afs: Don't cache preferred address

In the AFS fileserver rotation algorithm, don't cache the preferred address
for the server as that will override the explicit preference if a
non-preferred address responds first.

Fixes: 495f2ae9 ("afs: Fix fileserver rotation")
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/20240313081505.3060173-2-dhowells@redhat.comReviewed-by: Marc Dionne <marc.dionne@auristor.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Signed-off-by: Christian Brauner <brauner@kernel.org>

fs/afs/rotate.c

@@ -602,6 +602,8 @@ bool afs_select_fileserver(struct afs_operation *op)
 		goto wait_for_more_probe_results;
 
 	alist = op->estate->addresses;
+	best_prio = -1;
+	addr_index = 0;
 	for (i = 0; i < alist->nr_addrs; i++) {
 		if (alist->addrs[i].prio > best_prio) {
 			addr_index = i;
@@ -609,9 +611,7 @@ bool afs_select_fileserver(struct afs_operation *op)
 		}
 	}
 
-	addr_index = READ_ONCE(alist->preferred);
-	if (!test_bit(addr_index, &set))
-		addr_index = __ffs(set);
+	alist->preferred = addr_index;
 
 	op->addr_index = addr_index;
 	set_bit(addr_index, &op->addr_tried);
@@ -656,12 +656,6 @@ bool afs_select_fileserver(struct afs_operation *op)
 next_server:
 	trace_afs_rotate(op, afs_rotate_trace_next_server, 0);
 	_debug("next");
-	ASSERT(op->estate);
-	alist = op->estate->addresses;
-	if (op->call_responded &&
-	    op->addr_index != READ_ONCE(alist->preferred) &&
-	    test_bit(alist->preferred, &op->addr_tried))
-		WRITE_ONCE(alist->preferred, op->addr_index);
 	op->estate = NULL;
 	goto pick_server;
 
@@ -690,14 +684,7 @@ bool afs_select_fileserver(struct afs_operation *op)
 failed:
 	trace_afs_rotate(op, afs_rotate_trace_failed, 0);
 	op->flags |= AFS_OPERATION_STOP;
-	if (op->estate) {
-		alist = op->estate->addresses;
-		if (op->call_responded &&
-		    op->addr_index != READ_ONCE(alist->preferred) &&
-		    test_bit(alist->preferred, &op->addr_tried))
-			WRITE_ONCE(alist->preferred, op->addr_index);
-		op->estate = NULL;
-	}
+	op->estate = NULL;
 	_leave(" = f [failed %d]", afs_op_error(op));
 	return false;
 }