4 files changed, 63 insertions, 11 deletions

diff --git a/include/linux/sunrpc/auth.h b/include/linux/sunrpc/auth.h
index 862c0d8c8381..534cdc7be58d 100644
--- a/include/linux/sunrpc/auth.h
+++ b/include/linux/sunrpc/auth.h
@@ -20,9 +20,6 @@
 /* size of the nodename buffer */
 #define UNX_MAXNODENAME 32
 
-/* Maximum size (in bytes) of an rpc credential or verifier */
-#define RPC_MAX_AUTH_SIZE (400)
-
 /* Work around the lack of a VFS credential */
 struct auth_cred {
         uid_t   uid;
diff --git a/include/linux/sunrpc/msg_prot.h b/include/linux/sunrpc/msg_prot.h
index 8d10d148834e..1e65f2dd80e5 100644
--- a/include/linux/sunrpc/msg_prot.h
+++ b/include/linux/sunrpc/msg_prot.h
@@ -11,6 +11,9 @@
 
 #define RPC_VERSION 2
 
+/* size of an XDR encoding unit in bytes, i.e. 32bit */
+#define XDR_UNIT        (4)
+
 /* spec defines authentication flavor as an unsigned 32 bit integer */
 typedef u32     rpc_authflavor_t;
 
@@ -34,6 +37,9 @@ enum rpc_auth_flavors {
         RPC_AUTH_GSS_SPKMP = 390011,
 };
 
+/* Maximum size (in bytes) of an rpc credential or verifier */
+#define RPC_MAX_AUTH_SIZE (400)
+
 enum rpc_msg_type {
         RPC_CALL = 0,
         RPC_REPLY = 1
@@ -101,5 +107,39 @@ typedef __be32	rpc_fraghdr;
 #define RPC_FRAGMENT_SIZE_MASK          (~RPC_LAST_STREAM_FRAGMENT)
 #define RPC_MAX_FRAGMENT_SIZE           ((1U << 31) - 1)
 
+/*
+ * RPC call and reply header size as number of 32bit words (verifier
+ * size computed separately, see below)
+ */
+#define RPC_CALLHDRSIZE         (6)
+#define RPC_REPHDRSIZE          (4)
+
+
+/*
+ * Maximum RPC header size, including authentication,
+ * as number of 32bit words (see RFCs 1831, 1832).
+ *
+ *      xid                         1 xdr unit = 4 bytes
+ *      mtype                       1
+ *      rpc_version                 1
+ *      program                     1
+ *      prog_version                1
+ *      procedure                   1
+ *      cred {
+ *          flavor                  1
+ *          length                  1
+ *          body<RPC_MAX_AUTH_SIZE> 100 xdr units = 400 bytes
+ *      }
+ *      verf {
+ *          flavor                  1
+ *          length                  1
+ *          body<RPC_MAX_AUTH_SIZE> 100 xdr units = 400 bytes
+ *      }
+ *      TOTAL                       210 xdr units = 840 bytes
+ */
+#define RPC_MAX_HEADER_WITH_AUTH \
+        (RPC_CALLHDRSIZE + 2*(2+RPC_MAX_AUTH_SIZE/4))
+
+
 #endif /* __KERNEL__ */
 #endif /* _LINUX_SUNRPC_MSGPROT_H_ */
diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
index cb0ed9beb227..74e52c245da4 100644
--- a/include/linux/sunrpc/svc.h
+++ b/include/linux/sunrpc/svc.h
@@ -13,6 +13,7 @@
 #include <linux/in.h>
 #include <linux/sunrpc/types.h>
 #include <linux/sunrpc/xdr.h>
+#include <linux/sunrpc/auth.h>
 #include <linux/sunrpc/svcauth.h>
 #include <linux/wait.h>
 #include <linux/mm.h>
@@ -95,8 +96,28 @@ static inline void svc_get(struct svc_serv *serv)
  * Maximum payload size supported by a kernel RPC server.
  * This is use to determine the max number of pages nfsd is
  * willing to return in a single READ operation.
+ *
+ * These happen to all be powers of 2, which is not strictly
+ * necessary but helps enforce the real limitation, which is
+ * that they should be multiples of PAGE_CACHE_SIZE.
+ *
+ * For UDP transports, a block plus NFS,RPC, and UDP headers
+ * has to fit into the IP datagram limit of 64K.  The largest
+ * feasible number for all known page sizes is probably 48K,
+ * but we choose 32K here.  This is the same as the historical
+ * Linux limit; someone who cares more about NFS/UDP performance
+ * can test a larger number.
+ *
+ * For TCP transports we have more freedom.  A size of 1MB is
+ * chosen to match the client limit.  Other OSes are known to
+ * have larger limits, but those numbers are probably beyond
+ * the point of diminishing returns.
  */
-#define RPCSVC_MAXPAYLOAD       (64*1024u)
+#define RPCSVC_MAXPAYLOAD       (1*1024*1024u)
+#define RPCSVC_MAXPAYLOAD_TCP   RPCSVC_MAXPAYLOAD
+#define RPCSVC_MAXPAYLOAD_UDP   (32*1024u)
+
+extern u32 svc_max_payload(const struct svc_rqst *rqstp);
 
 /*
  * RPC Requsts and replies are stored in one or more pages.
diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h
index 6cf626580752..60394fbc4c70 100644
--- a/include/linux/sunrpc/xprt.h
+++ b/include/linux/sunrpc/xprt.h
@@ -15,6 +15,7 @@
 #include <linux/kref.h>
 #include <linux/sunrpc/sched.h>
 #include <linux/sunrpc/xdr.h>
+#include <linux/sunrpc/msg_prot.h>
 
 extern unsigned int xprt_udp_slot_table_entries;
 extern unsigned int xprt_tcp_slot_table_entries;
@@ -24,13 +25,6 @@ extern unsigned int xprt_tcp_slot_table_entries;
 #define RPC_MAX_SLOT_TABLE      (128U)
 
 /*
- * RPC call and reply header size as number of 32bit words (verifier
- * size computed separately)
- */
-#define RPC_CALLHDRSIZE         6
-#define RPC_REPHDRSIZE          4
-
-/*
  * Parameters for choosing a free port
  */
 extern unsigned int xprt_min_resvport;