[pbs-devel] [PATCH proxmox-backup] gc: attach context to index reader errors and ignore NotFound

[Stefan Reiter]

Ignore NotFound errors during phase 1, this just means that a snapshot
was forgotten or pruned between scanning for .fidx/.didx files and
actually opening the index to touch the chunks.

ignore_notfound has to be a real function, since generics are not
supported for closures.

The open methods for dynamic and fixed indices are switched from the
usual format_err! to err.context() to allow checking for the root error
(and thus the io::ErrorKind) further up the call chain.

Signed-off-by: Stefan Reiter <s.reiter at proxmox.com>
---
 src/backup/datastore.rs     | 28 ++++++++++++++++++++++++----
 src/backup/dynamic_index.rs |  5 ++++-
 src/backup/fixed_index.rs   |  7 +++++--
 3 files changed, 33 insertions(+), 7 deletions(-)

diff --git a/src/backup/datastore.rs b/src/backup/datastore.rs
index ebe47487..1f455d64 100644
--- a/src/backup/datastore.rs
+++ b/src/backup/datastore.rs
@@ -426,6 +426,20 @@ impl DataStore {
         Ok(())
     }
 
+    fn ignore_notfound<T>(res: Result<T, Error>) -> Result<Option<T>, Error> {
+        match res {
+            Ok(t) => Ok(Some(t)),
+            Err(err) => {
+                if let Some(ioerr) = err.downcast_ref::<std::io::Error>() {
+                    if ioerr.kind() == std::io::ErrorKind::NotFound {
+                        return Ok(None);
+                    }
+                }
+                Err(err)
+            }
+        }
+    }
+
     fn mark_used_chunks(&self, status: &mut GarbageCollectionStatus, worker: &WorkerTask) -> Result<(), Error> {
 
         let image_list = self.list_images()?;
@@ -443,11 +457,17 @@ impl DataStore {
 
             if let Ok(archive_type) = archive_type(&path) {
                 if archive_type == ArchiveType::FixedIndex {
-                    let index = self.open_fixed_reader(&path)?;
-                    self.index_mark_used_chunks(index, &path, status, worker)?;
+                    if let Some(index) = Self::ignore_notfound(self.open_fixed_reader(&path))? {
+                        self.index_mark_used_chunks(index, &path, status, worker)?;
+                    } else {
+                        worker.warn(format!("warning: could no longer find fixed index '{:?}'", &path));
+                    }
                 } else if archive_type == ArchiveType::DynamicIndex {
-                    let index = self.open_dynamic_reader(&path)?;
-                    self.index_mark_used_chunks(index, &path, status, worker)?;
+                    if let Some(index) = Self::ignore_notfound(self.open_dynamic_reader(&path))? {
+                        self.index_mark_used_chunks(index, &path, status, worker)?;
+                    } else {
+                        worker.warn(format!("warning: could no longer find dynamic index '{:?}'", &path));
+                    }
                 }
             }
             done += 1;
diff --git a/src/backup/dynamic_index.rs b/src/backup/dynamic_index.rs
index f70aa44f..a7ce0f24 100644
--- a/src/backup/dynamic_index.rs
+++ b/src/backup/dynamic_index.rs
@@ -86,7 +86,10 @@ impl DynamicIndexReader {
         File::open(path)
             .map_err(Error::from)
             .and_then(Self::new)
-            .map_err(|err| format_err!("Unable to open dynamic index {:?} - {}", path, err))
+            .map_err(|err| {
+                let msg = format!("Unable to open dynamic index {:?} - {}", path, err);
+                err.context(msg)
+            })
     }
 
     pub fn new(mut file: std::fs::File) -> Result<Self, Error> {
diff --git a/src/backup/fixed_index.rs b/src/backup/fixed_index.rs
index 5d6cc1ff..bf864173 100644
--- a/src/backup/fixed_index.rs
+++ b/src/backup/fixed_index.rs
@@ -1,4 +1,4 @@
-use anyhow::{bail, format_err, Error};
+use anyhow::{bail, Error};
 use std::io::{Seek, SeekFrom};
 
 use super::chunk_stat::*;
@@ -62,7 +62,10 @@ impl FixedIndexReader {
         File::open(path)
             .map_err(Error::from)
             .and_then(|file| Self::new(file))
-            .map_err(|err| format_err!("Unable to open fixed index {:?} - {}", path, err))
+            .map_err(|err| {
+                let msg = format!("Unable to open fixed index {:?} - {}", path, err);
+                err.context(msg)
+            })
     }
 
     pub fn new(mut file: std::fs::File) -> Result<Self, Error> {
-- 
2.20.1