Re: [PATCH v4 09/13] io_uring: create common fixed_rsrc_ref_node handling routines

[Bijan Mottahedeh <bijan.mottahedeh@oracle.com>]

On 1/6/2021 12:39 PM, Bijan Mottahedeh wrote:
> Create common routines to be used for both files/buffers registration.
> 
> Signed-off-by: Bijan Mottahedeh <bijan.mottahedeh@oracle.com>
> ---
>   fs/io_uring.c | 47 ++++++++++++++++++++++++-----------------------
>   1 file changed, 24 insertions(+), 23 deletions(-)
> 
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index 91be618..fbff8480 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -7303,15 +7303,12 @@ static void io_sqe_rsrc_set_node(struct io_ring_ctx *ctx,
>   	percpu_ref_get(&rsrc_data->refs);
>   }
>   
> -static int io_sqe_files_unregister(struct io_ring_ctx *ctx)
> +static int io_rsrc_ref_quiesce(struct fixed_rsrc_data *data,
> +			       struct io_ring_ctx *ctx)
>   {
> -	struct fixed_rsrc_data *data = ctx->file_data;
>   	struct fixed_rsrc_ref_node *backup_node, *ref_node = NULL;
> -	unsigned nr_tables, i;
>   	int ret;
>   
> -	if (!data)
> -		return -ENXIO;
>   	backup_node = alloc_fixed_file_ref_node(ctx);
                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

I introduced a bug here; I call the file allocator directly.  I've fixed 
it by passing in the proper allocator.  Will send it with the next patch 
set.


>   	if (!backup_node)
>   		return -ENOMEM;
> @@ -7339,6 +7336,23 @@ static int io_sqe_files_unregister(struct io_ring_ctx *ctx)
>   		}
>   	} while (1);
>   
> +	destroy_fixed_rsrc_ref_node(backup_node);
> +	return 0;
> +}
> +
> +static int io_sqe_files_unregister(struct io_ring_ctx *ctx)
> +{
> +	struct fixed_rsrc_data *data = ctx->file_data;
> +	unsigned int nr_tables, i;
> +	int ret;
> +
> +	if (!data)
> +		return -ENXIO;
> +
> +	ret = io_rsrc_ref_quiesce(data, ctx);
> +	if (ret)
> +		return ret;
> +
>   	__io_sqe_files_unregister(ctx);
>   	nr_tables = DIV_ROUND_UP(ctx->nr_user_files, IORING_MAX_FILES_TABLE);
>   	for (i = 0; i < nr_tables; i++)
> @@ -7348,7 +7362,6 @@ static int io_sqe_files_unregister(struct io_ring_ctx *ctx)
>   	kfree(data);
>   	ctx->file_data = NULL;
>   	ctx->nr_user_files = 0;
> -	destroy_fixed_rsrc_ref_node(backup_node);
>   	return 0;
>   }
>   
> @@ -8384,22 +8397,14 @@ static void io_buffers_map_free(struct io_ring_ctx *ctx)
>   static int io_sqe_buffers_unregister(struct io_ring_ctx *ctx)
>   {
>   	struct fixed_rsrc_data *data = ctx->buf_data;
> -	struct fixed_rsrc_ref_node *ref_node = NULL;
> +	int ret;
>   
>   	if (!data)
>   		return -ENXIO;
>   
> -	io_rsrc_ref_lock(ctx);
> -	ref_node = data->node;
> -	io_rsrc_ref_unlock(ctx);
> -	if (ref_node)
> -		percpu_ref_kill(&ref_node->refs);
> -
> -	percpu_ref_kill(&data->refs);
> -
> -	/* wait for all refs nodes to complete */
> -	flush_delayed_work(&ctx->rsrc_put_work);
> -	wait_for_completion(&data->done);
> +	ret = io_rsrc_ref_quiesce(data, ctx);
> +	if (ret)
> +		return ret;
>   
>   	io_buffers_unmap(ctx);
>   	io_buffers_map_free(ctx);
> @@ -8751,11 +8756,7 @@ static int io_sqe_buffers_register(struct io_ring_ctx *ctx, void __user *arg,
>   		return PTR_ERR(ref_node);
>   	}
>   
> -	buf_data->node = ref_node;
> -	io_rsrc_ref_lock(ctx);
> -	list_add(&ref_node->node, &ctx->rsrc_ref_list);
> -	io_rsrc_ref_unlock(ctx);
> -	percpu_ref_get(&buf_data->refs);
> +	io_sqe_rsrc_set_node(ctx, buf_data, ref_node);
>   	return 0;
>   }
>   
>