fuse: support large folios for writeback

Add support for folios larger than one page size for writeback.

Signed-off-by: Joanne Koong <[email protected]>
Reviewed-by: Josef Bacik <[email protected]>
Reviewed-by: Jeff Layton <[email protected]>
Signed-off-by: Miklos Szeredi <[email protected]>

Author: joannekoong

fs/fuse/file.c

@@ -1988,7 +1988,7 @@ static void fuse_writepage_args_page_fill(struct fuse_writepage_args *wpa, struc
 
 	ap->folios[folio_index] = folio;
 	ap->descs[folio_index].offset = 0;
-	ap->descs[folio_index].length = PAGE_SIZE;
+	ap->descs[folio_index].length = folio_size(folio);
 
 	inc_wb_stat(&inode_to_bdi(inode)->wb, WB_WRITEBACK);
 }
@@ -2062,6 +2062,7 @@ struct fuse_fill_wb_data {
 	struct fuse_file *ff;
 	struct inode *inode;
 	unsigned int max_folios;
+	unsigned int nr_pages;
 };
 
 static bool fuse_pages_realloc(struct fuse_fill_wb_data *data)
@@ -2109,15 +2110,15 @@ static bool fuse_writepage_need_send(struct fuse_conn *fc, struct folio *folio,
 	WARN_ON(!ap->num_folios);
 
 	/* Reached max pages */
-	if (ap->num_folios == fc->max_pages)
+	if (data->nr_pages + folio_nr_pages(folio) > fc->max_pages)
 		return true;
 
 	/* Reached max write bytes */
-	if ((ap->num_folios + 1) * PAGE_SIZE > fc->max_write)
+	if ((data->nr_pages * PAGE_SIZE) + folio_size(folio) > fc->max_write)
 		return true;
 
 	/* Discontinuity */
-	if (ap->folios[ap->num_folios - 1]->index + 1 != folio_index(folio))
+	if (folio_next_index(ap->folios[ap->num_folios - 1]) != folio_index(folio))
 		return true;
 
 	/* Need to grow the pages array?  If so, did the expansion fail? */
@@ -2148,6 +2149,7 @@ static int fuse_writepages_fill(struct folio *folio,
 	if (wpa && fuse_writepage_need_send(fc, folio, ap, data)) {
 		fuse_writepages_send(data);
 		data->wpa = NULL;
+		data->nr_pages = 0;
 	}
 
 	if (data->wpa == NULL) {
@@ -2162,6 +2164,7 @@ static int fuse_writepages_fill(struct folio *folio,
 	folio_start_writeback(folio);
 
 	fuse_writepage_args_page_fill(wpa, folio, ap->num_folios);
+	data->nr_pages += folio_nr_pages(folio);
 
 	err = 0;
 	ap->num_folios++;
@@ -2192,6 +2195,7 @@ static int fuse_writepages(struct address_space *mapping,
 	data.inode = inode;
 	data.wpa = NULL;
 	data.ff = NULL;
+	data.nr_pages = 0;
 
 	err = write_cache_pages(mapping, wbc, fuse_writepages_fill, &data);
 	if (data.wpa) {