diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 2d54c822c4c3f65b09b7caec7bccd336fd0a3faf..5e17d5f22a7e7757e921a133796d27769585ebd0 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1005,6 +1005,9 @@ static int ext4_indirect_calc_metadata_amount(struct inode *inode, int blocks)
  */
 static int ext4_calc_metadata_amount(struct inode *inode, int blocks)
 {
+	if (!blocks)
+		return 0;
+
 	if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)
 		return ext4_ext_calc_metadata_amount(inode, blocks);
 
@@ -1559,7 +1562,25 @@ static void ext4_da_release_space(struct inode *inode, int to_free)
 	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 	int total, mdb, mdb_free, release;
 
+	if (!to_free)
+		return;		/* Nothing to release, exit */
+
 	spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
+
+	if (!EXT4_I(inode)->i_reserved_data_blocks) {
+		/*
+		 * if there is no reserved blocks, but we try to free some
+		 * then the counter is messed up somewhere.
+		 * but since this function is called from invalidate
+		 * page, it's harmless to return without any action
+		 */
+		printk(KERN_INFO "ext4 delalloc try to release %d reserved "
+			    "blocks for inode %lu, but there is no reserved "
+			    "data blocks\n", to_free, inode->i_ino);
+		spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
+		return;
+	}
+
 	/* recalculate the number of metablocks still need to be reserved */
 	total = EXT4_I(inode)->i_reserved_data_blocks - to_free;
 	mdb = ext4_calc_metadata_amount(inode, total);