[PATCH] RPC: skip over transport-specific heads automatically
Add a generic mechanism for skipping over transport-specific headers
when constructing an RPC request. This removes another "xprt->stream"
dependency.
Test-plan:
Write-intensive workload on a single mount point (try both UDP and
TCP).
Signed-off-by: Chuck Lever <cel@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/include/linux/sunrpc/msg_prot.h b/include/linux/sunrpc/msg_prot.h
index 15f1153..f43f237 100644
--- a/include/linux/sunrpc/msg_prot.h
+++ b/include/linux/sunrpc/msg_prot.h
@@ -76,5 +76,30 @@
#define RPC_MAXNETNAMELEN 256
+/*
+ * From RFC 1831:
+ *
+ * "A record is composed of one or more record fragments. A record
+ * fragment is a four-byte header followed by 0 to (2**31) - 1 bytes of
+ * fragment data. The bytes encode an unsigned binary number; as with
+ * XDR integers, the byte order is from highest to lowest. The number
+ * encodes two values -- a boolean which indicates whether the fragment
+ * is the last fragment of the record (bit value 1 implies the fragment
+ * is the last fragment) and a 31-bit unsigned binary value which is the
+ * length in bytes of the fragment's data. The boolean value is the
+ * highest-order bit of the header; the length is the 31 low-order bits.
+ * (Note that this record specification is NOT in XDR standard form!)"
+ *
+ * The Linux RPC client always sends its requests in a single record
+ * fragment, limiting the maximum payload size for stream transports to
+ * 2GB.
+ */
+
+typedef u32 rpc_fraghdr;
+
+#define RPC_LAST_STREAM_FRAGMENT (1U << 31)
+#define RPC_FRAGMENT_SIZE_MASK (~RPC_LAST_STREAM_FRAGMENT)
+#define RPC_MAX_FRAGMENT_SIZE ((1U << 31) - 1)
+
#endif /* __KERNEL__ */
#endif /* _LINUX_SUNRPC_MSGPROT_H_ */