From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Teigland Date: Fri, 31 Jul 2009 11:21:12 -0500 Subject: [Ocfs2-devel] lvb length issue [was Re: [ocfs2-tools-devel] question of ocfs2_controld (Jun 27)] In-Reply-To: <4A72DC8C.303@suse.de> References: <4A451AB5.9070908@suse.de> <20090626193436.GC4478@mail.oracle.com> <4A45257C.6040704@suse.de> <20090629080023.GB8373@mail.oracle.com> <4A51ED7F.2040105@suse.de> <20090707160113.GA9140@redhat.com> <20090707174741.GA24163@mail.oracle.com> <20090708141542.GA8778@redhat.com> <20090709185338.GA11643@redhat.com> <4A72DC8C.303@suse.de> Message-ID: <20090731162112.GA24461@redhat.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: ocfs2-devel@oss.oracle.com On Fri, Jul 31, 2009 at 07:59:08PM +0800, Coly Li wrote: > > > David Teigland Wrote: > > On Wed, Jul 08, 2009 at 09:15:42AM -0500, David Teigland wrote: > >> On Tue, Jul 07, 2009 at 10:47:42AM -0700, Joel Becker wrote: > >>> In this case, it's userspace utilities locking to verify no one > >>> else is doing anything in the cluster. coly has noticed mkfs.ocfs2, but > >>> tunefs.ocfs2 and fsck.ocfs2 do the same thing. > >>> While a 64byte user lvb would be ideal, I think a flag to work > >>> around it would be great. If the flag says "I know this lockspace may > >>> have !32byte LVBs, but I promise not to use them", and you can error > >>> when someone tries to set/get LVBs in that case, I think it works. > > > > Here's a kernel patch that I've not yet tried. The code using libdlm will > > need to add the flag 0x00000010 to dlm_new_lockspace(). (Until we've added > > the new LVB64 define to libdlm.h.) > > > > +#define DLM_LSFL_LVB64 0x00000010 > > > Another difficulty is user space libdlm interface. Right now, the interface > mkfs.ocfs2 uses to create a lock space is, > dlm_lshandle_t dlm_create_lockspace(const char *name, mode_t mode) > { > return create_lockspace(name, mode, 0); > } > > There is no way to set flags in dlm_create_lockspace() and it is set to 0 inside > the interface. > > Is it possible to export create_lockspace() and release_lockspace() from libdlm > ? So ocfs2-tools can load these symbols with dlopen() and calls these routines > with flags (set DLM_LSFL_LVB64). > > Other 2 options might be, > 1) add flags in dlm_create_lockspace(), which will change libdlm api. > 2) update default lvb length from 32bytes to 64bytes. I don't think I'll bother with the LVB64 flag hack. Instead, I'm planning to do a larger API change to really support variable length lvb's from userspace. It's actually dlm_new_lockspace() that you would use to pass flags, and once we add variable length lvb's we'll need a new third call that adds an lvblen parameter. Dave