NFS refactor nfs_find_client and reference client across callback processing

Fixes a bug where the nfs_client could be freed during callback processing.
Refactor nfs_find_client to use minorversion specific means to locate the
correct nfs_client structure.

In the NFS layer, V4.0 clients are found using the callback_ident field in the
CB_COMPOUND header.  V4.1 clients are found using the sessionID in the
CB_SEQUENCE operation which is also compared against the sessionID associated
with the back channel thread after a successful CREATE_SESSION.

Each of these methods finds the one an only nfs_client associated
with the incoming callback request - so nfs_find_client_next is not needed.

In the RPC layer, the pg_authenticate call needs to find the nfs_client. For
the v4.0 callback service, the callback identifier has not been decoded so a
search by address, version, and minorversion is used.  The sessionid for the
sessions based callback service has (usually) not been set for the
pg_authenticate on a CB_NULL call which can be sent prior to the return
of a CREATE_SESSION call, so the sessionid associated with the back channel
thread is not used to find the client in pg_authenticate for CB_NULL calls.

Pass the referenced nfs_client to each CB_COMPOUND operation being proceesed
via the new cb_process_state structure. The reference is held across
cb_compound processing.

Use the new cb_process_state struct to move the NFS4ERR_RETRY_UNCACHED_REP
processing from process_op into nfs4_callback_sequence where it belongs.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/include/linux/sunrpc/bc_xprt.h b/include/linux/sunrpc/bc_xprt.h
index 7c91260c44a9..2c60e094fdec 100644
--- a/include/linux/sunrpc/bc_xprt.h
+++ b/include/linux/sunrpc/bc_xprt.h
@@ -47,6 +47,14 @@ static inline int svc_is_backchannel(const struct svc_rqst *rqstp)
                 return 1;
         return 0;
 }
+static inline struct nfs4_sessionid *bc_xprt_sid(struct svc_rqst *rqstp)
+{
+        if (svc_is_backchannel(rqstp))
+                return (struct nfs4_sessionid *)
+                                        rqstp->rq_server->bc_xprt->xpt_bc_sid;
+        return NULL;
+}
+
 #else /* CONFIG_NFS_V4_1 */
 static inline int xprt_setup_backchannel(struct rpc_xprt *xprt,
                                          unsigned int min_reqs)
@@ -59,6 +67,11 @@ static inline int svc_is_backchannel(const struct svc_rqst *rqstp)
         return 0;
 }
 
+static inline struct nfs4_sessionid *bc_xprt_sid(struct svc_rqst *rqstp)
+{
+        return NULL;
+}
+
 static inline void xprt_free_bc_request(struct rpc_rqst *req)
 {
 }