[PATCH] knfsd: Prepare knfsd for support of rsize/wsize of up to 1MB, over TCP

The limit over UDP remains at 32K.  Also, make some of the apparently
arbitrary sizing constants clearer.

The biggest change here involves replacing NFSSVC_MAXBLKSIZE by a function of
the rqstp.  This allows it to be different for different protocols (udp/tcp)
and also allows it to depend on the servers declared sv_bufsiz.

Note that we don't actually increase sv_bufsz for nfs yet.  That comes next.

Signed-off-by: Greg Banks <gnb@melbourne.sgi.com>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

4 files changed, 63 insertions, 11 deletions

diff --git a/include/linux/sunrpc/auth.h b/include/linux/sunrpc/auth.h
index 862c0d8c..534cdc7 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 8d10d14..1e65f2d 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 cb0ed9b..74e52c2 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 6cf6265..60394fb 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;