[pbs-devel] [PATCH v2 proxmox-backup 5/5] fix #5853: client: pxar: exclude stale files on metadata/link read

[Christian Ebner]

Skip and warn the user for files which returned a stale file handle
error while reading the metadata associated to that file, or the
target in case of a symbolic link.

Instead of returning with a hard error, report the stale file handle
and skip over encoding this file entry in the pxar archive.

Link to issue in bugtracker:
https://bugzilla.proxmox.com/show_bug.cgi?id=5853

Link to thread in community forum:
https://forum.proxmox.com/threads/156822/

Signed-off-by: Christian Ebner <c.ebner at proxmox.com>
---
changes since version 1:
- avoid return value tuples to signal stale file handles downcast
  anyhow::Error to Errno when check is required
- use report_stale_file_handle helper method

 pbs-client/src/pxar/create.rs | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/pbs-client/src/pxar/create.rs b/pbs-client/src/pxar/create.rs
index 3a6e9b157..5d7957970 100644
--- a/pbs-client/src/pxar/create.rs
+++ b/pbs-client/src/pxar/create.rs
@@ -740,14 +740,23 @@ impl Archiver {
             None => return Ok(()),
         };
 
-        let metadata = get_metadata(
+        let metadata = match get_metadata(
             fd.as_raw_fd(),
             stat,
             self.flags(),
             self.fs_magic,
             &mut self.fs_feature_flags,
             self.skip_e2big_xattr,
-        )?;
+        ) {
+            Ok(metadata) => metadata,
+            Err(err) => {
+                if let Some(Errno::ESTALE) = err.downcast_ref::<Errno>() {
+                    self.report_stale_file_handle(None);
+                    return Ok(());
+                }
+                return Err(err);
+            }
+        };
 
         if self.previous_payload_index.is_none() {
             return self
@@ -1294,7 +1303,14 @@ impl Archiver {
         file_name: &Path,
         metadata: &Metadata,
     ) -> Result<(), Error> {
-        let dest = nix::fcntl::readlinkat(fd.as_raw_fd(), &b""[..])?;
+        let dest = match nix::fcntl::readlinkat(fd.as_raw_fd(), &b""[..]) {
+            Ok(dest) => dest,
+            Err(Errno::ESTALE) => {
+                self.report_stale_file_handle(None);
+                return Ok(());
+            }
+            Err(err) => return Err(err.into()),
+        };
         encoder.add_symlink(metadata, file_name, dest).await?;
         Ok(())
     }
-- 
2.39.5