[PATCH v1 proxmox-backup 1/3] datastore: fix local path for .i.bad chunk files during S3 GC

[Robert Obkircher <r.obkircher@proxmox.com>]

Do not push an additional path segment with the extension, and rename
the confusing variable. The additional segment caused a rather cryptic
"TASK ERROR: Not a directory (os error 20)" error during Phase 2 if
the .i.bad file existed locally.

If it doesn't exist locally, the S3 object was and continues to be
deleted, unless it is the very first one and the corresponding chunk
expected marker exists. This behavior might not be desirable if the
files are missing because the datastore was recreated with the "reuse
existing datastore" option.

Fixes: 27e3f5b7b ("GC: fix: don't drop bad extension for S3 object to chunk path helper")
Signed-off-by: Robert Obkircher <r.obkircher@proxmox.com>
---
 pbs-datastore/src/datastore.rs | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/pbs-datastore/src/datastore.rs b/pbs-datastore/src/datastore.rs
index e2d1ae67c..3079fe833 100644
--- a/pbs-datastore/src/datastore.rs
+++ b/pbs-datastore/src/datastore.rs
@@ -2678,8 +2678,8 @@ impl DataStore {
         // Check object is actually a chunk
         let path = Path::new::<str>(object_key);
         // file_name() should always be Some, as objects will have a filename
-        let digest = path.file_name()?;
-        let bytes = digest.as_bytes();
+        let file_name = path.file_name()?;
+        let bytes = file_name.as_bytes();
         let bad_ext_len = ".0.bad".len();
         let bad_chunk = if bytes.len() == 64 + bad_ext_len {
             true
@@ -2693,19 +2693,15 @@ impl DataStore {
         }
 
         // Safe since contains valid ascii hexdigits only as checked above.
-        let digest_str = digest.to_string_lossy();
+        let digest_str = file_name.to_string_lossy();
         let hexdigit_prefix = unsafe { digest_str.get_unchecked(0..4) };
         let mut chunk_path = self.base_path();
         chunk_path.push(".chunks");
         chunk_path.push(hexdigit_prefix);
-        chunk_path.push(digest);
-        if bad_chunk {
-            let extension = unsafe { digest_str.get_unchecked(64..64 + bad_ext_len) };
-            chunk_path.push(extension);
-        }
+        chunk_path.push(file_name);
 
         let mut digest_bytes = [0u8; 32];
-        let digest = digest.as_bytes();
+        let digest = file_name.as_bytes();
         // safe to unwrap as already checked above
         hex::decode_to_slice(&digest[..64], &mut digest_bytes).unwrap();
 
-- 
2.47.3