CIFS: Add SMB2 credits support

For SMB2 protocol we can add more than one credit for one received
request: it depends on CreditRequest field in SMB2 response header.
Also we divide all requests by type: echoes, oplocks and others.
Each type uses its own slot pull.

Reviewed-by: Jeff Layton <jlayton@redhat.com>
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 3575f0f..480b638 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -343,6 +343,11 @@
 	char server_GUID[16];
 	__u16 sec_mode;
 	bool session_estab; /* mark when very first sess is established */
+#ifdef CONFIG_CIFS_SMB2
+	int echo_credits;  /* echo reserved slots */
+	int oplock_credits;  /* oplock break reserved slots */
+	bool echoes:1; /* enable echoes */
+#endif
 	u16 dialect; /* dialect index that server chose */
 	enum securityEnum secType;
 	bool oplocks:1; /* enable oplocks */