[PATCH -next 1/5] md/raid5: don't allow replacement while reshape is not done

[Yu Kuai]

From: Yu Kuai <yukuai3@xxxxxxxxxx>

Set rdev replacement has but not only two conditions:

1) MD_RECOVERY_RUNNING is not set;
2) rdev nr_pending is 0;

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@xxxxxxxxx>
Link: https://lore.kernel.org/linux-raid/e2f96772-bfbc-f43b-6da1-f520e5164536@xxxxxxxxx/
Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
---
 drivers/md/raid5.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index a58507a4345d..bd3b535c0739 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -8378,6 +8378,7 @@ 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);
-- 
2.39.2