bcachefs: Don't reuse bio in retry path

We can't reuse bios without reinitializing them, and in the retry path
it's safer to just make sure we don't reuse them at all.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/io.c

@@ -1447,6 +1447,7 @@ static void bch2_read_retry_nodecode(struct bch_fs *c, struct bch_read_bio *rbio
 	int ret;
 
 	flags &= ~BCH_READ_LAST_FRAGMENT;
+	flags |= BCH_READ_MUST_CLONE;
 
 	bch2_trans_init(&trans, c, 0, 0);