I was having a similar issue, getting a “Device does not have enough space for upgrade.” error message, but the fix was different.
I had /dev/sda4 mounted on /DataVolume, but it didn’t show up on df for some reason. When I used mount /dev/sda4 /DataVolume, I got a message that it was already mounted at /nfs/Music. This is what I had on mtab:
/dev/sda4 /DataVolume ext4 rw,noatime,nodiratime,user_xattr,barrier=0,data=writeback 0 0
/dev/sda4 /CacheVolume ext4 rw,noatime,nodiratime,user_xattr,barrier=0,data=writeback 0 0
/dev/sda4 /shares ext4 rw,noatime,nodiratime,user_xattr,barrier=0,data=writeback 0 0
/dev/sda4 /nfs/SmartWare ext4 rw,noatime,nodiratime,user_xattr,barrier=0,data=writeback 0 0
/dev/sda4 /nfs/Public ext4 rw,noatime,nodiratime,user_xattr,barrier=0,data=writeback 0 0
/dev/sda4 /nfs/TimeMachineBackup ext4 rw,noatime,nodiratime,user_xattr,barrier=0,data=writeback 0 0
/dev/sda4 /nfs/Music ext4 rw,noatime,nodiratime,user_xattr,barrier=0,data=writeback 0 0
So knowing that it wasn’t a mount/bindissue, I decided to look into the updateFirmwareFromFile.sh script. If you look into the portion that checks disk usage, it goes
dfout=`df | grep /DataVolume`
Problem is, df wasn’t listing the space for /DataVolume:
Filesystem 1K-blocks Used Available Use% Mounted on
rootfs 1968336 482224 1386124 26% /
/dev/root 1968336 482224 1386124 26% /
tmpfs 23056 332 22724 2% /run
tmpfs 40960 4 40956 1% /run/lock
tmpfs 10240 0 10240 0% /dev
tmpfs 5120 0 5120 0% /run/shm
tmpfs 102400 148 102252 1% /tmp
/dev/root 1968336 482224 1386124 26% /var/log.hdd
ramlog-tmpfs 20480 2644 17836 13% /var/log
So what I did was to simply change this line to
dfout=`df -a | grep /DataVolume`
and voilá… the script ran fine, firmware updated. I even reached out to WD support for assistance before going into the scripts but they only suggested me to do a full factory restore which I didn’t wanted to do. After the upgrade, df shows up all mounted drives. Probably this was caused by me running apt-get upgrade (ooops) when messing around… glad I figured it out.