dm thin: speed up cell_defer_no_holder()

Reduce the time that a spinlock is held in cell_defer_no_holder().

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>

diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 13d4677..0032342 100644 (file)
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -883,15 +883,17 @@ static void cell_defer_no_holder(struct thin_c *tc, struct dm_bio_prison_cell *c
 {
        struct pool *pool = tc->pool;
        unsigned long flags;
-       int has_work;
+       struct bio_list bios;
 
-       spin_lock_irqsave(&tc->lock, flags);
-       cell_release_no_holder(pool, cell, &tc->deferred_bio_list);
-       has_work = !bio_list_empty(&tc->deferred_bio_list);
-       spin_unlock_irqrestore(&tc->lock, flags);
+       bio_list_init(&bios);
+       cell_release_no_holder(pool, cell, &bios);
 
-       if (has_work)
+       if (!bio_list_empty(&bios)) {
+               spin_lock_irqsave(&tc->lock, flags);
+               bio_list_merge(&tc->deferred_bio_list, &bios);
+               spin_unlock_irqrestore(&tc->lock, flags);
                wake_worker(pool);
+       }
 }
 
 static void thin_defer_bio(struct thin_c *tc, struct bio *bio);