tune2fs: rewrite metadata checksums when resizing inode size

tune2fs: rewrite metadata checksums when resizing inode size

When we use tune2fs -I new_ino_size to change inode size, if
everything is OK, the corresponding ext4_group_desc.bg_free_blocks_count
will be decreased, so obviously, we need to re-compute the group
descriptor checksums, and the inode 's size has also changed, we also
need to recompute the checksums of inodes for metadata_csum
filesystem, so here we choose to call a rewrite_metadata_checksums(),
this will fix checksum issues.

Meanwhile, the patch will trigger an existing memory write overflow,
which will casue segfault, please see the next patch.

Signed-off-by: Xiaoguang Wang <wangxg.fnst@cn.fujitsu.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>