bcachefs: Better trigger ordering

Transactional triggers need to run in a defined ordering, which is not
quite the same as btree ID integer comparison.

Previously this was handled in a hacky way in
bch2_trans_commit_run_triggers(), since it was only the alloc btree that
needed special handling, but upcoming stripe btree changes are going to
require more ordering changes - so, define that ordering.

Next patch will change the transaction commit path to use it.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/btree_types.h

@@ -423,6 +423,7 @@ static inline struct bpos btree_node_pos(struct btree_bkey_cached_common *b)
 
 struct btree_insert_entry {
 	unsigned		flags;
+	u8			sort_order;
 	u8			bkey_type;
 	enum btree_id		btree_id:8;
 	u8			level:4;
@@ -853,6 +854,18 @@ static inline bool btree_type_uses_write_buffer(enum btree_id btree)
 	return BIT_ULL(btree) & mask;
 }
 
+static inline u8 btree_trigger_order(enum btree_id btree)
+{
+	switch (btree) {
+	case BTREE_ID_alloc:
+		return U8_MAX;
+	case BTREE_ID_stripes:
+		return U8_MAX - 1;
+	default:
+		return btree;
+	}
+}
+
 struct btree_root {
 	struct btree		*b;
 

fs/bcachefs/btree_update.c

@@ -397,6 +397,7 @@ bch2_trans_update_by_path(struct btree_trans *trans, btree_path_idx_t path_idx,
 
 	n = (struct btree_insert_entry) {
 		.flags		= flags,
+		.sort_order	= btree_trigger_order(path->btree_id),
 		.bkey_type	= __btree_node_type(path->level, path->btree_id),
 		.btree_id	= path->btree_id,
 		.level		= path->level,