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, 21 insertions, 7 deletions

diff --git a/fs/nfs/callback.h b/fs/nfs/callback.h
index 58d61a8ce8b9..25e8802a51d1 100644
--- a/fs/nfs/callback.h
+++ b/fs/nfs/callback.h
@@ -34,10 +34,17 @@ enum nfs4_callback_opnum {
         OP_CB_ILLEGAL = 10044,
 };
 
+struct cb_process_state {
+        __be32                  drc_status;
+        struct nfs_client       *clp;
+        struct nfs4_sessionid   *svc_sid; /* v4.1 callback service sessionid */
+};
+
 struct cb_compound_hdr_arg {
         unsigned int taglen;
         const char *tag;
         unsigned int minorversion;
+        unsigned int cb_ident; /* v4.0 callback identifier */
         unsigned nops;
 };
 
@@ -103,8 +110,9 @@ struct cb_sequenceres {
         uint32_t                        csr_target_highestslotid;
 };
 
-extern unsigned nfs4_callback_sequence(struct cb_sequenceargs *args,
-                                       struct cb_sequenceres *res);
+extern __be32 nfs4_callback_sequence(struct cb_sequenceargs *args,
+                                       struct cb_sequenceres *res,
+                                       struct cb_process_state *cps);
 
 extern int nfs41_validate_delegation_stateid(struct nfs_delegation *delegation,
                                              const nfs4_stateid *stateid);
@@ -118,19 +126,25 @@ struct cb_recallanyargs {
         uint32_t        craa_type_mask;
 };
 
-extern unsigned nfs4_callback_recallany(struct cb_recallanyargs *args, void *dummy);
+extern __be32 nfs4_callback_recallany(struct cb_recallanyargs *args,
+                                        void *dummy,
+                                        struct cb_process_state *cps);
 
 struct cb_recallslotargs {
         struct sockaddr *crsa_addr;
         uint32_t        crsa_target_max_slots;
 };
-extern unsigned nfs4_callback_recallslot(struct cb_recallslotargs *args,
-                                          void *dummy);
+extern __be32 nfs4_callback_recallslot(struct cb_recallslotargs *args,
+                                         void *dummy,
+                                         struct cb_process_state *cps);
 
 #endif /* CONFIG_NFS_V4_1 */
 
-extern __be32 nfs4_callback_getattr(struct cb_getattrargs *args, struct cb_getattrres *res);
-extern __be32 nfs4_callback_recall(struct cb_recallargs *args, void *dummy);
+extern __be32 nfs4_callback_getattr(struct cb_getattrargs *args,
+                                    struct cb_getattrres *res,
+                                    struct cb_process_state *cps);
+extern __be32 nfs4_callback_recall(struct cb_recallargs *args, void *dummy,
+                                   struct cb_process_state *cps);
 
 #ifdef CONFIG_NFS_V4
 extern int nfs_callback_up(u32 minorversion, struct rpc_xprt *xprt);