fs.meta.load: wait for in-flight entry creation before returning

On io.EOF and error paths the command returned while CreateEntry
goroutines were still running, so trailing entries could be silently
dropped once the shell exited. Wait for them on every exit path and
guard the shared error with a mutex.

weed/shell/command_fs_meta_load.go

@@ -96,9 +96,27 @@ func (c *commandFsMetaLoad) Do(args []string, commandEnv *CommandEnv, writer io.
 		waitChan := make(chan struct{}, *concurrency)
 		defer close(waitChan)
 		var wg sync.WaitGroup
+		var mu sync.Mutex
+		var loadErr error
+		getErr := func() error {
+			mu.Lock()
+			defer mu.Unlock()
+			return loadErr
+		}
+		setErr := func(e error) {
+			mu.Lock()
+			if loadErr == nil {
+				loadErr = e
+			}
+			mu.Unlock()
+		}
 
 		for {
 			if _, err := io.ReadFull(dst, sizeBuf); err != nil {
+				wg.Wait()
+				if loadErr := getErr(); loadErr != nil {
+					return loadErr
+				}
 				if err == io.EOF {
 					return nil
 				}
@@ -110,11 +128,13 @@ func (c *commandFsMetaLoad) Do(args []string, commandEnv *CommandEnv, writer io.
 			data := make([]byte, int(size))
 
 			if _, err := io.ReadFull(dst, data); err != nil {
+				wg.Wait()
 				return err
 			}
 
 			fullEntry := &filer_pb.FullEntry{}
 			if err = proto.Unmarshal(data, fullEntry); err != nil {
+				wg.Wait()
 				return err
 			}
 
@@ -139,6 +159,9 @@ func (c *commandFsMetaLoad) Do(args []string, commandEnv *CommandEnv, writer io.
 			fullEntry.Entry.Name = strings.ReplaceAll(fullEntry.Entry.Name, "/", "x")
 			if fullEntry.Entry.IsDirectory {
 				wg.Wait()
+				if loadErr := getErr(); loadErr != nil {
+					return loadErr
+				}
 				if errEntry := filer_pb.CreateEntry(context.Background(), client, &filer_pb.CreateEntryRequest{
 					Directory: fullEntry.Dir,
 					Entry:     fullEntry.Entry,
@@ -154,13 +177,14 @@ func (c *commandFsMetaLoad) Do(args []string, commandEnv *CommandEnv, writer io.
 						Directory: entry.Dir,
 						Entry:     entry.Entry,
 					}); errEntry != nil {
-						err = errEntry
+						setErr(errEntry)
 					}
 					defer wg.Done()
 					<-waitChan
 				}(fullEntry)
-				if err != nil {
-					return err
+				if loadErr := getErr(); loadErr != nil {
+					wg.Wait()
+					return loadErr
 				}
 				fileCount++
 			}