ext4: update the s_overhead_clusters in the backup sb's when resizing

ext4: update the s_overhead_clusters in the backup sb's when resizing

When the EXT4_IOC_RESIZE_FS ioctl is complete, update the backup
superblocks.  We don't do this for the old-style resize ioctls since
they are quite ancient, and only used by very old versions of
resize2fs --- and we don't want to update the backup superblocks every
time EXT4_IOC_GROUP_ADD is called, since it might get called a lot.

Signed-off-by: Theodore Ts'o <[email protected]>
Reviewed-by: Andreas Dilger <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Theodore Ts'o <[email protected]>