recursive submodules: git-reset!

index d2b512da90..d6b263f78e 100644
@@ -208,7 +208,8 @@ static int write_entry(struct cache_entry *ce,
 		sub = submodule_from_ce(ce);
 		if (sub)
 			return submodule_move_head(ce->name,
-				NULL, oid_to_hex(&ce->oid), SUBMODULE_MOVE_HEAD_FORCE);
+				NULL, oid_to_hex(&ce->oid),
+				state->force ? SUBMODULE_MOVE_HEAD_FORCE : 0);
 		break;
 	default:
 		return error("unknown file mode for %s in index", path);

@@ -282,12 +283,11 @@ int checkout_entry(struct cache_entry *ce,
 					unlink_or_warn(ce->name);
 
 				return submodule_move_head(ce->name,
-					NULL, oid_to_hex(&ce->oid),
-					SUBMODULE_MOVE_HEAD_FORCE);
+					NULL, oid_to_hex(&ce->oid), 0);
 			} else
 				return submodule_move_head(ce->name,
 					"HEAD", oid_to_hex(&ce->oid),
-					SUBMODULE_MOVE_HEAD_FORCE);
+					state->force ? SUBMODULE_MOVE_HEAD_FORCE : 0);
 		}
 
 		if (!changed)

index 6b7356dab2..4b3f9518e5 100644
@@ -252,14 +252,18 @@ static int check_submodule_move_head(const struct cache_entry *ce,
 				     const char *new_id,
 				     struct unpack_trees_options *o)
 {
+	unsigned flags = SUBMODULE_MOVE_HEAD_DRY_RUN;
 	const struct submodule *sub = submodule_from_ce(ce);
 	if (!sub)
 		return 0;
 
+	if (o->reset)
+		flags |= SUBMODULE_MOVE_HEAD_FORCE;
+
 	switch (sub->update_strategy.type) {
 	case SM_UPDATE_UNSPECIFIED:
 	case SM_UPDATE_CHECKOUT:
-		if (submodule_move_head(ce->name, old_id, new_id, SUBMODULE_MOVE_HEAD_DRY_RUN))
+		if (submodule_move_head(ce->name, old_id, new_id, flags))
 			return o->gently ? -1 :
 				add_rejected_path(o, ERROR_WOULD_LOSE_SUBMODULE, ce->name);
 		return 0;

@@ -308,6 +312,7 @@ static void unlink_entry(const struct cache_entry *ce)
 		case SM_UPDATE_CHECKOUT:
 		case SM_UPDATE_REBASE:
 		case SM_UPDATE_MERGE:
+			/* state.force is set at the caller. */
 			submodule_move_head(ce->name, "HEAD", NULL,
 					    SUBMODULE_MOVE_HEAD_FORCE);
 			break;

index 7c3c4b17fb..ccf8932731 100644
@@ -1333,6 +1333,9 @@ int submodule_move_head(const char *path,
 	struct child_process cp = CHILD_PROCESS_INIT;
 	const struct submodule *sub;
 
+	if (!is_submodule_initialized(path))
+		return 0;
+
 	sub = submodule_from_path(null_sha1, path);
 
 	if (!sub)

index ccf8932731..20ed5b5681 100644
@@ -1332,10 +1332,24 @@ int submodule_move_head(const char *path,
 	int ret = 0;
 	struct child_process cp = CHILD_PROCESS_INIT;
 	const struct submodule *sub;
+	int *error_code_ptr, error_code;
 
 	if (!is_submodule_initialized(path))
 		return 0;
 
+	if (flags & SUBMODULE_MOVE_HEAD_FORCE)
+		/*
+		 * Pass non NULL pointer to is_submodule_populated_gently
+		 * to prevent die()-ing. We'll use connect_work_tree_and_git_dir
+		 * to fixup the submodule in the force case later.
+		 */
+		error_code_ptr = &error_code;
+	else
+		error_code_ptr = NULL;
+
+	if (old && !is_submodule_populated_gently(path, error_code_ptr))
+		return 0;
+
 	sub = submodule_from_path(null_sha1, path);
 
 	if (!sub)

@@ -1353,15 +1367,21 @@ int submodule_move_head(const char *path,
 				absorb_git_dir_into_superproject("", path,
 					ABSORB_GITDIR_RECURSE_SUBMODULES);
 		} else {
-			struct strbuf sb = STRBUF_INIT;
-			strbuf_addf(&sb, "%s/modules/%s",
+			char *gitdir = xstrfmt("%s/modules/%s",
 				    get_git_common_dir(), sub->name);
-			connect_work_tree_and_git_dir(path, sb.buf);
-			strbuf_release(&sb);
+			connect_work_tree_and_git_dir(path, gitdir);
+			free(gitdir);
 
 			/* make sure the index is clean as well */
 			submodule_reset_index(path);
 		}
+
+		if (old && (flags & SUBMODULE_MOVE_HEAD_FORCE)) {
+			char *gitdir = xstrfmt("%s/modules/%s",
+				    get_git_common_dir(), sub->name);
+			connect_work_tree_and_git_dir(path, gitdir);
+			free(gitdir);
+		}
 	}
 
 	prepare_submodule_repo_env_no_git_dir(&cp.env_array);

index fc3b906c47..5ce27fcaed 100644
@@ -21,6 +21,27 @@
 #include "parse-options.h"
 #include "unpack-trees.h"
 #include "cache-tree.h"
+#include "submodule.h"
+#include "submodule-config.h"
+
+static int recurse_submodules = RECURSE_SUBMODULES_DEFAULT;
+
+static int option_parse_recurse_submodules(const struct option *opt,
+					   const char *arg, int unset)
+{
+	if (unset) {
+		recurse_submodules = RECURSE_SUBMODULES_OFF;
+		return 0;
+	}
+	if (arg)
+		recurse_submodules =
+			parse_update_recurse_submodules_arg(opt->long_name,
+							    arg);
+	else
+		recurse_submodules = RECURSE_SUBMODULES_ON;
+
+	return 0;
+}
 
 static const char * const git_reset_usage[] = {
 	N_("git reset [--mixed | --soft | --hard | --merge | --keep] [-q] [<commit>]"),

@@ -283,6 +304,9 @@ int cmd_reset(int argc, const char **argv, const char *prefix)
 				N_("reset HEAD, index and working tree"), MERGE),
 		OPT_SET_INT(0, "keep", &reset_type,
 				N_("reset HEAD but keep local changes"), KEEP),
+		{ OPTION_CALLBACK, 0, "recurse-submodules", &recurse_submodules,
+			    "reset", "control recursive updating of submodules",
+			    PARSE_OPT_OPTARG, option_parse_recurse_submodules },
 		OPT_BOOL('p', "patch", &patch_mode, N_("select hunks interactively")),
 		OPT_BOOL('N', "intent-to-add", &intent_to_add,
 				N_("record only the fact that removed paths will be added later")),

@@ -295,6 +319,12 @@ int cmd_reset(int argc, const char **argv, const char *prefix)
 						PARSE_OPT_KEEP_DASHDASH);
 	parse_args(&pathspec, argv, prefix, patch_mode, &rev);
 
+	if (recurse_submodules != RECURSE_SUBMODULES_DEFAULT) {
+		gitmodules_config();
+		git_config(submodule_config, NULL);
+		set_config_update_recurse_submodules(RECURSE_SUBMODULES_ON);
+	}
+
 	unborn = !strcmp(rev, "HEAD") && get_sha1("HEAD", oid.hash);
 	if (unborn) {
 		/* reset on unborn branch: treat as reset to empty tree */

index fc3b906c47..5ce27fcaed 100644
@@ -21,6 +21,27 @@
 #include "parse-options.h"
 #include "unpack-trees.h"
 #include "cache-tree.h"
+#include "submodule.h"
+#include "submodule-config.h"
+
+static int recurse_submodules = RECURSE_SUBMODULES_DEFAULT;
+
+static int option_parse_recurse_submodules(const struct option *opt,
+					   const char *arg, int unset)
+{
+	if (unset) {
+		recurse_submodules = RECURSE_SUBMODULES_OFF;
+		return 0;
+	}
+	if (arg)
+		recurse_submodules =
+			parse_update_recurse_submodules_arg(opt->long_name,
+							    arg);
+	else
+		recurse_submodules = RECURSE_SUBMODULES_ON;
+
+	return 0;
+}
 
 static const char * const git_reset_usage[] = {
 	N_("git reset [--mixed | --soft | --hard | --merge | --keep] [-q] [<commit>]"),

@@ -283,6 +304,9 @@ int cmd_reset(int argc, const char **argv, const char *prefix)
 				N_("reset HEAD, index and working tree"), MERGE),
 		OPT_SET_INT(0, "keep", &reset_type,
 				N_("reset HEAD but keep local changes"), KEEP),
+		{ OPTION_CALLBACK, 0, "recurse-submodules", &recurse_submodules,
+			    "reset", "control recursive updating of submodules",
+			    PARSE_OPT_OPTARG, option_parse_recurse_submodules },
 		OPT_BOOL('p', "patch", &patch_mode, N_("select hunks interactively")),
 		OPT_BOOL('N', "intent-to-add", &intent_to_add,
 				N_("record only the fact that removed paths will be added later")),

@@ -295,6 +319,12 @@ int cmd_reset(int argc, const char **argv, const char *prefix)
 						PARSE_OPT_KEEP_DASHDASH);
 	parse_args(&pathspec, argv, prefix, patch_mode, &rev);
 
+	if (recurse_submodules != RECURSE_SUBMODULES_DEFAULT) {
+		gitmodules_config();
+		git_config(submodule_config, NULL);
+		set_config_update_recurse_submodules(RECURSE_SUBMODULES_ON);
+	}
+
 	unborn = !strcmp(rev, "HEAD") && get_sha1("HEAD", oid.hash);
 	if (unborn) {
 		/* reset on unborn branch: treat as reset to empty tree */