On Wed, Aug 15, 2018 at 10:39:54AM +0300, Nikolay Borisov wrote:
> This is in preparation to refactor the giant loop in
> __btrfs_run_delayed_refs. As a first step define a new function
> which implements acquiring a reference to a btrfs_delayed_refs_head and
> use it. No functional changes.
>
> Signed-off-by: Nikolay Borisov <nborisov@xxxxxxxx>
> ---
> fs/btrfs/extent-tree.c | 54 ++++++++++++++++++++++++++++++++++----------------
> 1 file changed, 37 insertions(+), 17 deletions(-)
>
> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
> index de6f75f5547b..6a2c86c8a756 100644
> --- a/fs/btrfs/extent-tree.c
> +++ b/fs/btrfs/extent-tree.c
> @@ -2502,6 +2502,40 @@ static int cleanup_ref_head(struct btrfs_trans_handle *trans,
> return 0;
> }
>
> +STATIC
> +struct btrfs_delayed_ref_head *btrfs_obtain_ref_head(
> + struct btrfs_trans_handle *trans)
The STATIC is now gone from misc-next so it's just 'static'. Please
don't split the type and function name. It's allowed to fixup the style
once the function prototype is updated.
> +{
> + struct btrfs_delayed_ref_root *delayed_refs =
> + &trans->transaction->delayed_refs;
> + struct btrfs_delayed_ref_head *head = NULL;
> + int ret;
> +
> + spin_lock(&delayed_refs->lock);
> + head = btrfs_select_ref_head(trans);
> + if (!head) {
> + spin_unlock(&delayed_refs->lock);
> + return head;
> + }
> +
> + /*
> + * grab the lock that says we are going to process all the refs for
> + * this head
> + */
> + ret = btrfs_delayed_ref_lock(trans, head);
> + spin_unlock(&delayed_refs->lock);
> + /*
> + * we may have dropped the spin lock to get the head
> + * mutex lock, and that might have given someone else
> + * time to free the head. If that's true, it has been
> + * removed from our list and we can move on.
> + */
As you move the entire comment, you can reformat it or reword if you
find a better way what's is supposed to say.
Otherwise
Reviewed-by: David Sterba <dsterba@xxxxxxxx>
