afs: Improve server refcount/active count tracing

Improve server refcount/active count tracing to distinguish between simply
getting/putting a ref and using/unusing the server record (which changes
the activity count as well as the refcount).  This makes it a bit easier to
work out what's going on.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/20250224234154.2014840-10-dhowells@redhat.com/ # v1
Link: https://lore.kernel.org/r/20250310094206.801057-6-dhowells@redhat.com/ # v4

Author: dhowells

fs/afs/fsclient.c

@@ -1653,7 +1653,7 @@ int afs_fs_give_up_all_callbacks(struct afs_net *net, struct afs_server *server,
 	bp = call->request;
 	*bp++ = htonl(FSGIVEUPALLCALLBACKS);
 
-	call->server = afs_use_server(server, afs_server_trace_give_up_cb);
+	call->server = afs_use_server(server, afs_server_trace_use_give_up_cb);
 	afs_make_call(call, GFP_NOFS);
 	afs_wait_for_call_to_complete(call);
 	ret = call->error;
@@ -1760,7 +1760,7 @@ bool afs_fs_get_capabilities(struct afs_net *net, struct afs_server *server,
 		return false;
 
 	call->key	= key;
-	call->server	= afs_use_server(server, afs_server_trace_get_caps);
+	call->server	= afs_use_server(server, afs_server_trace_use_get_caps);
 	call->peer	= rxrpc_kernel_get_peer(estate->addresses->addrs[addr_index].peer);
 	call->probe	= afs_get_endpoint_state(estate, afs_estate_trace_get_getcaps);
 	call->probe_index = addr_index;

fs/afs/rxrpc.c

@@ -179,7 +179,7 @@ static void afs_free_call(struct afs_call *call)
 	if (call->type->destructor)
 		call->type->destructor(call);
 
-	afs_unuse_server_notime(call->net, call->server, afs_server_trace_put_call);
+	afs_unuse_server_notime(call->net, call->server, afs_server_trace_unuse_call);
 	kfree(call->request);
 
 	o = atomic_read(&net->nr_outstanding_calls);

fs/afs/server.c

@@ -33,7 +33,7 @@ struct afs_server *afs_find_server(struct afs_net *net, const struct rxrpc_peer
 
 	do {
 		if (server)
-			afs_unuse_server_notime(net, server, afs_server_trace_put_find_rsq);
+			afs_unuse_server_notime(net, server, afs_server_trace_unuse_find_rsq);
 		server = NULL;
 		seq++; /* 2 on the 1st/lockless path, otherwise odd */
 		read_seqbegin_or_lock(&net->fs_addr_lock, &seq);
@@ -49,7 +49,7 @@ struct afs_server *afs_find_server(struct afs_net *net, const struct rxrpc_peer
 		server = NULL;
 		continue;
 	found:
-		server = afs_maybe_use_server(server, afs_server_trace_get_by_addr);
+		server = afs_maybe_use_server(server, afs_server_trace_use_by_addr);
 
 	} while (need_seqretry(&net->fs_addr_lock, seq));
 
@@ -76,7 +76,7 @@ struct afs_server *afs_find_server_by_uuid(struct afs_net *net, const uuid_t *uu
 		 * changes.
 		 */
 		if (server)
-			afs_unuse_server(net, server, afs_server_trace_put_uuid_rsq);
+			afs_unuse_server(net, server, afs_server_trace_unuse_uuid_rsq);
 		server = NULL;
 		seq++; /* 2 on the 1st/lockless path, otherwise odd */
 		read_seqbegin_or_lock(&net->fs_lock, &seq);
@@ -91,7 +91,7 @@ struct afs_server *afs_find_server_by_uuid(struct afs_net *net, const uuid_t *uu
 			} else if (diff > 0) {
 				p = p->rb_right;
 			} else {
-				afs_use_server(server, afs_server_trace_get_by_uuid);
+				afs_use_server(server, afs_server_trace_use_by_uuid);
 				break;
 			}
 
@@ -273,7 +273,8 @@ static struct afs_addr_list *afs_vl_lookup_addrs(struct afs_cell *cell,
 }
 
 /*
- * Get or create a fileserver record.
+ * Get or create a fileserver record and return it with an active-use count on
+ * it.
  */
 struct afs_server *afs_lookup_server(struct afs_cell *cell, struct key *key,
 				     const uuid_t *uuid, u32 addr_version)

fs/afs/server_list.c

@@ -16,7 +16,7 @@ void afs_put_serverlist(struct afs_net *net, struct afs_server_list *slist)
 	if (slist && refcount_dec_and_test(&slist->usage)) {
 		for (i = 0; i < slist->nr_servers; i++)
 			afs_unuse_server(net, slist->servers[i].server,
-					 afs_server_trace_put_slist);
+					 afs_server_trace_unuse_slist);
 		kfree_rcu(slist, rcu);
 	}
 }
@@ -98,7 +98,7 @@ struct afs_server_list *afs_alloc_server_list(struct afs_volume *volume,
 		if (j < slist->nr_servers) {
 			if (slist->servers[j].server == server) {
 				afs_unuse_server(volume->cell->net, server,
-						 afs_server_trace_put_slist_isort);
+						 afs_server_trace_unuse_slist_isort);
 				continue;
 			}
 

include/trace/events/afs.h

@@ -132,22 +132,25 @@ enum yfs_cm_operation {
 	EM(afs_server_trace_destroy,		"DESTROY  ") \
 	EM(afs_server_trace_free,		"FREE     ") \
 	EM(afs_server_trace_gc,			"GC       ") \
-	EM(afs_server_trace_get_by_addr,	"GET addr ") \
-	EM(afs_server_trace_get_by_uuid,	"GET uuid ") \
-	EM(afs_server_trace_get_caps,		"GET caps ") \
 	EM(afs_server_trace_get_install,	"GET inst ") \
-	EM(afs_server_trace_get_new_cbi,	"GET cbi  ") \
 	EM(afs_server_trace_get_probe,		"GET probe") \
-	EM(afs_server_trace_give_up_cb,		"giveup-cb") \
 	EM(afs_server_trace_purging,		"PURGE    ") \
-	EM(afs_server_trace_put_call,		"PUT call ") \
 	EM(afs_server_trace_put_cbi,		"PUT cbi  ") \
-	EM(afs_server_trace_put_find_rsq,	"PUT f-rsq") \
 	EM(afs_server_trace_put_probe,		"PUT probe") \
-	EM(afs_server_trace_put_slist,		"PUT slist") \
-	EM(afs_server_trace_put_slist_isort,	"PUT isort") \
-	EM(afs_server_trace_put_uuid_rsq,	"PUT u-req") \
-	E_(afs_server_trace_update,		"UPDATE")
+	EM(afs_server_trace_see_expired,	"SEE expd ") \
+	EM(afs_server_trace_unuse_call,		"UNU call ") \
+	EM(afs_server_trace_unuse_create_fail,	"UNU cfail") \
+	EM(afs_server_trace_unuse_find_rsq,	"UNU f-rsq") \
+	EM(afs_server_trace_unuse_slist,	"UNU slist") \
+	EM(afs_server_trace_unuse_slist_isort,	"UNU isort") \
+	EM(afs_server_trace_unuse_uuid_rsq,	"PUT u-req") \
+	EM(afs_server_trace_update,		"UPDATE   ") \
+	EM(afs_server_trace_use_by_addr,	"USE addr ") \
+	EM(afs_server_trace_use_by_uuid,	"USE uuid ") \
+	EM(afs_server_trace_use_cm_call,	"USE cm-cl") \
+	EM(afs_server_trace_use_get_caps,	"USE gcaps") \
+	EM(afs_server_trace_use_give_up_cb,	"USE gvupc") \
+	E_(afs_server_trace_wait_create,	"WAIT crt ")
 
 #define afs_volume_traces \
 	EM(afs_volume_trace_alloc,		"ALLOC         ") \
@@ -1531,7 +1534,7 @@ TRACE_EVENT(afs_server,
 		    __entry->reason = reason;
 			   ),
 
-	    TP_printk("s=%08x %s u=%d a=%d",
+	    TP_printk("s=%08x %s r=%d a=%d",
 		      __entry->server,
 		      __print_symbolic(__entry->reason, afs_server_traces),
 		      __entry->ref,