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, 112 insertions, 59 deletions

diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index bc3a8620e8c3..11eb9934c747 100644
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -410,70 +410,28 @@ static int nfs_sockaddr_cmp(const struct sockaddr *sa1,
         return 0;
 }
 
-/*
- * Find a client by IP address and protocol version
- * - returns NULL if no such client
- */
-struct nfs_client *nfs_find_client(const struct sockaddr *addr, u32 nfsversion)
+/* Common match routine for v4.0 and v4.1 callback services */
+bool
+nfs4_cb_match_client(const struct sockaddr *addr, struct nfs_client *clp,
+                     u32 minorversion)
 {
-        struct nfs_client *clp;
+        struct sockaddr *clap = (struct sockaddr *)&clp->cl_addr;
 
-        spin_lock(&nfs_client_lock);
-        list_for_each_entry(clp, &nfs_client_list, cl_share_link) {
-                struct sockaddr *clap = (struct sockaddr *)&clp->cl_addr;
+        /* Don't match clients that failed to initialise */
+        if (!(clp->cl_cons_state == NFS_CS_READY ||
+            clp->cl_cons_state == NFS_CS_SESSION_INITING))
+                return false;
 
-                /* Don't match clients that failed to initialise properly */
-                if (!(clp->cl_cons_state == NFS_CS_READY ||
-                      clp->cl_cons_state == NFS_CS_SESSION_INITING))
-                        continue;
+        /* Match the version and minorversion */
+        if (clp->rpc_ops->version != 4 ||
+            clp->cl_minorversion != minorversion)
+                return false;
 
-                /* Different NFS versions cannot share the same nfs_client */
-                if (clp->rpc_ops->version != nfsversion)
-                        continue;
-
-                /* Match only the IP address, not the port number */
-                if (!nfs_sockaddr_match_ipaddr(addr, clap))
-                        continue;
+        /* Match only the IP address, not the port number */
+        if (!nfs_sockaddr_match_ipaddr(addr, clap))
+                return false;
 
-                atomic_inc(&clp->cl_count);
-                spin_unlock(&nfs_client_lock);
-                return clp;
-        }
-        spin_unlock(&nfs_client_lock);
-        return NULL;
-}
-
-/*
- * Find a client by IP address and protocol version
- * - returns NULL if no such client
- */
-struct nfs_client *nfs_find_client_next(struct nfs_client *clp)
-{
-        struct sockaddr *sap = (struct sockaddr *)&clp->cl_addr;
-        u32 nfsvers = clp->rpc_ops->version;
-
-        spin_lock(&nfs_client_lock);
-        list_for_each_entry_continue(clp, &nfs_client_list, cl_share_link) {
-                struct sockaddr *clap = (struct sockaddr *)&clp->cl_addr;
-
-                /* Don't match clients that failed to initialise properly */
-                if (clp->cl_cons_state != NFS_CS_READY)
-                        continue;
-
-                /* Different NFS versions cannot share the same nfs_client */
-                if (clp->rpc_ops->version != nfsvers)
-                        continue;
-
-                /* Match only the IP address, not the port number */
-                if (!nfs_sockaddr_match_ipaddr(sap, clap))
-                        continue;
-
-                atomic_inc(&clp->cl_count);
-                spin_unlock(&nfs_client_lock);
-                return clp;
-        }
-        spin_unlock(&nfs_client_lock);
-        return NULL;
+        return true;
 }
 
 /*
@@ -1172,6 +1130,101 @@ error:
 
 #ifdef CONFIG_NFS_V4
 /*
+ * NFSv4.0 callback thread helper
+ *
+ * Find a client by IP address, protocol version, and minorversion
+ *
+ * Called from the pg_authenticate method. The callback identifier
+ * is not used as it has not been decoded.
+ *
+ * Returns NULL if no such client
+ */
+struct nfs_client *
+nfs4_find_client_no_ident(const struct sockaddr *addr)
+{
+        struct nfs_client *clp;
+
+        spin_lock(&nfs_client_lock);
+        list_for_each_entry(clp, &nfs_client_list, cl_share_link) {
+                if (nfs4_cb_match_client(addr, clp, 0) == false)
+                        continue;
+                atomic_inc(&clp->cl_count);
+                spin_unlock(&nfs_client_lock);
+                return clp;
+        }
+        spin_unlock(&nfs_client_lock);
+        return NULL;
+}
+
+/*
+ * NFSv4.0 callback thread helper
+ *
+ * Find a client by callback identifier
+ */
+struct nfs_client *
+nfs4_find_client_ident(int cb_ident)
+{
+        struct nfs_client *clp;
+
+        spin_lock(&nfs_client_lock);
+        clp = idr_find(&cb_ident_idr, cb_ident);
+        if (clp)
+                atomic_inc(&clp->cl_count);
+        spin_unlock(&nfs_client_lock);
+        return clp;
+}
+
+#if defined(CONFIG_NFS_V4_1)
+/*
+ * NFSv4.1 callback thread helper
+ * For CB_COMPOUND calls, find a client by IP address, protocol version,
+ * minorversion, and sessionID
+ *
+ * CREATE_SESSION triggers a CB_NULL ping from servers. The callback service
+ * sessionid can only be set after the CREATE_SESSION return, so a CB_NULL
+ * can arrive before the callback sessionid is set. For CB_NULL calls,
+ * find a client by IP address protocol version, and minorversion.
+ *
+ * Returns NULL if no such client
+ */
+struct nfs_client *
+nfs4_find_client_sessionid(const struct sockaddr *addr,
+                           struct nfs4_sessionid *sid, int is_cb_compound)
+{
+        struct nfs_client *clp;
+
+        spin_lock(&nfs_client_lock);
+        list_for_each_entry(clp, &nfs_client_list, cl_share_link) {
+                if (nfs4_cb_match_client(addr, clp, 1) == false)
+                        continue;
+
+                if (!nfs4_has_session(clp))
+                        continue;
+
+                /* Match sessionid unless cb_null call*/
+                if (is_cb_compound && (memcmp(clp->cl_session->sess_id.data,
+                    sid->data, NFS4_MAX_SESSIONID_LEN) != 0))
+                        continue;
+
+                atomic_inc(&clp->cl_count);
+                spin_unlock(&nfs_client_lock);
+                return clp;
+        }
+        spin_unlock(&nfs_client_lock);
+        return NULL;
+}
+
+#else /* CONFIG_NFS_V4_1 */
+
+struct nfs_client *
+nfs4_find_client_sessionid(const struct sockaddr *addr,
+                           struct nfs4_sessionid *sid, int is_cb_compound)
+{
+        return NULL;
+}
+#endif /* CONFIG_NFS_V4_1 */
+
+/*
  * Initialize the NFS4 callback service
  */
 static int nfs4_init_callback(struct nfs_client *clp)