fix(crypt): premature close of MFile (#8132 close #8119)

* fix(crypt): premature close of MFile

* refactor

drivers/crypt/driver.go

@@ -282,8 +282,9 @@ func (d *Crypt) Link(ctx context.Context, file model.Obj, args model.LinkArgs) (
 			if err != nil {
 				return nil, err
 			}
-			// 可以直接返回，读取完也不会调用Close，直到连接断开Close
-			return remoteLink.MFile, nil
+			//keep reuse same MFile and close at last.
+			remoteClosers.Add(remoteLink.MFile)
+			return io.NopCloser(remoteLink.MFile), nil
 		}
 
 		return nil, errs.NotSupport

server/common/proxy.go

@@ -7,6 +7,7 @@ import (
 	"net/http"
 	"net/url"
 	"os"
+	"strings"
 
 	"github.com/alist-org/alist/v3/internal/model"
 	"github.com/alist-org/alist/v3/internal/net"
@@ -102,11 +103,15 @@ func attachHeader(w http.ResponseWriter, file model.Obj) {
 	w.Header().Set("Etag", GetEtag(file))
 }
 func GetEtag(file model.Obj) string {
+	hash := ""
 	for _, v := range file.GetHash().Export() {
-		if len(v) != 0 {
-			return fmt.Sprintf(`"%s"`, v)
+		if strings.Compare(v, hash) > 0 {
+			hash = v
 		}
 	}
+	if len(hash) > 0 {
+		return fmt.Sprintf(`"%s"`, hash)
+	}
 	// 参考nginx
 	return fmt.Sprintf(`"%x-%x"`, file.ModTime().Unix(), file.GetSize())
 }