From 5af9bef72c074dbe946da8b74eabd79cd5a9ff19 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Tue, 14 Jan 2014 15:16:10 +1100 Subject: [PATCH] md/raid5: fix a recently broken BUG_ON(). commit 6d183de4077191d1201283a9035ce57a9b05254d md/raid5: fix newly-broken locking in get_active_stripe. simplified a BUG_ON, but removed too much so now it sometimes fires when it shouldn't. When the STRIPE_EXPANDING flag is set, the stripe_head might be on a special list while multiple stripe_heads are collected, or it might not be on any list, even a 'free' list when the refcount is zero. As long as STRIPE_EXPANDING is set, it will be found and added back to a list eventually. So both of the BUG_ONs which test for the ->lru being empty or not need to avoid the case where STRIPE_EXPANDING is set. The patch which broke this was marked for -stable, so this patch needs to be applied to any branch that received 6d183de4 Fixes: 6d183de4077191d1201283a9035ce57a9b05254d Cc: stable@vger.kernel.org (any release to which above was applied) Signed-off-by: NeilBrown --- drivers/md/raid5.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 9168173deaf3..cbb15716a5db 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -687,7 +687,8 @@ get_active_stripe(struct r5conf *conf, sector_t sector, } else { if (!test_bit(STRIPE_HANDLE, &sh->state)) atomic_inc(&conf->active_stripes); - BUG_ON(list_empty(&sh->lru)); + BUG_ON(list_empty(&sh->lru) && + !test_bit(STRIPE_EXPANDING, &sh->state)); list_del_init(&sh->lru); if (sh->group) { sh->group->stripes_cnt--; -- 2.11.0