nfs/localio: remove redundant code and simplify LOCALIO enablement

Remove nfs_local_enable and nfs_local_disable, instead use
nfs_localio_enable_client and nfs_localio_disable_client.

Discontinue use of the NFS_CS_LOCAL_IO bit in the nfs_client struct's
cl_flags to reflect that LOCALIO is enabled; instead just test if the
net member of the nfs_uuid_t struct is set.

Also remove NFS_CS_LOCAL_IO.

Lastly, remove trace_nfs_local_enable and trace_nfs_local_disable
because comparable traces are available from nfs_localio.ko.

Suggested-by: NeilBrown <neilb@suse.de>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>

Author: Mike Snitzer

fs/nfs/client.c

@@ -38,7 +38,7 @@
 #include <linux/sunrpc/bc_xprt.h>
 #include <linux/nsproxy.h>
 #include <linux/pid_namespace.h>
-
+#include <linux/nfslocalio.h>
 
 #include "nfs4_fs.h"
 #include "callback.h"
@@ -243,7 +243,7 @@ static void pnfs_init_server(struct nfs_server *server)
  */
 void nfs_free_client(struct nfs_client *clp)
 {
-	nfs_local_disable(clp);
+	nfs_localio_disable_client(clp);
 
 	/* -EIO all pending I/O */
 	if (!IS_ERR(clp->cl_rpcclient))

fs/nfs/internal.h

@@ -455,7 +455,6 @@ extern int nfs_wait_bit_killable(struct wait_bit_key *key, int mode);
 
 #if IS_ENABLED(CONFIG_NFS_LOCALIO)
 /* localio.c */
-extern void nfs_local_disable(struct nfs_client *);
 extern void nfs_local_probe(struct nfs_client *);
 extern struct nfsd_file *nfs_local_open_fh(struct nfs_client *,
 					   const struct cred *,
@@ -472,7 +471,6 @@ extern int nfs_local_commit(struct nfsd_file *,
 extern bool nfs_server_is_local(const struct nfs_client *clp);
 
 #else /* CONFIG_NFS_LOCALIO */
-static inline void nfs_local_disable(struct nfs_client *clp) {}
 static inline void nfs_local_probe(struct nfs_client *clp) {}
 static inline struct nfsd_file *
 nfs_local_open_fh(struct nfs_client *clp, const struct cred *cred,

fs/nfs/localio.c

@@ -56,7 +56,7 @@ MODULE_PARM_DESC(localio_O_DIRECT_semantics,
 
 static inline bool nfs_client_is_local(const struct nfs_client *clp)
 {
-	return !!test_bit(NFS_CS_LOCAL_IO, &clp->cl_flags);
+	return !!rcu_access_pointer(clp->cl_uuid.net);
 }
 
 bool nfs_server_is_local(const struct nfs_client *clp)
@@ -121,24 +121,6 @@ const struct rpc_program nfslocalio_program = {
 	.stats			= &nfslocalio_rpcstat,
 };
 
-/*
- * nfs_local_enable - enable local i/o for an nfs_client
- */
-static void nfs_local_enable(struct nfs_client *clp)
-{
-	trace_nfs_local_enable(clp);
-	nfs_localio_enable_client(clp);
-}
-
-/*
- * nfs_local_disable - disable local i/o for an nfs_client
- */
-void nfs_local_disable(struct nfs_client *clp)
-{
-	trace_nfs_local_disable(clp);
-	nfs_localio_disable_client(clp);
-}
-
 /*
  * nfs_init_localioclient - Initialise an NFS localio client connection
  */
@@ -194,19 +176,19 @@ void nfs_local_probe(struct nfs_client *clp)
 	/* Disallow localio if disabled via sysfs or AUTH_SYS isn't used */
 	if (!localio_enabled ||
 	    clp->cl_rpcclient->cl_auth->au_flavor != RPC_AUTH_UNIX) {
-		nfs_local_disable(clp);
+		nfs_localio_disable_client(clp);
 		return;
 	}
 
 	if (nfs_client_is_local(clp)) {
 		/* If already enabled, disable and re-enable */
-		nfs_local_disable(clp);
+		nfs_localio_disable_client(clp);
 	}
 
 	if (!nfs_uuid_begin(&clp->cl_uuid))
 		return;
 	if (nfs_server_uuid_is_local(clp))
-		nfs_local_enable(clp);
+		nfs_localio_enable_client(clp);
 	nfs_uuid_end(&clp->cl_uuid);
 }
 EXPORT_SYMBOL_GPL(nfs_local_probe);
@@ -748,7 +730,7 @@ int nfs_local_doio(struct nfs_client *clp, struct nfsd_file *localio,
 
 	if (status != 0) {
 		if (status == -EAGAIN)
-			nfs_local_disable(clp);
+			nfs_localio_disable_client(clp);
 		nfs_local_file_put(localio);
 		hdr->task.tk_status = status;
 		nfs_local_hdr_release(hdr, call_ops);

fs/nfs/nfstrace.h

@@ -1714,38 +1714,6 @@ TRACE_EVENT(nfs_local_open_fh,
 		)
 );
 
-DECLARE_EVENT_CLASS(nfs_local_client_event,
-		TP_PROTO(
-			const struct nfs_client *clp
-		),
-
-		TP_ARGS(clp),
-
-		TP_STRUCT__entry(
-			__field(unsigned int, protocol)
-			__string(server, clp->cl_hostname)
-		),
-
-		TP_fast_assign(
-			__entry->protocol = clp->rpc_ops->version;
-			__assign_str(server);
-		),
-
-		TP_printk(
-			"server=%s NFSv%u", __get_str(server), __entry->protocol
-		)
-);
-
-#define DEFINE_NFS_LOCAL_CLIENT_EVENT(name) \
-	DEFINE_EVENT(nfs_local_client_event, name, \
-			TP_PROTO( \
-				const struct nfs_client *clp \
-			), \
-			TP_ARGS(clp))
-
-DEFINE_NFS_LOCAL_CLIENT_EVENT(nfs_local_enable);
-DEFINE_NFS_LOCAL_CLIENT_EVENT(nfs_local_disable);
-
 DECLARE_EVENT_CLASS(nfs_xdr_event,
 		TP_PROTO(
 			const struct xdr_stream *xdr,

fs/nfs_common/nfslocalio.c

@@ -37,7 +37,7 @@ static LIST_HEAD(nfs_uuids);
 
 void nfs_uuid_init(nfs_uuid_t *nfs_uuid)
 {
-	nfs_uuid->net = NULL;
+	RCU_INIT_POINTER(nfs_uuid->net, NULL);
 	nfs_uuid->dom = NULL;
 	nfs_uuid->list_lock = NULL;
 	INIT_LIST_HEAD(&nfs_uuid->list);
@@ -49,7 +49,7 @@ EXPORT_SYMBOL_GPL(nfs_uuid_init);
 bool nfs_uuid_begin(nfs_uuid_t *nfs_uuid)
 {
 	spin_lock(&nfs_uuid->lock);
-	if (nfs_uuid->net) {
+	if (rcu_access_pointer(nfs_uuid->net)) {
 		/* This nfs_uuid is already in use */
 		spin_unlock(&nfs_uuid->lock);
 		return false;
@@ -74,9 +74,9 @@ EXPORT_SYMBOL_GPL(nfs_uuid_begin);
 
 void nfs_uuid_end(nfs_uuid_t *nfs_uuid)
 {
-	if (nfs_uuid->net == NULL) {
+	if (!rcu_access_pointer(nfs_uuid->net)) {
 		spin_lock(&nfs_uuid->lock);
-		if (nfs_uuid->net == NULL) {
+		if (!rcu_access_pointer(nfs_uuid->net)) {
 			/* Not local, remove from nfs_uuids */
 			spin_lock(&nfs_uuids_lock);
 			list_del_init(&nfs_uuid->list);
@@ -139,28 +139,24 @@ EXPORT_SYMBOL_GPL(nfs_uuid_is_local);
 
 void nfs_localio_enable_client(struct nfs_client *clp)
 {
-	nfs_uuid_t *nfs_uuid = &clp->cl_uuid;
-
-	spin_lock(&nfs_uuid->lock);
-	set_bit(NFS_CS_LOCAL_IO, &clp->cl_flags);
+	/* nfs_uuid_is_local() does the actual enablement */
 	trace_nfs_localio_enable_client(clp);
-	spin_unlock(&nfs_uuid->lock);
 }
 EXPORT_SYMBOL_GPL(nfs_localio_enable_client);
 
 /*
  * Cleanup the nfs_uuid_t embedded in an nfs_client.
  * This is the long-form of nfs_uuid_init().
  */
-static void nfs_uuid_put(nfs_uuid_t *nfs_uuid)
+static bool nfs_uuid_put(nfs_uuid_t *nfs_uuid)
 {
 	LIST_HEAD(local_files);
 	struct nfs_file_localio *nfl, *tmp;
 
 	spin_lock(&nfs_uuid->lock);
-	if (unlikely(!nfs_uuid->net)) {
+	if (unlikely(!rcu_access_pointer(nfs_uuid->net))) {
 		spin_unlock(&nfs_uuid->lock);
-		return;
+		return false;
 	}
 	RCU_INIT_POINTER(nfs_uuid->net, NULL);
 
@@ -192,22 +188,14 @@ static void nfs_uuid_put(nfs_uuid_t *nfs_uuid)
 
 	module_put(nfsd_mod);
 	spin_unlock(&nfs_uuid->lock);
+
+	return true;
 }
 
 void nfs_localio_disable_client(struct nfs_client *clp)
 {
-	nfs_uuid_t *nfs_uuid = NULL;
-
-	spin_lock(&clp->cl_uuid.lock); /* aka &nfs_uuid->lock */
-	if (test_and_clear_bit(NFS_CS_LOCAL_IO, &clp->cl_flags)) {
-		/* &clp->cl_uuid is always not NULL, using as bool here */
-		nfs_uuid = &clp->cl_uuid;
+	if (nfs_uuid_put(&clp->cl_uuid))
 		trace_nfs_localio_disable_client(clp);
-	}
-	spin_unlock(&clp->cl_uuid.lock);
-
-	if (nfs_uuid)
-		nfs_uuid_put(nfs_uuid);
 }
 EXPORT_SYMBOL_GPL(nfs_localio_disable_client);
 

include/linux/nfs_fs_sb.h

@@ -50,7 +50,6 @@ struct nfs_client {
 #define NFS_CS_DS		7		/* - Server is a DS */
 #define NFS_CS_REUSEPORT	8		/* - reuse src port on reconnect */
 #define NFS_CS_PNFS		9		/* - Server used for pnfs */
-#define NFS_CS_LOCAL_IO		10		/* - client is local */
 	struct sockaddr_storage	cl_addr;	/* server identifier */
 	size_t			cl_addrlen;
 	char *			cl_hostname;	/* hostname of server */

include/linux/nfslocalio.h

@@ -111,6 +111,10 @@ static inline void nfs_close_local_fh(struct nfs_file_localio *nfl)
 static inline void nfsd_localio_ops_init(void)
 {
 }
+struct nfs_client;
+static inline void nfs_localio_disable_client(struct nfs_client *clp)
+{
+}
 
 #endif  /* CONFIG_NFS_LOCALIO */