bundle: remove unneeded code

The changes in commit c06793a (allow git-bundle to create bottomless
bundle, 2007-08-08) ensure annotated tags are properly preserved when
creating a bundle using a revision range operation.

At the time the range notation would peel the ends to their
corresponding commit, meaning ref v2.0 would point to the v2.0^0 commit.
So the above workaround was introduced. This code looks up the ref
before it's written to the bundle, and if the ref doesn't point to the
object we expect (for tags this would be a tag object), we skip the ref
from the bundle. Instead, when the ref is a tag that's the positive end
of the range (e.g. v2.0 from the range "v1.0..v2.0"), then that ref is
written to the bundle instead.

Later, in 895c5ba (revision: do not peel tags used in range notation,
2013-09-19), the behavior of parsing ranges was changed and the problem
was fixed at the cause. But the workaround in bundle.c was not reverted.

Now it seems this workaround can cause a race condition. git-bundle(1)
uses setup_revisions() to parse the input into `struct rev_info`. Later,
in write_bundle_refs(), it uses this info to write refs to the bundle.
As mentioned at this point each ref is looked up again and checked
whether it points to the object we expect. If not, the ref is not
written to the bundle. But, when creating a bundle in a heavy traffic
repository (a repo with many references, and frequent ref updates) it's
possible a branch ref was updated between setup_revisions() and
write_bundle_refs() and thus the extra check causes the ref to be
skipped.

The workaround was originally added to deal with tags, but the code path
also gets hit by non-tag refs, causing this race condition. Because it's
no longer needed, remove it and fix the possible race condition.

Signed-off-by: Toon Claes <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: To1ne

bundle.c

@@ -420,36 +420,6 @@ static int write_bundle_refs(int bundle_fd, struct rev_info *revs)
 				e->name);
 			goto skip_write_ref;
 		}
-		/*
-		 * If you run "git bundle create bndl v1.0..v2.0", the
-		 * name of the positive ref is "v2.0" but that is the
-		 * commit that is referenced by the tag, and not the tag
-		 * itself.
-		 */
-		if (!oideq(&oid, &e->item->oid)) {
-			/*
-			 * Is this the positive end of a range expressed
-			 * in terms of a tag (e.g. v2.0 from the range
-			 * "v1.0..v2.0")?
-			 */
-			struct commit *one = lookup_commit_reference(revs->repo, &oid);
-			struct object *obj;
-
-			if (e->item == &(one->object)) {
-				/*
-				 * Need to include e->name as an
-				 * independent ref to the pack-objects
-				 * input, so that the tag is included
-				 * in the output; otherwise we would
-				 * end up triggering "empty bundle"
-				 * error.
-				 */
-				obj = parse_object_or_die(&oid, e->name);
-				obj->flags |= SHOWN;
-				add_pending_object(revs, obj, e->name);
-			}
-			goto skip_write_ref;
-		}
 
 		ref_count++;
 		write_or_die(bundle_fd, oid_to_hex(&e->item->oid), the_hash_algo->hexsz);

t/t6020-bundle-misc.sh

@@ -505,6 +505,50 @@ test_expect_success 'unfiltered bundle with --objects' '
 	test_cmp expect actual
 '
 
+test_expect_success 'full bundle upto annotated tag' '
+	git bundle create v2.bdl \
+		v2 &&
+
+	git bundle verify v2.bdl |
+		make_user_friendly_and_stable_output >actual &&
+
+	format_and_save_expect <<-EOF &&
+	The bundle contains this ref:
+	<TAG-2> refs/tags/v2
+	The bundle records a complete history.
+	$HASH_MESSAGE
+	EOF
+	test_cmp expect actual
+'
+
+test_expect_success 'clone from full bundle upto annotated tag' '
+	git clone --mirror v2.bdl tag-clone.git &&
+	git -C tag-clone.git show-ref |
+		make_user_friendly_and_stable_output >actual &&
+	cat >expect <<-\EOF &&
+	<TAG-2> refs/tags/v2
+	EOF
+	test_cmp expect actual
+'
+
+test_expect_success 'incremental bundle between two annotated tags' '
+	git bundle create v1-v2.bdl \
+		v1..v2 &&
+
+	git bundle verify v1-v2.bdl |
+		make_user_friendly_and_stable_output >actual &&
+
+	format_and_save_expect <<-EOF &&
+	The bundle contains this ref:
+	<TAG-2> refs/tags/v2
+	The bundle requires these 2 refs:
+	<COMMIT-E> Z
+	<COMMIT-B> Z
+	$HASH_MESSAGE
+	EOF
+	test_cmp expect actual
+'
+
 for filter in "blob:none" "tree:0" "tree:1" "blob:limit=100"
 do
 	test_expect_success "filtered bundle: $filter" '