nfs: mark nfs_page reqs with flag for extra ref

Change the use of PG_INODE_REF - set it when taking extra reference on
subrequests and take care to only release once for each request.

Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index b6ee3a6..7368b21 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -251,8 +251,10 @@
 		/* grab extra ref if head request has extra ref from
 		 * the write/commit path to handle handoff between write
 		 * and commit lists */
-		if (test_bit(PG_INODE_REF, &prev->wb_head->wb_flags))
+		if (test_bit(PG_INODE_REF, &prev->wb_head->wb_flags)) {
+			set_bit(PG_INODE_REF, &req->wb_flags);
 			kref_get(&req->wb_kref);
+		}
 	}
 }