md/raid5: don't allow replacement while reshape is in progress

If reshape is interrupted(for example, echo frozen to sync_action), then
rdev replacement can be set. It's safe because reshape is always prior to
resync in md_check_recovery(). However, if system reboots, then kernel will
complain cannot handle concurrent replacement and reshape and this array
is not able to assemble anymore.

Fix this problem by don't allow replacement until reshape is done.

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/20230512015610.821290-2-yukuai1@huaweicloud.com

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 4739ed891e756eb3a8af3e7c48c6be0950b82db7..5950932323fcb6c8bed4149a75d3d2e68f71ed7a 100644 (file)
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -8377,6 +8377,7 @@ static int raid5_add_disk(struct mddev *mddev, struct md_rdev *rdev)
                p = conf->disks + disk;
                tmp = rdev_mdlock_deref(mddev, p->rdev);
                if (test_bit(WantReplacement, &tmp->flags) &&
+                   mddev->reshape_position == MaxSector &&
                    p->replacement == NULL) {
                        clear_bit(In_sync, &rdev->flags);
                        set_bit(Replacement, &rdev->flags);