linux-kernel - [PATCH] md/raid1,raid10: don't broken array on failfast metadata write fails

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Message-ID: <20250812090119.153697-1-k@mgml.me>
Date: Tue, 12 Aug 2025 18:01:19 +0900
From: Kenta Akagi <k@...l.me>
To: Song Liu <song@...nel.org>, Yu Kuai <yukuai3@...wei.com>,
        Mariusz Tkaczyk <mtkaczyk@...nel.org>
Cc: linux-raid@...r.kernel.org, linux-kernel@...r.kernel.org,
        Kenta Akagi <k@...l.me>
Subject: [PATCH] md/raid1,raid10: don't broken array on failfast metadata write fails

It is not intended for the array to fail when a metadata write with
MD_FAILFAST fails.
After commit 9631abdbf406 ("md: Set MD_BROKEN for RAID1 and RAID10"),
when md_error is called on the last device in RAID1/10,
the MD_BROKEN flag is set on the array.
Because of this, a failfast metadata write failure will
make the array "broken" state.

If rdev is not Faulty even after calling md_error,
the rdev is the last device, and there is nothing except
MD_BROKEN that prevents writes to the array.
Therefore, by clearing MD_BROKEN, the array will not become
"broken" after a failfast metadata write failure.

Fixes: 9631abdbf406 ("md: Set MD_BROKEN for RAID1 and RAID10")
Signed-off-by: Kenta Akagi <k@...l.me>
---
 drivers/md/md.c | 1 +
 drivers/md/md.h | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index ac85ec73a409..3ec4abf02fa0 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -1002,6 +1002,7 @@ static void super_written(struct bio *bio)
 		md_error(mddev, rdev);
 		if (!test_bit(Faulty, &rdev->flags)
 		    && (bio->bi_opf & MD_FAILFAST)) {
+			clear_bit(MD_BROKEN, &mddev->flags);
 			set_bit(MD_SB_NEED_REWRITE, &mddev->sb_flags);
 			set_bit(LastDev, &rdev->flags);
 		}
diff --git a/drivers/md/md.h b/drivers/md/md.h
index 51af29a03079..2f87bcc5d834 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -332,7 +332,7 @@ struct md_cluster_operations;
  *			       resync lock, need to release the lock.
  * @MD_FAILFAST_SUPPORTED: Using MD_FAILFAST on metadata writes is supported as
  *			    calls to md_error() will never cause the array to
- *			    become failed.
+ *			    become failed while fail_last_dev is not set.
  * @MD_HAS_PPL:  The raid array has PPL feature set.
  * @MD_HAS_MULTIPLE_PPLS: The raid array has multiple PPLs feature set.
  * @MD_NOT_READY: do_md_run() is active, so 'array_state', ust not report that
-- 
2.50.1