ocfs2: mount shared volume without ha stack

Usually we create and use a ocfs2 shared volume on the top of ha stack.
For pcmk based ha stack, which includes DLM, corosync and pacemaker
services.

The customers complained they could not mount existent ocfs2 volume in
the single node without ha stack, e.g.  single node backup/restore
scenario.

Like this case, the customers just want to access the data from the
existent ocfs2 volume quickly, but do not want to restart or setup ha
stack.

Then, I'd like to add a mount option "nocluster", if the users use this
option to mount a ocfs2 shared volume, the whole mount will not depend
on the ha related services.  the command will mount the existent ocfs2
volume directly (like local mount), for avoiding setup the ha stack.

Signed-off-by: Gang He <ghe@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Joseph Qi <jiangqi903@gmail.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Jun Piao <piaojun@huawei.com>
Link: http://lkml.kernel.org/r/20200423053300.22661-1-ghe@suse.com


Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>