unix: add IoctlLoop{Get,Set}Status64 on linux

These ioctls are used to get/set the status of a loop device. See
https://man7.org/linux/man-pages/man4/loop.4.html for details.

Change-Id: Ia66db639e6d9326af79954eea5c8f7515aa171d1
Reviewed-on: https://go-review.googlesource.com/c/sys/+/425296
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Heschi Kreinick <heschi@google.com>

unix/ioctl_linux.go

@@ -4,9 +4,7 @@
 
 package unix
 
-import (
+import "unsafe"
-	"unsafe"
-)
 
 // IoctlRetInt performs an ioctl operation specified by req on a device
 // associated with opened file descriptor fd, and returns a non-negative
@@ -217,3 +215,19 @@ func IoctlKCMAttach(fd int, info KCMAttach) error {
 func IoctlKCMUnattach(fd int, info KCMUnattach) error {
 	return ioctlPtr(fd, SIOCKCMUNATTACH, unsafe.Pointer(&info))
 }
+
+// IoctlLoopGetStatus64 gets the status of the loop device associated with the
+// file descriptor fd using the LOOP_GET_STATUS64 operation.
+func IoctlLoopGetStatus64(fd int) (*LoopInfo64, error) {
+	var value LoopInfo64
+	if err := ioctlPtr(fd, LOOP_GET_STATUS64, unsafe.Pointer(&value)); err != nil {
+		return nil, err
+	}
+	return &value, nil
+}
+
+// IoctlLoopSetStatus64 sets the status of the loop device associated with the
+// file descriptor fd using the LOOP_SET_STATUS64 operation.
+func IoctlLoopSetStatus64(fd int, value *LoopInfo64) error {
+	return ioctlPtr(fd, LOOP_SET_STATUS64, unsafe.Pointer(value))
+}