docs: filesystems: convert dlmfs.txt to ReST

- Add a SPDX header;
- Use copyright symbol;
- Adjust document title;
- Some whitespace fixes and new line breaks;
- Mark literal blocks as such;
- Add table markups;
- Add it to filesystems/index.rst.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/efc9e59925723e17d1a4741b11049616c221463e.1581955849.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

1 files changed, 0 insertions, 130 deletions

diff --git a/Documentation/filesystems/dlmfs.txt b/Documentation/filesystems/dlmfs.txt
deleted file mode 100644
index fcf4d509d118..000000000000
--- a/Documentation/filesystems/dlmfs.txt
+++ /dev/null
@@ -1,130 +0,0 @@
-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: http://oss.oracle.com/projects/ocfs2/mailman/
-
-All code copyright 2005 Oracle except when otherwise noted.
-
-CREDITS
-=======
-
-Some code taken from ramfs which is Copyright (C) 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.txt. 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.
-
-dlmfs handles lock caching automatically for the user, so a lock
-request for an already acquired lock will not generate another DLM
-call. Userspace programs are assumed to handle their own local
-locking.
-
-Two levels of locks are supported - Shared Read, and Exclusive.
-Also supported is a Trylock operation.
-
-For information on the libo2dlm interface, please see o2dlm.h,
-distributed with ocfs2-tools.
-
-Lock value blocks can be read and written to a resource via read(2)
-and write(2) against the fd obtained via your open(2) call. The
-maximum currently supported LVB length is 64 bytes (though that is an
-OCFS2 DLM limitation). Through this mechanism, users of dlmfs can share
-small amounts of data amongst their nodes.
-
-mkdir(2) signals dlmfs to join a domain (which will have the same name
-as the resulting directory)
-
-rmdir(2) signals dlmfs to leave the domain
-
-Locks for a given domain are represented by regular inodes inside the
-domain directory.  Locking against them is done via the open(2) system
-call.
-
-The open(2) call will not return until your lock has been granted or
-an error has occurred, unless it has been instructed to do a trylock
-operation. If the lock succeeds, you'll get an fd.
-
-open(2) with O_CREAT to ensure the resource inode is created - dlmfs does
-not automatically create inodes for existing lock resources.
-
-Open Flag     Lock Request Type
----------     -----------------
-O_RDONLY      Shared Read
-O_RDWR        Exclusive
-
-Open Flag     Resulting Locking Behavior
----------     --------------------------
-O_NONBLOCK    Trylock operation
-
-You must provide exactly one of O_RDONLY or O_RDWR.
-
-If O_NONBLOCK is also provided and the trylock operation was valid but
-could not lock the resource then open(2) will return ETXTBUSY.
-
-close(2) drops the lock associated with your fd.
-
-Modes passed to mkdir(2) or open(2) are adhered to locally. Chown is
-supported locally as well. This means you can use them to restrict
-access to the resources via dlmfs on your local node only.
-
-The resource LVB may be read from the fd in either Shared Read or
-Exclusive modes via the read(2) system call. It can be written via
-write(2) only when open in Exclusive mode.
-
-Once written, an LVB will be visible to other nodes who obtain Read
-Only or higher level locks on the resource.
-
-See Also
-========
-http://opendlm.sourceforge.net/cvsmirror/opendlm/docs/dlmbook_final.pdf
-
-For more information on the VMS distributed locking API.