On 26.06.2017 17:42, Nikolay Borisov wrote:
> With this patch applied pahole stats look like:
>
> /* size: 840, cachelines: 14, members: 40 */
> /* sum members: 833, holes: 1, sum holes: 7 */
> /* bit holes: 1, sum bit holes: 28 bits */
> /* last cacheline: 8 bytes */
>
> No functional changes.
>
> Signed-off-by: Nikolay Borisov <nborisov@xxxxxxxx>
> ---
> fs/btrfs/ctree.h | 14 +++++++-------
> 1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
> index cdd3775e930b..bdd06bbeb9aa 100644
> --- a/fs/btrfs/ctree.h
> +++ b/fs/btrfs/ctree.h
> @@ -586,6 +586,11 @@ struct btrfs_block_group_cache {
> unsigned int iref:1;
> unsigned int has_caching_ctl:1;
> unsigned int removed:1;
> + /*
> + * Does the block group need to be added to the free space tree?
> + * Protected by free_space_lock.
> + */
> + unsigned int needs_free_space:1;
Upon closer inspection of memory-barriers.txt I'm not confident in this
change. This puts fields protected by different locks in the same
bitfield which can lead to corrupted values.
>
> int disk_cache_state;
>
> @@ -608,6 +613,8 @@ struct btrfs_block_group_cache {
> /* usage count */
> atomic_t count;
>
> + atomic_t trimming
This one will likely eliminated 1 hole in the struct so I might end up
sending v2 of this patch.
> +
> /* List of struct btrfs_free_clusters for this block group.
> * Today it will only have one thing on it, but that may change
> */
> @@ -619,8 +626,6 @@ struct btrfs_block_group_cache {
> /* For read-only block groups */
> struct list_head ro_list;
>
> - atomic_t trimming;
> -
> /* For dirty block groups */
> struct list_head dirty_list;
> struct list_head io_list;
> @@ -651,11 +656,6 @@ struct btrfs_block_group_cache {
> /* Lock for free space tree operations. */
> struct mutex free_space_lock;
>
> - /*
> - * Does the block group need to be added to the free space tree?
> - * Protected by free_space_lock.
> - */
> - int needs_free_space;
>
> /* Record locked full stripes for RAID5/6 block group */
> struct btrfs_full_stripe_locks_tree full_stripe_locks_root;
>
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