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

[Jonathan E Brassow <jbrassow@redhat.com>]

thanks for the patch.

I've only compiled some of the kernels, since I'm still putting the 
finishing touches on the patches.  I'll try compiling all of them on a 
spare machine and fix any problems, then repost the patches.

  brassow

On Apr 20, 2006, at 3:50 PM, Simone Gotti wrote:

> 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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