Documentation/filesystems/dlmfs.rst

Source file repositories/reference/linux-study-clean/Documentation/filesystems/dlmfs.rst

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Documentation/filesystems/dlmfs.rst
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Support Tooling And Documentation
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Support Tooling And Documentation: documentation
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Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

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.. SPDX-License-Identifier: GPL-2.0
.. include:: <isonum.txt>

=====
DLMFS
=====

A minimal DLM userspace interface implemented via a virtual file
system.

dlmfs is built with OCFS2 as it requires most of its infrastructure.

:Project web page:    http://ocfs2.wiki.kernel.org
:Tools web page:      https://github.com/markfasheh/ocfs2-tools
:OCFS2 mailing lists: https://subspace.kernel.org/lists.linux.dev.html

All code copyright 2005 Oracle except when otherwise noted.

Credits
=======

Some code taken from ramfs which is Copyright |copy| 2000 Linus Torvalds
and Transmeta Corp.

Mark Fasheh <mark.fasheh@oracle.com>

Caveats
=======
- Right now it only works with the OCFS2 DLM, though support for other
  DLM implementations should not be a major issue.

Mount options
=============
None

Usage
=====

If you're just interested in OCFS2, then please see ocfs2.rst. The
rest of this document will be geared towards those who want to use
dlmfs for easy to setup and easy to use clustered locking in
userspace.

Setup
=====

dlmfs requires that the OCFS2 cluster infrastructure be in
place. Please download ocfs2-tools from the above url and configure a
cluster.

You'll want to start heartbeating on a volume which all the nodes in
your lockspace can access. The easiest way to do this is via
ocfs2_hb_ctl (distributed with ocfs2-tools). Right now it requires
that an OCFS2 file system be in place so that it can automatically
find its heartbeat area, though it will eventually support heartbeat
against raw disks.

Please see the ocfs2_hb_ctl and mkfs.ocfs2 manual pages distributed
with ocfs2-tools.

Once you're heartbeating, DLM lock 'domains' can be easily created /
destroyed and locks within them accessed.

Locking
=======

Users may access dlmfs via standard file system calls, or they can use
'libo2dlm' (distributed with ocfs2-tools) which abstracts the file
system calls and presents a more traditional locking api.

Annotation

Implementation Notes