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-rw-r--r--include/linux/sunrpc/svc.h23
1 files changed, 22 insertions, 1 deletions
diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
index cb0ed9beb22..74e52c245da 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.