Re: [PATCH 03/20] block: add a bdev_kobj helper

[Jan Kara <jack@xxxxxxx>]

On Wed 18-11-20 09:47:43, Christoph Hellwig wrote:
> Add a little helper to find the kobject for a struct block_device.
> 
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>

Looks good. You can add:

Reviewed-by: Jan Kara <jack@xxxxxxx>

                                                                Honza

> ---
>  drivers/md/bcache/super.c |  7 ++-----
>  drivers/md/md.c           |  4 +---
>  fs/btrfs/sysfs.c          | 15 +++------------
>  include/linux/blk_types.h |  3 +++
>  4 files changed, 9 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
> index 46a00134a36ae1..a6a5e21e4fd136 100644
> --- a/drivers/md/bcache/super.c
> +++ b/drivers/md/bcache/super.c
> @@ -1447,8 +1447,7 @@ static int register_bdev(struct cache_sb *sb, struct 
> cache_sb_disk *sb_disk,
>               goto err;
>  
>       err = "error creating kobject";
> -     if (kobject_add(&dc->disk.kobj, &part_to_dev(bdev->bd_part)->kobj,
> -                     "bcache"))
> +     if (kobject_add(&dc->disk.kobj, bdev_kobj(bdev), "bcache"))
>               goto err;
>       if (bch_cache_accounting_add_kobjs(&dc->accounting, &dc->disk.kobj))
>               goto err;
> @@ -2342,9 +2341,7 @@ static int register_cache(struct cache_sb *sb, struct 
> cache_sb_disk *sb_disk,
>               goto err;
>       }
>  
> -     if (kobject_add(&ca->kobj,
> -                     &part_to_dev(bdev->bd_part)->kobj,
> -                     "bcache")) {
> +     if (kobject_add(&ca->kobj, bdev_kobj(bdev), "bcache")) {
>               err = "error calling kobject_add";
>               ret = -ENOMEM;
>               goto out;
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index b2edf5e0f965b5..7ce6047c856ea2 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -2414,7 +2414,6 @@ EXPORT_SYMBOL(md_integrity_add_rdev);
>  static int bind_rdev_to_array(struct md_rdev *rdev, struct mddev *mddev)
>  {
>       char b[BDEVNAME_SIZE];
> -     struct kobject *ko;
>       int err;
>  
>       /* prevent duplicates */
> @@ -2477,9 +2476,8 @@ static int bind_rdev_to_array(struct md_rdev *rdev, 
> struct mddev *mddev)
>       if ((err = kobject_add(&rdev->kobj, &mddev->kobj, "dev-%s", b)))
>               goto fail;
>  
> -     ko = &part_to_dev(rdev->bdev->bd_part)->kobj;
>       /* failure here is OK */
> -     err = sysfs_create_link(&rdev->kobj, ko, "block");
> +     err = sysfs_create_link(&rdev->kobj, bdev_kobj(rdev->bdev), "block");
>       rdev->sysfs_state = sysfs_get_dirent_safe(rdev->kobj.sd, "state");
>       rdev->sysfs_unack_badblocks =
>               sysfs_get_dirent_safe(rdev->kobj.sd, 
> "unacknowledged_bad_blocks");
> diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
> index 279d9262b676d4..24b6c6dc69000a 100644
> --- a/fs/btrfs/sysfs.c
> +++ b/fs/btrfs/sysfs.c
> @@ -1232,8 +1232,6 @@ int btrfs_sysfs_add_space_info_type(struct 
> btrfs_fs_info *fs_info,
>  
>  void btrfs_sysfs_remove_device(struct btrfs_device *device)
>  {
> -     struct hd_struct *disk;
> -     struct kobject *disk_kobj;
>       struct kobject *devices_kobj;
>  
>       /*
> @@ -1243,11 +1241,8 @@ void btrfs_sysfs_remove_device(struct btrfs_device 
> *device)
>       devices_kobj = device->fs_info->fs_devices->devices_kobj;
>       ASSERT(devices_kobj);
>  
> -     if (device->bdev) {
> -             disk = device->bdev->bd_part;
> -             disk_kobj = &part_to_dev(disk)->kobj;
> -             sysfs_remove_link(devices_kobj, disk_kobj->name);
> -     }
> +     if (device->bdev)
> +             sysfs_remove_link(devices_kobj, bdev_kobj(device->bdev)->name);
>  
>       if (device->devid_kobj.state_initialized) {
>               kobject_del(&device->devid_kobj);
> @@ -1353,11 +1348,7 @@ int btrfs_sysfs_add_device(struct btrfs_device *device)
>       nofs_flag = memalloc_nofs_save();
>  
>       if (device->bdev) {
> -             struct hd_struct *disk;
> -             struct kobject *disk_kobj;
> -
> -             disk = device->bdev->bd_part;
> -             disk_kobj = &part_to_dev(disk)->kobj;
> +             struct kobject *disk_kobj = bdev_kobj(device->bdev);
>  
>               ret = sysfs_create_link(devices_kobj, disk_kobj, 
> disk_kobj->name);
>               if (ret) {
> diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
> index d9b69bbde5cc54..0069bee992063e 100644
> --- a/include/linux/blk_types.h
> +++ b/include/linux/blk_types.h
> @@ -48,6 +48,9 @@ struct block_device {
>       struct mutex            bd_fsfreeze_mutex;
>  } __randomize_layout;
>  
> +#define bdev_kobj(_bdev) \
> +     (&part_to_dev((_bdev)->bd_part)->kobj)
> +
>  /*
>   * Block error status values.  See block/blk-core:blk_errors for the details.
>   * Alpha cannot write a byte atomically, so we need to use 32-bit value.
> -- 
> 2.29.2
> 
-- 
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR