bcachefs: Fix journal_flush_seq()

The error check was inverted - leading fsyncs to get stuck and hang,
oops.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/journal.c

@@ -552,16 +552,13 @@ int bch2_journal_flush_seq_async(struct journal *j, u64 seq,
 	struct journal_buf *buf;
 	int ret = 0;
 
-	if (seq <= j->err_seq)
-		return -EIO;
-
 	if (seq <= j->seq_ondisk)
 		return 1;
 
 	spin_lock(&j->lock);
 
 	/* Recheck under lock: */
-	if (seq <= j->err_seq) {
+	if (j->err_seq && seq >= j->err_seq) {
 		ret = -EIO;
 		goto out;
 	}