bcachefs: Don't run transaction hooks multiple times

transaction hooks aren't supposed to run unless we know the transaction
is going to commit succesfully: this fixes a bug with attempting to
delete a subvolume multiple times.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/btree_update_leaf.c

@@ -622,14 +622,6 @@ bch2_trans_commit_write_locked(struct btree_trans *trans, unsigned flags,
 
 	prefetch(&trans->c->journal.flags);
 
-	h = trans->hooks;
-	while (h) {
-		ret = h->fn(trans, h);
-		if (ret)
-			return ret;
-		h = h->next;
-	}
-
 	trans_for_each_update(trans, i) {
 		/* Multiple inserts might go to same leaf: */
 		if (!same_leaf_as_prev(trans, i))
@@ -696,6 +688,14 @@ bch2_trans_commit_write_locked(struct btree_trans *trans, unsigned flags,
 			goto revert_fs_usage;
 	}
 
+	h = trans->hooks;
+	while (h) {
+		ret = h->fn(trans, h);
+		if (ret)
+			goto revert_fs_usage;
+		h = h->next;
+	}
+
 	trans_for_each_update(trans, i)
 		if (BTREE_NODE_TYPE_HAS_MEM_TRIGGERS & (1U << i->bkey_type)) {
 			ret = run_one_mem_trigger(trans, i, i->flags);