diff --git a/fs/ocfs2/alloc.c b/fs/ocfs2/alloc.c
index dc7411fe185d99652cc98f93436e1b46bdfd380d..8750ae1b8636f5904bdc921ea657c8aba69406b0 100644
--- a/fs/ocfs2/alloc.c
+++ b/fs/ocfs2/alloc.c
@@ -7260,14 +7260,8 @@ int ocfs2_trim_fs(struct super_block *sb, struct fstrim_range *range)
 	start = range->start >> osb->s_clustersize_bits;
 	len = range->len >> osb->s_clustersize_bits;
 	minlen = range->minlen >> osb->s_clustersize_bits;
-	trimmed = 0;
-
-	if (!len) {
-		range->len = 0;
-		return 0;
-	}
 
-	if (minlen >= osb->bitmap_cpg)
+	if (minlen >= osb->bitmap_cpg || range->len < sb->s_blocksize)
 		return -EINVAL;
 
 	main_bm_inode = ocfs2_get_system_file_inode(osb,
@@ -7293,6 +7287,7 @@ int ocfs2_trim_fs(struct super_block *sb, struct fstrim_range *range)
 		goto out_unlock;
 	}
 
+	len = range->len >> osb->s_clustersize_bits;
 	if (start + len > le32_to_cpu(main_bm->i_clusters))
 		len = le32_to_cpu(main_bm->i_clusters) - start;
 
@@ -7307,6 +7302,7 @@ int ocfs2_trim_fs(struct super_block *sb, struct fstrim_range *range)
 	last_group = ocfs2_which_cluster_group(main_bm_inode, start + len - 1);
 	last_bit = osb->bitmap_cpg;
 
+	trimmed = 0;
 	for (group = first_group; group <= last_group;) {
 		if (first_bit + len >= osb->bitmap_cpg)
 			last_bit = osb->bitmap_cpg;