docs: filesystems: convert gfs2.txt to ReST

- Add a SPDX header;
- 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>
Acked-by: Bob Peterson <rpeterso@redhat.com>
Link: https://lore.kernel.org/r/6d7a296de025bcfed7a229da7f8cc1678944f304.1581955849.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

1 files changed, 53 insertions, 0 deletions

diff --git a/Documentation/filesystems/gfs2.rst b/Documentation/filesystems/gfs2.rst
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+.. SPDX-License-Identifier: GPL-2.0
+
+==================
+Global File System
+==================
+
+https://fedorahosted.org/cluster/wiki/HomePage
+
+GFS is a cluster file system. It allows a cluster of computers to
+simultaneously use a block device that is shared between them (with FC,
+iSCSI, NBD, etc).  GFS reads and writes to the block device like a local
+file system, but also uses a lock module to allow the computers coordinate
+their I/O so file system consistency is maintained.  One of the nifty
+features of GFS is perfect consistency -- changes made to the file system
+on one machine show up immediately on all other machines in the cluster.
+
+GFS uses interchangeable inter-node locking mechanisms, the currently
+supported mechanisms are:
+
+  lock_nolock
+    - allows gfs to be used as a local file system
+
+  lock_dlm
+    - uses a distributed lock manager (dlm) for inter-node locking.
+      The dlm is found at linux/fs/dlm/
+
+Lock_dlm depends on user space cluster management systems found
+at the URL above.
+
+To use gfs as a local file system, no external clustering systems are
+needed, simply::
+
+  $ mkfs -t gfs2 -p lock_nolock -j 1 /dev/block_device
+  $ mount -t gfs2 /dev/block_device /dir
+
+If you are using Fedora, you need to install the gfs2-utils package
+and, for lock_dlm, you will also need to install the cman package
+and write a cluster.conf as per the documentation. For F17 and above
+cman has been replaced by the dlm package.
+
+GFS2 is not on-disk compatible with previous versions of GFS, but it
+is pretty close.
+
+The following man pages can be found at the URL above:
+
+  ============		=============================================
+  fsck.gfs2		to repair a filesystem
+  gfs2_grow		to expand a filesystem online
+  gfs2_jadd		to add journals to a filesystem online
+  tunegfs2		to manipulate, examine and tune a filesystem
+  gfs2_convert		to convert a gfs filesystem to gfs2 in-place
+  mkfs.gfs2		to make a filesystem
+  ============		=============================================