blkdev: generalize flags for blkdev_issue_fn functions

The patch just convert all blkdev_issue_xxx function to common
set of flags. Wait/allocation semantics preserved.

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index 503b842..bf011dc 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -854,7 +854,8 @@
 				if ((start + nr_sects) != blk) {
 					rv = blkdev_issue_discard(bdev, start,
 							    nr_sects, GFP_NOFS,
-							    DISCARD_FL_BARRIER);
+							    BLKDEV_IFL_WAIT |
+							    BLKDEV_IFL_BARRIER);
 					if (rv)
 						goto fail;
 					nr_sects = 0;
@@ -869,7 +870,7 @@
 	}
 	if (nr_sects) {
 		rv = blkdev_issue_discard(bdev, start, nr_sects, GFP_NOFS,
-					 DISCARD_FL_BARRIER);
+					 BLKDEV_IFL_WAIT | BLKDEV_IFL_BARRIER);
 		if (rv)
 			goto fail;
 	}