Add way to query server fs info for smb3

The server exports information about the share and underlying
device under an SMB3 export, including its attributes and
capabilities, which is stored by cifs.ko when first connecting
to the share.

Add ioctl to cifs.ko to allow user space smb3 helper utilities
(in cifs-utils) to display this (e.g. via smb3util).

This information is also useful for debugging and for
resolving configuration errors.

Signed-off-by: Steve French <steve.french@primarydata.com>

fs/cifs/cifspdu.h

@@ -2245,6 +2245,20 @@ typedef struct {
 #define FILE_DEVICE_VIRTUAL_DISK        0x00000024
 #define FILE_DEVICE_NETWORK_REDIRECTOR  0x00000028
 
+/* Device Characteristics */
+#define FILE_REMOVABLE_MEDIA			0x00000001
+#define FILE_READ_ONLY_DEVICE			0x00000002
+#define FILE_FLOPPY_DISKETTE			0x00000004
+#define FILE_WRITE_ONCE_MEDIA			0x00000008
+#define FILE_REMOTE_DEVICE			0x00000010
+#define FILE_DEVICE_IS_MOUNTED			0x00000020
+#define FILE_VIRTUAL_VOLUME			0x00000040
+#define FILE_DEVICE_SECURE_OPEN			0x00000100
+#define FILE_CHARACTERISTIC_TS_DEVICE		0x00001000
+#define FILE_CHARACTERISTIC_WEBDAV_DEVICE	0x00002000
+#define FILE_PORTABLE_DEVICE			0x00004000
+#define FILE_DEVICE_ALLOW_APPCONTAINER_TRAVERSAL 0x00020000
+
 typedef struct {
 	__le32 DeviceType;
 	__le32 DeviceCharacteristics;