1 files changed, 30 insertions, 5 deletions

diff --git a/builtin/update-index.c b/builtin/update-index.c
index 187203e8bb..876112abb2 100644
--- a/builtin/update-index.c
+++ b/builtin/update-index.c
@@ -606,7 +606,7 @@ static struct cache_entry *read_one_ent(const char *which,
 			error("%s: not in %s branch.", path, which);
 		return NULL;
 	}
-	if (mode == S_IFDIR) {
+	if (!the_index.sparse_index && mode == S_IFDIR) {
 		if (which)
 			error("%s: not a blob in %s branch.", path, which);
 		return NULL;
@@ -743,8 +743,6 @@ static int do_reupdate(int ac, const char **av,
 		 */
 		has_head = 0;
  redo:
-	/* TODO: audit for interaction with sparse-index. */
-	ensure_full_index(&the_index);
 	for (pos = 0; pos < active_nr; pos++) {
 		const struct cache_entry *ce = active_cache[pos];
 		struct cache_entry *old = NULL;
@@ -761,6 +759,16 @@ static int do_reupdate(int ac, const char **av,
 			discard_cache_entry(old);
 			continue; /* unchanged */
 		}
+
+		/* At this point, we know the contents of the sparse directory are
+		 * modified with respect to HEAD, so we expand the index and restart
+		 * to process each path individually
+		 */
+		if (S_ISSPARSEDIR(ce->ce_mode)) {
+			ensure_full_index(&the_index);
+			goto redo;
+		}
+
 		/* Be careful.  The working tree may not have the
 		 * path anymore, in which case, under 'allow_remove',
 		 * or worse yet 'allow_replace', active_nr may decrease.
@@ -787,6 +795,17 @@ static int refresh(struct refresh_params *o, unsigned int flag)
 	setup_work_tree();
 	read_cache();
 	*o->has_errors |= refresh_cache(o->flags | flag);
+	if (has_racy_timestamp(&the_index)) {
+		/*
+		 * Even if nothing else has changed, updating the file
+		 * increases the chance that racy timestamps become
+		 * non-racy, helping future run-time performance.
+		 * We do that even in case of "errors" returned by
+		 * refresh_cache() as these are no actual errors.
+		 * cmd_status() does the same.
+		 */
+		active_cache_changed |= SOMETHING_CHANGED;
+	}
 	return 0;
 }
 
@@ -1077,6 +1096,9 @@ int cmd_update_index(int argc, const char **argv, const char *prefix)
 
 	git_config(git_default_config, NULL);
 
+	prepare_repo_settings(r);
+	the_repository->settings.command_requires_full_index = 0;
+
 	/* we will diagnose later if it turns out that we need to update it */
 	newfd = hold_locked_index(&lock_file, 0);
 	if (newfd < 0)
@@ -1214,14 +1236,17 @@ int cmd_update_index(int argc, const char **argv, const char *prefix)
 	}
 
 	if (fsmonitor > 0) {
-		if (git_config_get_fsmonitor() == 0)
+		enum fsmonitor_mode fsm_mode = fsm_settings__get_mode(r);
+		if (fsm_mode == FSMONITOR_MODE_DISABLED) {
 			warning(_("core.fsmonitor is unset; "
 				"set it if you really want to "
 				"enable fsmonitor"));
+		}
 		add_fsmonitor(&the_index);
 		report(_("fsmonitor enabled"));
 	} else if (!fsmonitor) {
-		if (git_config_get_fsmonitor() == 1)
+		enum fsmonitor_mode fsm_mode = fsm_settings__get_mode(r);
+		if (fsm_mode > FSMONITOR_MODE_DISABLED)
 			warning(_("core.fsmonitor is set; "
 				"remove it if you really want to "
 				"disable fsmonitor"));