mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-11-17 01:04:19 +08:00
40e47125e6
Signed-off-by: Masanari Iida <standby24x7@gmail.com> Acked-by: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
101 lines
3.7 KiB
Plaintext
101 lines
3.7 KiB
Plaintext
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
|
|
is successful, an ONLINE uevent will follow. If it is not successful
|
|
then a REMOVE uevent will follow.
|
|
|
|
The ADD uevent has two environment variables: SPECTATOR=[0|1]
|
|
and RDONLY=[0|1] that specify the spectator status (a read-only mount
|
|
with no journal assigned), and read-only (with journal assigned) status
|
|
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
|
|
uevent, along with the two environment variables for spectator and
|
|
RDONLY are a relatively recent addition (2.6.32-rc+) and will not
|
|
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).
|
|
This is used as a signal by gfs_controld that it is then ok for other
|
|
nodes in the cluster to mount the filesystem.
|
|
|
|
The other CHANGE uevent is used to inform of the completion
|
|
of journal recovery for one of the filesystems journals. It has
|
|
two environment variables, JID= which specifies the journal id which
|
|
has just been recovered, and RECOVERY=[Done|Failed] to indicate the
|
|
success (or otherwise) of the operation. These uevents are generated
|
|
for every journal recovered, whether it is during the initial mount
|
|
process or as the result of gfs_controld requesting a specific journal
|
|
recovery via the /sys/fs/gfs2/<fsname>/lock_module/recovery file.
|
|
|
|
Because the CHANGE uevent was used (in early versions of gfs_controld)
|
|
without checking the environment variables to discover the state, we
|
|
cannot add any more functions to it without running the risk of
|
|
someone using an older version of the user tools and breaking their
|
|
cluster. For this reason the ONLINE uevent was used when adding a new
|
|
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
|
|
information about what the error is, which is something that needs to
|
|
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
|
|
have been preceded by at least an ADD uevent for the same filesystem,
|
|
and unlike the other uevents is generated automatically by the kernel's
|
|
kobject subsystem.
|
|
|
|
|
|
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
|
|
as well as providing the information for a lock_dlm mount to be
|
|
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
|
|
lock_nolock or lock_dlm. In the future other lock managers
|
|
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
|
|
be included in every uevent relating to the filesystem.
|
|
|
|
|
|
|