Re: [PATCH 13/18] btrfs: inline owner ref lookup helper

[Josef Bacik <josef@toxicpanda.com>]

On Wed, Jul 05, 2023 at 04:20:50PM -0700, Boris Burkov wrote:
> Inline ref parsing is a bit tricky and relies on a decent amount of
> implicit information, so I think it is beneficial to have a helper
> function for reading the owner ref, if only to "document" the format,
> along with the write path.
> 
> The main subtlety of note which I was missing by open-coding this was
> that it is important to check whether or not inline refs are present
> *at all*. i.e., if we are writing out a new extent under squotas, we
> will always use a big enough item for the inline ref and have it.
> However, it is possible that some random item predating squotas will not
> have any inline refs. In that case, trying to read the "type" field of
> the first inline ref will just be reading garbage in the form of
> whatever is in the next item.
> 
> This will be used by the extent free-ing path, which looks up data
> extent owners as well as a relocation path which needs to grab the owner
> before relocating an extent.
> 
> Signed-off-by: Boris Burkov <boris@bur.io>

Reviewed-by: Josef Bacik <josef@toxicpanda.com>

Thanks,

Josef