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Commit d5ee37bc authored by Miao Xie's avatar Miao Xie Committed by Chris Mason
Browse files

Btrfs: make the device lock and its protected data in the same cacheline 



The lock in btrfs_device structure was far away from its protected data, it would
make CPU load the cache line twice when we accessed them, move them together.

Signed-off-by: default avatarMiao Xie <miaox@cn.fujitsu.com>
Signed-off-by: default avatarChris Mason <clm@fb.com>
parent 5f546063

fs/btrfs/volumes.h

+12 −13
Original line number Diff line number Diff line
@@ -36,30 +36,31 @@ struct btrfs_device { 
	struct list_head dev_list;

	struct list_head dev_alloc_list;

	struct btrfs_fs_devices *fs_devices;



	struct btrfs_root *dev_root;



	struct rcu_string *name;



	u64 generation;



	spinlock_t io_lock ____cacheline_aligned;

	int running_pending;

	/* regular prio bios */

	struct btrfs_pending_bios pending_bios;

	/* WRITE_SYNC bios */

	struct btrfs_pending_bios pending_sync_bios;



	u64 generation;

	int running_pending;

	struct block_device *bdev;



	/* the mode sent to blkdev_get */

	fmode_t mode;



	int writeable;

	int in_fs_metadata;

	int missing;

	int can_discard;

	int is_tgtdev_for_dev_replace;



	spinlock_t io_lock;

	/* the mode sent to blkdev_get */

	fmode_t mode;



	struct block_device *bdev;





	struct rcu_string *name;



	/* the internal btrfs device id */

	u64 devid;
@@ -83,7 +84,6 @@ struct btrfs_device { 
	/* minimal io size for this device */

	u32 sector_size;





	/* physical drive uuid (or lvm uuid) */

	u8 uuid[BTRFS_UUID_SIZE];
@@ -107,7 +107,6 @@ struct btrfs_device { 
	struct radix_tree_root reada_zones;

	struct radix_tree_root reada_extents;





	/* disk I/O failure stats. For detailed description refer to

	 * enum btrfs_dev_stat_values in ioctl.h */

	int dev_stats_valid;