diff --git a/fs/xfs/xfs_rtalloc.c b/fs/xfs/xfs_rtalloc.c
index e5d6031d47bb..4bec890d93d2 100644
--- a/fs/xfs/xfs_rtalloc.c
+++ b/fs/xfs/xfs_rtalloc.c
@@ -1070,6 +1070,9 @@ xfs_growfs_rt(
 			nsbp->sb_rbmblocks;
 		nrsumblocks = XFS_B_TO_FSB(mp, nrsumsize);
 		nmp->m_rsumsize = nrsumsize = XFS_FSB_TO_B(mp, nrsumblocks);
+		/* recompute growfsrt reservation from new rsumsize */
+		xfs_trans_resv_calc(nmp, &nmp->m_resv);
+
 		/*
 		 * Start a transaction, get the log reservation.
 		 */
@@ -1153,6 +1156,8 @@ error_cancel:
 		 */
 		mp->m_rsumlevels = nrsumlevels;
 		mp->m_rsumsize = nrsumsize;
+		/* recompute growfsrt reservation from new rsumsize */
+		xfs_trans_resv_calc(mp, &mp->m_resv);
 
 		error = xfs_trans_commit(tp);
 		if (error)