Re: [PATCH 3/6] btrfs: cleanup extent_op handling

[Nikolay Borisov <nborisov@suse.com>]

On 21.11.18 г. 20:59 ч., Josef Bacik wrote:
> From: Josef Bacik <jbacik@fb.com>
> 
> The cleanup_extent_op function actually would run the extent_op if it
> needed running, which made the name sort of a misnomer.  Change it to
> run_and_cleanup_extent_op, and move the actual cleanup work to
> cleanup_extent_op so it can be used by check_ref_cleanup() in order to
> unify the extent op handling.

The whole name extent_op is actually a misnomer since AFAIR this is some
sort of modification of the references of metadata nodes. I don't see
why it can't be made as yet another type of reference which is run for a
given node.

> 
> Signed-off-by: Josef Bacik <jbacik@fb.com>
> ---
>  fs/btrfs/extent-tree.c | 36 +++++++++++++++++++++++-------------
>  1 file changed, 23 insertions(+), 13 deletions(-)
> 
> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
> index e3ed3507018d..8a776dc9cb38 100644
> --- a/fs/btrfs/extent-tree.c
> +++ b/fs/btrfs/extent-tree.c
> @@ -2424,19 +2424,33 @@ static void unselect_delayed_ref_head(struct btrfs_delayed_ref_root *delayed_ref
>  	btrfs_delayed_ref_unlock(head);
>  }
>  
> -static int cleanup_extent_op(struct btrfs_trans_handle *trans,
> -			     struct btrfs_delayed_ref_head *head)
> +static struct btrfs_delayed_extent_op *
> +cleanup_extent_op(struct btrfs_trans_handle *trans,
> +		  struct btrfs_delayed_ref_head *head)
>  {
>  	struct btrfs_delayed_extent_op *extent_op = head->extent_op;
> -	int ret;
>  
>  	if (!extent_op)
> -		return 0;
> -	head->extent_op = NULL;
> +		return NULL;
> +
>  	if (head->must_insert_reserved) {
> +		head->extent_op = NULL;
>  		btrfs_free_delayed_extent_op(extent_op);
> -		return 0;
> +		return NULL;
>  	}
> +	return extent_op;
> +}
> +
> +static int run_and_cleanup_extent_op(struct btrfs_trans_handle *trans,
> +				     struct btrfs_delayed_ref_head *head)
> +{
> +	struct btrfs_delayed_extent_op *extent_op =
> +		cleanup_extent_op(trans, head);
> +	int ret;
> +
> +	if (!extent_op)
> +		return 0;
> +	head->extent_op = NULL;
>  	spin_unlock(&head->lock);
>  	ret = run_delayed_extent_op(trans, head, extent_op);
>  	btrfs_free_delayed_extent_op(extent_op);
> @@ -2488,7 +2502,7 @@ static int cleanup_ref_head(struct btrfs_trans_handle *trans,
>  
>  	delayed_refs = &trans->transaction->delayed_refs;
>  
> -	ret = cleanup_extent_op(trans, head);
> +	ret = run_and_cleanup_extent_op(trans, head);
>  	if (ret < 0) {
>  		unselect_delayed_ref_head(delayed_refs, head);
>  		btrfs_debug(fs_info, "run_delayed_extent_op returned %d", ret);
> @@ -6977,12 +6991,8 @@ static noinline int check_ref_cleanup(struct btrfs_trans_handle *trans,
>  	if (!RB_EMPTY_ROOT(&head->ref_tree.rb_root))
>  		goto out;
>  
> -	if (head->extent_op) {
> -		if (!head->must_insert_reserved)
> -			goto out;
> -		btrfs_free_delayed_extent_op(head->extent_op);
> -		head->extent_op = NULL;
> -	}
> +	if (cleanup_extent_op(trans, head) != NULL)
> +		goto out;
>  
>  	/*
>  	 * waiting for the lock here would deadlock.  If someone else has it
>