Re: [PATCH 03/10] btrfs: add a comment for new_bytenr in bacref_cache_node

[Boris Burkov <boris@bur.io>]

On Thu, Oct 03, 2024 at 11:43:05AM -0400, Josef Bacik wrote:

s/bacref/backref/
in the commit title

> Add a comment for this field so we know what it is used for.  Previously
> we used it to update the backref cache, so people may mistakenly think
> it is useless, but in fact exists to make sure the backref cache makes
> sense.
> 
> Signed-off-by: Josef Bacik <josef@toxicpanda.com>
> ---
>  fs/btrfs/backref.h | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/fs/btrfs/backref.h b/fs/btrfs/backref.h
> index a810253d7b8a..754c71bdc9ce 100644
> --- a/fs/btrfs/backref.h
> +++ b/fs/btrfs/backref.h
> @@ -318,6 +318,12 @@ struct btrfs_backref_node {
>  		u64 bytenr;
>  	}; /* Use rb_simple_node for search/insert */
>  
> +	/*
> +	 * This is a sanity check, whenever we cow a block we will update
> +	 * new_bytenr with it's current location, and we will check this in
> +	 * various places to validate that the cache makes sense, it shouldn't
> +	 * be used for anything else.
> +	 */
>  	u64 new_bytenr;
>  	/* Objectid of tree block owner, can be not uptodate */
>  	u64 owner;
> -- 
> 2.43.0
>