pnfsblock: basic extent code

Adds structures and basic create/delete code for extents.

Signed-off-by: Fred Isaman <iisaman@citi.umich.edu>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: Zhang Jingwang <Jingwang.Zhang@emc.com>
Signed-off-by: Benny Halevy <bhalevy@tonian.com>
Signed-off-by: Jim Rees <rees@umich.edu>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/blocklayout/blocklayout.h b/fs/nfs/blocklayout/blocklayout.h
index 8bfa466..98e2f60 100644
--- a/fs/nfs/blocklayout/blocklayout.h
+++ b/fs/nfs/blocklayout/blocklayout.h
@@ -88,4 +88,5 @@
 	return container_of(lo, struct pnfs_block_layout, bl_layout);
 }
 
+void bl_put_extent(struct pnfs_block_extent *be);
 #endif /* FS_NFS_NFS4BLOCKLAYOUT_H */