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fcntl() locking does not pair at all with dlm locking. So both ocfs2
and gfs2<br>
use a special scheme just for this lock. Both use the ordered
messaging <br>
provided by the corosync cluster engine. This lock is fully
synchronised and<br>
thus is not as performant as it can be. (Both cman and pacemaker use
cce.)<br>
<br>
But that's ok because fcntl()'s locking semantics is not what you
think it is.<br>
The lock is almost useless in this day and age. The only use is
supporting<br>
legacy apps. For more refer to Jeremy Allison's overview of this
user lock.<br>
<a class="moz-txt-link-freetext" href="http://www.samba.org/samba/news/articles/low_point/tale_two_stds_os2.html">http://www.samba.org/samba/news/articles/low_point/tale_two_stds_os2.html</a><br>
<br>
Given that and considering most apps allow users to choose between
fcntl()<br>
and flock(), we've decided for now to just support the latter with
o2cb.<br>
<br>
flock() pairs well with dlm locking.<br>
<br>
On 01/18/2011 10:22 AM, Dan Warner wrote:
<blockquote
cite="mid:AANLkTinfLRxt3=-9B8sk4ms=iyicigHD2tEP=gYGDQ8C@mail.gmail.com"
type="cite">OK thanks for the clarification.<br>
<br>
Is the support of fcntl() locking within o2cb, on the wishlist of
features to be implemented at a future date? Is it even a priority
to do?<br>
<br>
Thanks, Dan<br>
<br>
<div class="gmail_quote">
On 18 January 2011 18:00, Sunil Mushran <span dir="ltr"><<a
moz-do-not-send="true"
href="mailto:sunil.mushran@oracle.com">sunil.mushran@oracle.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt
0.8ex; border-left: 1px solid rgb(204, 204, 204);
padding-left: 1ex;">
<div bgcolor="#ffffff" text="#000000"> ping_long tests the
fcntl() user locks.<br>
<br>
ocfs2 supports clustered fcntl() locking with cman and
pacemaker<br>
cluster stacks. Not with o2cb.<br>
<br>
ocfs2 supports clustered flock() with all stacks. o2cb, cman
and pacemaker. </div>
</blockquote>
</div>
<br>
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