The counter conf->empty_inactive_list_nr is only used for determine if
the raid5 is congested which is deal with in function
raid5_congested(). It was increased in get_free_stripe() when
conf->inactive_list got emptied and decreased in
release_inactive_stripe_list() when splice temp_inactive_list to
conf->inactive_list. However, this could cause to problem when
raid5_get_active_stripe was called, this function may call
list_del_init(&sh->lru) to delete sh from "conf->inactive_list +
hash" which may cause "conf->inactive_list + hash" to be empty when
atomic_inc_not_zero(&sh->count) got false.
I have found conf->empty_inactive_list_nr to be negative number
during my random test.
Is there anything out of my thinking?
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -659,6 +659,7 @@ raid5_get_active_stripe(struct r5conf *conf,
sector_t sector,
{
struct stripe_head *sh;
int hash = stripe_hash_locks_hash(sector);
+ int inc_empty_inactive_list_flag;
pr_debug("get_stripe, sector %llu\n", (unsigned long long)sector);
@@ -703,7 +704,14 @@ raid5_get_active_stripe(struct r5conf *conf,
sector_t sector,
atomic_inc(&conf->active_stripes);
BUG_ON(list_empty(&sh->lru) &&
!test_bit(STRIPE_EXPANDING, &sh->state));
+
+ inc_empty_inactive_list_flag = 0;
+ if(!list_empty(conf->inactive_list + hash))
+ inc_empty_inactive_list_flag = 1;
list_del_init(&sh->lru);
+ if(list_empty(conf->inactive_list +
hash) && inc_empty_inactive_list_flag)
+
atomic_inc(&conf->empty_inactive_list_nr);
+
if (sh->group) {
sh->group->stripes_cnt--;
sh->group = NULL;
--
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