[#2200] shard: Fix blobstor obj fetching

In the previous implementation any non-nil error that preceded object
fetching from blobstor led to iterating over every storage (in other words,
no storage ID information was taken into account). Now storage ID is
skipped only if metabase (storage ID source) returns any error.

Signed-off-by: Pavel Karpy <p.karpy@yadro.com>
Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>

CHANGELOG.md

@@ -10,6 +10,7 @@ Changelog for FrostFS Node
 ### Fixed
 - Big object removal with non-local parts (#1978)
 - Disable pilorama when moving to degraded mode (#2197)
+- Fetching blobovnicza objects that not found in write-cache (#2206)
 - Correct status error for expired session token (#2207)
 
 ### Removed

pkg/local_object_storage/shard/get.go

@@ -94,8 +94,8 @@ func (s *Shard) Get(prm GetPrm) (GetRes, error) {
 // fetchObjectData looks through writeCache and blobStor to find object.
 func (s *Shard) fetchObjectData(addr oid.Address, skipMeta bool, cb storFetcher, wc func(w writecache.Cache) (*objectSDK.Object, error)) (*objectSDK.Object, bool, error) {
 	var (
-		err error
-		res *objectSDK.Object
+		mErr error
+		mRes meta.ExistsRes
 	)
 
 	var exists bool
@@ -103,15 +103,15 @@ func (s *Shard) fetchObjectData(addr oid.Address, skipMeta bool, cb storFetcher,
 		var mPrm meta.ExistsPrm
 		mPrm.SetAddress(addr)
 
-		mRes, err := s.metaBase.Exists(mPrm)
-		if err != nil && !s.info.Mode.NoMetabase() {
-			return res, false, err
+		mRes, mErr = s.metaBase.Exists(mPrm)
+		if mErr != nil && !s.info.Mode.NoMetabase() {
+			return nil, false, mErr
 		}
 		exists = mRes.Exists()
 	}
 
 	if s.hasWriteCache() {
-		res, err = wc(s.writeCache)
+		res, err := wc(s.writeCache)
 		if err == nil || IsErrOutOfRange(err) {
 			return res, false, err
 		}
@@ -123,8 +123,8 @@ func (s *Shard) fetchObjectData(addr oid.Address, skipMeta bool, cb storFetcher,
 		}
 	}
 
-	if skipMeta || err != nil {
-		res, err = cb(s.blobStor, nil)
+	if skipMeta || mErr != nil {
+		res, err := cb(s.blobStor, nil)
 		return res, false, err
 	}
 
@@ -135,12 +135,12 @@ func (s *Shard) fetchObjectData(addr oid.Address, skipMeta bool, cb storFetcher,
 	var mPrm meta.StorageIDPrm
 	mPrm.SetAddress(addr)
 
-	mRes, err := s.metaBase.StorageID(mPrm)
+	mExRes, err := s.metaBase.StorageID(mPrm)
 	if err != nil {
 		return nil, true, fmt.Errorf("can't fetch blobovnicza id from metabase: %w", err)
 	}
 
-	res, err = cb(s.blobStor, mRes.StorageID())
+	res, err := cb(s.blobStor, mExRes.StorageID())
 
 	return res, true, err
 }