pnfs: change lo refcounting to atomic_t

This will be required to allow us to grab reference outside of i_lock.
While we are at it, make put_layout_hdr take the same argument as all the
related functions.

Signed-off-by: Fred Isaman <iisaman@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/pnfs.h b/fs/nfs/pnfs.h
index 698380d..8aaab56 100644
--- a/fs/nfs/pnfs.h
+++ b/fs/nfs/pnfs.h
@@ -65,7 +65,7 @@
 };
 
 struct pnfs_layout_hdr {
-	unsigned long		plh_refcount;
+	atomic_t		plh_refcount;
 	struct list_head	plh_layouts;   /* other client layouts */
 	struct list_head	plh_segs;      /* layout segments list */
 	nfs4_stateid		plh_stateid;
@@ -147,7 +147,7 @@
 int pnfs_layout_process(struct nfs4_layoutget *lgp);
 void pnfs_destroy_layout(struct nfs_inode *);
 void pnfs_destroy_all_layouts(struct nfs_client *);
-void put_layout_hdr(struct inode *inode);
+void put_layout_hdr(struct pnfs_layout_hdr *lo);
 int pnfs_choose_layoutget_stateid(nfs4_stateid *dst,
 				  struct pnfs_layout_hdr *lo,
 				  struct nfs4_state *open_state);