Re: [PATCH 2/3] libxfs: better describe why m_ddev_targp can be set in libxfs_buftarg_init

["Darrick J. Wong" <djwong@kernel.org>]

On Fri, Sep 11, 2026 at 04:45:43PM +0200, Christoph Hellwig wrote:
> I had to wade through this to understand what is going on here, so dump
> the thoughts in a comment to make it easier for the next person to
> understand the logic.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  libxfs/init.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/libxfs/init.c b/libxfs/init.c
> index 2a46ddf086ed..a47e610934e9 100644
> --- a/libxfs/init.c
> +++ b/libxfs/init.c
> @@ -534,7 +534,12 @@ libxfs_buftarg_init(
>  	}
>  
>  	if (mp->m_ddev_targp) {
> -		/* should already have all buftargs initialised */
> +		/*
> +		 * This can happen if the utility called libxfs_buftarg_init
> +		 * manually before libxfs_mount, which calls us again.

That's much clearer about how we get into this state. :)

Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>

--D

> +		 *
> +		 * In this case all buftargs should be initialized already.
> +		 */
>  		if (mp->m_ddev_targp->bt_bdev != xi->data.dev ||
>  		    mp->m_ddev_targp->bt_mount != mp) {
>  			fprintf(stderr,
> -- 
> 2.53.0
> 
>