Re: [PATCH 4/4] exportfs,nfsd: rework checking for layout-based block device access support

[Jeff Layton <jlayton@kernel.org>]

On Wed, 2026-04-01 at 16:40 +0200, Christoph Hellwig wrote:
> Currently NFSD hard codes checking support for block-style layouts.
> Lift the checks into a file system-helper and provide a exportfs-level
> helper to implement the typical checks.
> 
> This prepares for supporting block layout export of multiple devices
> per file system.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Reviewed-by: Jeff Layton <jlayton@kernel.org>
> ---
>  fs/nfsd/export.c               |  3 +-
>  fs/nfsd/nfs4layouts.c          | 26 +++++------------
>  fs/xfs/xfs_pnfs.c              | 13 +++++++++
>  include/linux/exportfs_block.h | 52 +++++++++++++++++++++++++++++++++-
>  4 files changed, 73 insertions(+), 21 deletions(-)
> 
> diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c
> index 8e8a76a44ff0..e20298f9212f 100644
> --- a/fs/nfsd/export.c
> +++ b/fs/nfsd/export.c
> @@ -735,7 +735,8 @@ static int svc_export_parse(struct cache_detail *cd, char *mesg, int mlen)
>  			goto out4;
>  		err = 0;
>  
> -		nfsd4_setup_layout_type(&exp);
> +		if (exp.ex_flags & NFSEXP_PNFS)
> +			nfsd4_setup_layout_type(&exp);
>  	}
>  

There is a (minor) problem with this patch. There is a second call to
nfsd4_setup_layout_type() in Chuck's nfsd-next branch, in
nfsd_nl_parse_one_export(). It needs to be gated on this flag now, or
we end up enabling pnfs unconditionally.

-- 
Jeff Layton <jlayton@kernel.org>