Tails

#3 Updated by segfault 2020-02-09 19:23:28

intrigeri wrote:
> segfault, as our in-house udisks expert: do you have the kind of hardware needed to reproduce this and possibly debug the corresponding udisks code?

I currently don’t have any spare 1TB disk which I could use to reproduce the issue.

I took a quick look at the code to see where the error message comes from. The “Failed to meet partition size on device” part originates in resize_part() in libblockdev.git:src/plugins/part.c. IIUC, udisks calls bd_part_create_part(), which calls add_part_to_disk(), which calls resize_part(). I would have to be able to reproduce the issue to further debug it.

#5 Updated by intrigeri 2020-02-10 07:57:08

Hi,

segfault wrote:
> intrigeri wrote:
>> segfault, as our in-house udisks expert: do you have the kind of hardware needed to reproduce this and possibly debug the corresponding udisks code?
>
> I currently don’t have any spare 1TB disk which I could use to reproduce the issue.

I tried to reproduce on a spare 750GB SATA disk plugged via a USB-SATA adapter enclosure.

I’m wondering if we could try to reproduce via our automated test suite: presumably, even with significantly less than 1TB of disk space available, we could create a 1TB qcow2 virtual disk (thanks to sparse files and/or compression).

This might be a relevant starting point:

--- a/features/step_definitions/snapshots.rb
+++ b/features/step_definitions/snapshots.rb
@@ -66,7 +66,7 @@ def checkpoints
:description => "I have started Tails without network from a USB drive without a persistent partition and stopped at Tails Greeter's login screen",
:parent_checkpoint => nil,
:steps => [
-        'I create a 7200 MiB disk named "__internal"',
+        'I create a 1000000 MiB disk named "__internal"',
'I plug USB drive "__internal"',
'I write the Tails USB image to disk "__internal"',
'I start Tails from USB drive "__internal" with network unplugged',

Do you want to pursue this? Otherwise, I could give it a try :)

> I took a quick look at the code to see where the error message comes from. The “Failed to meet partition size on device” part originates in resize_part() in libblockdev.git:src/plugins/part.c. IIUC, udisks calls bd_part_create_part(), which calls add_part_to_disk(), which calls resize_part(). I would have to be able to reproduce the issue to further debug it.

OK, thanks for looking into it!

I’m a bit surprised to see anything related to resizing partitions in there but I did not look at the code so perhaps it does something different than what I would guess.

#6 Updated by intrigeri 2020-02-10 07:58:54

intrigeri wrote:
> I tried to reproduce on a spare 750GB SATA disk plugged via a USB-SATA adapter enclosure.

Gah, forgot to make it clear: I tried and failed to reproduce. The persistent volume was created just fine. It might be because 750GB << 1TB, or it could be related to sector size.

#7 Updated by segfault 2020-02-12 23:20:37

intrigeri wrote:
> I’m wondering if we could try to reproduce via our automated test suite: presumably, even with significantly less than 1TB of disk space available, we could create a 1TB qcow2 virtual disk (thanks to sparse files and/or compression).

I tried that, but the disk creation step fails with “Need 1000000 MiB but only X MiB available”.

Then I created a 1 TiB qcow2 disk locally, which worked:

qemu-img create -f qcow2 test.qcow2 1T

But I could not reproduce the issue. I tried attaching it to a Tails VM and creating 992G partition with GNOME Disks, which worked just fine.
Then I copied a USB image to the disk (after associating it with a block device via qemu-nbd), booted it in a VM, and created a persistent partition on it, which also worked fine.

> I’m a bit surprised to see anything related to resizing partitions in there but I did not look at the code so perhaps it does something different than what I would guess.

Yes, I was also surprised about that, but that’s what libblockdev does. But I did also not investigate further why it does that.

#8 Updated by segfault 2020-02-12 23:25:13

> Then I copied a USB image to the disk (after associating it with a block device via qemu-nbd), booted it in a VM, and created a persistent partition on it, which also worked fine.

FWIW, the resulting persistent partition has a size of 1.1 TB (1,099,511,627,776 bytes).

I suspect that the issue only occurs for very specific partition sizes. The 992G you quoted might be rounded.