Re: [PATCH v2 2/2] fuse: remove tmp folio for writebacks and internal rb tree

[Jingbo Xu <jefflexu@linux.alibaba.com>]

On 10/15/24 2:22 AM, Joanne Koong wrote:
>  static void fuse_writepage_args_page_fill(struct fuse_writepage_args *wpa, struct folio *folio,
> -					  struct folio *tmp_folio, uint32_t page_index)
> +					  uint32_t page_index)
>  {
>  	struct inode *inode = folio->mapping->host;
>  	struct fuse_args_pages *ap = &wpa->ia.ap;
>  
> -	folio_copy(tmp_folio, folio);
> -
> -	ap->pages[page_index] = &tmp_folio->page;
> +	folio_get(folio);

Why folio_get() is needed?


>  
> @@ -2203,68 +2047,11 @@ static void fuse_writepages_send(struct fuse_fill_wb_data *data)
>  	struct fuse_writepage_args *wpa = data->wpa;
>  	struct inode *inode = data->inode;
>  	struct fuse_inode *fi = get_fuse_inode(inode);
> -	int num_pages = wpa->ia.ap.num_pages;
> -	int i;
>  
>  	spin_lock(&fi->lock);
>  	list_add_tail(&wpa->queue_entry, &fi->queued_writes);

Could we also drop fi->queued_writes list and writectr counter after we
dropping the temp folio?  I'm not sure.  When I grep all callsites of
fuse_set_nowrite(), it seems that apart from the direct IO
path(fuse_direct_io -> fuse_sync_writes), the truncation related code
also relies on this writectr mechanism.



-- 
Thanks,
Jingbo