bcachefs: Fix lost wakeup on journal shutdown

We need to check for journal shutdown first in __journal_res_get() -
after the journal is shutdown, j->watermark won't be changing anymore.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/journal.c

@@ -511,18 +511,18 @@ static int __journal_res_get(struct journal *j, struct journal_res *res,
 	if (journal_res_get_fast(j, res, flags))
 		return 0;
 
+	if (bch2_journal_error(j))
+		return -BCH_ERR_erofs_journal_err;
+
+	if (j->blocked)
+		return -BCH_ERR_journal_res_get_blocked;
+
 	if ((flags & BCH_WATERMARK_MASK) < j->watermark) {
 		ret = JOURNAL_ERR_journal_full;
 		can_discard = j->can_discard;
 		goto out;
 	}
 
-	if (j->blocked)
-		return -BCH_ERR_journal_res_get_blocked;
-
-	if (bch2_journal_error(j))
-		return -BCH_ERR_erofs_journal_err;
-
 	if (nr_unwritten_journal_entries(j) == ARRAY_SIZE(j->buf) && !journal_entry_is_open(j)) {
 		ret = JOURNAL_ERR_max_in_flight;
 		goto out;