Unhelpful error message when trying to unmount busy device

[Mr.Mizzen]

If you try to unmount a busy device you will get an error message. However, that error message is completely useless to people without a specific knowledge, i.e. knowing how to use the 'lsof' command.
Ideally a dialogue would show up showing what processes are preventing you from unmounting it, including a "Force" button and PolicyKit integration.

However, this is a bit of work, so a temporary solution could be to make the error message clearer, e.g. "The device you're trying to unmount is currently still in use by one or more applications. Please close those first."

The original description stated that the error message mentioned above is only triggered when there has been data written.

[Sense Egbert Hofstede (sense)]

Thank you for helping with making Ubuntu and DeviceKit better by reporting this bug. However, I have a strong suspicion that this is a duplicate. Could you please have a look at bug #466575 and tell if this problem has the same symptoms named there?
Thansk in advance.

[Mr.Mizzen (mr-mizzen)]

Possibly a duplicate of bug #466575.
However, when I use smaller non-encrypted USB drives, they don't complain about unmounting.
(some are FAT some are ext3 format)
Anything that has dm-crypt luks (large or small), gives the error.

[Sense Egbert Hofstede (sense)]

The bug you've reported is actually a problem with the way the error message is presented, like the changes I've just made explain. You can't unmount the device because it is still being used by some application, you first need to kill that.
If you want to know what files are being used, and by what processes, you could use the command 'lsof'. This will show a list of files that are currently being used by processes.
However, please be careful with terminating processes as they may be still moving data to the device.

[Mr.Mizzen (mr-mizzen)]

Sequence Clarification:

Attach drive > Popup box to decrypt drive > Drive mounts and shows on desktop.
rsync data to drive
Some time later - minutes or even hours.....
Right click drive on desktop > "Safely remove drive"
Sometimes there is an animated popup asking to wait while the file write is completed. Some times there is no such popup.
Animated Verification of write complete or not -
the error message of "device busy unable to unmount" always pops up, but the device is in fact unmounted.
If I remount the drive and rsync again, there is no indication that a file did not complete the transfer.

Just a thought, but it could be rsync that is holding something open, or perhaps "cryptsetup luksclose" gets hung up.

[Sebastien Bacher (seb128)]

the issue should be fixed in the current version