLvol
r.ActiveChain[len(r.ActiveChain)-1] = snapSvcLvol
r.ActiveChain = append(r.ActiveChain, r.Head)
r.ChainLength++
r.SnapshotLvolMap[snapLvolName] = snapSvcLvol
updateRequired = true

Expand Down Expand Up @@ -1034,11 +1025,10 @@ func (r *Replica) removeLvolFromActiveChainWithoutLock(snapLvolName string) int

// Cannot remove backing image lvol or head lvol
prevChain := r.ActiveChain
if pos >= 1 && pos < r.ChainLength-1 {
if pos >= 1 && pos < len(r.ActiveChain)-1 {
r.ActiveChain = append([]*Lvol{}, prevChain[:pos]...)
r.ActiveChain = append(r.ActiveChain, prevChain[pos+1:]...)
}
r.ChainLength = len(r.ActiveChain)

return pos
}
Expand Down Expand Up @@ -1072,20 +1062,19 @@ func (r *Replica) SnapshotRevert(spdkClient *spdkclient.Client, snapshotName str
}
}()

if r.ChainLength < 2 {
return nil, fmt.Errorf("invalid chain length %d for replica snapshot revert", r.ChainLength)
if len(r.ActiveChain) < 2 {
return nil, fmt.Errorf("invalid chain length %d for replica snapshot revert", len(r.ActiveChain))
}

if _, err := spdkClient.BdevLvolDelete(r.Alias); err != nil && !jsonrpc.IsJSONRPCRespErrorNoSuchDevice(err) {
return nil, err
}
// The parent of the old head lvol is a valid snapshot lvol or backing image lvol
if r.ActiveChain[r.ChainLength-2] != nil {
delete(r.ActiveChain[r.ChainLength-2].Children, r.Name)
if r.ActiveChain[len(r.ActiveChain)-2] != nil {
delete(r.ActiveChain[len(r.ActiveChain)-2].Children, r.Name)
}
r.Head = nil
r.ChainLength--
r.ActiveChain = r.ActiveChain[:r.ChainLength]
r.ActiveChain = r.ActiveChain[:len(r.ActiveChain)-1]

// TODO: If the below steps fail, there will be no head lvol for the replica. Need to guarantee that the replica can be cleaned up correctly in this case

Expand Down Expand Up @@ -1117,7 +1106,6 @@ func (r *Replica) SnapshotRevert(spdkClient *spdkclient.Client, snapshotName str

r.Head = newChain[len(newChain)-1]
r.ActiveChain = newChain
r.ChainLength = len(r.ActiveChain)
r.SnapshotLvolMap = newSnapshotLvolMap

if r.IsExposed {
Expand Down Expand Up @@ -1160,8 +1148,8 @@ func (r *Replica) SnapshotPurge(spdkClient *spdkclient.Client) (err error) {
}
}()

if r.ChainLength < 2 {
return fmt.Errorf("invalid chain length %d for replica snapshot purge", r.ChainLength)
if len(r.ActiveChain) < 2 {
return fmt.Errorf("invalid chain length %d for replica snapshot purge", len(r.ActiveChain))
}

// delete all non-user-created snapshots
Expand Down Expand Up @@ -1407,8 +1395,8 @@ func (r *Replica) RebuildingDstStart(spdkClient *spdkclient.Client, srcReplicaNa
updateRequired = true
}()

if r.ChainLength != 2 {
return "", fmt.Errorf("invalid chain length %d for dst replica %v rebuilding start", r.ChainLength, r.Name)
if len(r.ActiveChain) != 2 {
return "", fmt.Errorf("invalid chain length %d for dst replica %v rebuilding start", len(r.ActiveChain), r.Name)
}

// Replica.Delete and Replica.Create do not guarantee that the previous rebuilding src replica info is cleaned up
Expand Down Expand Up @@ -1534,8 +1522,8 @@ func (r *Replica) RebuildingDstFinish(spdkClient *spdkclient.Client) (err error)
updateRequired = true
}()

if r.ChainLength < 2 {
return fmt.Errorf("invalid chain length %d for dst replica %v rebuilding finish", r.ChainLength, r.Name)
if len(r.ActiveChain) < 2 {
return fmt.Errorf("invalid chain length %d for dst replica %v rebuilding finish", len(r.ActiveChain), r.Name)
}

// Switch from the external snapshot to use rebuilt snapshots
Expand Down

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