bcachefs: Fsck code refactoring

Change fsck code to always put btree iterators - also, make some flow
control improvements to deal with lock restarts better, and refactor
check_extents() to not walk extents twice for counting/checking
i_sectors.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/btree_iter.c

@@ -1496,7 +1496,7 @@ void bch2_btree_iter_set_pos(struct btree_iter *iter, struct bpos new_pos)
 	btree_iter_set_search_pos(iter, btree_iter_search_key(iter));
 }
 
-static inline bool bch2_btree_iter_advance_pos(struct btree_iter *iter)
+inline bool bch2_btree_iter_advance_pos(struct btree_iter *iter)
 {
 	struct bpos pos = iter->k.p;
 	bool ret = bkey_cmp(pos, POS_MAX) != 0;
@@ -1507,7 +1507,7 @@ static inline bool bch2_btree_iter_advance_pos(struct btree_iter *iter)
 	return ret;
 }
 
-static inline bool bch2_btree_iter_rewind_pos(struct btree_iter *iter)
+inline bool bch2_btree_iter_rewind_pos(struct btree_iter *iter)
 {
 	struct bpos pos = bkey_start_pos(&iter->k);
 	bool ret = bkey_cmp(pos, POS_MIN) != 0;

fs/bcachefs/btree_iter.h

@@ -175,6 +175,8 @@ struct bkey_s_c bch2_btree_iter_prev_slot(struct btree_iter *);
 
 struct bkey_s_c bch2_btree_iter_peek_cached(struct btree_iter *);
 
+bool bch2_btree_iter_advance_pos(struct btree_iter *);
+bool bch2_btree_iter_rewind_pos(struct btree_iter *);
 void bch2_btree_iter_set_pos(struct btree_iter *, struct bpos);
 
 /* Sort order for locking btree iterators: */