Re: [PATCH 13/13] NFS: Request fh_expire_type attribute in "server caps" operation

[Matthew Treinish <treinish@linux.vnet.ibm.com>]

On Wed, Feb 15, 2012 at 04:36:34PM -0500, Chuck Lever wrote:
> The fh_expire_type file attribute is a filesystem wide attribute that
> consists of flags that indicate what characteristics file handles
> on this FSID have.
> 
> Our client won't support volatile file handles, but it should find
> out at mount time whether the server is going to play shenanighans
> with file handles during a migration.
> 
> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
> ---
> 
>  fs/nfs/nfs4proc.c         |    1 +
>  fs/nfs/nfs4xdr.c          |   26 ++++++++++++++++++++++++++
>  include/linux/nfs_fs_sb.h |    3 +++
>  include/linux/nfs_xdr.h   |    1 +
>  4 files changed, 31 insertions(+), 0 deletions(-)
> 
<snip>
> index 6532d7b..f07d966 100644
> --- a/include/linux/nfs_fs_sb.h
> +++ b/include/linux/nfs_fs_sb.h
> @@ -144,6 +144,9 @@ struct nfs_server {
>  	u32			acl_bitmask;	/* V4 bitmask representing the ACEs
>  						   that are supported on this
>  						   filesystem */
> +	u32			fh_expire_type;	/* V4 bitmask representing file
> +						   handle volatility type for
> +						   this filesystem */
>  	struct pnfs_layoutdriver_type  *pnfs_curr_ld; /* Active layout driver */
>  	struct rpc_wait_queue	roc_rpcwaitq;
>  	void			*pnfs_ld_data;	/* per mount point data */
> diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
> index d609631..ff74d94 100644
> --- a/include/linux/nfs_xdr.h
> +++ b/include/linux/nfs_xdr.h
> @@ -973,6 +973,7 @@ struct nfs4_server_caps_res {
>  	u32				acl_bitmask;
>  	u32				has_links;
>  	u32				has_symlinks;
> +	u32				fh_expire_type;
>  	struct nfs4_sequence_res	seq_res;
>  };

I had a similar patch in my volatile file handle tree, 
(http://www.spinics.net/lists/linux-nfs/msg26069.html) but in my commit I used 
fs_info instead of server caps. If I remember the spec correctly, it says that
the attribute is set per file system, that's why I put it in fs_info. I'm just
curious why you used server caps, not that it really makes a difference.

-Matt Treinish