Merge branch 'btrfs-clone' of https://github.com/bozaro/git-lfs into bozaro-btrfs-clone

lfs/util.go

@@ -45,6 +45,12 @@ func (w *CallbackReader) Read(p []byte) (int, error) {
 }
 
 func CopyWithCallback(writer io.Writer, reader io.Reader, totalSize int64, cb CopyCallback) (int64, error) {
+	if success, _ := CloneFile(writer, reader); success {
+		if cb != nil {
+			cb(totalSize, totalSize, 0)
+		}
+		return totalSize, nil
+	}
 	if cb == nil {
 		return io.Copy(writer, reader)
 	}

lfs/util_generic.go

@@ -0,0 +1,11 @@
+// +build !linux !cgo
+
+package lfs
+
+import (
+	"io"
+)
+
+func CloneFile(writer io.Writer, reader io.Reader) (bool, error) {
+	return false, nil
+}

lfs/util_linux.go

@@ -0,0 +1,35 @@
+// +build linux,cgo
+
+package lfs
+
+/*
+#include <sys/ioctl.h>
+
+#undef BTRFS_IOCTL_MAGIC
+#define BTRFS_IOCTL_MAGIC 0x94
+#undef BTRFS_IOC_CLONE
+#define BTRFS_IOC_CLONE _IOW (BTRFS_IOCTL_MAGIC, 9, int)
+*/
+import "C"
+
+import (
+	"os"
+	"io"
+	"syscall"
+)
+
+const (
+	BtrfsIocClone = C.BTRFS_IOC_CLONE
+)
+
+func CloneFile(writer io.Writer, reader io.Reader) (bool, error) {
+	fdst, fdstFound := writer.(*os.File)
+	fsrc, fsrcFound := reader.(*os.File)
+	if fdstFound && fsrcFound {
+		if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, fdst.Fd(), BtrfsIocClone, fsrc.Fd()); err != 0 {
+			return false, err
+		}
+		return true, nil
+	}
+	return false, nil
+}