dm thin: wake worker when discard is prepared

When discards are prepared it is best to directly wake the worker that
will process them.  The worker will be woken anyway, via periodic
commit, but there is no reason to not wake_worker here.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 41c9e81ba74a1d3a4764f4896ea61ef1e4713501..aeb9e20f59782ed1dca39d6dc5c9c32ef4acd258 100644 (file)
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -2676,10 +2676,13 @@ static int thin_endio(struct dm_target *ti,
        if (h->all_io_entry) {
                INIT_LIST_HEAD(&work);
                dm_deferred_entry_dec(h->all_io_entry, &work);
-               spin_lock_irqsave(&pool->lock, flags);
-               list_for_each_entry_safe(m, tmp, &work, list)
-                       list_add(&m->list, &pool->prepared_discards);
-               spin_unlock_irqrestore(&pool->lock, flags);
+               if (!list_empty(&work)) {
+                       spin_lock_irqsave(&pool->lock, flags);
+                       list_for_each_entry_safe(m, tmp, &work, list)
+                               list_add(&m->list, &pool->prepared_discards);
+                       spin_unlock_irqrestore(&pool->lock, flags);
+                       wake_worker(pool);
+               }
        }
 
        mempool_free(h, pool->endio_hook_pool);