From: Guoqing Jiang <guoqing.jiang@cloud.ionos.com>
Date: Wed, 27 Nov 2019 17:57:50 +0100
Subject: raid5: need to set STRIPE_HANDLE for batch head
Git-commit: a7ede3d16808b8f3915c8572d783530a82b2f027
Patch-mainline: 5.5-rc2
References: bnc#1151927 5.3.17

With commit 6ce220dd2f8ea71d6afc29b9a7524c12e39f374a ("raid5: don't set
STRIPE_HANDLE to stripe which is in batch list"), we don't want to set
STRIPE_HANDLE flag for sh which is already in batch list.

However, the stripe which is the head of batch list should set this flag,
otherwise panic could happen inside init_stripe at BUG_ON(sh->batch_head),
it is reproducible with raid5 on top of nvdimm devices per Xiao oberserved.

Thanks for Xiao's effort to verify the change.

Fixes: 6ce220dd2f8ea ("raid5: don't set STRIPE_HANDLE to stripe which is in batch list")
Reported-by: Xiao Ni <xni@redhat.com>
Tested-by: Xiao Ni <xni@redhat.com>
Signed-off-by: Guoqing Jiang <guoqing.jiang@cloud.ionos.com>
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 drivers/md/raid5.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -5721,7 +5721,7 @@ static bool raid5_make_request(struct md
 				do_flush = false;
 			}
 
-			if (!sh->batch_head)
+			if (!sh->batch_head || sh == sh->batch_head)
 				set_bit(STRIPE_HANDLE, &sh->state);
 			clear_bit(STRIPE_DELAYED, &sh->state);
 			if ((!sh->batch_head || sh == sh->batch_head) &&