Re: [pve-devel] [RFC container] fix #3606: drop --inplace from suspend backups

["Fabian Grünbichler" <f.gruenbichler@proxmox.com>]

ping - this still regularly hits users in the forum, and given rsyncs 
rather terse output it's really hard to disambiguate from other error 
conditions causing error "23".

On September 8, 2021 12:04 pm, Fabian Grünbichler wrote:
> for bullseye-based systems, the 'fs.protected_regular'[0] sysctl is set
> to '2' by default[1] (as opposed to the old value of '0'). this breaks
> rsync's `--inplace` mode for such protected files, since opening them
> with O_CREAT is not even possible for the root user anymore.
> 
> one example in the wild are debian (-based) containers using PHP, where
> the session dir '/var/lib/php/sessions' is sticky, world-writable, owned
> by root and contains sessions files usually owned by www-data. if any of
> these session files are modified between the first and second rsync run,
> the second run and thus the backup will fail.
> 
> the downside of this change is that containers with large files that are
> updated between the first and second run will now see more (temp) space
> usage - but suspend mode is not space efficient anyway and such setups
> should consider switching to snapshot mode anyway.
> 
> additionaly, this commit drops the now no longer needed $first parameter
> previously used to decide between different parameters for first and
> second rsync run.
> 
> 0: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=30aba6656f61ed44cba445a3c0d38b296fa9e8f5
> 1: https://salsa.debian.org/debian/procps/-/commit/299f4a1a10810e2995e666374b880b543af8e8e4
> 
> Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
> ---
> RFC in case anybody has a better solution other than setting the sysctl
> to 0 again ;)
> 
>  src/PVE/VZDump/LXC.pm | 9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)
> 
> diff --git a/src/PVE/VZDump/LXC.pm b/src/PVE/VZDump/LXC.pm
> index b7f7463..19b5c16 100644
> --- a/src/PVE/VZDump/LXC.pm
> +++ b/src/PVE/VZDump/LXC.pm
> @@ -20,7 +20,7 @@ use base qw (PVE::VZDump::Plugin);
>  my $default_mount_point = "/mnt/vzsnap0";
>  
>  my $rsync_vm = sub {
> -    my ($self, $task, $to, $text, $first) = @_;
> +    my ($self, $task, $to, $text) = @_;
>  
>      my $disks = $task->{disks};
>      my $from = $disks->[0]->{dir};
> @@ -32,8 +32,7 @@ my $rsync_vm = sub {
>  
>      my $rsync = ['rsync', '--stats', '-h', @xattr, '--numeric-ids',
>                   '-aH', '--delete', '--no-whole-file',
> -                 ($first ? '--sparse' : '--inplace'),
> -                 '--one-file-system', '--relative'];
> +                 '--sparse', '--one-file-system', '--relative'];
>      push @$rsync, "--bwlimit=$opts->{bwlimit}" if $opts->{bwlimit};
>      push @$rsync, map { "--exclude=$_" } @{$self->{vzdump}->{findexcl}};
>      push @$rsync, map { "--exclude=$_" } @{$task->{exclude_dirs}};
> @@ -260,13 +259,13 @@ sub copy_data_phase1 {
>  	}
>      }
>  
> -    $self->$rsync_vm($task, $task->{snapdir}, "first", 1);
> +    $self->$rsync_vm($task, $task->{snapdir}, "first");
>  }
>  
>  sub copy_data_phase2 {
>      my ($self, $task) = @_;
>  
> -    $self->$rsync_vm($task, $task->{snapdir}, "final", 0);
> +    $self->$rsync_vm($task, $task->{snapdir}, "final");
>  }
>  
>  sub stop_vm {
> -- 
> 2.30.2
> 
> 
> 
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