linux-kernel - [PATCH v3 0/3] Do not set MD_BROKEN on failfast io failure

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Message-ID: <20250828163216.4225-1-k@mgml.me>
Date: Fri, 29 Aug 2025 01:32:13 +0900
From: Kenta Akagi <k@...l.me>
To: Song Liu <song@...nel.org>, Yu Kuai <yukuai3@...wei.com>,
        Mariusz Tkaczyk <mtkaczyk@...nel.org>,
        Guoqing Jiang <jgq516@...il.com>
Cc: linux-raid@...r.kernel.org, linux-kernel@...r.kernel.org,
        Kenta Akagi <k@...l.me>
Subject: [PATCH v3 0/3] Do not set MD_BROKEN on failfast io failure

Changes from V2:
- Fix to prevent the array from being marked broken for all
  Failfast IOs, not just metadata.
- Reflecting the review, update raid{1,10}_error to clear
  FailfastIOFailure so that devices are properly marked Faulty.
Changes from V1:
- Avoid setting MD_BROKEN instead of clearing it
- Add pr_crit() when setting MD_BROKEN
- Fix the message may shown after all rdevs failure:
  "Operation continuing on 0 devices"

v2: https://lore.kernel.org/linux-raid/20250817172710.4892-1-k@mgml.me/
v1: https://lore.kernel.org/linux-raid/20250812090119.153697-1-k@mgml.me/

A failfast bio, for example in the case of nvme-tcp, bio will fail
immediately if the connection to the target is briefly lost and
the device enters a reconnecting state - even though it would
recover given few seconds. This behavior is by design in failfast.

However, md treats Failfast IO failures as fatal,
potentially marking the array as MD_BROKEN when a connection is lost.

For example, if an initiator - that is, a machine loading the md
module - loses all connections briefly, the array is marked
as MD_BROKEN, preventing subsequent writes.
This is the issue I am currently facing, and which this patch aims to fix.

The 1st patch changes the behavior on MD_FAILFAST IO failures on
the last rdev. The 2nd and 3rd patches modify the pr_crit messages.

Kenta Akagi (3):
  md/raid1,raid10: Do not set MD_BROKEN on failfast io failure
  md/raid1,raid10: Add error message when setting MD_BROKEN
  md/raid1,raid10: Fix: Operation continuing on 0 devices.

 drivers/md/md.c     | 14 +++++++++-----
 drivers/md/md.h     | 13 +++++++------
 drivers/md/raid1.c  | 32 ++++++++++++++++++++++++++------
 drivers/md/raid10.c | 35 ++++++++++++++++++++++++++++-------
 4 files changed, 70 insertions(+), 24 deletions(-)

-- 
2.50.1