Re: [PATCH RFC v0 06/49] pnfsd: define pnfs_export_operations

["J. Bruce Fields" <bfields@redhat.com>]

On Thu, Sep 26, 2013 at 02:40:15PM -0400, Benny Halevy wrote:
> From: Benny Halevy <bhalevy@panasas.com>
> 
> struct pnfs_export_operations defines the VFS level API for pNFS,
> not including callbacks.  A pnfs-exportable filesystem sets
> a pointer to its pnfs export vector in its struct super_block.s_pnfs_op.
> 
> The file system provides the per-superblock layout_type method that
> determines if it supports pnfs for the filesystem identified by
> the superblock, and if so, with which layout type (only one per-sb is
> supported).
> 
> Device ops:
> get_device_iter is used to fill-in the device list for GETDEVICELIST
> and get_device_info is used to encode the device info for GETDEVICEINFO.
> 
> Layout ops:
> layout_get, layout_commit, and layout_return implement the file system- and
> layout type- specific parts of their respective protocol operations: LAYOUTGET,
> LAYOUTCOMMIT, and LAYOUTRETURN.
> 
> The following methods are mandatory to be implemented:
> layout_type, get_device_info, and layout_get.
> 
> Note: define pnfs export operations in a stub form in this patch.
> Actual operations are defined along with their usage.

Patches touching the superblock or the new pnfs export operations should
probably all be cc'd to linux-fsdevel.

--b.

> 
> [pnfsd: provide default no-op operations]
> Signed-off-by: Benny Halevy <bhalevy@panasas.com>
> [pnfsd: compile fixes for pnfsd branch]
> Signed-off-by: Fred Isaman <iisaman@citi.umich.edu>
> [gfs2: set pnfs_dlm_export_ops only for CONFIG_PNFSD]
> [pnfsd: handle s_pnfs_op==NULL]
> Signed-off-by: Benny Halevy <bhalevy@panasas.com>
> Signed-off-by: Benny Halevy <bhalevy@primarydata.com>
> ---
>  fs/nfsd/export.c                |  2 +-
>  include/linux/fs.h              |  2 ++
>  include/linux/nfsd/nfsd4_pnfs.h | 14 ++++++++++++++
>  3 files changed, 17 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c
> index 5f38ea3..f26b0b9 100644
> --- a/fs/nfsd/export.c
> +++ b/fs/nfsd/export.c
> @@ -16,7 +16,7 @@
>  #include <linux/module.h>
>  #include <linux/exportfs.h>
>  #include <linux/sunrpc/svc_xprt.h>
> -
> +#include <linux/nfsd/nfsd4_pnfs.h>
>  #include <net/ipv6.h>
>  
>  #include "nfsd.h"
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 3f40547..d9186a4 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -34,6 +34,7 @@
>  #include <uapi/linux/fs.h>
>  
>  struct export_operations;
> +struct pnfs_export_operations;
>  struct hd_geometry;
>  struct iovec;
>  struct nameidata;
> @@ -1251,6 +1252,7 @@ struct super_block {
>  	const struct dquot_operations	*dq_op;
>  	const struct quotactl_ops	*s_qcop;
>  	const struct export_operations *s_export_op;
> +	const struct pnfs_export_operations *s_pnfs_op;
>  	unsigned long		s_flags;
>  	unsigned long		s_magic;
>  	struct dentry		*s_root;
> diff --git a/include/linux/nfsd/nfsd4_pnfs.h b/include/linux/nfsd/nfsd4_pnfs.h
> index 9e7d95e..ff6613e 100644
> --- a/include/linux/nfsd/nfsd4_pnfs.h
> +++ b/include/linux/nfsd/nfsd4_pnfs.h
> @@ -34,4 +34,18 @@
>  #ifndef _LINUX_NFSD_NFSD4_PNFS_H
>  #define _LINUX_NFSD_NFSD4_PNFS_H
>  
> +/*
> + * pNFS export operations vector.
> + *
> + * The filesystem must implement the following methods:
> + *   layout_type
> + *   get_device_info
> + *   layout_get
> + *
> + * All other methods are optional and can be set to NULL if not implemented.
> + */
> +struct pnfs_export_operations {
> +	/* stub */
> +};
> +
>  #endif /* _LINUX_NFSD_NFSD4_PNFS_H */
> -- 
> 1.8.3.1
>