Revert "bcachefs: Fix bch2_btree_node_upgrade()"

This reverts commit 62448af.

six_lock_tryupgrade fails only if there is an intent lock held,
it won't fail no matter how many read locks are held.

Signed-off-by: Alan Huang <mmpgouride@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Author: alanskind

fs/bcachefs/btree_locking.c

@@ -512,7 +512,6 @@ bool bch2_btree_node_upgrade(struct btree_trans *trans,
 			     struct btree_path *path, unsigned level)
 {
 	struct btree *b = path->l[level].b;
-	struct six_lock_count count = bch2_btree_node_lock_counts(trans, path, &b->c, level);
 
 	if (!is_btree_node(path, level))
 		return false;
@@ -536,24 +535,11 @@ bool bch2_btree_node_upgrade(struct btree_trans *trans,
 	if (race_fault())
 		return false;
 
-	if (btree_node_locked(path, level)) {
-		bool ret;
-
-		six_lock_readers_add(&b->c.lock, -count.n[SIX_LOCK_read]);
-		ret = six_lock_tryupgrade(&b->c.lock);
-		six_lock_readers_add(&b->c.lock, count.n[SIX_LOCK_read]);
-
-		if (ret)
-			goto success;
-	} else {
-		if (six_relock_type(&b->c.lock, SIX_LOCK_intent, path->l[level].lock_seq))
-			goto success;
-	}
+	if (btree_node_locked(path, level)
+	    ? six_lock_tryupgrade(&b->c.lock)
+	    : six_relock_type(&b->c.lock, SIX_LOCK_intent, path->l[level].lock_seq))
+		goto success;
 
-	/*
-	 * Do we already have an intent lock via another path? If so, just bump
-	 * lock count:
-	 */
 	if (btree_node_lock_seq_matches(path, b, level) &&
 	    btree_node_lock_increment(trans, &b->c, level, BTREE_NODE_INTENT_LOCKED)) {
 		btree_node_unlock(trans, path, level);