[PATCH 6.12.y 4/8] rxrpc: Allow the app to store private data on peer structs

[Sasha Levin <sashal@kernel.org>]

From: David Howells <dhowells@redhat.com>

[ Upstream commit f3a123b25429dc03508e3bf598373005220b7203 ]

Provide a way for the application (e.g. the afs filesystem) to store
private data on the rxrpc_peer structs for later retrieval via the call
object.

This will allow afs to store a pointer to the afs_server object on the
rxrpc_peer struct, thereby obviating the need for afs to keep lookup tables
by which it can associate an incoming call with server that transmitted it.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: Jakub Kicinski <kuba@kernel.org>
cc: "David S. Miller" <davem@davemloft.net>
cc: Eric Dumazet <edumazet@google.com>
cc: Paolo Abeni <pabeni@redhat.com>
cc: Simon Horman <horms@kernel.org>
cc: linux-afs@lists.infradead.org
cc: linux-fsdevel@vger.kernel.org
cc: netdev@vger.kernel.org
Link: https://lore.kernel.org/r/20250224234154.2014840-13-dhowells@redhat.com/ # v1
Link: https://lore.kernel.org/r/20250310094206.801057-9-dhowells@redhat.com/ # v4
Stable-dep-of: 330e2c514823 ("afs: Fix dynamic lookup to fail on cell lookup failure")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 include/net/af_rxrpc.h  |  2 ++
 net/rxrpc/ar-internal.h |  1 +
 net/rxrpc/peer_object.c | 26 ++++++++++++++++++++++++++
 3 files changed, 29 insertions(+)

diff --git a/include/net/af_rxrpc.h b/include/net/af_rxrpc.h
index 0754c463224a43..cf793d18e5df51 100644
--- a/include/net/af_rxrpc.h
+++ b/include/net/af_rxrpc.h
@@ -69,6 +69,8 @@ struct rxrpc_peer *rxrpc_kernel_get_peer(struct rxrpc_peer *peer);
 struct rxrpc_peer *rxrpc_kernel_get_call_peer(struct socket *sock, struct rxrpc_call *call);
 const struct sockaddr_rxrpc *rxrpc_kernel_remote_srx(const struct rxrpc_peer *peer);
 const struct sockaddr *rxrpc_kernel_remote_addr(const struct rxrpc_peer *peer);
+unsigned long rxrpc_kernel_set_peer_data(struct rxrpc_peer *peer, unsigned long app_data);
+unsigned long rxrpc_kernel_get_peer_data(const struct rxrpc_peer *peer);
 unsigned int rxrpc_kernel_get_srtt(const struct rxrpc_peer *);
 int rxrpc_kernel_charge_accept(struct socket *, rxrpc_notify_rx_t,
 			       rxrpc_user_attach_call_t, unsigned long, gfp_t,
diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index 61dd1298124f62..346fb8fa2cafcd 100644
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -334,6 +334,7 @@ struct rxrpc_peer {
 	struct hlist_head	error_targets;	/* targets for net error distribution */
 	struct rb_root		service_conns;	/* Service connections */
 	struct list_head	keepalive_link;	/* Link in net->peer_keepalive[] */
+	unsigned long		app_data;	/* Application data (e.g. afs_server) */
 	unsigned int		last_tx_at;	/* Last time packet sent here (time64_t LSW) */
 	seqlock_t		service_conn_lock;
 	spinlock_t		lock;		/* access lock */
diff --git a/net/rxrpc/peer_object.c b/net/rxrpc/peer_object.c
index 956fc7ea4b7346..5664469fdd0c77 100644
--- a/net/rxrpc/peer_object.c
+++ b/net/rxrpc/peer_object.c
@@ -509,3 +509,29 @@ const struct sockaddr *rxrpc_kernel_remote_addr(const struct rxrpc_peer *peer)
 		(peer ? &peer->srx.transport : &rxrpc_null_addr.transport);
 }
 EXPORT_SYMBOL(rxrpc_kernel_remote_addr);
+
+/**
+ * rxrpc_kernel_set_peer_data - Set app-specific data on a peer.
+ * @peer: The peer to alter
+ * @app_data: The data to set
+ *
+ * Set the app-specific data on a peer.  AF_RXRPC makes no effort to retain
+ * anything the data might refer to.  The previous app_data is returned.
+ */
+unsigned long rxrpc_kernel_set_peer_data(struct rxrpc_peer *peer, unsigned long app_data)
+{
+	return xchg(&peer->app_data, app_data);
+}
+EXPORT_SYMBOL(rxrpc_kernel_set_peer_data);
+
+/**
+ * rxrpc_kernel_get_peer_data - Get app-specific data from a peer.
+ * @peer: The peer to query
+ *
+ * Retrieve the app-specific data from a peer.
+ */
+unsigned long rxrpc_kernel_get_peer_data(const struct rxrpc_peer *peer)
+{
+	return peer->app_data;
+}
+EXPORT_SYMBOL(rxrpc_kernel_get_peer_data);
-- 
2.53.0