linux-kernel - [PATCH 4.19 137/211] raid5: dont increment read

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Message-Id: <20191003154518.443511325@linuxfoundation.org>
Date:   Thu,  3 Oct 2019 17:53:23 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Nigel Croxon <ncroxon@...hat.com>,
        Song Liu <songliubraving@...com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 137/211] raid5: dont increment read_errors on EILSEQ return

From: Nigel Croxon <ncroxon@...hat.com>

[ Upstream commit b76b4715eba0d0ed574f58918b29c1b2f0fa37a8 ]

While MD continues to count read errors returned by the lower layer.
If those errors are -EILSEQ, instead of -EIO, it should NOT increase
the read_errors count.

When RAID6 is set up on dm-integrity target that detects massive
corruption, the leg will be ejected from the array.  Even if the
issue is correctable with a sector re-write and the array has
necessary redundancy to correct it.

The leg is ejected because it runs up the rdev->read_errors beyond
conf->max_nr_stripes.  The return status in dm-drypt when there is
a data integrity error is -EILSEQ (BLK_STS_PROTECTION).

Signed-off-by: Nigel Croxon <ncroxon@...hat.com>
Signed-off-by: Song Liu <songliubraving@...com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/md/raid5.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index d26e5e9bea427..dbc4655a95768 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -2540,7 +2540,8 @@ static void raid5_end_read_request(struct bio * bi)
 		int set_bad = 0;
 
 		clear_bit(R5_UPTODATE, &sh->dev[i].flags);
-		atomic_inc(&rdev->read_errors);
+		if (!(bi->bi_status == BLK_STS_PROTECTION))
+			atomic_inc(&rdev->read_errors);
 		if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
 			pr_warn_ratelimited(
 				"md/raid:%s: read error on replacement device (sector %llu on %s).\n",
-- 
2.20.1