Re: [PATCH 1/3] Btrfs: introduce lock_ref/unlock_ref

[Dave Chinner <david@fromorbit.com>]

On Wed, Dec 18, 2013 at 04:07:27PM -0500, Josef Bacik wrote:
> qgroups need to have a consistent view of the references for a particular extent
> record.  Currently they do this through sequence numbers on delayed refs, but
> this is no longer acceptable.  So instead introduce lock_ref/unlock_ref.  This
> will provide the qgroup code with a consistent view of the reference while it
> does its accounting calculations without interfering with the delayed ref code.
> Thanks,
> 
> Signed-off-by: Josef Bacik <jbacik@fb.com>
> ---
>  fs/btrfs/ctree.h       |  11 ++++++
>  fs/btrfs/delayed-ref.c |   2 +
>  fs/btrfs/delayed-ref.h |   1 +
>  fs/btrfs/extent-tree.c | 102 +++++++++++++++++++++++++++++++++++++++++++++++--
>  4 files changed, 113 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
> index a924274..8b3fd61 100644
> --- a/fs/btrfs/ctree.h
> +++ b/fs/btrfs/ctree.h
> @@ -1273,6 +1273,9 @@ struct btrfs_block_group_cache {
>  
>  	/* For delayed block group creation */
>  	struct list_head new_bg_list;
> +
> +	/* For locking reference modifications */
> +	struct extent_io_tree ref_lock;
>  };
>  
>  /* delayed seq elem */
> @@ -3319,6 +3322,14 @@ int btrfs_init_space_info(struct btrfs_fs_info *fs_info);
>  int btrfs_delayed_refs_qgroup_accounting(struct btrfs_trans_handle *trans,
>  					 struct btrfs_fs_info *fs_info);
>  int __get_raid_index(u64 flags);
> +int lock_ref(struct btrfs_fs_info *fs_info, u64 root_objectid, u64 bytenr,
> +	     u64 num_bytes, int for_cow,
> +	     struct btrfs_block_group_cache **block_group,
> +	     struct extent_state **cached_state);
> +int unlock_ref(struct btrfs_fs_info *fs_info, u64 root_objectid, u64 bytenr,
> +	       u64 num_bytes, int for_cow,
> +	       struct btrfs_block_group_cache *block_group,
> +	       struct extent_state **cached_state);

Please namespace these - they are far too similar to the generic
struct lockref name and manipulation functions....

Cheers,

Dave.

-- 
Dave Chinner
david@fromorbit.com