rgw/sfs: recognize delete-marker on DeleteObj

RGWDeleteObj::execute() relies on the return code from
rgw::sal::Object::get_obj_state() to ascert the object being deleted is
a regular object rather than a delete-marker.
The rule is to return -ENOENT to signal a delete-marker.
get_obj_state() in rgw/sfs was returning always 0 for any object,
therefore also a delete-marker fell into a regular object in
RGWDeleteObj::execute().
This is wrong because, when dealing with object lock checks, a delete-marker
is always allowed to be deleted regardless of the object's retention mode.
Returing 0 was incorrectly preventing a delete-marker to be deleted for
object-lock protected objects.

Fixes: https://github.com/aquarist-labs/s3gw/issues/690
Signed-off-by: Giuseppe Baccini <[email protected]>

qa/rgw/store/sfs/tests/fixtures/s3-tests.txt

@@ -470,7 +470,7 @@ test_object_lock_get_obj_retention_invalid_bucket
 # test_object_lock_put_obj_retention_shorten_period
 # test_object_lock_put_obj_retention_shorten_period_bypass
 # test_object_lock_delete_object_with_retention
-# test_object_lock_delete_object_with_retention_and_marker
+test_object_lock_delete_object_with_retention_and_marker
 # test_object_lock_multi_delete_object_with_retention
 # test_object_lock_put_legal_hold
 test_object_lock_put_legal_hold_invalid_bucket

qa/rgw/store/sfs/tests/fixtures/s3tr_excuses.csv

@@ -18,7 +18,6 @@ test_bucket_recreate_overwrite_acl;https://github.com/aquarist-labs/s3gw/issues/
 test_logging_toggle;https://tracker.ceph.com/issues/984;Not supported by RGW
 test_object_copy_replacing_metadata;https://github.com/aquarist-labs/s3gw/issues/525;BUG
 test_object_copy_to_itself_with_metadata;https://github.com/aquarist-labs/s3gw/issues/525;BUG
-test_object_lock_delete_object_with_retention_and_marker;https://github.com/aquarist-labs/s3gw/issues/690;BUG
 test_object_read_unreadable;https://docs.aws.amazon.com/AmazonS3/latest/userguide/object-keys.html;Broken test, Object names are UTF-8
 test_object_requestid_matches_header_on_error;https://github.com/aquarist-labs/s3gw/issues/689;BUG
 test_object_set_get_unicode_metadata;https://github.com/aquarist-labs/s3gw/issues/688;BUG, maybe upstream

src/rgw/driver/sfs/object.cc

@@ -463,7 +463,7 @@ int SFSObject::get_obj_state(
 ) {
   refresh_meta();
   *_state = &state;
-  return 0;
+  return objref->deleted ? -ENOENT : 0;
 }
 
 int SFSObject::set_obj_attrs(