adjust hardlink update

simplify logic, pass entity content directly to hard link. The "weed mount" handles the logic to calculate hard link counter.

weed/filer/filerstore_hardlink.go

@@ -0,0 +1,95 @@
+package filer
+
+import (
+	"context"
+	"fmt"
+	"github.com/chrislusf/seaweedfs/weed/glog"
+	"github.com/chrislusf/seaweedfs/weed/pb/filer_pb"
+)
+
+func (fsw *FilerStoreWrapper) handleUpdateToHardLinks(ctx context.Context, entry *Entry) error {
+	if entry.HardLinkId == 0 {
+		return nil
+	}
+	// handle hard links
+	if err := fsw.setHardLink(ctx, entry); err != nil {
+		return fmt.Errorf("setHardLink %d: %v", entry.HardLinkId, err)
+	}
+
+	// check what is existing entry
+	existingEntry, err := fsw.ActualStore.FindEntry(ctx, entry.FullPath)
+	if err != nil && err != filer_pb.ErrNotFound {
+		return fmt.Errorf("update existing entry %s: %v", entry.FullPath, err)
+	}
+
+	// remove old hard link
+	if err == nil && existingEntry.HardLinkId != entry.HardLinkId {
+		if err = fsw.DeleteHardLink(ctx, existingEntry.HardLinkId); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (fsw *FilerStoreWrapper) setHardLink(ctx context.Context, entry *Entry) error {
+	if entry.HardLinkId == 0 {
+		return nil
+	}
+	key := entry.HardLinkId.Key()
+
+	newBlob, encodeErr := entry.EncodeAttributesAndChunks()
+	if encodeErr != nil {
+		return encodeErr
+	}
+
+	return fsw.KvPut(ctx, key, newBlob)
+}
+
+func (fsw *FilerStoreWrapper) maybeReadHardLink(ctx context.Context, entry *Entry) error {
+	if entry.HardLinkId == 0 {
+		return nil
+	}
+	key := entry.HardLinkId.Key()
+
+	value, err := fsw.KvGet(ctx, key)
+	if err != nil {
+		glog.Errorf("read %s hardlink %d: %v", entry.FullPath, entry.HardLinkId, err)
+		return err
+	}
+
+	if err = entry.DecodeAttributesAndChunks(value); err != nil {
+		glog.Errorf("decode %s hardlink %d: %v", entry.FullPath, entry.HardLinkId, err)
+		return err
+	}
+
+	return nil
+}
+
+func (fsw *FilerStoreWrapper) DeleteHardLink(ctx context.Context, hardLinkId HardLinkId) error {
+	key := hardLinkId.Key()
+	value, err := fsw.KvGet(ctx, key)
+	if err == ErrKvNotFound {
+		return nil
+	}
+	if err != nil {
+		return err
+	}
+
+	entry := &Entry{}
+	if err = entry.DecodeAttributesAndChunks(value); err != nil {
+		return err
+	}
+
+	entry.HardLinkCounter--
+	if entry.HardLinkCounter <= 0 {
+		return fsw.KvDelete(ctx, key)
+	}
+
+	newBlob, encodeErr := entry.EncodeAttributesAndChunks()
+	if encodeErr != nil {
+		return encodeErr
+	}
+
+	return fsw.KvPut(ctx, key, newBlob)
+
+}