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>
diff --git a/fs/cifs/cifs_ioctl.h b/fs/cifs/cifs_ioctl.h
new file mode 100644
index 0000000..0065256
--- /dev/null
+++ b/fs/cifs/cifs_ioctl.h
@@ -0,0 +1,42 @@
+/*
+ *   fs/cifs/cifs_ioctl.h
+ *
+ *   Structure definitions for io control for cifs/smb3
+ *
+ *   Copyright (c) 2015 Steve French <steve.french@primarydata.com>
+ *
+ *   This library is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU Lesser General Public License as published
+ *   by the Free Software Foundation; either version 2.1 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This library is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
+ *   the GNU Lesser General Public License for more details.
+ *
+ */
+
+struct smb_mnt_fs_info {
+	__u32	version; /* 0001 */
+	__u16	protocol_id;
+	__u16	tcon_flags;
+	__u32	vol_serial_number;
+	__u32	vol_create_time;
+	__u32	share_caps;
+	__u32	share_flags;
+	__u32	sector_flags;
+	__u32	optimal_sector_size;
+	__u32	max_bytes_chunk;
+	__u32	fs_attributes;
+	__u32	max_path_component;
+	__u32	device_type;
+	__u32	device_characteristics;
+	__u32	maximal_access;
+	__u64   cifs_posix_caps;
+} __packed;
+
+#define CIFS_IOCTL_MAGIC	0xCF
+#define CIFS_IOC_COPYCHUNK_FILE	_IOW(CIFS_IOCTL_MAGIC, 3, int)
+#define CIFS_IOC_SET_INTEGRITY  _IO(CIFS_IOCTL_MAGIC, 4)
+#define CIFS_IOC_GET_MNT_INFO _IOR(CIFS_IOCTL_MAGIC, 5, struct smb_mnt_fs_info)