dm: skip dm-stats work in alloc_io() unless needed

Don't dm_stats_record_start() if dm_stats_used() is false.

Signed-off-by: Mike Snitzer <snitzer@kernel.org>

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 658323aff676f4843e88508991f387d0919a975b..ea1671c39ba131ab2e49b93289d1094cda5cfb25 100644 (file)
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -597,7 +597,8 @@ static struct dm_io *alloc_io(struct mapped_device *md, struct bio *bio)
        if (blk_queue_io_stat(md->queue))
                dm_io_set_flag(io, DM_IO_BLK_STAT);
 
-       if (static_branch_unlikely(&stats_enabled))
+       if (static_branch_unlikely(&stats_enabled) &&
+           unlikely(dm_stats_used(&md->stats)))
                dm_stats_record_start(&md->stats, &io->stats_aux);
 
        return io;