[PATCH 6.1 001/451] md: fix data corruption for raid456 when reshape restart while grow up

Sasha Levin
2024-03-24T23:12:11Z

From: Yu Kuai <yukuai3@huawei.com>

[ Upstream commit 873f50ece41aad5c4f788a340960c53774b5526e ]

Currently, if reshape is interrupted, echo "reshape" to sync_action will
restart reshape from scratch, for example:

echo frozen > sync_action
echo reshape > sync_action

This will corrupt data before reshape_position if the array is growing,
fix the problem by continue reshape from reshape_position.

Reported-by: Peter Neuwirth <reddunur@online.de>
Link: https://lore.kernel.org/linux-raid/e2f96772-bfbc-f43b-6da1-f520e5164536@online.de/
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20230512015610.821290-3-yukuai1@huaweicloud.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/md/md.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 846bdee4daa0e..1c87f3e708094 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -4903,11 +4903,21 @@ action_store(struct mddev *mddev, const char *page, size_t len)
return -EINVAL;
err = mddev_lock(mddev);
if (!err) {
- if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
+ if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery)) {
err = -EBUSY;
- else {
+ } else if (mddev->reshape_position == MaxSector ||
+ mddev->pers->check_reshape == NULL ||
+ mddev->pers->check_reshape(mddev)) {
clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
err = mddev->pers->start_reshape(mddev);
+ } else {
+ /*
+ * If reshape is still in progress, and
+ * md_check_recovery() can continue to reshape,
+ * don't restart reshape because data can be
+ * corrupted for raid456.
+ */
+ clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
}
mddev_unlock(mddev);
}
--
2.43.0