Workaround for volume shadow copy in WSL1

docs/usage/general/environment.rst.inc

@@ -94,6 +94,11 @@ General:
             Using this does not affect data safety, but might result in a more bursty
             write to disk behaviour (not continuously streaming to disk).
 
+        retry_erofs
+            Retry opening a file without O_NOATIME if opening a file with O_NOATIME
+            caused EROFS. You will need this to make archives from volume shadow copies
+            in WSL1 (Windows Subsystem for Linux 1).
+
 Some automatic "answerers" (if set, they automatically answer confirmation questions):
     BORG_UNKNOWN_UNENCRYPTED_REPO_ACCESS_IS_OK=no (or =yes)
         For "Warning: Attempting to access a previously unknown unencrypted repository"

src/borg/archive.py

@@ -37,6 +37,7 @@ from .helpers import bin_to_hex
 from .helpers import safe_ns
 from .helpers import ellipsis_truncate, ProgressIndicatorPercent, log_multi
 from .helpers import msgpack
+from .helpers import workarounds
 from .patterns import PathPrefixPattern, FnmatchPattern, IECommand
 from .item import Item, ArchiveItem
 from .platform import acl_get, acl_set, set_flags, get_flags, swidth, hostname
@@ -1115,6 +1116,12 @@ Utilization of max. archive size: {csize_max:.0%}
                 raise
             # Was this EPERM due to the O_NOATIME flag? Try again without it:
             return os.open(path, flags_normal)
+        except OSError as exc:
+            # O_NOATIME causes EROFS when accessing a volume shadow copy in WSL1
+            if 'retry_erofs' in workarounds and exc.errno == errno.EROFS and flags_noatime != flags_normal:
+                return os.open(path, flags_normal)
+            else:
+                raise
 
 
 def valid_msgpacked_dict(d, keys_serialized):