Re: [linux-lvm] dmeventd_mirror problem and some questions.

[Simone Gotti <simone.gotti@email.it>]

On Wed, 2006-04-19 at 09:00 -0500, Jonathan E Brassow wrote: 

> Kernel patches are located at http://www.brassow.com/mirroring.  Last 
> updated on April 3rd... I'll be updating those either today or tomorrow 
> as well.

Thanks, 
I tried the version of the 3 April and the new version of yesterday.
I applied the patches in the order provided by the "series" file, used
the standard fedora .config, but on both the versions I got this
compilation error:

  CC [M]  drivers/md/dm-log.o
drivers/md/dm-log.c: In function ‘dm_register_dirty_log_type’:
drivers/md/dm-log.c:19: error: ‘_lock’ undeclared (first use in this
function)
drivers/md/dm-log.c:19: error: (Each undeclared identifier is reported
only once
drivers/md/dm-log.c:19: error: for each function it appears in.)
drivers/md/dm-log.c: In function ‘dm_unregister_dirty_log_type’:
drivers/md/dm-log.c:29: error: ‘_lock’ undeclared (first use in this
function)
drivers/md/dm-log.c: In function ‘get_type’:
drivers/md/dm-log.c:46: error: ‘_lock’ undeclared (first use in this
function)
drivers/md/dm-log.c: In function ‘put_type’:
drivers/md/dm-log.c:64: error: ‘_lock’ undeclared (first use in this
function)
make[2]: *** [drivers/md/dm-log.o] Error 1
make[1]: *** [drivers/md] Error 2
make: *** [drivers] Error 2

I am missing something?


> There are some kernel patches that you need.  Either way, the DSO 
> shouldn't be crashing, so I'll look into that.

My temporary workaround was to check the number of returned arguments:

Index: dmeventd_mirror.c
===================================================================
RCS file: /cvs/lvm2/LVM2/dmeventd/mirror/dmeventd_mirror.c,v
retrieving revision 1.5
diff -u -b -B -p -r1.5 dmeventd_mirror.c
--- dmeventd_mirror.c   6 Feb 2006 19:34:45 -0000       1.5
+++ dmeventd_mirror.c   20 Apr 2006 20:42:18 -0000
@@ -39,6 +39,7 @@ static int _get_mirror_event(char *param
 {
        int i, rtn = ME_INSYNC;
        int max_args = 30;  /* should support at least 8-way mirrors */
+       int output_args;
        char *args[max_args];
        char *dev_status_str;
        char *log_status_str;
@@ -46,11 +47,17 @@ static int _get_mirror_event(char *param
        char *p;
        int log_argc, num_devs, num_failures=0;

-       if (max_args <= split_words(params, max_args, args)) {
+       output_args = split_words(params, max_args, args);
+       if (max_args <= output_args) {
                syslog(LOG_ERR, "Unable to split mirror parameters: Arg
list too long");
                return -E2BIG;
        }

+       if (output_args <= 4) {
+               syslog(LOG_ERR, "Mirror status not provided by the
kernel module");
+               return ME_IGNORE;
+       };
+
        /*
         * Unused:  0 409600 mirror
         * Used  :  2 253:4 253:5 400/400 1 AA 3 cluster 253:3 A


Thanks!

Bye!
>   brassow
> 
> On Apr 18, 2006, at 7:40 AM, Simone Gotti wrote:
> 
> > Hi All,
> >
> > I was curious to try the experimental dmeventd + the mirror checking
> > dso.
> > Everytime I created a mirror volume, dmeventd was crashing when the
> > mirror finished the syncing process.
> > I tracked it down to _get_mirror_event that is expeting a return string
> > from the status ioctl to dm like "2 253:4 253:5 400/400 1 AA 3 cluster
> > 253:3 A" but it gets only "2 253:4 253:5 400/400" so it SIGSEGV when is
> > going to read over the number of returned arguments in the "args" array
> > from split_words.
> >
> > The same string is returned by "dmsetup status".
> >
> > Do these informations aren't already implemented in the ioctl, or are
> > there some patches around that I can try? (my kernel is the latest
> > available in fedora rawhide: 2.6.16-1.2131_FC6)
> >
> > Another question, If I understand it correctly, the mirror library for
> > dmeventd will look to possible problems (eg the lost of a PV containing
> > a mirror), and it will call the right lvm command to fix it?
> > For example, if a PV containing a side of a 2 way mirrored volume is
> > lost, what are the various actions that it will do (I noticed an
> > lvreduce --removemissing, but my fear is that this command will also
> > remove unmirrored volumes)?
> >
> > Thanks!
> >
> > Bye!
> >
> > Simone Gotti.
> >
> >
> >
> >
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> >
> 
> 
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