fs: Remove fs meta lock when PutObject() fails (#4114)

Removing the fs meta lock file when PutObject() encounters any error
during its execution, such as upload getting permatuerly cancelled
by the client.

cmd/fs-v1.go

@@ -492,7 +492,9 @@ func (fs fsObjects) GetObjectInfo(bucket, object string) (ObjectInfo, error) {
 // until EOF, writes data directly to configured filesystem path.
 // Additionally writes `fs.json` which carries the necessary metadata
 // for future object operations.
-func (fs fsObjects) PutObject(bucket string, object string, size int64, data io.Reader, metadata map[string]string, sha256sum string) (objInfo ObjectInfo, err error) {
+func (fs fsObjects) PutObject(bucket string, object string, size int64, data io.Reader, metadata map[string]string, sha256sum string) (objInfo ObjectInfo, retErr error) {
+	var err error
+
 	// This is a special case with size as '0' and object ends with
 	// a slash separator, we treat it like a valid operation and
 	// return success.
@@ -517,13 +519,21 @@ func (fs fsObjects) PutObject(bucket string, object string, size int64, data io.
 
 	var wlk *lock.LockedFile
 	if bucket != minioMetaBucket {
-		fsMetaPath := pathJoin(fs.fsPath, minioMetaBucket, bucketMetaPrefix, bucket, object, fsMetaJSONFile)
+		bucketMetaDir := pathJoin(fs.fsPath, minioMetaBucket, bucketMetaPrefix)
+		fsMetaPath := pathJoin(bucketMetaDir, bucket, object, fsMetaJSONFile)
 		wlk, err = fs.rwPool.Create(fsMetaPath)
 		if err != nil {
 			return ObjectInfo{}, toObjectErr(traceError(err), bucket, object)
 		}
 		// This close will allow for locks to be synchronized on `fs.json`.
 		defer wlk.Close()
+		defer func() {
+			// Remove meta file when PutObject encounters any error
+			if retErr != nil {
+				tmpDir := pathJoin(fs.fsPath, minioMetaTmpBucket, fs.fsUUID)
+				fsRemoveMeta(bucketMetaDir, fsMetaPath, tmpDir)
+			}
+		}()
 	}
 
 	// Uploaded object will first be written to the temporary location which will eventually