Re: [PATCH 5/7] super: remove bd_fsfreeze_{mutex,sb}

["Darrick J. Wong" <djwong@kernel.org>]

On Wed, Sep 27, 2023 at 03:21:18PM +0200, Christian Brauner wrote:
> Both bd_fsfreeze_mutex and bd_fsfreeze_sb are now unused and can be
> removed. Also move bd_fsfreeze_count down to not have it weirdly placed
> in the middle of the holder fields.
> 
> Suggested-by: Jan Kara <jack@suse.cz>
> Suggested-by: Christoph Hellwig <hch@lst.de>
> Signed-off-by: Christian Brauner <brauner@kernel.org>
> ---
>  block/bdev.c              | 1 -
>  include/linux/blk_types.h | 7 ++-----
>  2 files changed, 2 insertions(+), 6 deletions(-)
> 
> diff --git a/block/bdev.c b/block/bdev.c
> index 3deccd0ffcf2..084855b669f7 100644
> --- a/block/bdev.c
> +++ b/block/bdev.c
> @@ -392,7 +392,6 @@ struct block_device *bdev_alloc(struct gendisk *disk, u8 partno)
>  	mapping_set_gfp_mask(&inode->i_data, GFP_USER);
>  
>  	bdev = I_BDEV(inode);
> -	mutex_init(&bdev->bd_fsfreeze_mutex);
>  	spin_lock_init(&bdev->bd_size_lock);
>  	mutex_init(&bdev->bd_holder_lock);
>  	bdev->bd_partno = partno;
> diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
> index 88e1848b0869..0238236852b7 100644
> --- a/include/linux/blk_types.h
> +++ b/include/linux/blk_types.h
> @@ -56,14 +56,11 @@ struct block_device {
>  	void *			bd_holder;

Hmmm.  get_bdev_super from patch 3 now requires that bd_holder is a
pointer to a struct super_block.  AFAICT it's only called in conjunction
with fs_holder_ops, so I suggest that the declaration for that should
grow a comment to that effect:

	/*
	 * For filesystems, the @holder argument passed to blkdev_get_* and
	 * bd_prepare_to_claim must point to a super_block object.
	 */
	extern const struct blk_holder_ops fs_holder_ops;

This patch itself looks ok so:
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

>  	const struct blk_holder_ops *bd_holder_ops;
>  	struct mutex		bd_holder_lock;
> -	/* The counter of freeze processes */
> -	atomic_t		bd_fsfreeze_count;
>  	int			bd_holders;
>  	struct kobject		*bd_holder_dir;
>  
> -	/* Mutex for freeze */
> -	struct mutex		bd_fsfreeze_mutex;
> -	struct super_block	*bd_fsfreeze_sb;
> +	/* The counter of freeze processes */
> +	atomic_t		bd_fsfreeze_count;
>  
>  	struct partition_meta_info *bd_meta_info;
>  #ifdef CONFIG_FAIL_MAKE_REQUEST
> 
> -- 
> 2.34.1
>