tree 7de602d2fb78b4bfa042f8176ccd09712b6f5f56
parent 2ba45aafc22ff2fed91f8cd191beb85578b7b9bc
author Ken Sumrall <ksumrall@android.com> 1360114788 -0800
committer Ken Sumrall <ksumrall@android.com> 1360278354 -0800

Enable allow_discards if dm-crypt supports it

dm-crypt version 1.11.0 and later supports the allow_discards option
when setting up a crypto device.  This passes discard requests from
the filesytem to the underlying block device.  This helps make flash
based storage faster.  So query the dm-crypt version, and pass the
option if the version is 1.11.0 or greater.

Change-Id: If30e9db5a2dbd6ea0281d91344e5b2c35e75131e