- uevents and GFS2
- ==================
+.. SPDX-License-Identifier: GPL-2.0
+
+================
+uevents and GFS2
+================
During the lifetime of a GFS2 mount, a number of uevents are generated.
This document explains what the events are and what they are used
for (by gfs_controld in gfs2-utils).
A list of GFS2 uevents
------------------------
+======================
1. ADD
+------
The ADD event occurs at mount time. It will always be the first
uevent generated by the newly created filesystem. If the mount
of the filesystem respectively.
2. ONLINE
+---------
The ONLINE uevent is generated after a successful mount or remount. It
has the same environment variables as the ADD uevent. The ONLINE
be generated by older kernels.
3. CHANGE
+---------
The CHANGE uevent is used in two places. One is when reporting the
successful mount of the filesystem by the first node (FIRSTMOUNT=Done).
uevent for a successful mount or remount.
4. OFFLINE
+----------
The OFFLINE uevent is only generated due to filesystem errors and is used
as part of the "withdraw" mechanism. Currently this doesn't give any
be fixed.
5. REMOVE
+---------
The REMOVE uevent is generated at the end of an unsuccessful mount
or at the end of a umount of the filesystem. All REMOVE uevents will
Information common to all GFS2 uevents (uevent environment variables)
-----------------------------------------------------------------------
+=====================================================================
1. LOCKTABLE=
+--------------
The LOCKTABLE is a string, as supplied on the mount command
line (locktable=) or via fstab. It is used as a filesystem label
able to join the cluster.
2. LOCKPROTO=
+-------------
The LOCKPROTO is a string, and its value depends on what is set
on the mount command line, or via fstab. It will be either
may be supported.
3. JOURNALID=
+-------------
If a journal is in use by the filesystem (journals are not
assigned for spectator mounts) then this will give the
numeric journal id in all GFS2 uevents.
4. UUID=
+--------
With recent versions of gfs2-utils, mkfs.gfs2 writes a UUID
into the filesystem superblock. If it exists, this will