storage: Refetch file status after open

This partly reverts my previous patch f88de3eb. We need to
get file status after open, as given path could have been symlink,
so fstat() will operate on different file than lstat().

src/storage/storage_backend.c

@@ -1041,6 +1041,14 @@ virStorageBackendVolOpenCheckMode(const char *path, unsigned int flags)
         return -1;
     }
 
+    if (fstat(fd, &sb) < 0) {
+        virReportSystemError(errno,
+                             _("cannot stat file '%s'"),
+                             path);
+        VIR_FORCE_CLOSE(fd);
+        return -1;
+    }
+
     if (S_ISREG(sb.st_mode))
         mode = VIR_STORAGE_VOL_OPEN_REG;
     else if (S_ISCHR(sb.st_mode))