linux-kernel - [PATCH AUTOSEL for 4.14 036/100] md/raid5: correct degraded calculation in raid5

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Date:   Sun, 28 Jan 2018 22:26:21 +0000
From:   Sasha Levin <Alexander.Levin@...rosoft.com>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
CC:     bingjingc <bingjingc@...ology.com>, Shaohua Li <shli@...com>,
        Sasha Levin <Alexander.Levin@...rosoft.com>
Subject: [PATCH AUTOSEL for 4.14 036/100] md/raid5: correct degraded
 calculation in raid5_error

From: bingjingc <bingjingc@...ology.com>

[ Upstream commit aff69d89bdebc39235cddb4445371eb979b49685 ]

When disk failure occurs on new disks for reshape, mddev->degraded
is not calculated correctly. Faulty bit of the failure device is not
set before raid5_calc_degraded(conf).

mdadm --create /dev/md0 --level=5 --raid-devices=3 /dev/loop[012]
mdadm /dev/md0 -a /dev/loop3
mdadm /dev/md0 --grow -n4
mdadm /dev/md0 -f /dev/loop3 # simulating disk failure

cat /sys/block/md0/md/degraded # it outputs 0, but it should be 1.

However, mdadm -D /dev/md0 will show that it is degraded. It's a bug.
It can be fixed by moving the resources raid5_calc_degraded() depends
on before it.

Reported-by: Roy Chung <roychung@...ology.com>
Reviewed-by: Alex Wu <alexwu@...ology.com>
Signed-off-by: BingJing Chang <bingjingc@...ology.com>
Signed-off-by: Shaohua Li <shli@...com>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
---
 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 c406f16f5295..7ec822ced80b 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -2678,13 +2678,13 @@ static void raid5_error(struct mddev *mddev, struct md_rdev *rdev)
 	pr_debug("raid456: error called\n");
 
 	spin_lock_irqsave(&conf->device_lock, flags);
+	set_bit(Faulty, &rdev->flags);
 	clear_bit(In_sync, &rdev->flags);
 	mddev->degraded = raid5_calc_degraded(conf);
 	spin_unlock_irqrestore(&conf->device_lock, flags);
 	set_bit(MD_RECOVERY_INTR, &mddev->recovery);
 
 	set_bit(Blocked, &rdev->flags);
-	set_bit(Faulty, &rdev->flags);
 	set_mask_bits(&mddev->sb_flags, 0,
 		      BIT(MD_SB_CHANGE_DEVS) | BIT(MD_SB_CHANGE_PENDING));
 	pr_crit("md/raid:%s: Disk failure on %s, disabling device.\n"
-- 
2.11.0