diff --git a/models/migration.go b/models/migration.go
index f1d87f2..a4bdc89 100644
--- a/models/migration.go
+++ b/models/migration.go
@@ -106,6 +106,7 @@ solid #e9e9e9;"bgcolor="#fff"><tbody><tr style="font-family: 'Helvetica Neue',He
 		{Name: "doc_preview_timeout", Value: `60`, Type: "timeout"},
 		{Name: "upload_credential_timeout", Value: `1800`, Type: "timeout"},
 		{Name: "upload_session_timeout", Value: `86400`, Type: "timeout"},
+		{Name: "slave_api_timeout", Value: `60`, Type: "timeout"},
 		{Name: "allowdVisitorDownload", Value: `false`, Type: "share"},
 		{Name: "login_captcha", Value: `0`, Type: "login"},
 		{Name: "qq_login", Value: `0`, Type: "login"},
diff --git a/models/setting.go b/models/setting.go
index b038c25..265ab08 100644
--- a/models/setting.go
+++ b/models/setting.go
@@ -4,6 +4,7 @@ import (
 	"github.com/HFO4/cloudreve/pkg/cache"
 	"github.com/jinzhu/gorm"
 	"net/url"
+	"strconv"
 )
 
 // Setting 系统设置模型
@@ -72,3 +73,13 @@ func GetSiteURL() *url.URL {
 	}
 	return base
 }
+
+// GetIntSetting 获取整形设置值，如果转换失败则返回默认值defaultVal
+// TODO 测试
+func GetIntSetting(key string, defaultVal int) int {
+	res, err := strconv.Atoi(GetSettingByName(key))
+	if err != nil {
+		return defaultVal
+	}
+	return res
+}
diff --git a/pkg/filesystem/file.go b/pkg/filesystem/file.go
index 21c3a9e..edf28ec 100644
--- a/pkg/filesystem/file.go
+++ b/pkg/filesystem/file.go
@@ -9,7 +9,6 @@ import (
 	"github.com/HFO4/cloudreve/pkg/util"
 	"github.com/juju/ratelimit"
 	"io"
-	"strconv"
 )
 
 /* ============
@@ -107,16 +106,8 @@ func (fs *FileSystem) Preview(ctx context.Context, path string) (*response.Conte
 	}
 
 	// 否则重定向到签名的预览URL
-	ttl, err := strconv.ParseInt(model.GetSettingByName("preview_timeout"), 10, 64)
-	if err != nil {
-		return nil,
-			serializer.NewError(
-				serializer.CodeInternalSetting,
-				"无法获取预览地址有效期设定",
-				err,
-			)
-	}
-	previewURL, err := fs.signURL(ctx, &fs.FileTarget[0], ttl, false)
+	ttl := model.GetIntSetting("preview_timeout", 60)
+	previewURL, err := fs.signURL(ctx, &fs.FileTarget[0], int64(ttl), false)
 	if err != nil {
 		return nil, err
 	}
@@ -222,20 +213,11 @@ func (fs *FileSystem) GetDownloadURL(ctx context.Context, path string, timeout s
 	fileTarget := &fs.FileTarget[0]
 
 	// 生成下載地址
-	ttl, err := strconv.ParseInt(model.GetSettingByName(timeout), 10, 64)
-	if err != nil {
-		return "",
-			serializer.NewError(
-				serializer.CodeInternalSetting,
-				"无法获取下载地址有效期",
-				err,
-			)
-	}
-
+	ttl := model.GetIntSetting(timeout, 60)
 	source, err := fs.signURL(
 		ctx,
 		fileTarget,
-		ttl,
+		int64(ttl),
 		true,
 	)
 	if err != nil {
diff --git a/pkg/filesystem/file_test.go b/pkg/filesystem/file_test.go
index 50175f3..7394cc9 100644
--- a/pkg/filesystem/file_test.go
+++ b/pkg/filesystem/file_test.go
@@ -548,28 +548,6 @@ func TestFileSystem_Preview(t *testing.T) {
 		asserts.NoError(resp.Content.Close())
 	}
 
-	// 需要重定向，无法解析有效期设置
-	{
-		fs := FileSystem{
-			User: &model.User{},
-		}
-		fs.FileTarget = []model.File{
-			{
-				SourceName: "tests/file1.txt",
-				PolicyID:   1,
-				Policy: model.Policy{
-					Model: gorm.Model{ID: 1},
-					Type:  "remote",
-				},
-			},
-		}
-		asserts.NoError(cache.Set("setting_preview_timeout", "test", 0))
-		resp, err := fs.Preview(ctx, "/1.txt")
-		asserts.Error(err)
-		asserts.Nil(resp)
-		asserts.Equal(serializer.CodeInternalSetting, err.(serializer.AppError).Code)
-	}
-
 	// 需要重定向，成功
 	{
 		fs := FileSystem{
diff --git a/pkg/filesystem/filesystem.go b/pkg/filesystem/filesystem.go
index be0b825..daa53eb 100644
--- a/pkg/filesystem/filesystem.go
+++ b/pkg/filesystem/filesystem.go
@@ -3,6 +3,7 @@ package filesystem
 import (
 	"context"
 	"github.com/HFO4/cloudreve/models"
+	"github.com/HFO4/cloudreve/pkg/auth"
 	"github.com/HFO4/cloudreve/pkg/conf"
 	"github.com/HFO4/cloudreve/pkg/filesystem/local"
 	"github.com/HFO4/cloudreve/pkg/filesystem/remote"
@@ -152,8 +153,9 @@ func (fs *FileSystem) dispatchHandler() error {
 		return nil
 	case "remote":
 		fs.Handler = remote.Handler{
-			Policy: currentPolicy,
-			Client: request.HTTPClient{},
+			Policy:       currentPolicy,
+			Client:       request.HTTPClient{},
+			AuthInstance: auth.HMACAuth{[]byte(currentPolicy.SecretKey)},
 		}
 		return nil
 	default:
diff --git a/pkg/filesystem/remote/handler.go b/pkg/filesystem/remote/handler.go
index f80715d..e21fd04 100644
--- a/pkg/filesystem/remote/handler.go
+++ b/pkg/filesystem/remote/handler.go
@@ -22,8 +22,9 @@ import (
 
 // Handler 远程存储策略适配器
 type Handler struct {
-	Client request.Client
-	Policy *model.Policy
+	Client       request.Client
+	Policy       *model.Policy
+	AuthInstance auth.Auth
 }
 
 // getAPI 获取接口请求地址
@@ -55,7 +56,6 @@ func (handler Handler) Put(ctx context.Context, file io.ReadCloser, dst string,
 
 // Delete 删除一个或多个文件，
 // 返回未删除的文件，及遇到的最后一个错误
-// TODO 测试
 func (handler Handler) Delete(ctx context.Context, files []string) ([]string, error) {
 	// 封装接口请求正文
 	reqBody := serializer.RemoteDeleteRequest{
@@ -68,12 +68,12 @@ func (handler Handler) Delete(ctx context.Context, files []string) ([]string, er
 
 	// 发送删除请求
 	bodyReader := strings.NewReader(string(reqBodyEncoded))
-	authInstance := auth.HMACAuth{SecretKey: []byte(handler.Policy.SecretKey)}
+	signTTL := model.GetIntSetting("slave_api_timeout", 60)
 	resp, err := handler.Client.Request(
 		"POST",
 		handler.getAPI("delete"),
 		bodyReader,
-		request.WithCredential(authInstance, 60),
+		request.WithCredential(handler.AuthInstance, int64(signTTL)),
 	).GetResponse(200)
 	if err != nil {
 		return files, err
@@ -105,7 +105,6 @@ func (handler Handler) Thumb(ctx context.Context, path string) (*response.Conten
 }
 
 // Source 获取外链URL
-// TODO 测试
 func (handler Handler) Source(
 	ctx context.Context,
 	path string,
@@ -138,9 +137,8 @@ func (handler Handler) Source(
 
 	// 签名下载地址
 	sourcePath := base64.RawURLEncoding.EncodeToString([]byte(file.SourceName))
-	authInstance := auth.HMACAuth{SecretKey: []byte(handler.Policy.SecretKey)}
 	signedURI, err = auth.SignURI(
-		authInstance,
+		handler.AuthInstance,
 		fmt.Sprintf("%s/%d/%s/%s", controller, speed, sourcePath, file.Name),
 		expires,
 	)
@@ -180,8 +178,7 @@ func (handler Handler) Token(ctx context.Context, TTL int64, key string) (serial
 	uploadRequest.Header = map[string][]string{
 		"X-Policy": {policyEncoded},
 	}
-	remoteAuth := auth.HMACAuth{SecretKey: []byte(handler.Policy.SecretKey)}
-	auth.SignRequest(remoteAuth, uploadRequest, time.Now().Unix()+TTL)
+	auth.SignRequest(handler.AuthInstance, uploadRequest, time.Now().Unix()+TTL)
 
 	if credential, ok := uploadRequest.Header["Authorization"]; ok && len(credential) == 1 {
 		return serializer.UploadCredential{
diff --git a/pkg/filesystem/remote/handler_test.go b/pkg/filesystem/remote/handler_test.go
index 1cc5b9e..0008da2 100644
--- a/pkg/filesystem/remote/handler_test.go
+++ b/pkg/filesystem/remote/handler_test.go
@@ -30,6 +30,7 @@ func TestHandler_Token(t *testing.T) {
 				FileType: []string{"txt"},
 			},
 		},
+		AuthInstance: auth.HMACAuth{},
 	}
 	ctx := context.Background()
 	auth.General = auth.HMACAuth{SecretKey: []byte("test")}
@@ -56,7 +57,9 @@ func TestHandler_Source(t *testing.T) {
 
 	// 无法获取上下文
 	{
-		handler := Handler{}
+		handler := Handler{
+			AuthInstance: auth.HMACAuth{},
+		}
 		ctx := context.Background()
 		res, err := handler.Source(ctx, "", url.URL{}, 0, true, 0)
 		asserts.Error(err)
@@ -66,7 +69,8 @@ func TestHandler_Source(t *testing.T) {
 	// 成功
 	{
 		handler := Handler{
-			Policy: &model.Policy{Server: "/"},
+			Policy:       &model.Policy{Server: "/"},
+			AuthInstance: auth.HMACAuth{},
 		}
 		file := model.File{
 			SourceName: "1.txt",
@@ -80,7 +84,8 @@ func TestHandler_Source(t *testing.T) {
 	// 成功 预览
 	{
 		handler := Handler{
-			Policy: &model.Policy{Server: "/"},
+			Policy:       &model.Policy{Server: "/"},
+			AuthInstance: auth.HMACAuth{},
 		}
 		file := model.File{
 			SourceName: "1.txt",
@@ -108,8 +113,10 @@ func TestHandler_Delete(t *testing.T) {
 			SecretKey: "test",
 			Server:    "http://test.com",
 		},
+		AuthInstance: auth.HMACAuth{},
 	}
 	ctx := context.Background()
+	cache.Set("setting_slave_api_timeout", "60", 0)
 
 	// 成功
 	{
diff --git a/pkg/filesystem/upload.go b/pkg/filesystem/upload.go
index 6773e0d..6072171 100644
--- a/pkg/filesystem/upload.go
+++ b/pkg/filesystem/upload.go
@@ -9,7 +9,6 @@ import (
 	"github.com/HFO4/cloudreve/pkg/util"
 	"github.com/gin-gonic/gin"
 	"path/filepath"
-	"strconv"
 )
 
 /* ================
@@ -142,32 +141,14 @@ func (fs *FileSystem) CancelUpload(ctx context.Context, path string, file FileHe
 // GetUploadToken 生成新的上传凭证
 func (fs *FileSystem) GetUploadToken(ctx context.Context, path string, size uint64) (*serializer.UploadCredential, error) {
 	// 获取相关有效期设置
-	ttls := model.GetSettingByNames([]string{"upload_credential_timeout", "upload_session_timeout"})
+	credentialTTL := model.GetIntSetting("upload_credential_timeout", 3600)
+	callBackSessionTTL := model.GetIntSetting("upload_session_timeout", 86400)
 
-	var (
-		err                error
-		credentialTTL      int64 = 3600
-		callBackSessionTTL int64 = 86400
-	)
-	// 获取上传凭证的有效期
-	if ttlStr, ok := ttls["upload_credential_timeout"]; ok {
-		credentialTTL, err = strconv.ParseInt(ttlStr, 10, 64)
-		if err != nil {
-			return nil, serializer.NewError(serializer.CodeInternalSetting, "上传凭证有效期设置无效", err)
-		}
-	}
-
-	// 获取回调会话的有效期
-	if ttlStr, ok := ttls["upload_session_timeout"]; ok {
-		callBackSessionTTL, err = strconv.ParseInt(ttlStr, 10, 64)
-		if err != nil {
-			return nil, serializer.NewError(serializer.CodeInternalSetting, "上传会话有效期设置无效", err)
-		}
-	}
+	var err error
 
 	// 获取上传凭证
 	callbackKey := util.RandStringRunes(32)
-	credential, err := fs.Handler.Token(ctx, credentialTTL, callbackKey)
+	credential, err := fs.Handler.Token(ctx, int64(credentialTTL), callbackKey)
 	if err != nil {
 		return nil, serializer.NewError(serializer.CodeEncryptError, "无法获取上传凭证", err)
 	}
@@ -180,7 +161,7 @@ func (fs *FileSystem) GetUploadToken(ctx context.Context, path string, size uint
 			PolicyID:    fs.User.GetPolicyID(),
 			VirtualPath: path,
 		},
-		int(callBackSessionTTL),
+		callBackSessionTTL,
 	)
 	if err != nil {
 		return nil, err
diff --git a/pkg/filesystem/upload_test.go b/pkg/filesystem/upload_test.go
index 1b50efa..229b41c 100644
--- a/pkg/filesystem/upload_test.go
+++ b/pkg/filesystem/upload_test.go
@@ -199,26 +199,4 @@ func TestFileSystem_GetUploadToken(t *testing.T) {
 		testHandller.AssertExpectations(t)
 		asserts.Error(err)
 	}
-
-	// 上传有效期错误
-	{
-		cache.SetSettings(map[string]string{
-			"upload_credential_timeout": "？10",
-			"upload_session_timeout":    "10",
-		}, "setting_")
-
-		_, err := fs.GetUploadToken(ctx, "/", 10)
-		asserts.Error(err)
-	}
-
-	// 上传会话有效期错误
-	{
-		cache.SetSettings(map[string]string{
-			"upload_credential_timeout": "10",
-			"upload_session_timeout":    "？10",
-		}, "setting_")
-
-		_, err := fs.GetUploadToken(ctx, "/", 10)
-		asserts.Error(err)
-	}
 }
diff --git a/pkg/webdav/webdav.go b/pkg/webdav/webdav.go
index 94638fb..5eb8a10 100644
--- a/pkg/webdav/webdav.go
+++ b/pkg/webdav/webdav.go
@@ -221,6 +221,8 @@ func (h *Handler) handleOptions(w http.ResponseWriter, r *http.Request, fs *file
 
 // OK
 func (h *Handler) handleGetHeadPost(w http.ResponseWriter, r *http.Request, fs *filesystem.FileSystem) (status int, err error) {
+	defer fs.Recycle()
+
 	reqPath, status, err := h.stripPrefix(r.URL.Path, fs.User.ID)
 	if err != nil {
 		return status, err
@@ -249,6 +251,8 @@ func (h *Handler) handleGetHeadPost(w http.ResponseWriter, r *http.Request, fs *
 
 // OK
 func (h *Handler) handleDelete(w http.ResponseWriter, r *http.Request, fs *filesystem.FileSystem) (status int, err error) {
+	defer fs.Recycle()
+
 	reqPath, status, err := h.stripPrefix(r.URL.Path, fs.User.ID)
 	if err != nil {
 		return status, err
@@ -353,6 +357,8 @@ func (h *Handler) handlePut(w http.ResponseWriter, r *http.Request, fs *filesyst
 
 // OK
 func (h *Handler) handleMkcol(w http.ResponseWriter, r *http.Request, fs *filesystem.FileSystem) (status int, err error) {
+	defer fs.Recycle()
+
 	reqPath, status, err := h.stripPrefix(r.URL.Path, fs.User.ID)
 	if err != nil {
 		return status, err
@@ -376,6 +382,8 @@ func (h *Handler) handleMkcol(w http.ResponseWriter, r *http.Request, fs *filesy
 
 // OK
 func (h *Handler) handleCopyMove(w http.ResponseWriter, r *http.Request, fs *filesystem.FileSystem) (status int, err error) {
+	defer fs.Recycle()
+
 	hdr := r.Header.Get("Destination")
 	if hdr == "" {
 		return http.StatusBadRequest, errInvalidDestination
@@ -460,6 +468,8 @@ func (h *Handler) handleCopyMove(w http.ResponseWriter, r *http.Request, fs *fil
 
 // OK
 func (h *Handler) handleLock(w http.ResponseWriter, r *http.Request, fs *filesystem.FileSystem) (retStatus int, retErr error) {
+	defer fs.Recycle()
+
 	duration, err := parseTimeout(r.Header.Get("Timeout"))
 	if err != nil {
 		return http.StatusBadRequest, err
@@ -555,6 +565,8 @@ func (h *Handler) handleLock(w http.ResponseWriter, r *http.Request, fs *filesys
 
 // OK
 func (h *Handler) handleUnlock(w http.ResponseWriter, r *http.Request, fs *filesystem.FileSystem) (status int, err error) {
+	defer fs.Recycle()
+
 	// http://www.webdav.org/specs/rfc4918.html#HEADER_Lock-Token says that the
 	// Lock-Token value is a Coded-URL. We strip its angle brackets.
 	t := r.Header.Get("Lock-Token")
@@ -579,6 +591,8 @@ func (h *Handler) handleUnlock(w http.ResponseWriter, r *http.Request, fs *files
 
 // OK
 func (h *Handler) handlePropfind(w http.ResponseWriter, r *http.Request, fs *filesystem.FileSystem) (status int, err error) {
+	defer fs.Recycle()
+
 	reqPath, status, err := h.stripPrefix(r.URL.Path, fs.User.ID)
 	if err != nil {
 		return status, err
@@ -646,6 +660,8 @@ func (h *Handler) handlePropfind(w http.ResponseWriter, r *http.Request, fs *fil
 }
 
 func (h *Handler) handleProppatch(w http.ResponseWriter, r *http.Request, fs *filesystem.FileSystem) (status int, err error) {
+	defer fs.Recycle()
+
 	reqPath, status, err := h.stripPrefix(r.URL.Path, fs.User.ID)
 	if err != nil {
 		return status, err
diff --git a/service/explorer/objects.go b/service/explorer/objects.go
index 340b5c0..5fa9782 100644
--- a/service/explorer/objects.go
+++ b/service/explorer/objects.go
@@ -12,7 +12,6 @@ import (
 	"github.com/HFO4/cloudreve/pkg/util"
 	"github.com/gin-gonic/gin"
 	"net/url"
-	"strconv"
 	"time"
 )
 
@@ -62,10 +61,7 @@ func (service *ItemService) Archive(ctx context.Context, c *gin.Context) seriali
 		return serializer.Err(serializer.CodeNotSet, "无法解析站点URL", err)
 	}
 	zipID := util.RandStringRunes(16)
-	ttl, err := strconv.Atoi(model.GetSettingByName("archive_timeout"))
-	if err != nil {
-		ttl = 30
-	}
+	ttl := model.GetIntSetting("archive_timeout", 30)
 	signedURI, err := auth.SignURI(
 		auth.General,
 		fmt.Sprintf("/api/v3/file/archive/%s/archive.zip", zipID),