[PATCH proxmox-backup 5/5] fix #7533: restore-daemon: last resort fallback to mount via ntfs-3g

[Christian Ebner <c.ebner@proxmox.com>]

Some Windows NTFS partitions fail to mount with the current in-kernel
filesystem implementations. The same filesystems can however be
mounted using the user space ntfs-3g implementation.

Provide a last resort fallback if all other attempts fail to mount ai
disk or partition, trying to use the FUSE implementation of ntfs-3g.

Fixes: https://bugzilla.proxmox.com/show_bug.cgi?id=7544
Signed-off-by: Christian Ebner <c.ebner@proxmox.com>
---
Tested this by a modified version where the in-kernel ntfs and ntfs3
were excluded from the supported fs list.

 .../src/proxmox_restore_daemon/disk.rs                   | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/proxmox-restore-daemon/src/proxmox_restore_daemon/disk.rs b/proxmox-restore-daemon/src/proxmox_restore_daemon/disk.rs
index 7936dc764..e1777d1b1 100644
--- a/proxmox-restore-daemon/src/proxmox_restore_daemon/disk.rs
+++ b/proxmox-restore-daemon/src/proxmox_restore_daemon/disk.rs
@@ -344,6 +344,15 @@ impl Filesystems {
             }
         }
 
+        info!("All provided in-kernel filesystems failed: try FUSE mount using ntfs-3g");
+
+        let mut cmd = Command::new("/usr/bin/ntfs-3g");
+        cmd.args(["-o", "ro", source, target].iter());
+        match run_command(cmd, None) {
+            Ok(_) => return Ok(()),
+            Err(err) => warn!("ntfs-3g mount failed for '{source}': {err:#}"),
+        }
+
         bail!("all mounts failed or no supported file system")
     }
 
-- 
2.47.3