There is no need for special handling of stripe-batches when the array
is degraded.

There may be if there is a failure in the batch, but STRIPE_DEGRADED
does not imply an error.

So don't set STRIPE_BATCH_ERR in ops_run_io just because the array is
degraded.
This actually causes a bug: the STRIPE_DEGRADED flag gets cleared in
check_break_stripe_batch_list() and so the bitmap bit gets cleared
when it shouldn't.

So in check_break_stripe_batch_list(), split the batch up completely -
again STRIPE_DEGRADED isn't meaningful.

Also don't set STRIPE_BATCH_ERR when there is a write error to a
replacement device.  This simply removes the replacement device and
requires no extra handling.

Signed-off-by: NeilBrown <redacted>
---
 drivers/md/raid5.c |   17 +++--------------
 1 file changed, 3 insertions(+), 14 deletions(-)

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 3873eaa6fa2e..1ba97fdc6df1 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c

@@ -1078,9 +1078,6 @@ again:
 			pr_debug("skip op %ld on disc %d for sector %llu\n",
 				bi->bi_rw, i, (unsigned long long)sh->sector);
 			clear_bit(R5_LOCKED, &sh->dev[i].flags);
-			if (sh->batch_head)
-				set_bit(STRIPE_BATCH_ERR,
-					&sh->batch_head->state);
 			set_bit(STRIPE_HANDLE, &sh->state);
 		}