Re: [pbs-devel] [PATCH proxmox-backup 2/6] feature #3690: add wipe_blockdev & change_parttype rust equivalent

[Lukas Wagner <l.wagner@proxmox.com>]

Hi Markus,

some comments inline.

On 11/10/23 14:50, Markus Frank wrote:
> The wipe_blockdev & change_parttype functions are similar to
> PVE::Diskmanage's wipe_blockdev & change_parttype functions.
> 
> The partition_by_name & complete_partition_name functions are
> modified disk_by_name & complete_disk_name functions for partitions.
> 
> Signed-off-by: Markus Frank <m.frank@proxmox.com>
> ---
>   src/tools/disks/mod.rs | 90 +++++++++++++++++++++++++++++++++++++++++-
>   1 file changed, 89 insertions(+), 1 deletion(-)
> 
> diff --git a/src/tools/disks/mod.rs b/src/tools/disks/mod.rs
> index 72e374ca..75d84696 100644
> --- a/src/tools/disks/mod.rs
> +++ b/src/tools/disks/mod.rs
> @@ -19,7 +19,7 @@ use proxmox_lang::{io_bail, io_format_err};
>   use proxmox_schema::api;
>   use proxmox_sys::linux::procfs::{mountinfo::Device, MountInfo};
>   
> -use pbs_api_types::BLOCKDEVICE_NAME_REGEX;
> +use pbs_api_types::{BLOCKDEVICE_NAME_REGEX, BLOCKDEVICE_PARTITION_NAME_REGEX};
>   
>   mod zfs;
>   pub use zfs::*;
> @@ -111,6 +111,12 @@ impl DiskManage {
>           self.disk_by_sys_path(syspath)
>       }
>   
> +    /// Get a `Disk` for a name in `/sys/class/block/<name>`.
> +    pub fn partition_by_name(self: Arc<Self>, name: &str) -> io::Result<Disk> {
> +        let syspath = format!("/sys/class/block/{}", name);
> +        self.disk_by_sys_path(syspath)
> +    }
> +
>       /// Gather information about mounted disks:
>       fn mounted_devices(&self) -> Result<&HashSet<dev_t>, Error> {
>           self.mounted_devices
> @@ -1056,6 +1062,72 @@ pub fn inititialize_gpt_disk(disk: &Disk, uuid: Option<&str>) -> Result<(), Erro
>       Ok(())
>   }
>   
> +/// Wipes all labels and the first 200 MiB of a disk/partition (or the whole if it is smaller).
> +/// If called with a partition, also sets the partition type to 0x83 'Linux filesystem'.
> +pub fn wipe_blockdev(disk: &Disk) -> Result<(), Error> {
> +    let disk_path = disk.device_path().unwrap();

Really don't like the .unwrap() here. If you can prove that this option
will never be `None` there should be a comment that explains it,
otherwise I'd just convert the None to an appropriate Error and bubble
it up to the caller.

> +
> +    let mut is_partition = false;
> +    for disk_i in get_lsblk_info()?.iter() {
Maybe call it `disk_info` instead?

> +        if disk_i.path == disk_path.to_str().unwrap() && disk_i.partition_type.is_some() {
                                                 ^
`to_str` can return None (e.g. in case the path is not valid unicode) - 
better be defensive here and return an error.


> +            is_partition = true;
> +        }
> +    }
> +
> +    let mut to_wipe: Vec<PathBuf> = Vec::new();
> +
> +    let partitions_map = disk.partitions()?;
> +    for (_, part_disk) in partitions_map.iter() {
Since you discard the key, you should use partions_map.values():

    for part_disk in partitions_map.values() {
       ...
    }


> +        let part_path = part_disk.device_path().unwrap();
                                                             ^
Unwrap again

> +        to_wipe.push(part_path.to_path_buf());
> +    }
> +
> +    to_wipe.push(disk_path.to_path_buf());
> +
> +    println!("Wiping block device {}", disk_path.display());

This is never printed to the task log. Instead of printing to
stdout, you should pass the worker task to the function and then use
`task_log!`

Note: Once Gabriel's tracing-patches have landed, this should probably 
be a tracing::info!, the reference to the worker task is not needed any 
more after that.

> +
> +    let mut wipefs_command = std::process::Command::new("wipefs");
> +    wipefs_command.arg("--all").args(&to_wipe);
> +
> +    proxmox_sys::command::run_command(wipefs_command, None)?;

This returns a String, which contains the stdout/sterr output from 
wipefs. Maybe log the output (I don't know if wipefs actually logs 
anything, but even if not it would not hurt)?

> +
> +    let size = disk.size().map(|size| size / 1024 / 1024)?;
> +    let count = size.min(200);
> +
> +    let mut dd_command = std::process::Command::new("dd");
> +    let args = [
> +        "if=/dev/zero",
> +        &format!("of={}", disk_path.display()),

.display() can be lossy (skipping anything that is not valid unicode)

But since .args wants AsRef<&OsStr> anyway, you could:

let mut of_path = OsString::from("of=");
of_path.push(disk_path);

and then use that in `args`? I guess then
the other params need to be the same type of course.
(e.g. "if=/dev/zero".into())


> +        "bs=1M",
> +        "conv=fdatasync",
> +        &format!("count={}", count),
> +    ];
> +    dd_command.args(args);
> +
> +    proxmox_sys::command::run_command(dd_command, None)?;
Same here, I think the output should be logged.

> +
> +    if is_partition {
> +        change_parttype(&disk, "8300")?;
Maybe extract this into a constant e.g. PARTITION_TYPE_LINUX ?
Or, alternatively, add a comment that explains what this magic
string actually is.

> +    }
> +
> +    Ok(())
> +}
> +
> +pub fn change_parttype(part_disk: &Disk, part_type: &str) -> Result<(), Error> {
> +    let part_path = part_disk.device_path().unwrap();
.unwrap again

> +    if let Ok(stat) = nix::sys::stat::stat(part_path) {
> +        let mut sgdisk_command = std::process::Command::new("sgdisk");
> +        let major = unsafe { libc::major(stat.st_rdev) };
> +        let minor = unsafe { libc::minor(stat.st_rdev) };
> +        let partnum_path = &format!("/sys/dev/block/{}:{}/partition", major, minor);
> +        let partnum: u32 = std::fs::read_to_string(partnum_path)?.trim_end().parse()?;
> +        sgdisk_command.arg(&format!("-t{}:{}", partnum, part_type));
> +        sgdisk_command.arg(&part_disk.parent().unwrap().device_path().unwrap());
.unwraps again

> +        proxmox_sys::command::run_command(sgdisk_command, None)?;
Same as above, maybe log the output? (not sure again if sgdisk actually 
prints anything. Maybe there is a --verbose that could be used then?

Maybe it would also be good to print the command that was executed to 
the logs - so that in case anything goes wrong, the admin sees what 
steps were performed. (applies to the other commands as well)

> +    }
> +    Ok(())
> +}
> +
>   /// Create a single linux partition using the whole available space
>   pub fn create_single_linux_partition(disk: &Disk) -> Result<Disk, Error> {
>       let disk_path = match disk.device_path() {
> @@ -1136,6 +1208,22 @@ pub fn complete_disk_name(_arg: &str, _param: &HashMap<String, String>) -> Vec<S
>           .collect()
>   }
>   
> +/// Block device partition name completion helper
> +pub fn complete_partition_name(_arg: &str, _param: &HashMap<String, String>) -> Vec<String> {
> +    let dir = match proxmox_sys::fs::scan_subdir(
> +        libc::AT_FDCWD,
> +        "/sys/class/block",
> +        &BLOCKDEVICE_PARTITION_NAME_REGEX,
> +    ) {
> +        Ok(dir) => dir,
> +        Err(_) => return vec![],
> +    };
> +
> +    dir.flatten()
> +        .map(|item| item.file_name().to_str().unwrap().to_string())
> +        .collect()
> +}
> +
>   /// Read the FS UUID (parse blkid output)
>   ///
>   /// Note: Calling blkid is more reliable than using the udev ID_FS_UUID property.

-- 
- Lukas