bcachefs: Tracepoint improvements

This improves the transaction restart tracepoints - adding distinct
tracepoints for all the locations and reasons a transaction might have
been restarted, and ensures that there's a tracepoint for every
transaction restart.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

fs/bcachefs/btree_cache.c

@@ -665,6 +665,8 @@ static noinline struct btree *bch2_btree_node_fill(struct bch_fs *c,
 	 * been freed:
 	 */
 	if (trans && !bch2_btree_node_relock(trans, path, level + 1)) {
+		trace_trans_restart_relock_parent_for_fill(trans->fn,
+					_THIS_IP_, btree_id, &path->pos);
 		btree_trans_restart(trans);
 		return ERR_PTR(-EINTR);
 	}
@@ -712,6 +714,8 @@ static noinline struct btree *bch2_btree_node_fill(struct bch_fs *c,
 	}
 
 	if (!six_relock_type(&b->c.lock, lock_type, seq)) {
+		trace_trans_restart_relock_after_fill(trans->fn, _THIS_IP_,
+					   btree_id, &path->pos);
 		btree_trans_restart(trans);
 		return ERR_PTR(-EINTR);
 	}

fs/bcachefs/btree_iter.c

@@ -166,19 +166,25 @@ bool __bch2_btree_node_relock(struct btree_trans *trans,
 	int want = __btree_lock_want(path, level);
 
 	if (!is_btree_node(path, level))
-		return false;
+		goto fail;
 
 	if (race_fault())
-		return false;
+		goto fail;
 
 	if (six_relock_type(&b->c.lock, want, path->l[level].lock_seq) ||
 	    (btree_node_lock_seq_matches(path, b, level) &&
 	     btree_node_lock_increment(trans, b, level, want))) {
 		mark_btree_node_locked(path, level, want);
 		return true;
-	} else {
-		return false;
 	}
+fail:
+	trace_btree_node_relock_fail(trans->fn, _RET_IP_,
+				     path->btree_id,
+				     &path->pos,
+				     (unsigned long) b,
+				     path->l[level].lock_seq,
+				     is_btree_node(path, level) ? b->c.lock.state.seq : 0);
+	return false;
 }
 
 bool bch2_btree_node_upgrade(struct btree_trans *trans,
@@ -225,7 +231,7 @@ bool bch2_btree_node_upgrade(struct btree_trans *trans,
 
 static inline bool btree_path_get_locks(struct btree_trans *trans,
 					struct btree_path *path,
-					bool upgrade, unsigned long trace_ip)
+					bool upgrade)
 {
 	unsigned l = path->level;
 	int fail_idx = -1;
@@ -427,6 +433,8 @@ bool bch2_btree_path_relock_intent(struct btree_trans *trans,
 		if (!bch2_btree_node_relock(trans, path, l)) {
 			__bch2_btree_path_unlock(path);
 			btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE);
+			trace_trans_restart_relock_path_intent(trans->fn, _RET_IP_,
+						   path->btree_id, &path->pos);
 			btree_trans_restart(trans);
 			return false;
 		}
@@ -439,10 +447,13 @@ __flatten
 static bool bch2_btree_path_relock(struct btree_trans *trans,
 			struct btree_path *path, unsigned long trace_ip)
 {
-	bool ret = btree_path_get_locks(trans, path, false, trace_ip);
+	bool ret = btree_path_get_locks(trans, path, false);
 
-	if (!ret)
+	if (!ret) {
+		trace_trans_restart_relock_path(trans->fn, trace_ip,
+						path->btree_id, &path->pos);
 		btree_trans_restart(trans);
+	}
 	return ret;
 }
 
@@ -456,7 +467,7 @@ bool __bch2_btree_path_upgrade(struct btree_trans *trans,
 
 	path->locks_want = new_locks_want;
 
-	if (btree_path_get_locks(trans, path, true, _THIS_IP_))
+	if (btree_path_get_locks(trans, path, true))
 		return true;
 
 	/*
@@ -484,7 +495,7 @@ bool __bch2_btree_path_upgrade(struct btree_trans *trans,
 		    linked->btree_id == path->btree_id &&
 		    linked->locks_want < new_locks_want) {
 			linked->locks_want = new_locks_want;
-			btree_path_get_locks(trans, linked, true, _THIS_IP_);
+			btree_path_get_locks(trans, linked, true);
 		}
 
 	return false;
@@ -1955,7 +1966,7 @@ struct btree_path *bch2_path_get(struct btree_trans *trans,
 	locks_want = min(locks_want, BTREE_MAX_DEPTH);
 	if (locks_want > path->locks_want) {
 		path->locks_want = locks_want;
-		btree_path_get_locks(trans, path, true, _THIS_IP_);
+		btree_path_get_locks(trans, path, true);
 	}
 
 	return path;
@@ -2090,6 +2101,8 @@ struct btree *bch2_btree_iter_next_node(struct btree_iter *iter)
 		__bch2_btree_path_unlock(path);
 		path->l[path->level].b = BTREE_ITER_NO_NODE_GET_LOCKS;
 		path->l[path->level + 1].b = BTREE_ITER_NO_NODE_GET_LOCKS;
+		trace_trans_restart_relock_next_node(trans->fn, _THIS_IP_,
+					   path->btree_id, &path->pos);
 		btree_trans_restart(trans);
 		ret = -EINTR;
 		goto err;

fs/bcachefs/btree_key_cache.c

@@ -223,7 +223,8 @@ static int btree_key_cache_fill(struct btree_trans *trans,
 		goto err;
 
 	if (!bch2_btree_node_relock(trans, ck_path, 0)) {
-		trace_transaction_restart_ip(trans->fn, _THIS_IP_);
+		trace_trans_restart_relock_key_cache_fill(trans->fn,
+				_THIS_IP_, ck_path->btree_id, &ck_path->pos);
 		ret = btree_trans_restart(trans);
 		goto err;
 	}

fs/bcachefs/trace.h

@@ -346,6 +346,52 @@ TRACE_EVENT(btree_cache_scan,
 		  __entry->ret)
 );
 
+TRACE_EVENT(btree_node_relock_fail,
+	TP_PROTO(const char *trans_fn,
+		 unsigned long caller_ip,
+		 enum btree_id btree_id,
+		 struct bpos *pos,
+		 unsigned long node,
+		 u32 iter_lock_seq,
+		 u32 node_lock_seq),
+	TP_ARGS(trans_fn, caller_ip, btree_id, pos, node, iter_lock_seq, node_lock_seq),
+
+	TP_STRUCT__entry(
+		__array(char,			trans_fn, 24	)
+		__array(char,			caller, 32	)
+		__field(u8,			btree_id	)
+		__field(u64,			pos_inode	)
+		__field(u64,			pos_offset	)
+		__field(u32,			pos_snapshot	)
+		__field(unsigned long,		node		)
+		__field(u32,			iter_lock_seq	)
+		__field(u32,			node_lock_seq	)
+	),
+
+	TP_fast_assign(
+		strncpy(__entry->trans_fn, trans_fn, sizeof(__entry->trans_fn));
+		snprintf(__entry->caller, sizeof(__entry->caller), "%pS", (void *) caller_ip);
+		__entry->btree_id		= btree_id;
+		__entry->pos_inode		= pos->inode;
+		__entry->pos_offset		= pos->offset;
+		__entry->pos_snapshot		= pos->snapshot;
+		__entry->node			= node;
+		__entry->iter_lock_seq		= iter_lock_seq;
+		__entry->node_lock_seq		= node_lock_seq;
+	),
+
+	TP_printk("%s %s btree %u pos %llu:%llu:%u, node %lu iter seq %u lock seq %u",
+		  __entry->trans_fn,
+		  __entry->caller,
+		  __entry->btree_id,
+		  __entry->pos_inode,
+		  __entry->pos_offset,
+		  __entry->pos_snapshot,
+		  __entry->node,
+		  __entry->iter_lock_seq,
+		  __entry->node_lock_seq)
+);
+
 /* Garbage collection */
 
 DEFINE_EVENT(btree_node, btree_gc_rewrite_node,
@@ -621,7 +667,7 @@ DECLARE_EVENT_CLASS(transaction_restart_iter,
 
 	TP_STRUCT__entry(
 		__array(char,			trans_fn, 24	)
-		__field(unsigned long,		caller_ip	)
+		__array(char,			caller, 32	)
 		__field(u8,			btree_id	)
 		__field(u64,			pos_inode	)
 		__field(u64,			pos_offset	)
@@ -630,16 +676,16 @@ DECLARE_EVENT_CLASS(transaction_restart_iter,
 
 	TP_fast_assign(
 		strncpy(__entry->trans_fn, trans_fn, sizeof(__entry->trans_fn));
-		__entry->caller_ip		= caller_ip;
+		snprintf(__entry->caller, sizeof(__entry->caller), "%pS", (void *) caller_ip);
 		__entry->btree_id		= btree_id;
 		__entry->pos_inode		= pos->inode;
 		__entry->pos_offset		= pos->offset;
 		__entry->pos_snapshot		= pos->snapshot;
 	),
 
-	TP_printk("%s %pS btree %u pos %llu:%llu:%u",
+	TP_printk("%s %s btree %u pos %llu:%llu:%u",
 		  __entry->trans_fn,
-		  (void *) __entry->caller_ip,
+		  __entry->caller,
 		  __entry->btree_id,
 		  __entry->pos_inode,
 		  __entry->pos_offset,
@@ -694,6 +740,54 @@ DEFINE_EVENT(transaction_restart_iter,	trans_restart_relock,
 	TP_ARGS(trans_fn, caller_ip, btree_id, pos)
 );
 
+DEFINE_EVENT(transaction_restart_iter,	trans_restart_relock_next_node,
+	TP_PROTO(const char *trans_fn,
+		 unsigned long caller_ip,
+		 enum btree_id btree_id,
+		 struct bpos *pos),
+	TP_ARGS(trans_fn, caller_ip, btree_id, pos)
+);
+
+DEFINE_EVENT(transaction_restart_iter,	trans_restart_relock_parent_for_fill,
+	TP_PROTO(const char *trans_fn,
+		 unsigned long caller_ip,
+		 enum btree_id btree_id,
+		 struct bpos *pos),
+	TP_ARGS(trans_fn, caller_ip, btree_id, pos)
+);
+
+DEFINE_EVENT(transaction_restart_iter,	trans_restart_relock_after_fill,
+	TP_PROTO(const char *trans_fn,
+		 unsigned long caller_ip,
+		 enum btree_id btree_id,
+		 struct bpos *pos),
+	TP_ARGS(trans_fn, caller_ip, btree_id, pos)
+);
+
+DEFINE_EVENT(transaction_restart_iter,	trans_restart_relock_key_cache_fill,
+	TP_PROTO(const char *trans_fn,
+		 unsigned long caller_ip,
+		 enum btree_id btree_id,
+		 struct bpos *pos),
+	TP_ARGS(trans_fn, caller_ip, btree_id, pos)
+);
+
+DEFINE_EVENT(transaction_restart_iter,	trans_restart_relock_path,
+	TP_PROTO(const char *trans_fn,
+		 unsigned long caller_ip,
+		 enum btree_id btree_id,
+		 struct bpos *pos),
+	TP_ARGS(trans_fn, caller_ip, btree_id, pos)
+);
+
+DEFINE_EVENT(transaction_restart_iter,	trans_restart_relock_path_intent,
+	TP_PROTO(const char *trans_fn,
+		 unsigned long caller_ip,
+		 enum btree_id btree_id,
+		 struct bpos *pos),
+	TP_ARGS(trans_fn, caller_ip, btree_id, pos)
+);
+
 DEFINE_EVENT(transaction_restart_iter,	trans_restart_traverse,
 	TP_PROTO(const char *trans_fn,
 		 unsigned long caller_ip,