Re: [PATCH 1/5] kernfs: implement i_generation

[Christoph Hellwig <hch@infradead.org>]

On Mon, May 22, 2017 at 03:53:05PM -0700, Shaohua Li wrote:
> Set i_generation for kernfs inod. This is required to implement exportfs
> operations.
> 
> Signed-off-by: Shaohua Li <shli@fb.com>
> ---
>  fs/kernfs/dir.c        | 2 ++
>  fs/kernfs/inode.c      | 1 +
>  include/linux/kernfs.h | 2 ++
>  3 files changed, 5 insertions(+)
> 
> diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
> index db5900aaa..09d093e 100644
> --- a/fs/kernfs/dir.c
> +++ b/fs/kernfs/dir.c
> @@ -634,6 +634,7 @@ static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root,
>  	if (ret < 0)
>  		goto err_out2;
>  	kn->ino = ret;
> +	kn->generation = atomic_inc_return(&root->next_generation);

i_generation is only supposed to be valid on a per-inode basis, so this
global counter seems really odd.