Re: [PATCH RFC v2 11/19] fuse: Add support to copy from/to the ring buffer

[Josef Bacik <josef@toxicpanda.com>]

On Wed, May 29, 2024 at 08:00:46PM +0200, Bernd Schubert wrote:
> This adds support to existing fuse copy code to copy
> from/to the ring buffer. The ring buffer is here mmaped
> shared between kernel and userspace.
> 
> This also fuse_ prefixes the copy_out_args function
> 
> Signed-off-by: Bernd Schubert <bschubert@ddn.com>
> ---
>  fs/fuse/dev.c        | 60 ++++++++++++++++++++++++++++++----------------------
>  fs/fuse/fuse_dev_i.h | 38 +++++++++++++++++++++++++++++++++
>  2 files changed, 73 insertions(+), 25 deletions(-)
> 
> diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
> index 05a87731b5c3..a7d26440de39 100644
> --- a/fs/fuse/dev.c
> +++ b/fs/fuse/dev.c
> @@ -637,21 +637,7 @@ static int unlock_request(struct fuse_req *req)
>  	return err;
>  }
>  
> -struct fuse_copy_state {
> -	int write;
> -	struct fuse_req *req;
> -	struct iov_iter *iter;
> -	struct pipe_buffer *pipebufs;
> -	struct pipe_buffer *currbuf;
> -	struct pipe_inode_info *pipe;
> -	unsigned long nr_segs;
> -	struct page *pg;
> -	unsigned len;
> -	unsigned offset;
> -	unsigned move_pages:1;
> -};
> -
> -static void fuse_copy_init(struct fuse_copy_state *cs, int write,
> +void fuse_copy_init(struct fuse_copy_state *cs, int write,
>  			   struct iov_iter *iter)
>  {
>  	memset(cs, 0, sizeof(*cs));
> @@ -662,6 +648,7 @@ static void fuse_copy_init(struct fuse_copy_state *cs, int write,
>  /* Unmap and put previous page of userspace buffer */
>  static void fuse_copy_finish(struct fuse_copy_state *cs)
>  {
> +

Extraneous newline.

>  	if (cs->currbuf) {
>  		struct pipe_buffer *buf = cs->currbuf;
>  
> @@ -726,6 +713,10 @@ static int fuse_copy_fill(struct fuse_copy_state *cs)
>  			cs->pipebufs++;
>  			cs->nr_segs++;
>  		}
> +	} else if (cs->is_uring) {
> +		if (cs->ring.offset > cs->ring.buf_sz)
> +			return -ERANGE;
> +		cs->len = cs->ring.buf_sz - cs->ring.offset;
>  	} else {
>  		size_t off;
>  		err = iov_iter_get_pages2(cs->iter, &page, PAGE_SIZE, 1, &off);
> @@ -744,21 +735,35 @@ static int fuse_copy_fill(struct fuse_copy_state *cs)
>  static int fuse_copy_do(struct fuse_copy_state *cs, void **val, unsigned *size)
>  {
>  	unsigned ncpy = min(*size, cs->len);
> +
>  	if (val) {
> -		void *pgaddr = kmap_local_page(cs->pg);
> -		void *buf = pgaddr + cs->offset;
> +
> +		void *pgaddr = NULL;
> +		void *buf;
> +
> +		if (cs->is_uring) {
> +			buf = cs->ring.buf + cs->ring.offset;
> +			cs->ring.offset += ncpy;
> +
> +		} else {
> +			pgaddr = kmap_local_page(cs->pg);
> +			buf = pgaddr + cs->offset;
> +		}
>  
>  		if (cs->write)
>  			memcpy(buf, *val, ncpy);
>  		else
>  			memcpy(*val, buf, ncpy);
>  
> -		kunmap_local(pgaddr);
> +		if (pgaddr)
> +			kunmap_local(pgaddr);
> +
>  		*val += ncpy;
>  	}
>  	*size -= ncpy;
>  	cs->len -= ncpy;
>  	cs->offset += ncpy;
> +

Extraneous newline.

Once those nits are fixed you can add

Reviewed-by: Josef Bacik <josef@toxicpanda.com>

Thanks,

Josef