[pbs-devel] [PATCH proxmox-backup 1/4] client: pxar: skip directories on stale file handle

[Christian Ebner]

Skip over the whole directory in case the file handle was invalidated
and therefore the filesystem type check returns with ESTALE.

Encode the directory start entry in the archive and the catalog only
after the filesystem type check, so the directory can be fully skipped.
At this point it is still possible to ignore the invalidated
directory. If the directory is invalidated afterwards, it will be
backed up only partially.

Signed-off-by: Christian Ebner <c.ebner at proxmox.com>
---
 pbs-client/src/pxar/create.rs | 28 +++++++++++++++++++---------
 1 file changed, 19 insertions(+), 9 deletions(-)

diff --git a/pbs-client/src/pxar/create.rs b/pbs-client/src/pxar/create.rs
index c48524c4c..a2b9b3e30 100644
--- a/pbs-client/src/pxar/create.rs
+++ b/pbs-client/src/pxar/create.rs
@@ -72,7 +72,7 @@ pub struct PxarPrevRef {
     pub archive_name: String,
 }
 
-fn detect_fs_type(fd: RawFd) -> Result<i64, Error> {
+fn detect_fs_type(fd: RawFd) -> Result<i64, Errno> {
     let mut fs_stat = std::mem::MaybeUninit::uninit();
     let res = unsafe { libc::fstatfs(fd, fs_stat.as_mut_ptr()) };
     Errno::result(res)?;
@@ -1169,20 +1169,23 @@ impl Archiver {
     ) -> Result<(), Error> {
         let dir_name = OsStr::from_bytes(c_dir_name.to_bytes());
 
-        if !self.cache.caching_enabled() {
-            if let Some(ref catalog) = self.catalog {
-                catalog.lock().unwrap().start_directory(c_dir_name)?;
-            }
-            encoder.create_directory(dir_name, metadata).await?;
-        }
-
         let old_fs_magic = self.fs_magic;
         let old_fs_feature_flags = self.fs_feature_flags;
         let old_st_dev = self.current_st_dev;
 
         let mut skip_contents = false;
         if old_st_dev != stat.st_dev {
-            self.fs_magic = detect_fs_type(dir.as_raw_fd())?;
+            match detect_fs_type(dir.as_raw_fd()) {
+                Ok(fs_magic) => self.fs_magic = fs_magic,
+                Err(Errno::ESTALE) => {
+                    log::warn!(
+                        "encountered stale file handle, skipping directory: {:?}",
+                        self.path
+                    );
+                    return Ok(());
+                }
+                Err(err) => return Err(err.into()),
+            }
             self.fs_feature_flags = Flags::from_magic(self.fs_magic);
             self.current_st_dev = stat.st_dev;
 
@@ -1193,6 +1196,13 @@ impl Archiver {
             }
         }
 
+        if !self.cache.caching_enabled() {
+            if let Some(ref catalog) = self.catalog {
+                catalog.lock().unwrap().start_directory(c_dir_name)?;
+            }
+            encoder.create_directory(dir_name, metadata).await?;
+        }
+
         let result = if skip_contents {
             log::info!("skipping mount point: {:?}", self.path);
             Ok(())
-- 
2.39.5