Re: [PATCH v5 03/11] fuse: refactor fuse_fill_write_pages()

[Bernd Schubert <bernd.schubert@fastmail.fm>]

On 4/26/25 02:08, Joanne Koong wrote:
> Refactor the logic in fuse_fill_write_pages() for copying out write
> data. This will make the future change for supporting large folios for
> writes easier. No functional changes.
> 
> Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
> Reviewed-by: Josef Bacik <josef@toxicpandewa.com>
> Reviewed-by: Jeff Layton <jlayton@kernel.org>

Reviewed-by: Bernd Schubert <bschubert@ddn.com>

> ---
>  fs/fuse/file.c | 19 +++++++++----------
>  1 file changed, 9 insertions(+), 10 deletions(-)
> 
> diff --git a/fs/fuse/file.c b/fs/fuse/file.c
> index e203dd4fcc0f..edc86485065e 100644
> --- a/fs/fuse/file.c
> +++ b/fs/fuse/file.c
> @@ -1132,21 +1132,21 @@ static ssize_t fuse_fill_write_pages(struct fuse_io_args *ia,
>  	struct fuse_args_pages *ap = &ia->ap;
>  	struct fuse_conn *fc = get_fuse_conn(mapping->host);
>  	unsigned offset = pos & (PAGE_SIZE - 1);
> -	unsigned int nr_pages = 0;
>  	size_t count = 0;
> +	unsigned int num;
>  	int err;
>  
> +	num = min(iov_iter_count(ii), fc->max_write);
> +	num = min(num, max_pages << PAGE_SHIFT);
> +
>  	ap->args.in_pages = true;
>  	ap->descs[0].offset = offset;
>  
> -	do {
> +	while (num) {
>  		size_t tmp;
>  		struct folio *folio;
>  		pgoff_t index = pos >> PAGE_SHIFT;
> -		size_t bytes = min_t(size_t, PAGE_SIZE - offset,
> -				     iov_iter_count(ii));
> -
> -		bytes = min_t(size_t, bytes, fc->max_write - count);
> +		unsigned bytes = min(PAGE_SIZE - offset, num);
>  
>   again:
>  		folio = __filemap_get_folio(mapping, index, FGP_WRITEBEGIN,
> @@ -1182,10 +1182,10 @@ static ssize_t fuse_fill_write_pages(struct fuse_io_args *ia,
>  		ap->folios[ap->num_folios] = folio;
>  		ap->descs[ap->num_folios].length = tmp;
>  		ap->num_folios++;
> -		nr_pages++;
>  
>  		count += tmp;
>  		pos += tmp;
> +		num -= tmp;
>  		offset += tmp;
>  		if (offset == PAGE_SIZE)
>  			offset = 0;
> @@ -1200,10 +1200,9 @@ static ssize_t fuse_fill_write_pages(struct fuse_io_args *ia,
>  			ia->write.folio_locked = true;
>  			break;
>  		}
> -		if (!fc->big_writes)
> +		if (!fc->big_writes || offset != 0)
>  			break;
> -	} while (iov_iter_count(ii) && count < fc->max_write &&
> -		 nr_pages < max_pages && offset == 0);
> +	}
>  
>  	return count > 0 ? count : err;
>  }