Resolve get_url paths from explicit repo root

dvc/repo/__init__.py

@@ -387,15 +387,17 @@ def get_data_index_entry(
         path: str,
         workspace: str = "repo",
     ) -> tuple["DataIndex", "DataIndexEntry"]:
+        fs_path = path if self.fs.isabs(path) else self.fs.join(self.root_dir, path)
         if self.subrepos:
-            fs_path = self.dvcfs.from_os_path(path)
+            fs_path = self.dvcfs.from_os_path(fs_path)
+            fs_path = self.dvcfs.join(self.dvcfs.root_marker, fs_path)
             fs = self.dvcfs.fs
             key = fs._get_key_from_relative(fs_path)
             subrepo, _, key = fs._get_subrepo_info(key)
             index = subrepo.index.data[workspace]
         else:
             index = self.index.data[workspace]
-            key = self.fs.relparts(path, self.root_dir)
+            key = self.fs.relparts(fs_path, self.root_dir)
 
         try:
             return index, index[key]

tests/func/api/test_data.py

@@ -94,6 +94,20 @@ def test_get_url_ignore_scm(tmp_dir, dvc, cloud, scm):
         api.get_url("foo", repo=repo_url, config={"core": {"no_scm": True}})
 
 
+def test_get_url_with_explicit_repo_from_subdir(tmp_dir, dvc, scm, cloud):
+    tmp_dir.add_remote(config=cloud.config)
+    tmp_dir.dvc_gen("foo", "foo", commit="add foo")
+    (tmp_dir / "subdir").mkdir()
+
+    expected_url = (
+        cloud / "files" / "md5" / "ac" / "bd18db4cc2f85cedef654fccc4a4d8"
+    ).url
+    with (tmp_dir / "subdir").chdir():
+        assert api.get_url("foo", repo=os.fspath(tmp_dir)) == expected_url
+        _, entry = dvc.get_data_index_entry("foo")
+        assert entry.hash_info.value == "acbd18db4cc2f85cedef654fccc4a4d8"
+
+
 def test_open_external(tmp_dir, erepo_dir, cloud):
     erepo_dir.add_remote(config=cloud.config)
 
@@ -262,6 +276,13 @@ def test_get_url_subrepos(tmp_dir, scm, local_cloud):
     )
     assert api.get_url(os.path.join("subrepo", "dir", "foo")) == expected_url
     assert api.get_url(os.path.join("subrepo", "dir", "foo"), repo=".") == expected_url
+    subdir = tmp_dir / "subdir"
+    subdir.mkdir()
+    with subdir.chdir():
+        assert (
+            api.get_url(os.path.join("subrepo", "dir", "foo"), repo=os.fspath(tmp_dir))
+            == expected_url
+        )
 
     expected_url = os.fspath(
         local_cloud / "files" / "md5" / "37" / "b51d194a7513e45b56f6524f2d51f2"