linux-kernel - [PATCH v4 7/9] md/raid10: fix failfast read error not rescheduled

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250915034210.8533-8-k@mgml.me>
Date: Mon, 15 Sep 2025 12:42:08 +0900
From: Kenta Akagi <k@...l.me>
To: Song Liu <song@...nel.org>, Yu Kuai <yukuai3@...wei.com>,
        Mariusz Tkaczyk <mtkaczyk@...nel.org>, Shaohua Li <shli@...com>,
        Guoqing Jiang <jgq516@...il.com>
Cc: linux-raid@...r.kernel.org, linux-kernel@...r.kernel.org,
        Kenta Akagi <k@...l.me>
Subject: [PATCH v4 7/9] md/raid10: fix failfast read error not rescheduled

raid10_end_read_request lacks a path to retry when a FailFast IO fails.
As a result, when Failfast Read IOs fail on all rdevs, the upper layer
receives EIO, without read rescheduled.

Looking at the two commits below, it seems only raid10_end_read_request
lacks the failfast read retry handling, while raid1_end_read_request has
it. In RAID1, the retry works as expected.
* commit 8d3ca83dcf9c ("md/raid10: add failfast handling for reads.")
* commit 2e52d449bcec ("md/raid1: add failfast handling for reads.")

I don't know why raid10_end_read_request lacks this, but it is probably
just a simple oversight.

This commit will make the failfast read bio for the last rdev in raid10
retry if it fails.

Fixes: 8d3ca83dcf9c ("md/raid10: add failfast handling for reads.")
Signed-off-by: Kenta Akagi <k@...l.me>
---
 drivers/md/raid10.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 92cf3047dce6..86c0eacd37cb 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -399,6 +399,11 @@ static void raid10_end_read_request(struct bio *bio)
 		 * wait for the 'master' bio.
 		 */
 		set_bit(R10BIO_Uptodate, &r10_bio->state);
+	} else if (test_bit(FailFast, &rdev->flags) &&
+		 test_bit(R10BIO_FailFast, &r10_bio->state)) {
+		/* This was a fail-fast read so we definitely
+		 * want to retry */
+		;
 	} else if (!raid1_should_handle_error(bio)) {
 		uptodate = 1;
 	} else {
-- 
2.50.1