NFSv4.1 Fix gdia_maxcount calculation to fit in ca_maxresponsesize

The GETDEVICEINFO gdia_maxcount represents all of the data being returned
within the GETDEVICEINFO4resok structure and includes the XDR overhead.

The CREATE_SESSION ca_maxresponsesize is the maximum reply and includes the RPC
headers (including security flavor credentials and verifiers).

Split out the struct pnfs_device field maxcount which is the gdia_maxcount
from the pglen field which is the reply (the total) buffer length.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/pnfs.h b/fs/nfs/pnfs.h
index 1441dff..a4f4181 100644
--- a/fs/nfs/pnfs.h
+++ b/fs/nfs/pnfs.h
@@ -149,9 +149,10 @@
 	struct nfs4_deviceid dev_id;
 	unsigned int  layout_type;
 	unsigned int  mincount;
+	unsigned int  maxcount;	/* gdia_maxcount */
 	struct page **pages;
 	unsigned int  pgbase;
-	unsigned int  pglen;
+	unsigned int  pglen;	/* reply buffer length */
 };
 
 #define NFS4_PNFS_GETDEVLIST_MAXNUM 16