GNU bug report logs - #43366
"error: rmdir: Device or resource busy" when using btrfs

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Fredrik Salomonsson <plattfot <at> posteo.net>
To: bug-guix <at> gnu.org
Subject: "error: rmdir: Device or resource busy" when using btrfs
Date: Sat, 12 Sep 2020 20:37:35 -0700

[Message part 1 (text/plain, inline)]

When you have separate btrfs subvolumes for /gnu and /var/guix, you'll
encounter this error running `guix system init /mnt/etc/config.scm /mnt`
when it tries to copy things to /mnt. My guess is that guix is trying to
remove one of them but fails as they're mounted.

I encountered this issue while I tried installing guix system on my main
laptop. But I have encountered this before [1]. When I installed guix
system on my secondary laptop. I worked around it back then by using
guix-0.15.0.

For my secondary laptop I have this layout
| subvol                | Mountpoint | Comment         |
|-----------------------+------------+-----------------|
| __current/guixsd-root | /          | root for GuixSD |
| __current/grub        | /boot/grub | grub config     |
| __current/guix        | /var/guix  | guix stuff      |
| __current/gnu         | /gnu       | Store etc       |
| __current/home        | /home      | home partition  |

For my main laptop I tried:
| subvol | Mountpoint | Comment        |
|--------+------------+----------------|
| @      | /          | root for Guix  |
| @grub  | /boot/grub | grub config    |
| @guix  | /var/guix  | guix stuff     |
| @gnu   | /gnu       | Store etc      |
| @home  | /home      | home partition |

Found another thread that also had this issue [2], and the same
workaround worked for me. I.e. simplified the layout:
| subvol    | Mountpoint | Comment        |
|-----------+------------+----------------|
| @         | /          | root for Guix  |
| @home     | /home      | home partition |

This seems to just be an issue when running guix system init, as I've
been using my secondary laptop with separate subvolumes for /gnu and
/var/guix without any issues since 0.15.

The guix version I used to install my main laptop with was
1.1.0-25.44c6e6f. I generated it with

  guix system disk-image --file-system-type=iso9660 \
       gnu/system/install.scm

As described in the manual.

Thanks

[1] https://lists.gnu.org/archive/html/help-guix/2018-12/msg00055.html
[2] https://lists.gnu.org/archive/html/help-guix/2019-06/msg00259.html

[heimdal-sway.scm (text/plain, attachment)]

[Message part 3 (text/plain, inline)]

-- 
s/Fred[re]+i[ck]+/Fredrik/g

Message #8 received at 43366 <at> debbugs.gnu.org (full text, mbox):

From: Maxim Cournoyer <maxim.cournoyer <at> gmail.com>
To: 43366 <at> debbugs.gnu.org
Cc: Fredrik Salomonsson <plattfot <at> gmail.com>,
 Maxim Cournoyer <maxim.cournoyer <at> gmail.com>
Subject: [PATCH core-updates] utils: Do not raise exceptions in
 delete-file-recursively.
Date: Tue, 15 Sep 2020 00:08:37 -0400

This makes it so that delete-file-recursively honors its docstring, which says
it should "report but ignore errors".

Fixes <https://issues.guix.gnu.org/43366>.

* guix/build/utils.scm (warn-on-error): New syntax.
(delete-file-recursively): Use it to catch exceptions and print warning
messages.

Reported-by: Fredrik Salomonsson <plattfot <at> gmail.com>
---
 guix/build/utils.scm | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/guix/build/utils.scm b/guix/build/utils.scm
index 0a04032834..fbf4f2d61a 100644
--- a/guix/build/utils.scm
+++ b/guix/build/utils.scm
@@ -6,6 +6,7 @@
 ;;; Copyright © 2018 Arun Isaac <arunisaac <at> systemreboot.net>
 ;;; Copyright © 2018, 2019 Ricardo Wurmus <rekado <at> elephly.net>
 ;;; Copyright © 2020 Efraim Flashner <efraim <at> flashner.co.il>
+;;; Copyright © 2020 Maxim Cournoyer <maxim.cournoyer <at> gmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -366,6 +367,16 @@ verbose output to the LOG port."
                         stat
                         lstat)))
 
+(define-syntax-rule (warn-on-error expr file)
+  (catch 'system-error
+    (lambda ()
+      expr)
+    (lambda args
+      (format (current-error-port)
+              "warning: failed to delete ~a: ~a~%"
+              file (strerror
+                    (system-error-errno args))))))
+
 (define* (delete-file-recursively dir
                                   #:key follow-mounts?)
   "Delete DIR recursively, like `rm -rf', without following symlinks.  Don't
@@ -376,10 +387,10 @@ errors."
                         (or follow-mounts?
                             (= dev (stat:dev stat))))
                       (lambda (file stat result)   ; leaf
-                        (delete-file file))
+                        (warn-on-error (delete-file file) file))
                       (const #t)                   ; down
                       (lambda (dir stat result)    ; up
-                        (rmdir dir))
+                        (warn-on-error (rmdir dir) dir))
                       (const #t)                   ; skip
                       (lambda (file stat errno result)
                         (format (current-error-port)
-- 
2.28.0

Message #11 received at 43366 <at> debbugs.gnu.org (full text, mbox):

From: Maxim Cournoyer <maxim.cournoyer <at> gmail.com>
To: Fredrik Salomonsson <plattfot <at> posteo.net>
Cc: 43366 <at> debbugs.gnu.org
Subject: Re: bug#43366: "error: rmdir: Device or resource busy" when using
 btrfs
Date: Tue, 15 Sep 2020 00:15:46 -0400

Hi Fredrik,

I just sent a patch now, but here's a bit more background on what led to
it.

Fredrik Salomonsson <plattfot <at> posteo.net> writes:

> When you have separate btrfs subvolumes for /gnu and /var/guix, you'll
> encounter this error running `guix system init /mnt/etc/config.scm /mnt`
> when it tries to copy things to /mnt. My guess is that guix is trying to
> remove one of them but fails as they're mounted.

The issue seems to be with:

--8<---------------cut here---------------start------------->8---
  ;; If a previous installation was attempted, make sure we start anew; in
  ;; particular, we don't want to keep a store database that might not
  ;; correspond to what we're actually putting in the store.
  (let ((state (string-append target "/var/guix")))
    (when (file-exists? state)
      (delete-file-recursively state)))
--8<---------------cut here---------------end--------------->8---

Which is part of the install procedure (which gets called when using
'guix system init /some/target').  So your guess was correct :-).

To confirm this was the case, I did:

sudo btrfs subvolume create /tmp/toto
mkdir /tmp/tata
sudo mount -o subvol=/tmp/toto /dev/mapper/cryptroot /tmp/tata

sudo -E guix repl
> ,import (guix build utils)
> (delete-file-recursively "/tmp/tata/")
ice-9/boot-9.scm:1669:16: In procedure raise-exception:
In procedure rmdir: Device or resource busy

Bingo!

Reading the docstring of delete-file-recursively, it says it should
"report but ignore errors", so that's a bug.

Maxim

Message #14 received at 43366 <at> debbugs.gnu.org (full text, mbox):

From: Fredrik Salomonsson <plattfot <at> posteo.net>
To: Maxim Cournoyer <maxim.cournoyer <at> gmail.com>
Cc: 43366 <at> debbugs.gnu.org
Subject: Re: bug#43366: "error: rmdir: Device or resource busy" when using
 btrfs
Date: Tue, 15 Sep 2020 11:15:40 -0700

Hi Maxim,

Maxim Cournoyer <maxim.cournoyer <at> gmail.com> writes:

> I just sent a patch now, but here's a bit more background on what led to
> it.

Nice find! I'm unable to test out the patch right now on my original use
case as I soft bricked my laptop fiddling around with coreboot. And I'm
having some issues with my external flasher.

> The issue seems to be with:
>
> --8<---------------cut here---------------start------------->8---
>   ;; If a previous installation was attempted, make sure we start anew; in
>   ;; particular, we don't want to keep a store database that might not
>   ;; correspond to what we're actually putting in the store.
>   (let ((state (string-append target "/var/guix")))
>     (when (file-exists? state)
>       (delete-file-recursively state)))
> --8<---------------cut here---------------end--------------->8---
>
> Which is part of the install procedure (which gets called when using
> 'guix system init /some/target').  So your guess was correct :-).

Yay!

> To confirm this was the case, I did:
>
> sudo btrfs subvolume create /tmp/toto
> mkdir /tmp/tata
> sudo mount -o subvol=/tmp/toto /dev/mapper/cryptroot /tmp/tata
>
> sudo -E guix repl
>> ,import (guix build utils)
>> (delete-file-recursively "/tmp/tata/")
> ice-9/boot-9.scm:1669:16: In procedure raise-exception:
> In procedure rmdir: Device or resource busy
>
> Bingo!
>
> Reading the docstring of delete-file-recursively, it says it should
> "report but ignore errors", so that's a bug.

Yeah, that's is the same error I get when running guix init. So this
sounds like it will fix my issue!

Thanks for the speedy fix.

-- 
s/Fred[re]+i[ck]+/Fredrik/g

Message #21 received at 43366-done <at> debbugs.gnu.org (full text, mbox):

From: Maxim Cournoyer <maxim.cournoyer <at> gmail.com>
To: Fredrik Salomonsson <plattfot <at> posteo.net>
Cc: 43366-done <at> debbugs.gnu.org
Subject: Re: bug#43366: "error: rmdir: Device or resource busy" when using
 btrfs
Date: Thu, 08 Oct 2020 11:44:10 -0400

Hello,

Pushed to core-updates with commit
7102c18678dc02d5ee6c77a9a70ae344482af841.

Closing.

Thanks,
Maxim

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