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>

misc/tune2fs.c

@@ -2908,8 +2908,7 @@ int main(int argc, char **argv)
 				EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
 			rewrite_checksums = 1;
 	}
-	if (rewrite_checksums)
-		rewrite_metadata_checksums(fs);
+
 	if (I_flag) {
 		if (mount_flags & EXT2_MF_MOUNTED) {
 			fputs(_("The inode size may only be "
@@ -2935,13 +2934,17 @@ int main(int argc, char **argv)
 		if (resize_inode(fs, new_inode_size) == 0) {
 			printf(_("Setting inode size %lu\n"),
 							new_inode_size);
+			rewrite_checksums = 1;
 		} else {
 			printf("%s", _("Failed to change inode size\n"));
 			rc = 1;
 			goto closefs;
 		}
 	}
 
+	if (rewrite_checksums)
+		rewrite_metadata_checksums(fs);
+
 	if (l_flag)
 		list_super(sb);
 	if (stride_set) {