[pbs-devel] [RFC proxmox-backup] backup/backup_info: ignore vanished backup dirs during listing

[Fabian Grünbichler]

when looking at the call sites of list_backup_files, this seems wrong - 
e.g. when listing a BackupGroup's backups, such a no-longer-existing 
snapshot is now returned but has no files. when creating a new 
BackupInfo from a BackupDir, or listing a BackupInfo's files, it returns 
Ok but contains no files.

the decision whether to ignore such an error must be made at the call 
sites of the call sites above, since in most cases I'd want to ignore 
the snapshot and not just the file listing..

list_snapshot_files already throws an error if it can't read the 
manifest, list_snapshots and list_groups seem to include it with no 
files?

On January 27, 2021 2:43 pm, Dominik Csapak wrote:
> this had the effect that that a snapshot listing errored out when called
> during a prune action
> 
> we now ignore such errors and simply return no files
> 
> also add some context for the error if one happens
> 
> Signed-off-by: Dominik Csapak <d.csapak at proxmox.com>
> ---
> maybe we also want to filter such snapshots out one level higher?
> so that we do not show 'empty' snapshots
> 
>  src/backup/backup_info.rs | 28 ++++++++++++++++++++++------
>  1 file changed, 22 insertions(+), 6 deletions(-)
> 
> diff --git a/src/backup/backup_info.rs b/src/backup/backup_info.rs
> index 5ff1a6f8..dba3fea5 100644
> --- a/src/backup/backup_info.rs
> +++ b/src/backup/backup_info.rs
> @@ -1,4 +1,7 @@
> -use crate::tools;
> +use crate::tools::{
> +    self,
> +    fs::FileIterOps,
> +};
>  
>  use anyhow::{bail, format_err, Error};
>  use std::os::unix::io::RawFd;
> @@ -339,11 +342,24 @@ impl BackupInfo {
>  fn list_backup_files<P: ?Sized + nix::NixPath>(dirfd: RawFd, path: &P) -> Result<Vec<String>, Error> {
>      let mut files = vec![];
>  
> -    tools::scandir(dirfd, path, &BACKUP_FILE_REGEX, |_, filename, file_type| {
> -        if file_type != nix::dir::Type::File { return Ok(()); }
> -        files.push(filename.to_owned());
> -        Ok(())
> -    })?;
> +    match tools::fs::read_subdir(dirfd, path) {
> +        Ok(iter) => {
> +            for entry in iter.filter_file_name_regex(&BACKUP_FILE_REGEX) {
> +                let entry = entry?;
> +                let file_type = entry.file_type().ok_or_else(|| format_err!("unable to detect file type"))?;
> +                if file_type == nix::dir::Type::File {
> +                    // ok because we filtered with BACKUP_FILE_REGEX
> +                    let filename = unsafe { entry.file_name_utf8_unchecked() };
> +                    files.push(filename.to_owned());
> +                }
> +            }
> +        },
> +        Err(nix::Error::Sys(errno)) if errno == nix::errno::Errno::ENOENT => {
> +            // ignore vanished backup dirs
> +            eprintln!("backup dir vanished during listing");
> +        },
> +        Err(err) => bail!("error listing backup files: {}", err),
> +    }
>  
>      Ok(files)
>  }
> -- 
> 2.20.1
> 
> 
> 
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