LVM2 problem after resize

[roelvdh]

I have a very large LVM device containing end-of-year backups. It grows every year and thus extensions are sometimes necessary. During the last extension something must have gone wrong. The newly extended device could correctly be activated but failed being mounted, as the filesystem size now seems to differ from the physical size of the device.
I haven't yet tried to shrink the device back to its former state as I am unsure whether this would be the best approach.
Any better ideas?

[aks]

It's hard to know, since we don't know what the problem is.
With filesystems and disks damage is often permanent...

[gerald_clark]

If it is an ext filesystem, and the lv size was increased, resize2fs with no size option will resize it to the size of the logical volume.

[TrevorH]

Are you sure you didn't shrink it instead of growing it? There's a major difference between e.g. lvextend -L+64G ... and lvextend -L64G ...