Merge "Change the remount command to be more container-friendly" (d24c8484) · Commits · e / os / android_system_core

adb/remount_service.cpp

+19 −7

Original line number	Original line	Diff line number	Diff line
	@@ -62,8 +62,8 @@ static std::string find_fstab_mount(const char* dir) {

	// The proc entry for / is full of lies, so check fstab instead.		// The proc entry for / is full of lies, so check fstab instead.
	// /proc/mounts lists rootfs and /dev/root, neither of which is what we want.		// /proc/mounts lists rootfs and /dev/root, neither of which is what we want.
	static std::string find_mount(const char* dir) {		static std::string find_mount(const char* dir, bool is_root) {
	if (strcmp(dir, "/") == 0) {		if (is_root) {
	return find_fstab_mount(dir);		return find_fstab_mount(dir);
	} else {		} else {
	return find_proc_mount(dir);		return find_proc_mount(dir);
	@@ -86,17 +86,29 @@ static bool remount_partition(int fd, const char* dir) {
	if (!directory_exists(dir)) {		if (!directory_exists(dir)) {
	return true;		return true;
	}		}
	std::string dev = find_mount(dir);		bool is_root = strcmp(dir, "/") == 0;
	if (dev.empty()) {		std::string dev = find_mount(dir, is_root);
			// Even if the device for the root is not found, we still try to remount it
			// as rw. This typically only happens when running Android in a container:
			// the root will almost always be in a loop device, which is dynamic, so
			// it's not convenient to put in the fstab.
			if (dev.empty() && !is_root) {
	return true;		return true;
	}		}
	if (!make_block_device_writable(dev)) {		if (!dev.empty() && !make_block_device_writable(dev)) {
	WriteFdFmt(fd, "remount of %s failed; couldn't make block device %s writable: %s\n",		WriteFdFmt(fd, "remount of %s failed; couldn't make block device %s writable: %s\n",
	dir, dev.c_str(), strerror(errno));		dir, dev.c_str(), strerror(errno));
	return false;		return false;
	}		}
			if (mount(dev.c_str(), dir, "none", MS_REMOUNT \| MS_BIND, nullptr) == -1) {
			// This is useful for cases where the superblock is already marked as
			// read-write, but the mount itself is read-only, such as containers
			// where the remount with just MS_REMOUNT is forbidden by the kernel.
			WriteFdFmt(fd, "remount of the %s mount failed: %s.\n", dir, strerror(errno));
			return false;
			}
	if (mount(dev.c_str(), dir, "none", MS_REMOUNT, nullptr) == -1) {		if (mount(dev.c_str(), dir, "none", MS_REMOUNT, nullptr) == -1) {
	WriteFdFmt(fd, "remount of %s failed: %s\n", dir, strerror(errno));		WriteFdFmt(fd, "remount of the %s superblock failed: %s\n", dir, strerror(errno));
	return false;		return false;
	}		}
	return true;		return true;