devicemapper: split out devicemapper bindings

This is a first pass at splitting out devicemapper into separate, usable
bindings.

Signed-off-by: Vincent Batts <vbatts@redhat.com>

devicemapper/ioctl.go

@@ -0,0 +1,72 @@
+// +build linux
+
+package devicemapper
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+func ioctlLoopCtlGetFree(fd uintptr) (int, error) {
+	index, _, err := syscall.Syscall(syscall.SYS_IOCTL, fd, LoopCtlGetFree, 0)
+	if err != 0 {
+		return 0, err
+	}
+	return int(index), nil
+}
+
+func ioctlLoopSetFd(loopFd, sparseFd uintptr) error {
+	if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, loopFd, LoopSetFd, sparseFd); err != 0 {
+		return err
+	}
+	return nil
+}
+
+func ioctlLoopSetStatus64(loopFd uintptr, loopInfo *LoopInfo64) error {
+	if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, loopFd, LoopSetStatus64, uintptr(unsafe.Pointer(loopInfo))); err != 0 {
+		return err
+	}
+	return nil
+}
+
+func ioctlLoopClrFd(loopFd uintptr) error {
+	if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, loopFd, LoopClrFd, 0); err != 0 {
+		return err
+	}
+	return nil
+}
+
+func ioctlLoopGetStatus64(loopFd uintptr) (*LoopInfo64, error) {
+	loopInfo := &LoopInfo64{}
+
+	if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, loopFd, LoopGetStatus64, uintptr(unsafe.Pointer(loopInfo))); err != 0 {
+		return nil, err
+	}
+	return loopInfo, nil
+}
+
+func ioctlLoopSetCapacity(loopFd uintptr, value int) error {
+	if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, loopFd, LoopSetCapacity, uintptr(value)); err != 0 {
+		return err
+	}
+	return nil
+}
+
+func ioctlBlkGetSize64(fd uintptr) (int64, error) {
+	var size int64
+	if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, fd, BlkGetSize64, uintptr(unsafe.Pointer(&size))); err != 0 {
+		return 0, err
+	}
+	return size, nil
+}
+
+func ioctlBlkDiscard(fd uintptr, offset, length uint64) error {
+	var r [2]uint64
+	r[0] = offset
+	r[1] = length
+
+	if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, fd, BlkDiscard, uintptr(unsafe.Pointer(&r[0]))); err != 0 {
+		return err
+	}
+	return nil
+}