raid5: fix a race of stripe count check

I hit another BUG_ON with e240c1839d. In __get_priority_stripe(),
stripe count equals to 0 initially. Between atomic_inc and BUG_ON,
get_active_stripe() finds the stripe. So the stripe count isn't 1 any more.

V2: keeps the BUG_ON suggested by Neil.

Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
This commit is contained in:
Shaohua Li 2014-04-15 09:12:54 +08:00 committed by NeilBrown
parent e240c1839d
commit c7a6d35e46

View File

@ -4370,8 +4370,7 @@ static struct stripe_head *__get_priority_stripe(struct r5conf *conf, int group)
sh->group = NULL;
}
list_del_init(&sh->lru);
atomic_inc(&sh->count);
BUG_ON(atomic_read(&sh->count) != 1);
BUG_ON(atomic_inc_return(&sh->count) != 1);
return sh;
}