dm: move hot dm_io members to same cacheline as dm_target_io

Just saves some cacheline bouncing for members accessed during cloned bio submission and completion. Signed-off-by: Mike Snitzer <snitzer@kernel.org>

Author: Mike Snitzer

drivers/md/dm-core.h

@@ -250,17 +250,19 @@ static inline bool dm_tio_is_normal(struct dm_target_io *tio)
 #define DM_IO_MAGIC 19577
 struct dm_io {
 unsigned short magic;
-blk_short_t flags;
-atomic_t io_count;
-struct mapped_device *md;
-struct bio *orig_bio;
-blk_status_t status;
+
 spinlock_t lock;
 unsigned long start_time;
 void *data;
 struct hlist_node node;
 struct task_struct *map_task;
 struct dm_stats_aux stats_aux;
+
+blk_short_t flags;
+blk_status_t status;
+atomic_t io_count;
+struct mapped_device *md;
+struct bio *orig_bio;
 /* last member of dm_target_io is 'struct bio' */
 struct dm_target_io tio;
 };