Re: [PATCH v5 1/3] libfs: Add directory operations for stable offsets

[Christian Brauner <brauner@kernel.org>]

On Tue, Jun 27, 2023 at 04:53:09PM -0400, Chuck Lever wrote:
> From: Chuck Lever <chuck.lever@oracle.com>
> 
> Create a vector of directory operations in fs/libfs.c that handles
> directory seeks and readdir via stable offsets instead of the
> current cursor-based mechanism.
> 
> For the moment these are unused.
> 
> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
> ---

Could we just drop the "stable_" prefix and just have:

// internal helpers
offset_dir_emit()
offset_get()
offset_set()
offset_dir_llseek()
find_next_offset()
I'd also collapse offset_iterate_dir() into offset_readdir().

// exported and published helpers
simple_offset_init()
simple_offset_add()
simple_offset_rename_exchange()
simple_offset_destroy()

struct offset_ctx *(*get_offset)(struct inode *inode);

const struct file_operations simple_offset_dir_operations;

>  fs/libfs.c         |  252 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/fs.h |   19 ++++
>  2 files changed, 271 insertions(+)
> 
> diff --git a/fs/libfs.c b/fs/libfs.c
> index 89cf614a3271..9940dce049e6 100644
> --- a/fs/libfs.c
> +++ b/fs/libfs.c
> @@ -239,6 +239,258 @@ const struct inode_operations simple_dir_inode_operations = {
>  };
>  EXPORT_SYMBOL(simple_dir_inode_operations);
>  
> +static struct stable_offset_ctx *stable_ctx_get(struct inode *inode)
> +{
> +	return inode->i_op->get_so_ctx(inode);
> +}

I would suggest to get rid of this helper. It just needlessly hides that
all we do is inode->i_op->().