exofs: fix pnfs_osd re-definitions in pre-pnfs trees

Some on disk exofs constants and types are defined in the pnfs_osd_xdr.h
file. Since we needed these types before the pnfs-objects code was
accepted to mainline we duplicated the minimal needed definitions into
an exofs local header. The definitions where conditionally included
depending on !CONFIG_PNFS defined. So if PNFS was present in the tree
definitions are taken from there and if not they are defined locally.

That was all good but, the CONFIG_PNFS is planed to be included upstream
before the pnfs-objects is also included. (The first pnfs batch might be
pnfs-files only)

So condition exofs local definitions on the absence of pnfs_osd_xdr.h
inclusion (__PNFS_OSD_XDR_H__ not defined). User code must make sure
that in future pnfs_osd_xdr.h will be included before fs/exofs/pnfs.h,
which happens to be so in current code.

Once pnfs-objects hits mainline, exofs's local header will be removed.
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>

fs/exofs/pnfs.h

@@ -15,13 +15,7 @@
 #ifndef __EXOFS_PNFS_H__
 #define __EXOFS_PNFS_H__
 
-#if defined(CONFIG_PNFS)
-
-
-/* FIXME: move this file to: linux/exportfs/pnfs_osd_xdr.h */
-#include "../nfs/objlayout/pnfs_osd_xdr.h"
-
-#else /* defined(CONFIG_PNFS) */
+#if ! defined(__PNFS_OSD_XDR_H__)
 
 enum pnfs_iomode {
 	IOMODE_READ = 1,
@@ -46,6 +40,6 @@ struct pnfs_osd_data_map {
 	u32	odm_raid_algorithm;
 };
 
-#endif /* else defined(CONFIG_PNFS) */
+#endif /* ! defined(__PNFS_OSD_XDR_H__) */
 
 #endif /* __EXOFS_PNFS_H__ */