pnfs-obj: objlayout_encode_layoutcommit implementation

* Define API for io-engines to report delta_space_used in IOs
* Encode the osd-layout specific information of the layoutcommit
  XDR buffer.

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
diff --git a/fs/nfs/objlayout/objlayout.c b/fs/nfs/objlayout/objlayout.c
index f7caecff..dc3956c 100644
--- a/fs/nfs/objlayout/objlayout.c
+++ b/fs/nfs/objlayout/objlayout.c
@@ -225,6 +225,7 @@
 		struct objlayout *objlay = OBJLAYOUT(state->lseg->pls_layout);
 
 		spin_lock(&objlay->lock);
+		objlay->delta_space_valid = OBJ_DSU_INVALID;
 		list_add(&objlay->err_list, &state->err_list);
 		spin_unlock(&objlay->lock);
 	}
@@ -433,6 +434,35 @@
 	return PNFS_ATTEMPTED;
 }
 
+void
+objlayout_encode_layoutcommit(struct pnfs_layout_hdr *pnfslay,
+			      struct xdr_stream *xdr,
+			      const struct nfs4_layoutcommit_args *args)
+{
+	struct objlayout *objlay = OBJLAYOUT(pnfslay);
+	struct pnfs_osd_layoutupdate lou;
+	__be32 *start;
+
+	dprintk("%s: Begin\n", __func__);
+
+	spin_lock(&objlay->lock);
+	lou.dsu_valid = (objlay->delta_space_valid == OBJ_DSU_VALID);
+	lou.dsu_delta = objlay->delta_space_used;
+	objlay->delta_space_used = 0;
+	objlay->delta_space_valid = OBJ_DSU_INIT;
+	lou.olu_ioerr_flag = !list_empty(&objlay->err_list);
+	spin_unlock(&objlay->lock);
+
+	start = xdr_reserve_space(xdr, 4);
+
+	BUG_ON(pnfs_osd_xdr_encode_layoutupdate(xdr, &lou));
+
+	*start = cpu_to_be32((xdr->p - start - 1) * 4);
+
+	dprintk("%s: Return delta_space_used %lld err %d\n", __func__,
+		lou.dsu_delta, lou.olu_ioerr_flag);
+}
+
 static int
 err_prio(u32 oer_errno)
 {