On Fri, Sep 02 2016, Guoqing Jiang wrote:
> The md-cluster is compiled as module by default,
> if it is compiled by built-in way, then we can't
> make md-cluster works.
>
> [64782.630008] md/raid1:md127: active with 2 out of 2 mirrors
> [64782.630528] md-cluster module not found.
> [64782.630530] md127: Could not setup cluster service (-2)
>
> Fixes: edb39c9 ("Introduce md_cluster_operations to handle cluster functions")
> Cc: stable@xxxxxxxxxxxxxxx # v4.1+
> Cc: NeilBrown <neilb@xxxxxxxx>
> Reported-by: Marc Smith <marc.smith@xxxxxxx>
> Signed-off-by: Guoqing Jiang <gqjiang@xxxxxxxx>
> ---
> drivers/md/md.c | 21 +++++++++------------
> 1 file changed, 9 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index bdbbb6e1..3b19d21 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -7619,20 +7619,17 @@ EXPORT_SYMBOL(unregister_md_cluster_operations);
>
> int md_setup_cluster(struct mddev *mddev, int nodes)
> {
> - int err;
> -
> - err = request_module("md-cluster");
> - if (err) {
> - pr_err("md-cluster module not found.\n");
> - return -ENOENT;
> - }
> -
> - spin_lock(&pers_lock);
> - if (!md_cluster_ops || !try_module_get(md_cluster_mod)) {
> + if (!md_cluster_ops) {
> + /* load module and ensure it won't be unloaded */
> + request_module("md-cluster");
> + spin_lock(&pers_lock);
> + if (!try_module_get(md_cluster_mod)) {
> + pr_err("can't get md-cluster module reference.\n");
> + spin_unlock(&pers_lock);
> + return -ENODEV;
> + }
> spin_unlock(&pers_lock);
> - return -ENOENT;
> }
> - spin_unlock(&pers_lock);
>
> return md_cluster_ops->join(mddev, nodes);
> }
> --
> 2.6.6
No good. If md_cluster_ops is set, try_module_get() won't be called, so
it will be possible to unload the module while it is in use.
NeilBrown
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