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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Xiao Ni <xni@redhat.com>,
        Guoqing Jiang <guoqing.jiang@cloud.ionos.com>,
        Song Liu <songliubraving@fb.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.4 043/191] raid5: need to set STRIPE_HANDLE for batch head
Date:   Tue,  7 Jan 2020 21:52:43 +0100
Message-Id: <20200107205335.298040834@linuxfoundation.org>
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From: Guoqing Jiang <guoqing.jiang@cloud.ionos.com>

[ Upstream commit a7ede3d16808b8f3915c8572d783530a82b2f027 ]

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: Sasha Levin <sashal@kernel.org>
---
 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 12a8ce83786e..36cd7c2fbf40 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -5726,7 +5726,7 @@ static bool raid5_make_request(struct mddev *mddev, struct bio * bi)
 				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) &&
-- 
2.20.1