Re: [PATCH 12/13] fuse: convert direct io to use folios

[Josef Bacik <josef@toxicpanda.com>]

On Wed, Oct 02, 2024 at 09:52:52AM -0700, Joanne Koong wrote:
> Convert direct io requests to use folios instead of pages.
> 
> No functional changes.
> 
> Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
> ---
>  fs/fuse/file.c | 88 ++++++++++++++++++++++----------------------------
>  1 file changed, 38 insertions(+), 50 deletions(-)
> 
> diff --git a/fs/fuse/file.c b/fs/fuse/file.c
> index 1fa870fb3cc4..38ed9026f286 100644
> --- a/fs/fuse/file.c
> +++ b/fs/fuse/file.c
> @@ -665,11 +665,11 @@ static void fuse_release_user_pages(struct fuse_args_pages *ap,
>  {
>  	unsigned int i;
>  
> -	for (i = 0; i < ap->num_pages; i++) {
> +	for (i = 0; i < ap->num_folios; i++) {
>  		if (should_dirty)
> -			set_page_dirty_lock(ap->pages[i]);
> +			folio_mark_dirty_lock(ap->folios[i]);
>  		if (ap->args.is_pinned)
> -			unpin_user_page(ap->pages[i]);
> +			unpin_folio(ap->folios[i]);
>  	}
>  }
>  
> @@ -739,24 +739,6 @@ static void fuse_aio_complete(struct fuse_io_priv *io, int err, ssize_t pos)
>  	kref_put(&io->refcnt, fuse_io_release);
>  }
>  
> -static struct fuse_io_args *fuse_io_alloc(struct fuse_io_priv *io,
> -					  unsigned int npages)
> -{
> -	struct fuse_io_args *ia;
> -
> -	ia = kzalloc(sizeof(*ia), GFP_KERNEL);
> -	if (ia) {
> -		ia->io = io;
> -		ia->ap.pages = fuse_pages_alloc(npages, GFP_KERNEL,
> -						&ia->ap.descs);
> -		if (!ia->ap.pages) {
> -			kfree(ia);
> -			ia = NULL;
> -		}
> -	}
> -	return ia;
> -}
> -
>  static struct fuse_io_args *fuse_io_folios_alloc(struct fuse_io_priv *io,
>  						 unsigned int nfolios)
>  {
> @@ -776,12 +758,6 @@ static struct fuse_io_args *fuse_io_folios_alloc(struct fuse_io_priv *io,
>  	return ia;
>  }
>  
> -static void fuse_io_free(struct fuse_io_args *ia)
> -{
> -	kfree(ia->ap.pages);
> -	kfree(ia);
> -}
> -
>  static void fuse_io_folios_free(struct fuse_io_args *ia)
>  {
>  	kfree(ia->ap.folios);
> @@ -814,7 +790,7 @@ static void fuse_aio_complete_req(struct fuse_mount *fm, struct fuse_args *args,
>  	}
>  
>  	fuse_aio_complete(io, err, pos);
> -	fuse_io_free(ia);
> +	fuse_io_folios_free(ia);
>  }
>  
>  static ssize_t fuse_async_req_send(struct fuse_mount *fm,
> @@ -1518,10 +1494,11 @@ static inline size_t fuse_get_frag_size(const struct iov_iter *ii,
>  
>  static int fuse_get_user_pages(struct fuse_args_pages *ap, struct iov_iter *ii,
>  			       size_t *nbytesp, int write,
> -			       unsigned int max_pages)
> +			       unsigned int max_folios)
>  {
>  	size_t nbytes = 0;  /* # bytes already packed in req */
>  	ssize_t ret = 0;
> +	ssize_t i = 0;
>  
>  	/* Special case for kernel I/O: can copy directly into the buffer */
>  	if (iov_iter_is_kvec(ii)) {
> @@ -1538,15 +1515,23 @@ static int fuse_get_user_pages(struct fuse_args_pages *ap, struct iov_iter *ii,
>  		return 0;
>  	}
>  
> -	while (nbytes < *nbytesp && ap->num_pages < max_pages) {
> -		unsigned npages;
> +	/*
> +	 * Until there is support for iov_iter_extract_folios(), we have to
> +	 * manually extract pages using iov_iter_extract_pages() and then
> +	 * copy that to a folios array.
> +	 */
> +	struct page **pages = kzalloc((max_folios - ap->num_folios) * sizeof(struct page *),
> +				      GFP_KERNEL);
> +	if (!pages)
> +		return -ENOMEM;
> +
> +	while (nbytes < *nbytesp && ap->num_folios < max_folios) {
> +		unsigned nfolios;
>  		size_t start;
> -		struct page **pt_pages;
>  
> -		pt_pages = &ap->pages[ap->num_pages];
> -		ret = iov_iter_extract_pages(ii, &pt_pages,
> +		ret = iov_iter_extract_pages(ii, &pages,
>  					     *nbytesp - nbytes,
> -					     max_pages - ap->num_pages,
> +					     max_folios - ap->num_folios,
>  					     0, &start);
>  		if (ret < 0)
>  			break;
> @@ -1554,15 +1539,18 @@ static int fuse_get_user_pages(struct fuse_args_pages *ap, struct iov_iter *ii,
>  		nbytes += ret;
>  
>  		ret += start;
> -		npages = DIV_ROUND_UP(ret, PAGE_SIZE);
> +		nfolios = DIV_ROUND_UP(ret, PAGE_SIZE);
>  
> -		ap->descs[ap->num_pages].offset = start;
> -		fuse_page_descs_length_init(ap->descs, ap->num_pages, npages);
> +		ap->folio_descs[ap->num_folios].offset = start;
> +		fuse_folio_descs_length_init(ap->folio_descs, ap->num_folios, nfolios);

With this conversion fuse_page_descs_length_init now has no users, so I'd add a
followup patch at the end of the series to remove it.  Thanks,

Josef