rxrpc, afs: Allow afs to pin rxrpc_peer objects

Change rxrpc's API such that:

 (1) A new function, rxrpc_kernel_lookup_peer(), is provided to look up an
     rxrpc_peer record for a remote address and a corresponding function,
     rxrpc_kernel_put_peer(), is provided to dispose of it again.

 (2) When setting up a call, the rxrpc_peer object used during a call is
     now passed in rather than being set up by rxrpc_connect_call().  For
     afs, this meenat passing it to rxrpc_kernel_begin_call() rather than
     the full address (the service ID then has to be passed in as a
     separate parameter).

 (3) A new function, rxrpc_kernel_remote_addr(), is added so that afs can
     get a pointer to the transport address for display purposed, and
     another, rxrpc_kernel_remote_srx(), to gain a pointer to the full
     rxrpc address.

 (4) The function to retrieve the RTT from a call, rxrpc_kernel_get_srtt(),
     is then altered to take a peer.  This now returns the RTT or -1 if
     there are insufficient samples.

 (5) Rename rxrpc_kernel_get_peer() to rxrpc_kernel_call_get_peer().

 (6) Provide a new function, rxrpc_kernel_get_peer(), to get a ref on a
     peer the caller already has.

This allows the afs filesystem to pin the rxrpc_peer records that it is
using, allowing faster lookups and pointer comparisons rather than
comparing sockaddr_rxrpc contents.  It also makes it easier to get hold of
the RTT.  The following changes are made to afs:

 (1) The addr_list struct's addrs[] elements now hold a peer struct pointer
     and a service ID rather than a sockaddr_rxrpc.

 (2) When displaying the transport address, rxrpc_kernel_remote_addr() is
     used.

 (3) The port arg is removed from afs_alloc_addrlist() since it's always
     overridden.

 (4) afs_merge_fs_addr4() and afs_merge_fs_addr6() do peer lookup and may
     now return an error that must be handled.

 (5) afs_find_server() now takes a peer pointer to specify the address.

 (6) afs_find_server(), afs_compare_fs_alists() and afs_merge_fs_addr[46]{}
     now do peer pointer comparison rather than address comparison.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org

1 files changed, 37 insertions, 21 deletions

diff --git a/net/rxrpc/peer_object.c b/net/rxrpc/peer_object.c
index 8d7a715a0bb1..49dcda67a0d5 100644
--- a/net/rxrpc/peer_object.c
+++ b/net/rxrpc/peer_object.c
@@ -22,6 +22,8 @@
 #include <net/ip6_route.h>
 #include "ar-internal.h"
 
+static const struct sockaddr_rxrpc rxrpc_null_addr;
+
 /*
  * Hash a peer key.
  */
@@ -457,39 +459,53 @@ void rxrpc_destroy_all_peers(struct rxrpc_net *rxnet)
 }
 
 /**
- * rxrpc_kernel_get_peer - Get the peer address of a call
+ * rxrpc_kernel_get_call_peer - Get the peer address of a call
  * @sock: The socket on which the call is in progress.
  * @call: The call to query
- * @_srx: Where to place the result
  *
- * Get the address of the remote peer in a call.
+ * Get a record for the remote peer in a call.
  */
-void rxrpc_kernel_get_peer(struct socket *sock, struct rxrpc_call *call,
-			   struct sockaddr_rxrpc *_srx)
+struct rxrpc_peer *rxrpc_kernel_get_call_peer(struct socket *sock, struct rxrpc_call *call)
 {
-	*_srx = call->peer->srx;
+	return call->peer;
 }
-EXPORT_SYMBOL(rxrpc_kernel_get_peer);
+EXPORT_SYMBOL(rxrpc_kernel_get_call_peer);
 
 /**
  * rxrpc_kernel_get_srtt - Get a call's peer smoothed RTT
- * @sock: The socket on which the call is in progress.
- * @call: The call to query
- * @_srtt: Where to store the SRTT value.
+ * @peer: The peer to query
  *
- * Get the call's peer smoothed RTT in uS.
+ * Get the call's peer smoothed RTT in uS or UINT_MAX if we have no samples.
  */
-bool rxrpc_kernel_get_srtt(struct socket *sock, struct rxrpc_call *call,
-			   u32 *_srtt)
+unsigned int rxrpc_kernel_get_srtt(const struct rxrpc_peer *peer)
 {
-	struct rxrpc_peer *peer = call->peer;
+	return peer->rtt_count > 0 ? peer->srtt_us >> 3 : UINT_MAX;
+}
+EXPORT_SYMBOL(rxrpc_kernel_get_srtt);
 
-	if (peer->rtt_count == 0) {
-		*_srtt = 1000000; /* 1S */
-		return false;
-	}
+/**
+ * rxrpc_kernel_remote_srx - Get the address of a peer
+ * @peer: The peer to query
+ *
+ * Get a pointer to the address from a peer record.  The caller is responsible
+ * for making sure that the address is not deallocated.
+ */
+const struct sockaddr_rxrpc *rxrpc_kernel_remote_srx(const struct rxrpc_peer *peer)
+{
+	return peer ? &peer->srx : &rxrpc_null_addr;
+}
+EXPORT_SYMBOL(rxrpc_kernel_remote_srx);
 
-	*_srtt = call->peer->srtt_us >> 3;
-	return true;
+/**
+ * rxrpc_kernel_remote_addr - Get the peer transport address of a call
+ * @peer: The peer to query
+ *
+ * Get a pointer to the transport address from a peer record.  The caller is
+ * responsible for making sure that the address is not deallocated.
+ */
+const struct sockaddr *rxrpc_kernel_remote_addr(const struct rxrpc_peer *peer)
+{
+	return (const struct sockaddr *)
+		(peer ? &peer->srx.transport : &rxrpc_null_addr.transport);
 }
-EXPORT_SYMBOL(rxrpc_kernel_get_srtt);
+EXPORT_SYMBOL(rxrpc_kernel_remote_addr);