CIFS: Replace netfid with cifs_fid struct in cifsFileInfo

This is help us to extend the code for future protocols that can use
another fid mechanism (as SMB2 that has it divided into two parts:
persistent and violatile).

Also rename variables and refactor the code around the changes.

Reviewed-by: Jeff Layton <jlayton@samba.org>
Signed-off-by: Pavel Shilovsky <pshilovsky@samba.org>
Signed-off-by: Steve French <smfrench@gmail.com>
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 843356f..a2a3865 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -746,6 +746,10 @@
 	bool smallBuf:1; /* so we know which buf_release function to call */
 };
 
+struct cifs_fid {
+	__u16 netfid;
+};
+
 struct cifsFileInfo {
 	struct list_head tlist;	/* pointer to next fid owned by tcon */
 	struct list_head flist;	/* next fid (file instance) for this inode */
@@ -755,7 +759,7 @@
 				 */
 	unsigned int uid;	/* allows finding which FileInfo structure */
 	__u32 pid;		/* process id who opened file */
-	__u16 netfid;		/* file id from remote */
+	struct cifs_fid fid;	/* file id from remote */
 	/* BB add lock scope info here if needed */ ;
 	/* lock scope id (0 if none) */
 	struct dentry *dentry;