When deleting loose refs, then we also have to delete the refs in the
packed backend. This is done by calling `refs_delete_refs()`, which
then uses the packed-backend's logic to delete refs. This doesn't allow
us to exercise any control over the reference transaction which is being
created in the packed backend, which is required in a subsequent commit.

Extract a new function `packed_refs_delete_refs()`, which hosts most of
the logic to delete refs except for creating the transaction itself.
Like this, we can easily create the transactionion in the files backend
and thus exert more control over it.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
---
 refs/files-backend.c  | 12 +++++++++---
 refs/packed-backend.c | 28 +++++++++++++++++++++-------
 refs/packed-backend.h |  6 ++++++
 3 files changed, 36 insertions(+), 10 deletions(-)

diff --git a/refs/files-backend.c b/refs/files-backend.c
index 90b671025a..5795e54020 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -1249,6 +1249,7 @@ static int files_delete_refs(struct ref_store *ref_store, const char *msg,
 {
 	struct files_ref_store *refs =
 		files_downcast(ref_store, REF_STORE_WRITE, "delete_refs");
+	struct ref_transaction *transaction = NULL;
 	struct strbuf err = STRBUF_INIT;
 	int i, result = 0;
 
@@ -1258,10 +1259,14 @@ static int files_delete_refs(struct ref_store *ref_store, const char *msg,
 	if (packed_refs_lock(refs->packed_ref_store, 0, &err))
 		goto error;
 
-	if (refs_delete_refs(refs->packed_ref_store, msg, refnames, flags)) {
-		packed_refs_unlock(refs->packed_ref_store);
+	transaction = ref_store_transaction_begin(refs->packed_ref_store, &err);
+	if (!transaction)
+		goto error;
+
+	result = packed_refs_delete_refs(refs->packed_ref_store,
+					 transaction, msg, refnames, flags);
+	if (result)
 		goto error;
-	}
 
 	packed_refs_unlock(refs->packed_ref_store);
 
@@ -1288,6 +1293,7 @@ static int files_delete_refs(struct ref_store *ref_store, const char *msg,
 	else
 		error(_("could not delete references: %s"), err.buf);
 
+	ref_transaction_free(transaction);
 	strbuf_release(&err);
 	return -1;
 }
diff --git a/refs/packed-backend.c b/refs/packed-backend.c
index 67152c664e..e97d67f932 100644
--- a/refs/packed-backend.c
+++ b/refs/packed-backend.c
@@ -1522,15 +1522,10 @@ static int packed_initial_transaction_commit(struct ref_store *ref_store,
 static int packed_delete_refs(struct ref_store *ref_store, const char *msg,
 			     struct string_list *refnames, unsigned int flags)
 {
-	struct packed_ref_store *refs =
-		packed_downcast(ref_store, REF_STORE_WRITE, "delete_refs");
 	struct strbuf err = STRBUF_INIT;
 	struct ref_transaction *transaction;
-	struct string_list_item *item;
 	int ret;
 
-	(void)refs; /* We need the check above, but don't use the variable */
-
 	if (!refnames->nr)
 		return 0;
 
@@ -1544,6 +1539,27 @@ static int packed_delete_refs(struct ref_store *ref_store, const char *msg,
 	if (!transaction)
 		return -1;
 
+	ret = packed_refs_delete_refs(ref_store, transaction,
+				      msg, refnames, flags);
+
+	ref_transaction_free(transaction);
+	return ret;
+}
+
+int packed_refs_delete_refs(struct ref_store *ref_store,
+			    struct ref_transaction *transaction,
+			    const char *msg,
+			    struct string_list *refnames,
+			    unsigned int flags)
+{
+	struct packed_ref_store *refs =
+		packed_downcast(ref_store, REF_STORE_WRITE, "delete_refs");
+	struct strbuf err = STRBUF_INIT;
+	struct string_list_item *item;
+	int ret;
+
+	(void)(refs); /* We need the check above, but don't use the variable */
+
 	for_each_string_list_item(item, refnames) {
 		if (ref_transaction_delete(transaction, item->string, NULL,
 					   flags, msg, &err)) {
@@ -1554,7 +1570,6 @@ static int packed_delete_refs(struct ref_store *ref_store, const char *msg,
 	}
 
 	ret = ref_transaction_commit(transaction, &err);
-
 	if (ret) {
 		if (refnames->nr == 1)
 			error(_("could not delete reference %s: %s"),
@@ -1563,7 +1578,6 @@ static int packed_delete_refs(struct ref_store *ref_store, const char *msg,
 			error(_("could not delete references: %s"), err.buf);
 	}
 
-	ref_transaction_free(transaction);
 	strbuf_release(&err);
 	return ret;
 }
diff --git a/refs/packed-backend.h b/refs/packed-backend.h
index f61a73ec25..5e0dd7d08e 100644
--- a/refs/packed-backend.h
+++ b/refs/packed-backend.h
@@ -27,6 +27,12 @@ int packed_refs_lock(struct ref_store *ref_store, int flags, struct strbuf *err)
 void packed_refs_unlock(struct ref_store *ref_store);
 int packed_refs_is_locked(struct ref_store *ref_store);
 
+int packed_refs_delete_refs(struct ref_store *ref_store,
+			    struct ref_transaction *transaction,
+			    const char *msg,
+			    struct string_list *refnames,
+			    unsigned int flags);
+
 /*
  * Return true if `transaction` really needs to be carried out against
  * the specified packed_ref_store, or false if it can be skipped
-- 
2.34.1