[pbs-devel] [PATCH proxmox-backup v2] etc: provide and enable mount unit for /run/proxmox-backup

[Fabian Grünbichler]

On November 19, 2025 3:31 pm, Christian Ebner wrote:
> Since the introduction of per-chunk file locks for datastores with s3
> backend, the inodes on the tmpfs backing /run/proxmox-backup might be
> to limited, the kernel dynamically calculating the limit based on
> available system memory [0]. To not limit the number of inodes,
> provide a systemd mount unit to create a dedicated tmpfs for
> /run/proxmox-backup.
> 
> The mount unit is only enabled but not started by dh_installsystemd,
> so this has only effect after a reboot.
> 
> [0] https://docs.kernel.org/filesystems/tmpfs.html
> 
> Fixes: https://forum.proxmox.com/threads/176228/
> Signed-off-by: Christian Ebner <c.ebner at proxmox.com>

Reviewed-by: Fabian Grünbichler <f.gruenbichler at proxmox.com>

> ---
> Changes since version 1 (thanks @Fabian):
> - Drop unneeded systemctl enable ...
> - Add comment for why the inodes are unlimited
> - Correctly set mountpoint uid:gid
> 
>  debian/proxmox-backup-server.install |  1 +
>  "etc/run-proxmox\\x2dbackup.mount"   | 14 ++++++++++++++
>  2 files changed, 15 insertions(+)
>  create mode 100644 "etc/run-proxmox\\x2dbackup.mount"
> 
> diff --git a/debian/proxmox-backup-server.install b/debian/proxmox-backup-server.install
> index d06f026cf..11dd037e8 100644
> --- a/debian/proxmox-backup-server.install
> +++ b/debian/proxmox-backup-server.install
> @@ -6,6 +6,7 @@ etc/proxmox-backup-daily-update.timer /usr/lib/systemd/system/
>  etc/proxmox-backup-proxy.service /usr/lib/systemd/system/
>  etc/proxmox-backup.service /usr/lib/systemd/system/
>  etc/removable-device-attach at .service /usr/lib/systemd/system/
> +etc/run-proxmox\x2dbackup.mount /usr/lib/systemd/system/
>  usr/bin/pmt
>  usr/bin/pmtx
>  usr/bin/proxmox-tape
> diff --git "a/etc/run-proxmox\\x2dbackup.mount" "b/etc/run-proxmox\\x2dbackup.mount"
> new file mode 100644
> index 000000000..cad35594d
> --- /dev/null
> +++ "b/etc/run-proxmox\\x2dbackup.mount"
> @@ -0,0 +1,14 @@
> +[Unit]
> +Description=Mount tmpfs at /run/proxmox-backup
> +Conflicts=umount.target
> +Before=local-fs.target umount.target
> +
> +[Mount]
> +Type=tmpfs
> +What=tmpfs
> +Where=/run/proxmox-backup
> +# Unlimited inodes as this stores per-chunk file locks
> +Options=rw,nosuid,nodev,noexec,relatime,uid=34,gid=34,nr_inodes=0,mode=755,inode64

one small nit: this could use `backup` instead of `34` (although it's
pretty much guaranteed to not matter, we do so in other parts of the
code base as well..)

> +
> +[Install]
> +WantedBy=local-fs.target
> -- 
> 2.47.3
> 
> 
> 
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