Re: [RFC PATCH] nfsd: allow nfsd to advertise multiple layout types

[Jeff Layton <jlayton@poochiereds.net>]

On Sun, 2016-05-29 at 16:59 -0400, Jeff Layton wrote:
> If the underlying filesystem supports multiple layout types, then there
> is little reason not to advertise that fact to clients and let them
> choose what type to use.
> 
> Turn the ex_layout_type field into a bitfield. For each supported
> layout type, we set a bit in that field. When the client requests a
> layout, ensure that the bit for that layout type is set. When the
> client requests attributes, send back a list of supported types.
> 
> Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
> ---
>  fs/nfsd/export.c      |  4 ++--
>  fs/nfsd/export.h      |  2 +-
>  fs/nfsd/nfs4layouts.c |  6 +++---
>  fs/nfsd/nfs4proc.c    |  4 ++--
>  fs/nfsd/nfs4xdr.c     | 30 ++++++++++++++----------------
>  5 files changed, 22 insertions(+), 24 deletions(-)
> 
> diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c
> index b4d84b579f20..f97ba49d5e66 100644
> --- a/fs/nfsd/export.c
> +++ b/fs/nfsd/export.c
> @@ -706,7 +706,7 @@ static void svc_export_init(struct cache_head *cnew, struct cache_head *citem)
>  	new->ex_fslocs.locations = NULL;
>  	new->ex_fslocs.locations_count = 0;
>  	new->ex_fslocs.migrated = 0;
> -	new->ex_layout_type = 0;
> +	new->ex_layout_types = 0;
>  	new->ex_uuid = NULL;
>  	new->cd = item->cd;
>  }
> @@ -731,7 +731,7 @@ static void export_update(struct cache_head *cnew, struct cache_head *citem)
>  	item->ex_fslocs.locations_count = 0;
>  	new->ex_fslocs.migrated = item->ex_fslocs.migrated;
>  	item->ex_fslocs.migrated = 0;
> -	new->ex_layout_type = item->ex_layout_type;
> +	new->ex_layout_types = item->ex_layout_types;
>  	new->ex_nflavors = item->ex_nflavors;
>  	for (i = 0; i < MAX_SECINFO_LIST; i++) {
>  		new->ex_flavors[i] = item->ex_flavors[i];
> diff --git a/fs/nfsd/export.h b/fs/nfsd/export.h
> index 2e315072bf3f..730f15eeb7ed 100644
> --- a/fs/nfsd/export.h
> +++ b/fs/nfsd/export.h
> @@ -57,7 +57,7 @@ struct svc_export {
>  	struct nfsd4_fs_locations ex_fslocs;
>  	uint32_t		ex_nflavors;
>  	struct exp_flavor_info	ex_flavors[MAX_SECINFO_LIST];
> -	enum pnfs_layouttype	ex_layout_type;
> +	u32			ex_layout_types;
>  	struct nfsd4_deviceid_map *ex_devid_map;
>  	struct cache_detail	*cd;
>  };
> diff --git a/fs/nfsd/nfs4layouts.c b/fs/nfsd/nfs4layouts.c
> index 6d98d16b3354..2be9602b0221 100644
> --- a/fs/nfsd/nfs4layouts.c
> +++ b/fs/nfsd/nfs4layouts.c
> @@ -139,21 +139,21 @@ void nfsd4_setup_layout_type(struct svc_export *exp)
>  	 * otherwise advertise the block layout.
>  	 */
>  #ifdef CONFIG_NFSD_FLEXFILELAYOUT
> -	exp->ex_layout_type = LAYOUT_FLEX_FILES;
> +	exp->ex_layout_types |= 1 << LAYOUT_FLEX_FILES;
>  #endif
>  #ifdef CONFIG_NFSD_BLOCKLAYOUT
>  	/* overwrite flex file layout selection if needed */
>  	if (sb->s_export_op->get_uuid &&
>  	    sb->s_export_op->map_blocks &&
>  	    sb->s_export_op->commit_blocks)
> -		exp->ex_layout_type = LAYOUT_BLOCK_VOLUME;
> +		exp->ex_layout_types |= 1 << LAYOUT_BLOCK_VOLUME;
>  #endif
>  #ifdef CONFIG_NFSD_SCSILAYOUT
>  	/* overwrite block layout selection if needed */
>  	if (sb->s_export_op->map_blocks &&
>  	    sb->s_export_op->commit_blocks &&
>  	    sb->s_bdev && sb->s_bdev->bd_disk->fops->pr_ops)
> -		exp->ex_layout_type = LAYOUT_SCSI;
> +		exp->ex_layout_types |= 1 << LAYOUT_SCSI;
>  #endif
>  }
>  
> diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
> index 2ee2dc170327..719c620753e2 100644
> --- a/fs/nfsd/nfs4proc.c
> +++ b/fs/nfsd/nfs4proc.c
> @@ -1219,12 +1219,12 @@ nfsd4_verify(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>  static const struct nfsd4_layout_ops *
>  nfsd4_layout_verify(struct svc_export *exp, unsigned int layout_type)
>  {
> -	if (!exp->ex_layout_type) {
> +	if (!exp->ex_layout_types) {
>  		dprintk("%s: export does not support pNFS\n", __func__);
>  		return NULL;
>  	}
>  
> -	if (exp->ex_layout_type != layout_type) {
> +	if (!(exp->ex_layout_types & (1 << layout_type))) {
>  		dprintk("%s: layout type %d not supported\n",
>  			__func__, layout_type);
>  		return NULL;
> diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
> index 9df898ba648f..4d3ae75ad4c8 100644
> --- a/fs/nfsd/nfs4xdr.c
> +++ b/fs/nfsd/nfs4xdr.c
> @@ -2164,22 +2164,20 @@ nfsd4_encode_aclname(struct xdr_stream *xdr, struct svc_rqst *rqstp,
>  }
>  
>  static inline __be32
> -nfsd4_encode_layout_type(struct xdr_stream *xdr, enum pnfs_layouttype layout_type)
> +nfsd4_encode_layout_types(struct xdr_stream *xdr, u32 layout_types)
>  {
> -	__be32 *p;
> +	__be32		*p;
> +	unsigned long	i = hweight_long(layout_types);
>  
> -	if (layout_type) {
> -		p = xdr_reserve_space(xdr, 8);
> -		if (!p)
> -			return nfserr_resource;
> -		*p++ = cpu_to_be32(1);
> -		*p++ = cpu_to_be32(layout_type);
> -	} else {
> -		p = xdr_reserve_space(xdr, 4);
> -		if (!p)
> -			return nfserr_resource;
> -		*p++ = cpu_to_be32(0);
> -	}
> +	p = xdr_reserve_space(xdr, 4 + 4 * i);
> +	if (!p)
> +		return nfserr_resource;
> +
> +	*p++ = cpu_to_be32(i);
> +
> +	for (i = LAYOUT_NFSV4_1_FILES; i < LAYOUT_TYPE_MAX; ++i)
> +		if (layout_types & (1 << i))
> +			*p++ = cpu_to_be32(i);
>  
>  	return 0;
>  }
> @@ -2754,13 +2752,13 @@ out_acl:
>  	}
>  #ifdef CONFIG_NFSD_PNFS
>  	if (bmval1 & FATTR4_WORD1_FS_LAYOUT_TYPES) {
> -		status = nfsd4_encode_layout_type(xdr, exp->ex_layout_type);
> +		status = nfsd4_encode_layout_types(xdr, exp->ex_layout_types);
>  		if (status)
>  			goto out;
>  	}
>  
>  	if (bmval2 & FATTR4_WORD2_LAYOUT_TYPES) {
> -		status = nfsd4_encode_layout_type(xdr, exp->ex_layout_type);
> +		status = nfsd4_encode_layout_types(xdr, exp->ex_layout_types);
>  		if (status)
>  			goto out;
>  	}


Just a (lightly-tested) RFC patch for now.

This seems to do the right thing WRT to GETATTR response that requests
a layout types list. The current client code spews this into the ring
buffer though:

    NFS: decode_first_pnfs_layout_type: Warning: Multiple pNFS layout drivers per filesystem not supported

...so that would need a little work. Wireshark also seems to not parse
the layout types list correctly.

Thoughts?
-- 
Jeff Layton <jlayton@poochiereds.net>