bcachefs: Fix journal deadlock

After we get a journal reservation, we need to use it - if we erorr out
of a transaction commit, we'll be eating into space in the journal and
if our transaction needs to make forward progress in order to reclaim
space in the journal, we'll deadlock.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/btree_update_leaf.c

@@ -426,6 +426,14 @@ bch2_trans_commit_write_locked(struct btree_trans *trans,
 		fs_usage = bch2_fs_usage_scratch_get(c);
 	}
 
+	/* Must be called under mark_lock: */
+	if (marking && trans->fs_usage_deltas &&
+	    bch2_replicas_delta_list_apply(c, &fs_usage->u,
+					   trans->fs_usage_deltas)) {
+		ret = BTREE_INSERT_NEED_MARK_REPLICAS;
+		goto err;
+	}
+
 	/*
 	 * Don't get journal reservation until after we know insert will
 	 * succeed:
@@ -462,14 +470,6 @@ bch2_trans_commit_write_locked(struct btree_trans *trans,
 				i->k->k.version = MAX_VERSION;
 	}
 
-	/* Must be called under mark_lock: */
-	if (marking && trans->fs_usage_deltas &&
-	    bch2_replicas_delta_list_apply(c, &fs_usage->u,
-					   trans->fs_usage_deltas)) {
-		ret = BTREE_INSERT_NEED_MARK_REPLICAS;
-		goto err;
-	}
-
 	trans_for_each_update(trans, i)
 		if (BTREE_NODE_TYPE_HAS_MEM_TRIGGERS & (1U << i->bkey_type))
 			bch2_mark_update(trans, i->iter, i->k,