On Sun, Jul 25 2021 at  1:54P -0400,
Christoph Hellwig <[email protected]> wrote:

> device mapper is currently the only outlier that tries to call
> register_disk after add_disk, leading to fairly inconsistent state
> of these block layer data structures.  Instead change device-mapper
> to just register the gendisk later now that the holder mechanism
> can cope with that.
> 
> Note that this introduces a user visible change: the dm kobject is
> now only visible after the initial table has been loaded.
> 
> Signed-off-by: Christoph Hellwig <[email protected]>

Reviewed-by: Mike Snitzer <[email protected]>

Jens, feel free to pick this series up once you're comfortable with it.

Thanks,
Mike


> ---
>  drivers/md/dm-rq.c |  1 -
>  drivers/md/dm.c    | 23 +++++++++++------------
>  2 files changed, 11 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c
> index 0dbd48cbdff9..5b95eea517d1 100644
> --- a/drivers/md/dm-rq.c
> +++ b/drivers/md/dm-rq.c
> @@ -559,7 +559,6 @@ int dm_mq_init_request_queue(struct mapped_device *md, 
> struct dm_table *t)
>       err = blk_mq_init_allocated_queue(md->tag_set, md->queue);
>       if (err)
>               goto out_tag_set;
> -     elevator_init_mq(md->queue);
>       return 0;
>  
>  out_tag_set:
> diff --git a/drivers/md/dm.c b/drivers/md/dm.c
> index f003bd5b93ce..7981b7287628 100644
> --- a/drivers/md/dm.c
> +++ b/drivers/md/dm.c
> @@ -1693,7 +1693,10 @@ static void cleanup_mapped_device(struct mapped_device 
> *md)
>               spin_lock(&_minor_lock);
>               md->disk->private_data = NULL;
>               spin_unlock(&_minor_lock);
> -             del_gendisk(md->disk);
> +             if (dm_get_md_type(md) != DM_TYPE_NONE) {
> +                     dm_sysfs_exit(md);
> +                     del_gendisk(md->disk);
> +             }
>               dm_queue_destroy_keyslot_manager(md->queue);
>               blk_cleanup_disk(md->disk);
>       }
> @@ -1788,7 +1791,6 @@ static struct mapped_device *alloc_dev(int minor)
>                       goto bad;
>       }
>  
> -     add_disk_no_queue_reg(md->disk);
>       format_dev_t(md->name, MKDEV(_major, minor));
>  
>       md->wq = alloc_workqueue("kdmflush", WQ_MEM_RECLAIM, 0);
> @@ -1989,19 +1991,12 @@ static struct dm_table *__unbind(struct mapped_device 
> *md)
>   */
>  int dm_create(int minor, struct mapped_device **result)
>  {
> -     int r;
>       struct mapped_device *md;
>  
>       md = alloc_dev(minor);
>       if (!md)
>               return -ENXIO;
>  
> -     r = dm_sysfs_init(md);
> -     if (r) {
> -             free_dev(md);
> -             return r;
> -     }
> -
>       *result = md;
>       return 0;
>  }
> @@ -2081,10 +2076,15 @@ int dm_setup_md_queue(struct mapped_device *md, 
> struct dm_table *t)
>       r = dm_table_set_restrictions(t, md->queue, &limits);
>       if (r)
>               return r;
> -     md->type = type;
>  
> -     blk_register_queue(md->disk);
> +     add_disk(md->disk);
>  
> +     r = dm_sysfs_init(md);
> +     if (r) {
> +             del_gendisk(md->disk);
> +             return r;
> +     }
> +     md->type = type;
>       return 0;
>  }
>  
> @@ -2190,7 +2190,6 @@ static void __dm_destroy(struct mapped_device *md, bool 
> wait)
>               DMWARN("%s: Forcibly removing mapped_device still in use! (%d 
> users)",
>                      dm_device_name(md), atomic_read(&md->holders));
>  
> -     dm_sysfs_exit(md);
>       dm_table_destroy(__unbind(md));
>       free_dev(md);
>  }
> -- 
> 2.30.2
> 

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