resize regular luks partition

I replaced a 750GB drive with a 1TB. I copied the old partitions over with DD. The problem is that the partitions didn't make use of the extra space. So, I needed to grow them. There is nothing special about the luks it seems. You just need to decrypt the drive and then proceed as if it was a regular file system. I performed the following steps with it unmounted. You can do it mounted. I just chose not to.

Grow the partition size.

localhost ~ # parted /dev/sdb
GNU Parted 3.2
Using /dev/sdb
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) resizepart 1                                                     
End?  [750GB]? 1000GB

Grow the filesystem

localhost ~ # resize2fs /dev/sdb1
resize2fs 1.43.1 (08-Jun-2016)
resize2fs: Device or resource busy while trying to open /dev/sdb1
Couldnt find valid filesystem superblock.

woops, I specified the wrong device name. I need to use the dev mapper name...

localhost ~ # resize2fs /dev/mapper/vol1
resize2fs 1.43.1 (08-Jun-2016)
Please run 'e2fsck -f /dev/mapper/vol1' first.

whatever you say sir

localhost ~ # e2fsck -f /dev/mapper/vol1
e2fsck 1.43.1 (08-Jun-2016)
Pass 1: Checking inodes, blocks, and sizes
Inode 18612229 extent tree (at level 2) could be narrower.  Fix<y>? yes
...
/dev/mapper/vol1: ***** FILE SYSTEM WAS MODIFIED *****
/dev/mapper/vol1: 352906/45793280 files (0.3% non-contiguous), 160544229/183142878 blocks
 
localhost ~ # resize2fs /dev/mapper/vol1
resize2fs 1.43.1 (08-Jun-2016)
Resizing the filesystem on /dev/mapper/vol1 to 244139857 (4k) blocks.
The filesystem on /dev/mapper/vol1 is now 244139857 (4k) blocks long.