pnfs: support multiple verfs per direct req

Support direct requests that span multiple pnfs data servers by
comparing nfs_pgio_header->verf to a cached verf in pnfs_commit_bucket.
Continue to use dreq->verf if the MDS is used / non-pNFS.

Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index ae63601..9a1396e 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -1112,6 +1112,7 @@
 	struct list_head committing;
 	struct pnfs_layout_segment *wlseg;
 	struct pnfs_layout_segment *clseg;
+	struct nfs_writeverf direct_verf;
 };
 
 struct pnfs_ds_commit_info {
@@ -1294,6 +1295,7 @@
 	__u64			mds_offset;	/* Filelayout dense stripe */
 	struct nfs_page_array	pages;
 	struct nfs_client	*ds_clp;	/* pNFS data server */
+	int			ds_idx;		/* ds index if ds_clp is set */
 };
 
 struct nfs_rw_header {