Re: mdadm --wait returns while array under construction? [patch question]

[Ross Boylan <ross@biostat.ucsf.edu>]

On Wed, 2012-11-21 at 08:43 +1100, NeilBrown wrote:
> On Tue, 20 Nov 2012 09:55:41 -0800 Ross Boylan <ross@biostat.ucsf.edu> wrote:
> 
> > While switching the disks a RAID 1 is based on I used the --wait command
> > to wait for the rebuild to finish.  It returned immediately, but a
> > subsequent query showed it had not been rebuilt.  Have I misunderstood
> > something, or is this an error?
> > 
> > While doing these commands a much larger rebuild was going on with a
> > different array, involving some of the same physical disks but different
> > partitions.  The partitions being rebuilt are on different physical
> > disks for the different arrays.
> > 
> > Here are the logs, with version info at the end (Debian Lenny + more
> > recent kernel):
> ....
> 
> > markov:~# uname -a
> > Linux markov 2.6.32-5-amd64 #1 SMP Wed Jan 12 03:40:32 UTC 2011 x86_64 GNU/Linux
> > markov:~# mdadm --version
> > mdadm - v2.6.7.2 - 14th November 2008
> > 
> > 
> > I notice that in this case, unlike the other array, the message during
> > the rebuild (the last detail report) does not include a line like
> > Rebuild Status : 0% complete
> > 
> > I just tried --wait again to see if there was some kind of race, but
> > once again it returned immediately, though detail says the spare is
> > rebuilding.
> 
> Can you test this patch to see if it fixes the problem?
> 
> diff --git a/Monitor.c b/Monitor.c
> index c4d57c3..a5e7aaa 100644
> --- a/Monitor.c
> +++ b/Monitor.c
> @@ -973,7 +973,7 @@ int Wait(char *dev)
>  			if (e->devnum == devnum)
>  				break;
>  
> -		if (!e || e->percent < 0) {
> +		if (!e || e->percent == RESYNC_NONE) {
>  			if (e && e->metadata_version &&
>  			    strncmp(e->metadata_version, "external:", 9) == 0) {
>  				if (is_subarray(&e->metadata_version[9]))
> 
> 
> NeilBrown
My source for 2.6.7.2 looks somewhat different.  It only has 627 lines;
I think this is the relevant code (at the end of the file):
/* Not really Monitor but ... */
int Wait(char *dev)
{
        struct stat stb;
        int devnum;
        int rv = 1;

        if (stat(dev, &stb) != 0) {
                fprintf(stderr, Name ": Cannot find %s: %s\n", dev,
                        strerror(errno));
                return 2;
        }
        if (major(stb.st_rdev) == MD_MAJOR)
                devnum = minor(stb.st_rdev);
        else
                devnum = -1-(minor(stb.st_rdev)/64);

        while(1) {
                struct mdstat_ent *ms = mdstat_read(1, 0);
                struct mdstat_ent *e;

                for (e=ms ; e; e=e->next)
                        if (e->devnum == devnum)
                                break;

                if (!e || e->percent < 0) {
                        free_mdstat(ms);
                        return rv;
                }
                free(ms);
                rv = 0;
                mdstat_wait(5);
        }
}


The section
                if (!e || e->percent < 0) {
                        free_mdstat(ms);
                        return rv;
 is the only one with e->percent < 0.  Is it OK to change that to 
if (!e || e->percent == RESYNC_NONE) {?

Thanks.
Ross