raid5: delayed stripe fix

There isn't locking setting STRIPE_DELAYED and STRIPE_PREREAD_ACTIVE bits, but
the two bits have relationship. A delayed stripe can be moved to hold list only
when preread active stripe count is below IO_THRESHOLD. If a stripe has both
the bits set, such stripe will be in delayed list and preread count not 0,
which will make such stripe never leave delayed list.

Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 51169ecd7787ebd18607440550396be3003cdd69..7245a9df35a942719f358cccd501d43ad70adf7a 100644 (file)
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -196,12 +196,14 @@ static void __release_stripe(struct r5conf *conf, struct stripe_head *sh)
                BUG_ON(!list_empty(&sh->lru));
                BUG_ON(atomic_read(&conf->active_stripes)==0);
                if (test_bit(STRIPE_HANDLE, &sh->state)) {
-                       if (test_bit(STRIPE_DELAYED, &sh->state))
+                       if (test_bit(STRIPE_DELAYED, &sh->state) &&
+                           !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
                                list_add_tail(&sh->lru, &conf->delayed_list);
                        else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
                                   sh->bm_seq - conf->seq_write > 0)
                                list_add_tail(&sh->lru, &conf->bitmap_list);
                        else {
+                               clear_bit(STRIPE_DELAYED, &sh->state);
                                clear_bit(STRIPE_BIT_DELAY, &sh->state);
                                list_add_tail(&sh->lru, &conf->handle_list);
                        }