nfsd4: Move callback setup to callback queue
Instead of creating the new rpc client from a regular server thread,
set a flag, kick off a null call, and allow the null call to do the work
of setting up the client on the callback workqueue.
Use a spinlock to ensure the callback work gets a consistent view of the
callback parameters.
This allows, for example, changing the callback from contexts where
sleeping is not allowed. I hope it will also keep the locking simple as
we add more session and trunking features, by serializing most of the
callback-specific work.
This also closes a small race where the the new cb_ident could be used
with an old connection (or vice-versa).
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
index 07c3be6..a269dbe 100644
--- a/fs/nfsd/nfs4callback.c
+++ b/fs/nfsd/nfs4callback.c
@@ -284,7 +284,7 @@
struct xdr_stream xdr;
struct nfs4_delegation *args = cb->cb_op;
struct nfs4_cb_compound_hdr hdr = {
- .ident = args->dl_ident,
+ .ident = cb->cb_clp->cl_cb_ident,
.minorversion = cb->cb_minorversion,
};
@@ -506,7 +506,8 @@
PTR_ERR(client));
return PTR_ERR(client);
}
- nfsd4_set_callback_client(clp, client);
+ clp->cl_cb_ident = conn->cb_ident;
+ clp->cl_cb_client = client;
return 0;
}
@@ -569,15 +570,12 @@
*/
void nfsd4_probe_callback(struct nfs4_client *clp, struct nfs4_cb_conn *conn)
{
- int status;
-
BUG_ON(atomic_read(&clp->cl_cb_set));
- status = setup_callback_client(clp, conn);
- if (status) {
- warn_no_callback_path(clp, status);
- return;
- }
+ spin_lock(&clp->cl_lock);
+ memcpy(&clp->cl_cb_conn, conn, sizeof(struct nfs4_cb_conn));
+ set_bit(NFSD4_CLIENT_CB_UPDATE, &clp->cl_cb_flags);
+ spin_unlock(&clp->cl_lock);
do_probe_callback(clp);
}
@@ -730,19 +728,16 @@
}
/* must be called under the state lock */
-void nfsd4_set_callback_client(struct nfs4_client *clp, struct rpc_clnt *new)
+void nfsd4_shutdown_callback(struct nfs4_client *clp)
{
- struct rpc_clnt *old = clp->cl_cb_client;
-
- clp->cl_cb_client = new;
+ set_bit(NFSD4_CLIENT_KILL, &clp->cl_cb_flags);
/*
- * After this, any work that saw the old value of cl_cb_client will
- * be gone:
+ * Note this won't actually result in a null callback;
+ * instead, nfsd4_do_callback_rpc() will detect the killed
+ * client, destroy the rpc client, and stop:
*/
+ do_probe_callback(clp);
flush_workqueue(callback_wq);
- /* So we can safely shut it down: */
- if (old)
- rpc_shutdown_client(old);
}
void nfsd4_release_cb(struct nfsd4_callback *cb)
@@ -751,15 +746,51 @@
cb->cb_ops->rpc_release(cb);
}
+void nfsd4_process_cb_update(struct nfsd4_callback *cb)
+{
+ struct nfs4_cb_conn conn;
+ struct nfs4_client *clp = cb->cb_clp;
+ int err;
+
+ /*
+ * This is either an update, or the client dying; in either case,
+ * kill the old client:
+ */
+ if (clp->cl_cb_client) {
+ rpc_shutdown_client(clp->cl_cb_client);
+ clp->cl_cb_client = NULL;
+ }
+ if (test_bit(NFSD4_CLIENT_KILL, &clp->cl_cb_flags))
+ return;
+ spin_lock(&clp->cl_lock);
+ /*
+ * Only serialized callback code is allowed to clear these
+ * flags; main nfsd code can only set them:
+ */
+ BUG_ON(!clp->cl_cb_flags);
+ clear_bit(NFSD4_CLIENT_CB_UPDATE, &clp->cl_cb_flags);
+ memcpy(&conn, &cb->cb_clp->cl_cb_conn, sizeof(struct nfs4_cb_conn));
+ spin_unlock(&clp->cl_lock);
+
+ err = setup_callback_client(clp, &conn);
+ if (err)
+ warn_no_callback_path(clp, err);
+}
+
void nfsd4_do_callback_rpc(struct work_struct *w)
{
struct nfsd4_callback *cb = container_of(w, struct nfsd4_callback, cb_work);
struct nfs4_client *clp = cb->cb_clp;
- struct rpc_clnt *clnt = clp->cl_cb_client;
+ struct rpc_clnt *clnt;
- if (clnt == NULL) {
+ if (clp->cl_cb_flags)
+ nfsd4_process_cb_update(cb);
+
+ clnt = clp->cl_cb_client;
+ if (!clnt) {
+ /* Callback channel broken, or client killed; give up: */
nfsd4_release_cb(cb);
- return; /* Client is shutting down; give up. */
+ return;
}
rpc_call_async(clnt, &cb->cb_msg, RPC_TASK_SOFT | RPC_TASK_SOFTCONN,
cb->cb_ops, cb);