Re: [PATCH v4 2/2] md-cluster: fix rmmod issue when md_cluster convert bitmap to none

[NeilBrown <neil@brown.name>]

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On Sun, Jul 19 2020, Zhao Heming wrote:

> update_array_info misses calling module_put when removing cluster bitmap.
>
> steps to reproduce:
> ```
> node1 # mdadm -C /dev/md0 -b clustered -e 1.2 -n 2 -l mirror /dev/sda
> /dev/sdb
> mdadm: array /dev/md0 started.
> node1 # lsmod | egrep "dlm|md_|raid1"
> md_cluster             28672  1
> dlm                   212992  14 md_cluster
> configfs               57344  2 dlm
> raid1                  53248  1
> md_mod                176128  2 raid1,md_cluster
> node1 # mdadm -G /dev/md0 -b none
> node1 # lsmod | egrep "dlm|md_|raid1"
> md_cluster             28672  1 <== should be zero
> dlm                   212992  9 md_cluster
> configfs               57344  2 dlm
> raid1                  53248  1
> md_mod                176128  2 raid1,md_cluster
> node1 # mdadm -G /dev/md0 -b clustered
> node1 # lsmod | egrep "dlm|md_|raid1"
> md_cluster             28672  2 <== increase
> dlm                   212992  14 md_cluster
> configfs               57344  2 dlm
> raid1                  53248  1
> md_mod                176128  2 raid1,md_cluster
> node1 # mdadm -G /dev/md0 -b none
> node1 # mdadm -G /dev/md0 -b clustered
> node1 # lsmod | egrep "dlm|md_|raid1"
> md_cluster             28672  3 <== increase
> dlm                   212992  14 md_cluster
> configfs               57344  2 dlm
> raid1                  53248  1
> md_mod                176128  2 raid1,md_cluster
> ```
>
> Signed-off-by: Zhao Heming <heming.zhao@suse.com>
> ---
>  drivers/md/md.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index e20f1d5a5261..ca791387e54d 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -7363,6 +7363,7 @@ static int update_array_info(struct mddev *mddev, mdu_array_info_t *info)
>  
>  				mddev->bitmap_info.nodes = 0;
>  				md_cluster_ops->leave(mddev);
> +				module_put(md_cluster_mod);
>  				mddev->safemode_delay = DEFAULT_SAFEMODE_DELAY;

I would make this a call to "md_cluster_stop()", and move the reset of
->safemode_delay" in there, but either way this is correct and needed.

  Reviewed-by: NeilBrown <neilb@suse.de>

Thanks,
NeilBrown


>  			}
>  			mddev_suspend(mddev);
> -- 
> 2.25.0

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