[PATCH backup-restore-image 0/2] fix #7500: add EROFS and SquashFS filesystem support

[PATCH backup-restore-image 0/2] fix #7500: add EROFS and SquashFS filesystem support

[Elias Huhsovitz]

This patch series addresses Bug #7500 [1], where the file-restore kernel
fails to mount EROFS-formatted partitions. This issue commonly affects
users attempting to restore files from backups of Home Assistant OS.

The configuration choices in these patches are based on the standard
Debian kernel configuration [2].

Patch 1/2 adds EROFS support, including the necessary
decompression backends as defined in [4].

Patch 2/2 adds SquashFS support. While this patch is optional for resolving
the specific Home Assistant OS bug, it ensures broad compatibility with
various embedded Linux distributions and container images that rely on
SquashFS.

For the SquashFS configuration, this series deliberately chooses
`CONFIG_SQUASHFS_FILE_CACHE=y` and
`CONFIG_SQUASHFS_COMPILE_DECOMP_SINGLE=y` instead of the Debian defaults
(`FILE_DIRECT` and `MULTI_PERCPU`). This is to reduce complexity, memory
footprint and memory overhead, which should be valued in a transient,
resource-constrained virtual machine.

References:
[1] https://bugzilla.proxmox.com/show_bug.cgi?id=7500
[2] https://salsa.debian.org/kernel-team/linux/-/blob/debian/latest/debian/config/config
[3] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/fs/squashfs/Kconfig
[4] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/fs/erofs/Kconfig

Elias Huhsovitz (2):
  fix #7500: add EROFS filesystem support
  add SquashFS filesystem support

 src/config-base | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

-- 
2.47.3

[PATCH backup-restore-image 1/2] fix #7500: add EROFS filesystem support

[Elias Huhsovitz]

The file-restore kernel previously lacked support for the Enhanced
Read-Only File System (EROFS). This caused mount failures when users
attempted to restore files from backups.
(For example: Home Assistant OS)

Enable EROFS support, including extended attributes, POSIX ACLs, and the
ZIP decompression framework (LZMA, DEFLATE, and ZSTD).

Signed-off-by: Elias Huhsovitz <e.huhsovitz@proxmox.com>
---
 src/config-base | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/config-base b/src/config-base
index fcebf07..3d49d2d 100644
--- a/src/config-base
+++ b/src/config-base
@@ -128,6 +128,13 @@ CONFIG_XFS_POSIX_ACL=y
 CONFIG_XFS_SUPPORT_V4=y
 CONFIG_BTRFS_FS=y
 CONFIG_BTRFS_FS_POSIX_ACL=y
+CONFIG_EROFS_FS=y
+CONFIG_EROFS_FS_XATTR=y
+CONFIG_EROFS_FS_POSIX_ACL=y
+CONFIG_EROFS_FS_ZIP=y
+CONFIG_EROFS_FS_ZIP_LZMA=y
+CONFIG_EROFS_FS_ZIP_DEFLATE=y
+CONFIG_EROFS_FS_ZIP_ZSTD=y
 CONFIG_F2FS_FS=y
 CONFIG_F2FS_FS_XATTR=y
 CONFIG_F2FS_FS_POSIX_ACL=y
-- 
2.47.3

[PATCH backup-restore-image 2/2] add SquashFS filesystem support

[Elias Huhsovitz]

Enable SquashFS with support for all major compression
algorithms (ZLIB, LZ4, LZO, XZ, ZSTD).

The configuration uses single-threaded decompression and intermediate
file caching, to prioritize reliability and reduce memory footprint.

Signed-off-by: Elias Huhsovitz <e.huhsovitz@proxmox.com>
---
 src/config-base | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/config-base b/src/config-base
index 3d49d2d..799ed17 100644
--- a/src/config-base
+++ b/src/config-base
@@ -160,6 +160,15 @@ CONFIG_MSDOS_FS=y
 CONFIG_VFAT_FS=y
 CONFIG_EXFAT_FS=y
 CONFIG_EXFAT_DEFAULT_IOCHARSET="utf8"
+CONFIG_SQUASHFS=y
+CONFIG_SQUASHFS_FILE_CACHE=y
+CONFIG_SQUASHFS_COMPILE_DECOMP_SINGLE=y
+CONFIG_SQUASHFS_XATTR=y
+CONFIG_SQUASHFS_ZLIB=y
+CONFIG_SQUASHFS_LZ4=y
+CONFIG_SQUASHFS_LZO=y
+CONFIG_SQUASHFS_XZ=y
+CONFIG_SQUASHFS_ZSTD=y
 
 # memory hotplug
 CONFIG_MEMORY_HOTPLUG=y
-- 
2.47.3

Re: [PATCH backup-restore-image 0/2] fix #7500: add EROFS and SquashFS filesystem support

[Christian Ebner]

On 7/27/26 3:49 PM, Elias Huhsovitz wrote:
> This patch series addresses Bug #7500 [1], where the file-restore kernel
> fails to mount EROFS-formatted partitions. This issue commonly affects
> users attempting to restore files from backups of Home Assistant OS.
> 
> The configuration choices in these patches are based on the standard
> Debian kernel configuration [2].
> 
> Patch 1/2 adds EROFS support, including the necessary
> decompression backends as defined in [4].
> 
> Patch 2/2 adds SquashFS support. While this patch is optional for resolving
> the specific Home Assistant OS bug, it ensures broad compatibility with
> various embedded Linux distributions and container images that rely on
> SquashFS.
> 
> For the SquashFS configuration, this series deliberately chooses
> `CONFIG_SQUASHFS_FILE_CACHE=y` and
> `CONFIG_SQUASHFS_COMPILE_DECOMP_SINGLE=y` instead of the Debian defaults
> (`FILE_DIRECT` and `MULTI_PERCPU`). This is to reduce complexity, memory
> footprint and memory overhead, which should be valued in a transient,
> resource-constrained virtual machine.
> 
> References:
> [1] https://bugzilla.proxmox.com/show_bug.cgi?id=7500
> [2] https://salsa.debian.org/kernel-team/linux/-/blob/debian/latest/debian/config/config
> [3] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/fs/squashfs/Kconfig
> [4] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/fs/erofs/Kconfig
> 

Thanks for the patches, welcome addition for Home Assistant user.

Build and tested single file restore using a backup from a Home 
Assistant OS VM.

Reviewed-by: Christian Ebner <c.ebner@proxmox.com>
Tested-by: Christian Ebner <c.ebner@proxmox.com>

applied: [PATCH backup-restore-image 0/2] fix #7500: add EROFS and SquashFS filesystem support

[Thomas Lamprecht]

On Mon, 27 Jul 2026 15:49:23 +0200, Elias Huhsovitz wrote:
> This patch series addresses Bug #7500 [1], where the file-restore kernel
> fails to mount EROFS-formatted partitions. This issue commonly affects
> users attempting to restore files from backups of Home Assistant OS.
> 
> The configuration choices in these patches are based on the standard
> Debian kernel configuration [2].
> 
> [...]

Applied, thanks!

[1/2] fix #7500: add EROFS filesystem support
      commit: f6e8b3b9c253a593f6e8139542f67fb26a1a9f38
[2/2] add SquashFS filesystem support
      commit: a91f261e513a9942ef06c9718cf918da8183622f