lockd: Use xdrgen XDR functions for the NLMv4 CANCEL procedure

The NLM CANCEL procedure allows clients to cancel outstanding
blocked lock requests, completing the set of lock-related
operations that share common lookup patterns. This patch
continues the xdrgen migration by converting the CANCEL
procedure, leveraging the same nlm4svc_lookup_host() and
nlm4svc_lookup_file() helpers established in the TEST procedure
conversion to maintain consistency across the series.

This patch converts the CANCEL procedure to use xdrgen functions
nlm4_svc_decode_nlm4_cancargs and nlm4_svc_encode_nlm4_res
generated from the NLM version 4 protocol specification. The
procedure handler uses xdrgen types through a wrapper structure
that bridges between generated code and the legacy nlm_lock
representation still used by the core lockd logic.

The pc_argzero field is set to zero because xdrgen decoders
reliably initialize all arguments in the argp->xdrgen field,
making the early defensive memset unnecessary. Remaining argp
fields are cleared as needed.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

diff --git a/fs/lockd/svc4proc.c b/fs/lockd/svc4proc.c
index 2cad72562ef2b4a2a84fdcaae9d06cadc4fe16f2..4a3815599a65097a5a83ffdeeaa3878a2b60f8b9 100644 (file)
--- a/fs/lockd/svc4proc.c
+++ b/fs/lockd/svc4proc.c
@@ -48,6 +48,13 @@ struct nlm4_lockargs_wrapper {
 
 static_assert(offsetof(struct nlm4_lockargs_wrapper, xdrgen) == 0);
 
+struct nlm4_cancargs_wrapper {
+       struct nlm4_cancargs            xdrgen;
+       struct nlm_lock                 lock;
+};
+
+static_assert(offsetof(struct nlm4_cancargs_wrapper, xdrgen) == 0);
+
 struct nlm4_testres_wrapper {
        struct nlm4_testres             xdrgen;
        struct nlm_lock                 lock;
@@ -495,10 +502,68 @@ __nlm4svc_proc_cancel(struct svc_rqst *rqstp, struct nlm_res *resp)
        return rpc_success;
 }
 
+/**
+ * nlm4svc_proc_cancel - CANCEL: Cancel an outstanding blocked lock request
+ * @rqstp: RPC transaction context
+ *
+ * Returns:
+ *   %rpc_success:             RPC executed successfully
+ *   %rpc_drop_reply:          Do not send an RPC reply
+ *
+ * RPC synopsis:
+ *   nlm4_res NLMPROC4_CANCEL(nlm4_cancargs) = 3;
+ *
+ * Permissible procedure status codes:
+ *   %NLM4_LCK_GRANTED:                The requested lock was canceled.
+ *   %NLM4_LCK_DENIED:         There was no lock to cancel.
+ *   %NLM4_DENIED_GRACE_PERIOD:        The server has recently restarted and is
+ *                             re-establishing existing locks, and is not
+ *                             yet ready to accept normal service requests.
+ *
+ * The Linux NLM server implementation also returns:
+ *   %NLM4_DENIED_NOLOCKS:     A needed resource could not be allocated.
+ *   %NLM4_STALE_FH:           The request specified an invalid file handle.
+ *   %NLM4_FBIG:               The request specified a length or offset
+ *                             that exceeds the range supported by the
+ *                             server.
+ *   %NLM4_FAILED:             The request failed for an unspecified reason.
+ */
 static __be32
 nlm4svc_proc_cancel(struct svc_rqst *rqstp)
 {
-       return __nlm4svc_proc_cancel(rqstp, rqstp->rq_resp);
+       struct nlm4_cancargs_wrapper *argp = rqstp->rq_argp;
+       unsigned char type = argp->xdrgen.exclusive ? F_WRLCK : F_RDLCK;
+       struct nlm4_res_wrapper *resp = rqstp->rq_resp;
+       struct net *net = SVC_NET(rqstp);
+       struct nlm_host *host = NULL;
+       struct nlm_file *file = NULL;
+
+       resp->xdrgen.cookie = argp->xdrgen.cookie;
+
+       resp->xdrgen.stat.stat = nlm_lck_denied_grace_period;
+       if (locks_in_grace(net))
+               goto out;
+
+       resp->xdrgen.stat.stat = nlm_lck_denied_nolocks;
+       host = nlm4svc_lookup_host(rqstp, argp->xdrgen.alock.caller_name, false);
+       if (!host)
+               goto out;
+
+       resp->xdrgen.stat.stat = nlm4svc_lookup_file(rqstp, host, &argp->lock,
+                                                    &file, &argp->xdrgen.alock,
+                                                    type);
+       if (resp->xdrgen.stat.stat)
+               goto out;
+
+       resp->xdrgen.stat.stat = nlmsvc_cancel_blocked(net, file, &argp->lock);
+       nlmsvc_release_lockowner(&argp->lock);
+
+out:
+       if (file)
+               nlm_release_file(file);
+       nlmsvc_release_host(host);
+       return resp->xdrgen.stat.stat == nlm__int__drop_reply ?
+               rpc_drop_reply : rpc_success;
 }
 
 /*
@@ -839,15 +904,15 @@ static const struct svc_procedure nlm4svc_procedures[24] = {
                .pc_xdrressize  = NLM4_nlm4_res_sz,
                .pc_name        = "LOCK",
        },
-       [NLMPROC_CANCEL] = {
-               .pc_func = nlm4svc_proc_cancel,
-               .pc_decode = nlm4svc_decode_cancargs,
-               .pc_encode = nlm4svc_encode_res,
-               .pc_argsize = sizeof(struct nlm_args),
-               .pc_argzero = sizeof(struct nlm_args),
-               .pc_ressize = sizeof(struct nlm_res),
-               .pc_xdrressize = Ck+St,
-               .pc_name = "CANCEL",
+       [NLMPROC4_CANCEL] = {
+               .pc_func        = nlm4svc_proc_cancel,
+               .pc_decode      = nlm4_svc_decode_nlm4_cancargs,
+               .pc_encode      = nlm4_svc_encode_nlm4_res,
+               .pc_argsize     = sizeof(struct nlm4_cancargs_wrapper),
+               .pc_argzero     = 0,
+               .pc_ressize     = sizeof(struct nlm4_res_wrapper),
+               .pc_xdrressize  = NLM4_nlm4_res_sz,
+               .pc_name        = "CANCEL",
        },
        [NLMPROC_UNLOCK] = {
                .pc_func = nlm4svc_proc_unlock,
@@ -1057,6 +1122,7 @@ static const struct svc_procedure nlm4svc_procedures[24] = {
 union nlm4svc_xdrstore {
        struct nlm4_testargs_wrapper    testargs;
        struct nlm4_lockargs_wrapper    lockargs;
+       struct nlm4_cancargs_wrapper    cancargs;
        struct nlm4_testres_wrapper     testres;
        struct nlm4_res_wrapper         res;
        struct nlm_args                 args;