Re: [Help] Can't login to my systemd-homed user account due to fallocate failure

From: Andrii Zymohliad <azymohliad@protonmail.com>
To: Andrei Borzenkov <arvidjaar@gmail.com>, Hugo Mills <hugo@carfax.org.uk>
Cc: "linux-btrfs@vger.kernel.org" <linux-btrfs@vger.kernel.org>
Subject: Re: [Help] Can't login to my systemd-homed user account due to fallocate failure
Date: Sun, 23 Aug 2020 16:55:36 +0000	[thread overview]
Message-ID: <uE-fvxC5rW1snQPXRetWASSP8a8cJVSTiDa1WNLmtVANT-M_cd6NUZxUlUtLBID2-EBEEJjP0yK7-Knt9-vjWob1dU6H9FE2Dhg0Y1XFOx4=@protonmail.com> (raw)
In-Reply-To: <251eb1e3-0fcd-eb22-72b9-8ab2f2a5e962@gmail.com>

On Sunday, August 23, 2020 7:21 PM, Andrei Borzenkov <arvidjaar@gmail.com> wrote:
> It's not about LUKS container. systemd tool attempts to reserve full
> size of image with LUKS inside using fallocate which fails. It never
> gets as far as actually unlocking it or mounting filesystem inside.

Yes, thanks Andrei for additional clarification. Here I unlocked and mounted home partition manually just to show what's the state of filesystem on it (I guess that's not important here). Usually, it should be unlocked and mounted by systemd, but it fails because of fallocate failure.

On Sunday, August 23, 2020 6:37 PM, Hugo Mills <hugo@carfax.org.uk> wrote:
> The / filesystem is a clear case of needing a data balance. See
> this link for what to do:
>
> https://btrfs.wiki.kernel.org/index.php/FAQ#if_your_device_is_large_.28.3E16GiB.29
>
> and see also this link for how to read the data you've pasted here:
>
> https://btrfs.wiki.kernel.org/index.php/FAQ#or_My_filesystem_is_full.2C_and_I.27ve_put_almost_nothing_into_it.21

Thanks for a very quick response and links, Hugo, those are definitely useful for me. But the issue here seems more complicated. I forgot to write about it, but the state of root filesystem differs before and after fallocate attempt (or trying to log in as systemd-homed user).

Before:

    # btrfs fi show

    Label: none  uuid: b68411ce-702a-4259-9121-ac21c9119ddf
    	Total devices 1 FS bytes used 299.71GiB
    	devid    1 size 476.44GiB used 301.03GiB path /dev/nvme0n1p2

    # btrfs fi df /

    Data, single: total=300.00GiB, used=299.29GiB
    System, single: total=32.00MiB, used=48.00KiB
    Metadata, single: total=1.00GiB, used=438.38MiB
    GlobalReserve, single: total=62.16MiB, used=0.00B

After:

    # btrfs fi show

    Label: none  uuid: b68411ce-702a-4259-9121-ac21c9119ddf
    	Total devices 1 FS bytes used 299.71GiB
    	devid    1 size 476.44GiB used 476.44GiB path /dev/nvme0n1p2

    btrfs fi df /

    Data, single: total=475.41GiB, used=299.29GiB
    System, single: total=32.00MiB, used=80.00KiB
    Metadata, single: total=1.00GiB, used=438.39MiB
    GlobalReserve, single: total=62.16MiB, used=0.00B

If I do "btrfs balance start /" it becomes like before fallocate attempt, but it still doesn't fix the issue for me. fallocate and hence "homectl authenticate" would still fail.