[Ocfs2-devel] lvb length issue [was Re: [ocfs2-tools-devel] question of ocfs2_controld (Jun 27)]

[Coly Li <coly.li@suse.de>]

David Teigland Wrote:
> On Mon, Jul 06, 2009 at 08:26:39PM +0800, Coly Li wrote:
>> DLM_USER_LVB_LEN is defined to 32.
> 
>> DLM_LVB_LEN is 64.
> 
> Yes, the kernel dlm api allows a variable lvb size, but the user dlm api fixes
> it at 32.
> 
> Do you need to actually use a 64 byte lvb from userspace?  Or do you just need
> to create the locksapce with a 64 byte lvb?  We could add a flag to work

When mkfs.ocfs2 checks a mounted ocfs2 volume, it tries to create a lockspace.
the kernel should create a 64 bytes lvb according the existed lvb created by
kernel dlm api.
In this case, the answer might be, to allow user space utilities to create 64
bytes lvb.

> around the later fairly easily.  Changing the dlm user/kernel interface to
> copy variable size lvb's would take some significant work.
> 

I checked ocfs2-tools code, it seems libo2dlm uses 32 bytes lvb.
Is it possible just extend DLM_USER_LVB_LEN to 64 bytes ? It seems OK for
ocfs2-tools code, but I don't know whether there is other negative effect.

Thanks.

-- 
Coly Li
SuSE Labs