diff --git a/fs/gfs2/trans.c b/fs/gfs2/trans.c
index cac93b2004cf0..f73d6b8f3b53b 100644
--- a/fs/gfs2/trans.c
+++ b/fs/gfs2/trans.c
@@ -54,8 +54,14 @@ int __gfs2_trans_begin(struct gfs2_trans *tr, struct gfs2_sbd *sdp,
 	tr->tr_blocks = blocks;
 	tr->tr_revokes = revokes;
 	tr->tr_reserved = 1;
-	if (blocks)
-		tr->tr_reserved += 6 + blocks;
+	if (blocks) {
+		/*
+		 * The reserved blocks are either used for data or metadata.
+		 * We can have mixed data and metadata, each with its own log
+		 * descriptor block; see calc_reserved().
+		 */
+		tr->tr_reserved += blocks + 1 + DIV_ROUND_UP(blocks - 1, databuf_limit(sdp));
+	}
 	if (revokes)
 		tr->tr_reserved += gfs2_struct2blk(sdp, revokes);
 	INIT_LIST_HEAD(&tr->tr_databuf);