scoutfs: initialize transaction block writer

As we shut down the transaction tries to destroy any remaining dirty
blocks in its writer context.  The block writer context was only
initialized by the client as it asked the server for the log trees.

This makes sure the writer is always initialized.

Signed-off-by: Zach Brown <zab@versity.com>

kmod/src/trans.c

@@ -508,6 +508,7 @@ int scoutfs_setup_trans(struct super_block *sb)
 		return -ENOMEM;
 
 	spin_lock_init(&tri->lock);
+	scoutfs_block_writer_init(sb, &tri->wri);
 
 	sbi->trans_write_workq = alloc_workqueue("scoutfs_trans",
 						 WQ_UNBOUND, 1);