[CIFS] Avoid extra large buffer allocation (and memcpy) in cifs_readpages

Signed-off-by: Steve French <sfrench@us.ibm.com>
diff --git a/fs/cifs/cifspdu.h b/fs/cifs/cifspdu.h
index 5253e77..3c09fb9 100644
--- a/fs/cifs/cifspdu.h
+++ b/fs/cifs/cifspdu.h
@@ -80,7 +80,11 @@
 #define NT_TRANSACT_GET_USER_QUOTA    0x07
 #define NT_TRANSACT_SET_USER_QUOTA    0x08
 
-#define MAX_CIFS_HDR_SIZE 256	/* is future chained NTCreateXReadX bigger? */
+#define MAX_CIFS_SMALL_BUFFER_SIZE 448 /* big enough for most */
+/* future chained NTCreateXReadX bigger, but for time being NTCreateX biggest */
+/* among the requests (NTCreateX response is bigger with wct of 34) */
+#define MAX_CIFS_HDR_SIZE 0x58 /* 4 len + 32 hdr + (2*24 wct) + 2 bct + 2 pad */
+#define CIFS_SMALL_PATH 120 /* allows for (448-88)/3 */
 
 /* internal cifs vfs structures */
 /*****************************************************************