btrfs: Use WARN_ON()'s return value in place of WARN_ON(1)

Use WARN_ON()'s return value in place of WARN_ON(1) for cleaner source
code that outputs a more descriptive warnings. Also fix the styling
warning of redundant braces that came up as a result of this fix.

Signed-off-by: Dulshani Gunawardhana <dulshani.gunawardhana89@gmail.com>
Reviewed-by: Zach Brown <zab@redhat.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 3aa5270..2d58461 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -1550,9 +1550,8 @@
 	if (ret && !insert) {
 		err = -ENOENT;
 		goto out;
-	} else if (ret) {
+	} else if (WARN_ON(ret)) {
 		err = -EIO;
-		WARN_ON(1);
 		goto out;
 	}
 
@@ -5752,9 +5751,8 @@
 			}
 			extent_slot = path->slots[0];
 		}
-	} else if (ret == -ENOENT) {
+	} else if (WARN_ON(ret == -ENOENT)) {
 		btrfs_print_leaf(extent_root, path->nodes[0]);
-		WARN_ON(1);
 		btrfs_err(info,
 			"unable to find ref byte nr %llu parent %llu root %llu  owner %llu offset %llu",
 			bytenr, parent, root_objectid, owner_objectid,
@@ -8317,10 +8315,9 @@
 					struct btrfs_space_info,
 					list);
 		if (btrfs_test_opt(info->tree_root, ENOSPC_DEBUG)) {
-			if (space_info->bytes_pinned > 0 ||
+			if (WARN_ON(space_info->bytes_pinned > 0 ||
 			    space_info->bytes_reserved > 0 ||
-			    space_info->bytes_may_use > 0) {
-				WARN_ON(1);
+			    space_info->bytes_may_use > 0)) {
 				dump_space_info(space_info, 0, 0);
 			}
 		}