Re: [PATCH 10/12] swap: add a swap_activate_fs_ops helper

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

On Tue, May 12, 2026 at 07:35:26AM +0200, Christoph Hellwig wrote:
> Add a helper abstracting away the low-level details of enabling
> fs_ops-based swapping.  This prepares for taking swap_info_struct
> private.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Looks good to me,
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>

--D

> ---
>  fs/nfs/file.c        | 4 +---
>  fs/smb/client/file.c | 3 +--
>  include/linux/swap.h | 5 +++++
>  mm/swapfile.c        | 7 +++++++
>  4 files changed, 14 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/nfs/file.c b/fs/nfs/file.c
> index 10ab2a923835..ce4d860c4e7a 100644
> --- a/fs/nfs/file.c
> +++ b/fs/nfs/file.c
> @@ -588,7 +588,7 @@ int nfs_swap_activate(struct file *file, struct swap_info_struct *sis)
>  	ret = rpc_clnt_swap_activate(clnt);
>  	if (ret)
>  		return ret;
> -	ret = add_swap_extent(sis, sis->max, NULL, 0);
> +	ret = swap_activate_fs_ops(sis);
>  	if (ret < 0) {
>  		rpc_clnt_swap_deactivate(clnt);
>  		return ret;
> @@ -596,8 +596,6 @@ int nfs_swap_activate(struct file *file, struct swap_info_struct *sis)
>  
>  	if (cl->rpc_ops->enable_swap)
>  		cl->rpc_ops->enable_swap(inode);
> -
> -	sis->flags |= SWP_FS_OPS;
>  	return 0;
>  }
>  EXPORT_SYMBOL_GPL(nfs_swap_activate);
> diff --git a/fs/smb/client/file.c b/fs/smb/client/file.c
> index e1bbc65ce7f3..e11065be1e64 100644
> --- a/fs/smb/client/file.c
> +++ b/fs/smb/client/file.c
> @@ -3326,8 +3326,7 @@ int cifs_swap_activate(struct file *swap_file, struct swap_info_struct *sis)
>  	 * from reading or writing the file
>  	 */
>  
> -	sis->flags |= SWP_FS_OPS;
> -	return add_swap_extent(sis, sis->max, NULL, 0);
> +	return swap_activate_fs_ops(sis);
>  }
>  
>  void cifs_swap_deactivate(struct file *file)
> diff --git a/include/linux/swap.h b/include/linux/swap.h
> index b1cbb67ddd8e..916889738f08 100644
> --- a/include/linux/swap.h
> +++ b/include/linux/swap.h
> @@ -406,6 +406,7 @@ extern void __meminit kswapd_stop(int nid);
>  int add_swap_extent(struct swap_info_struct *sis, unsigned long nr_pages,
>  		struct block_device *bdev, sector_t start_block);
>  int generic_swap_activate(struct file *swap_file, struct swap_info_struct *sis);
> +int swap_activate_fs_ops(struct swap_info_struct *sis);
>  
>  static inline unsigned long total_swapcache_pages(void)
>  {
> @@ -532,6 +533,10 @@ static inline int add_swap_extent(struct swap_info_struct *sis,
>  {
>  	return -EINVAL;
>  }
> +static inline int swap_activate_fs_ops(struct swap_info_struct *sis)
> +{
> +	return -EINVAL;
> +}
>  #endif /* CONFIG_SWAP */
>  #ifdef CONFIG_MEMCG
>  static inline int mem_cgroup_swappiness(struct mem_cgroup *memcg)
> diff --git a/mm/swapfile.c b/mm/swapfile.c
> index 2c9d2af736c4..26852c2ad36e 100644
> --- a/mm/swapfile.c
> +++ b/mm/swapfile.c
> @@ -2757,6 +2757,13 @@ add_swap_extent(struct swap_info_struct *sis, unsigned long nr_pages,
>  }
>  EXPORT_SYMBOL_GPL(add_swap_extent);
>  
> +int swap_activate_fs_ops(struct swap_info_struct *sis)
> +{
> +	sis->flags |= SWP_FS_OPS;
> +	return add_swap_extent(sis, sis->max, NULL, 0);
> +}
> +EXPORT_SYMBOL_GPL(swap_activate_fs_ops);
> +
>  /*
>   * A `swap extent' is a simple thing which maps a contiguous range of pages
>   * onto a contiguous range of disk blocks.  A rbtree of swap extents is
> -- 
> 2.53.0
> 
>