ext4: flush the extent status cache during EXT4_IOC_SWAP_BOOT

Previously we weren't swapping only some of the extent_status LRU
fields during the processing of the EXT4_IOC_SWAP_BOOT ioctl.  The
much safer thing to do is to just completely flush the extent status
tree when doing the swap.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: Zheng Liu <gnehzuil.liu@gmail.com>
Cc: stable@vger.kernel.org

fs/ext4/ioctl.c

@@ -77,8 +77,10 @@ static void swap_inode_data(struct inode *inode1, struct inode *inode2)
 	memswap(ei1->i_data, ei2->i_data, sizeof(ei1->i_data));
 	memswap(&ei1->i_flags, &ei2->i_flags, sizeof(ei1->i_flags));
 	memswap(&ei1->i_disksize, &ei2->i_disksize, sizeof(ei1->i_disksize));
-	memswap(&ei1->i_es_tree, &ei2->i_es_tree, sizeof(ei1->i_es_tree));
-	memswap(&ei1->i_es_lru_nr, &ei2->i_es_lru_nr, sizeof(ei1->i_es_lru_nr));
+	ext4_es_remove_extent(inode1, 0, EXT_MAX_BLOCKS);
+	ext4_es_remove_extent(inode2, 0, EXT_MAX_BLOCKS);
+	ext4_es_lru_del(inode1);
+	ext4_es_lru_del(inode2);
 
 	isize = i_size_read(inode1);
 	i_size_write(inode1, i_size_read(inode2));