device-mapper: Move all devicemapper spew to log through utils.Debugf().

devmapper/deviceset_devmapper.go

@@ -327,7 +327,18 @@ func setCloseOnExec(name string) {
 	}
 }
 
+func (devices *DeviceSetDM) log(level int, file string, line int, dmError int, message string)  {
+	if level >= 7 {
+		return // Ignore _LOG_DEBUG
+	}
+
+	utils.Debugf("libdevmapper(%d): %s:%d (%d) %s", level, file, line, dmError, message)
+}
+
+
 func (devices *DeviceSetDM) initDevmapper() error {
+	logInit(devices)
+
 	info, err := getInfo(devices.getPoolName())
 	if info == nil {
 		utils.Debugf("Error device getInfo: %s", err)

devmapper/devmapper.go

@@ -114,6 +114,28 @@ get_block_size(int fd)
   return (int64_t)size;
 }
 
+extern void DevmapperLogCallback(int level, char *file, int line, int dm_errno_or_class, char *str);
+
+static void
+log_cb(int level, const char *file, int line,
+       int dm_errno_or_class, const char *f, ...)
+{
+  char buffer[256];
+  va_list ap;
+
+  va_start(ap, f);
+  vsnprintf(buffer, 256, f, ap);
+  va_end(ap);
+
+  DevmapperLogCallback(level, (char *)file, line, dm_errno_or_class, buffer);
+}
+
+static void
+log_with_errno_init ()
+{
+  dm_log_with_errno_init(log_cb);
+}
+
 */
 import "C"
 
@@ -127,6 +149,10 @@ import (
 	"unsafe"
 )
 
+type DevmapperLogger interface  {
+	log(level int, file string, line int, dmError int, message string)
+}
+
 const (
 	DeviceCreate TaskType = iota
 	DeviceReload
@@ -351,6 +377,13 @@ func LogInitVerbose(level int) {
 	C.dm_log_init_verbose(C.int(level))
 }
 
+var dmLogger DevmapperLogger = nil
+
+func logInit(logger DevmapperLogger) {
+	dmLogger = logger
+	C.log_with_errno_init()
+}
+
 func SetDevDir(dir string) error {
 	c_dir := C.CString(dir)
 	defer free(c_dir)

devmapper/devmapper_log.go

@@ -0,0 +1,13 @@
+package devmapper
+
+import "C"
+
+// Due to the way cgo works this has to be in a separate file, as devmapper.go has
+// definitions in the cgo block, which is incompatible with using "//export"
+
+//export DevmapperLogCallback
+func DevmapperLogCallback(level C.int, file *C.char, line C.int, dm_errno_or_class C.int, message *C.char) {
+	if dmLogger != nil {
+		dmLogger.log(int(level), C.GoString(file), int(line), int(dm_errno_or_class), C.GoString(message))
+	}
+}