I after upgrading OS X to Yosemite, rEFInd did not start. Using the
Option key while rebooting, I selected my Ubuntu Trusty partition,
which booted with a warning that the MacintoshHD couldn't be mounted.
During the upgrade, the HFS+ partition where OS X resides was converted
to a logical volume of Apple Core Storage. I believe this is to support
encryption, but I declined the option during the upgrade. The Disk Util
app in OS X will not show this change, but the
diskutil command will.
The fix is trivial from the OS X terminal.
diskutil list command will reveal which partition was convert to a
logical volume on the physical disk.
diskutil list /dev/disk0 #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme *251.0 GB disk0 1: EFI 209.7 MB disk0s1 2: Apple_CoreStorage 175.6 GB disk0s2 3: Apple_Boot Recovery HD 650.0 MB disk0s3 4: Microsoft Basic Data 70.3 GB disk0s4 5: Linux Swap 4.2 GB disk0s5 /dev/disk1 #: TYPE NAME SIZE IDENTIFIER 0: Apple_HFS Macintosh HD *175.3 GB disk1 Logical Volume on disk0s2 41AF7850-5594-4959-A135-582BF79FDE46 Unencrypted
Your disk partitions for dual booting Ubuntu and OS X may be different.
I know there was no logical volume before I started the upgrade. I
restored the APPLE_HFS partition to the real disk0s2 with the
diskutil corestorage revert /dev/disk1
When I rebooted, rEFInd presented me with choice of OS X and Ubuntu. Ubuntu mounted with MacintoshHD when I signed in. All fixed.