lib/model: Add fsync of files and directories, option to disable (fixes #3711)

lib/config/config.go

@@ -26,7 +26,7 @@ import (
 
 const (
 	OldestHandledVersion = 10
-	CurrentVersion       = 16
+	CurrentVersion       = 17
 	MaxRescanIntervalS   = 365 * 24 * 60 * 60
 )
 
@@ -254,6 +254,9 @@ func (cfg *Configuration) clean() error {
 	if cfg.Version == 15 {
 		convertV15V16(cfg)
 	}
+	if cfg.Version == 16 {
+		convertV16V17(cfg)
+	}
 
 	// Build a list of available devices
 	existingDevices := make(map[protocol.DeviceID]bool)
@@ -327,6 +330,14 @@ func convertV15V16(cfg *Configuration) {
 	cfg.Version = 16
 }
 
+func convertV16V17(cfg *Configuration) {
+	for i := range cfg.Folders {
+		cfg.Folders[i].Fsync = true
+	}
+
+	cfg.Version = 17
+}
+
 func convertV13V14(cfg *Configuration) {
 	// Not using the ignore cache is the new default. Disable it on existing
 	// configurations.

lib/config/config_test.go

@@ -104,6 +104,7 @@ func TestDeviceConfig(t *testing.T) {
 				AutoNormalize:   true,
 				MinDiskFreePct:  1,
 				MaxConflicts:    -1,
+				Fsync:           true,
 				Versioning: VersioningConfiguration{
 					Params: map[string]string{},
 				},

lib/config/folderconfiguration.go

@@ -38,6 +38,7 @@ type FolderConfiguration struct {
 	MaxConflicts          int                         `xml:"maxConflicts" json:"maxConflicts"`
 	DisableSparseFiles    bool                        `xml:"disableSparseFiles" json:"disableSparseFiles"`
 	DisableTempIndexes    bool                        `xml:"disableTempIndexes" json:"disableTempIndexes"`
+	Fsync                 bool                        `xml:"fsync" json:"fsync"`
 
 	cachedPath string
 
@@ -85,6 +86,9 @@ func (f *FolderConfiguration) CreateMarker() error {
 			return err
 		}
 		fd.Close()
+		if err := osutil.SyncDir(filepath.Dir(marker)); err != nil {
+			l.Infof("fsync %q failed: %v", filepath.Dir(marker), err)
+		}
 		osutil.HideFile(marker)
 	}
 

lib/config/testdata/v17.xml

@@ -0,0 +1,15 @@
+<configuration version="17">
+    <folder id="test" path="testdata" type="readonly" ignorePerms="false" rescanIntervalS="600" autoNormalize="true">
+        <device id="AIR6LPZ-7K4PTTV-UXQSMUU-CPQ5YWH-OEDFIIQ-JUG777G-2YQXXR5-YD6AWQR"></device>
+        <device id="P56IOI7-MZJNU2Y-IQGDREY-DM2MGTI-MGL3BXN-PQ6W5BM-TBBZ4TJ-XZWICQ2"></device>
+        <minDiskFreePct>1</minDiskFreePct>
+        <maxConflicts>-1</maxConflicts>
+        <fsync>true</fsync>
+    </folder>
+    <device id="AIR6LPZ-7K4PTTV-UXQSMUU-CPQ5YWH-OEDFIIQ-JUG777G-2YQXXR5-YD6AWQR" name="node one" compression="metadata">
+        <address>tcp://a</address>
+    </device>
+    <device id="P56IOI7-MZJNU2Y-IQGDREY-DM2MGTI-MGL3BXN-PQ6W5BM-TBBZ4TJ-XZWICQ2" name="node two" compression="metadata">
+        <address>tcp://b</address>
+    </device>
+</configuration>