How do I mount my FileVault 2-encrypted volume? I have a Lion 10.7.2 system (on MacBook Air 13" 2011) which doesn't boot anymore after a restart. My HD is encrypted with FileVault 2, and after I click on my username and enter my password, it appears to be logging in but the apple logo turns into sort of a "forbidden" traffic sign, and stops there forever.

So I booted into Lion Recovery to try and repair permissions, but Disk Utility won't mount my Macintosh HD. It doesn't even allow me the option to mount or verify, they're greyed out.

An output from diskutil list recognizes my partition (/dev/disk0s2) as having the type Apple_CoreStorage.

Any way to make my encrypted partition mount?
You should be able to unlock or decrypt your FileVault 2-encrypted HD with Disk Utility. I've got a post on how to do this:

Using Disk Utility to unlock or decrypt your FileVault 2-encrypted boot drive:

http://derflounder.wordpress.com/2011/11/23/using-disk-utility-to-unlock-or-decrypt-your-filevault-2-encrypted-boot-drive/

If unlocking via Disk Utility isn't working, you may need to use your recovery key. I've got another post on how you can unlock using your recovery key using the command line:

Unlock or decrypt your FileVault 2-encrypted boot drive from the command line:

http://derflounder.wordpress.com/2011/11/23/using-the-command-line-to-unlock-or-decrypt-your-filevault-2-encrypted-boot-drive/