ops_run_reconstruct6() doesn't correctly chain asyn operations. The tx returned
by async_gen_syndrome should be added as the dependent tx of next stripe.

The issue is introduced by commit 59fc630b8b5f9f21c8ce3ba153341c107dce1b0c
    RAID5: batch adjacent full stripe write

Reported-and-tested-by: Maxime Ripard <redacted>
Signed-off-by: Shaohua Li <redacted>
---
 drivers/md/raid5.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 1ba97fd..b9f2b9c 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c

@@ -1822,7 +1822,7 @@ ops_run_reconstruct6(struct stripe_head *sh, struct raid5_percpu *percpu,
 	} else
 		init_async_submit(&submit, 0, tx, NULL, NULL,
 				  to_addr_conv(sh, percpu, j));
-	async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE,  &submit);
+	tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE,  &submit);
 	if (!last_stripe) {
 		j++;
 		sh = list_first_entry(&sh->batch_list, struct stripe_head,