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Commit 032482fd authored by Mike Snitzer's avatar Mike Snitzer
Browse files

dm: reorder 'struct mapped_device' members to fix alignment and holes 



Saves 16 bytes by eliminating 4 4byte holes but more importantly:
numerous members that crossed cachelines were fixed.

Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent 1d3aa6f6

drivers/md/dm.c

+18 −16
Original line number Original line Diff line number Diff line
@@ -126,8 +126,6 @@ struct dm_rq_clone_bio_info { 
struct mapped_device {

struct mapped_device {

	struct srcu_struct io_barrier;

	struct srcu_struct io_barrier;

	struct mutex suspend_lock;

	struct mutex suspend_lock;

	atomic_t holders;

	atomic_t open_count;





	/*

	/*

	 * The current mapping (struct dm_table *).

	 * The current mapping (struct dm_table *).
@@ -148,6 +146,9 @@ struct mapped_device { 
	/* Protect queue and type against concurrent access. */

	/* Protect queue and type against concurrent access. */

	struct mutex type_lock;

	struct mutex type_lock;





	atomic_t holders;

	atomic_t open_count;



	struct dm_target *immutable_target;

	struct dm_target *immutable_target;

	struct target_type *immutable_target_type;

	struct target_type *immutable_target_type;
@@ -162,8 +163,20 @@ struct mapped_device { 
	atomic_t pending[2];

	atomic_t pending[2];

	wait_queue_head_t wait;

	wait_queue_head_t wait;

	struct work_struct work;

	struct work_struct work;

	struct bio_list deferred;

	spinlock_t deferred_lock;

	spinlock_t deferred_lock;

	struct bio_list deferred;



	/*

	 * Event handling.

	 */

	wait_queue_head_t eventq;

	atomic_t event_nr;

	atomic_t uevent_seq;

	struct list_head uevent_list;

	spinlock_t uevent_lock; /* Protect access to uevent_list */



	/* the number of internal suspends */

	unsigned internal_suspend_count;





	/*

	/*

	 * Processing queue (flush)

	 * Processing queue (flush)
@@ -178,33 +191,22 @@ struct mapped_device { 




	struct bio_set *bs;

	struct bio_set *bs;





	/*

	 * Event handling.

	 */

	atomic_t event_nr;

	wait_queue_head_t eventq;

	atomic_t uevent_seq;

	struct list_head uevent_list;

	spinlock_t uevent_lock; /* Protect access to uevent_list */



	/*

	/*

	 * freeze/thaw support require holding onto a super block

	 * freeze/thaw support require holding onto a super block

	 */

	 */

	struct super_block *frozen_sb;

	struct super_block *frozen_sb;

	struct block_device *bdev;





	/* forced geometry settings */

	/* forced geometry settings */

	struct hd_geometry geometry;

	struct hd_geometry geometry;





	struct block_device *bdev;



	/* kobject and completion */

	/* kobject and completion */

	struct dm_kobject_holder kobj_holder;

	struct dm_kobject_holder kobj_holder;





	/* zero-length flush that will be cloned and submitted to targets */

	/* zero-length flush that will be cloned and submitted to targets */

	struct bio flush_bio;

	struct bio flush_bio;





	/* the number of internal suspends */

	unsigned internal_suspend_count;



	struct dm_stats stats;

	struct dm_stats stats;





	struct kthread_worker kworker;

	struct kthread_worker kworker;