[PATCH] knfsd: Allow lockd to drop replies as appropriate

It is possible for the ->fopen callback from lockd into nfsd to find that an
answer cannot be given straight away (an upcall is needed) and so the request
has to be 'dropped', to be retried later.  That error status is not currently
propagated back.

So:
  Change nlm_fopen to return nlm error codes (rather than a private
  protocol) and define a new nlm_drop_reply code.
  Cause nlm_drop_reply to cause the rpc request to get rpc_drop_reply
  when this error comes back.
  Cause svc_process to drop a request which returns a status of
  rpc_drop_reply.

[akpm@osdl.org: fix warning storm]
Cc: Marc Eshel <eshel@almaden.ibm.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, 13 insertions, 1 deletions

diff --git a/include/linux/lockd/bind.h b/include/linux/lockd/bind.h
index 81e3a185f951..aa50d89eacd7 100644
--- a/include/linux/lockd/bind.h
+++ b/include/linux/lockd/bind.h
@@ -10,6 +10,11 @@
 #define LINUX_LOCKD_BIND_H
 
 #include <linux/lockd/nlm.h>
+/* need xdr-encoded error codes too, so... */
+#include <linux/lockd/xdr.h>
+#ifdef CONFIG_LOCKD_V4
+#include <linux/lockd/xdr4.h>
+#endif
 
 /* Dummy declarations */
 struct svc_rqst;
diff --git a/include/linux/lockd/xdr.h b/include/linux/lockd/xdr.h
index bb0a0f1caa91..66fdae3b490c 100644
--- a/include/linux/lockd/xdr.h
+++ b/include/linux/lockd/xdr.h
@@ -13,6 +13,8 @@
 #include <linux/nfs.h>
 #include <linux/sunrpc/xdr.h>
 
+struct svc_rqst;
+
 #define NLM_MAXCOOKIELEN        32
 #define NLM_MAXSTRLEN           1024
 
@@ -22,6 +24,8 @@
 #define nlm_lck_blocked         __constant_htonl(NLM_LCK_BLOCKED)
 #define nlm_lck_denied_grace_period     __constant_htonl(NLM_LCK_DENIED_GRACE_PERIOD)
 
+#define nlm_drop_reply          __constant_htonl(30000)
+
 /* Lock info passed via NLM */
 struct nlm_lock {
         char *                  caller;
diff --git a/include/linux/sunrpc/msg_prot.h b/include/linux/sunrpc/msg_prot.h
index 1e65f2dd80e5..606cb2165232 100644
--- a/include/linux/sunrpc/msg_prot.h
+++ b/include/linux/sunrpc/msg_prot.h
@@ -56,7 +56,9 @@ enum rpc_accept_stat {
         RPC_PROG_MISMATCH = 2,
         RPC_PROC_UNAVAIL = 3,
         RPC_GARBAGE_ARGS = 4,
-        RPC_SYSTEM_ERR = 5
+        RPC_SYSTEM_ERR = 5,
+        /* internal use only */
+        RPC_DROP_REPLY = 60000,
 };
 
 enum rpc_reject_stat {
diff --git a/include/linux/sunrpc/xdr.h b/include/linux/sunrpc/xdr.h
index 953723b09bc6..ac69e5511606 100644
--- a/include/linux/sunrpc/xdr.h
+++ b/include/linux/sunrpc/xdr.h
@@ -74,6 +74,7 @@ struct xdr_buf {
 #define rpc_proc_unavail        __constant_htonl(RPC_PROC_UNAVAIL)
 #define rpc_garbage_args        __constant_htonl(RPC_GARBAGE_ARGS)
 #define rpc_system_err          __constant_htonl(RPC_SYSTEM_ERR)
+#define rpc_drop_reply          __constant_htonl(RPC_DROP_REPLY)
 
 #define rpc_auth_ok             __constant_htonl(RPC_AUTH_OK)
 #define rpc_autherr_badcred     __constant_htonl(RPC_AUTH_BADCRED)