Systemd/src/core/automount.h
Lennart Poettering a57f7e2c82 core: rework how we match mount units against each other
Previously to automatically create dependencies between mount units we
matched every mount unit agains all others resulting in O(n^2)
complexity. On setups with large amounts of mount units this might make
things slow.

This change replaces the matching code to use a hashtable that is keyed
by a path prefix, and points to a set of units that require that path to
be around. When a new mount unit is installed it is hence sufficient to
simply look up this set of units via its own file system paths to know
which units to order after itself.

This patch also changes all unit types to only create automatic mount
dependencies via the RequiresMountsFor= logic, and this is exposed to
the outside to make things more transparent.

With this change we still have some O(n) complexities in place when
handling mounts, but that's currently unavoidable due to kernel APIs,
and still substantially better than O(n^2) as before.

https://bugs.freedesktop.org/show_bug.cgi?id=69740
2013-09-26 20:20:30 +02:00

70 lines
1.8 KiB
C

/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
#pragma once
/***
This file is part of systemd.
Copyright 2010 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
typedef struct Automount Automount;
#include "unit.h"
typedef enum AutomountState {
AUTOMOUNT_DEAD,
AUTOMOUNT_WAITING,
AUTOMOUNT_RUNNING,
AUTOMOUNT_FAILED,
_AUTOMOUNT_STATE_MAX,
_AUTOMOUNT_STATE_INVALID = -1
} AutomountState;
typedef enum AutomountResult {
AUTOMOUNT_SUCCESS,
AUTOMOUNT_FAILURE_RESOURCES,
_AUTOMOUNT_RESULT_MAX,
_AUTOMOUNT_RESULT_INVALID = -1
} AutomountResult;
struct Automount {
Unit meta;
AutomountState state, deserialized_state;
char *where;
int pipe_fd;
mode_t directory_mode;
Watch pipe_watch;
dev_t dev_id;
Set *tokens;
AutomountResult result;
};
extern const UnitVTable automount_vtable;
int automount_send_ready(Automount *a, int status);
const char* automount_state_to_string(AutomountState i) _const_;
AutomountState automount_state_from_string(const char *s) _pure_;
const char* automount_result_to_string(AutomountResult i) _const_;
AutomountResult automount_result_from_string(const char *s) _pure_;