fuse: refactor out shared logic in fuse_writepages_fill() and fuse_writepage_locked()

This change refactors the shared logic in fuse_writepages_fill() and
fuse_writepages_locked() into two separate helper functions,
fuse_writepage_args_page_fill() and fuse_writepage_args_setup().

No functional changes added.
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

fs/fuse/file.c

@@ -2047,49 +2047,77 @@ static void fuse_writepage_add_to_bucket(struct fuse_conn *fc,
 	rcu_read_unlock();
 }
 
+static void fuse_writepage_args_page_fill(struct fuse_writepage_args *wpa, struct folio *folio,
+					  struct folio *tmp_folio, 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;
+	ap->descs[page_index].offset = 0;
+	ap->descs[page_index].length = PAGE_SIZE;
+
+	inc_wb_stat(&inode_to_bdi(inode)->wb, WB_WRITEBACK);
+	inc_node_page_state(&tmp_folio->page, NR_WRITEBACK_TEMP);
+}
+
+static struct fuse_writepage_args *fuse_writepage_args_setup(struct folio *folio,
+							     struct fuse_file *ff)
+{
+	struct inode *inode = folio->mapping->host;
+	struct fuse_conn *fc = get_fuse_conn(inode);
+	struct fuse_writepage_args *wpa;
+	struct fuse_args_pages *ap;
+
+	wpa = fuse_writepage_args_alloc();
+	if (!wpa)
+		return NULL;
+
+	fuse_writepage_add_to_bucket(fc, wpa);
+	fuse_write_args_fill(&wpa->ia, ff, folio_pos(folio), 0);
+	wpa->ia.write.in.write_flags |= FUSE_WRITE_CACHE;
+	wpa->inode = inode;
+	wpa->ia.ff = ff;
+
+	ap = &wpa->ia.ap;
+	ap->args.in_pages = true;
+	ap->args.end = fuse_writepage_end;
+
+	return wpa;
+}
+
 static int fuse_writepage_locked(struct folio *folio)
 {
 	struct address_space *mapping = folio->mapping;
 	struct inode *inode = mapping->host;
-	struct fuse_conn *fc = get_fuse_conn(inode);
 	struct fuse_inode *fi = get_fuse_inode(inode);
 	struct fuse_writepage_args *wpa;
 	struct fuse_args_pages *ap;
 	struct folio *tmp_folio;
+	struct fuse_file *ff;
 	int error = -ENOMEM;
 
-	folio_start_writeback(folio);
-
-	wpa = fuse_writepage_args_alloc();
-	if (!wpa)
-		goto err;
-	ap = &wpa->ia.ap;
-
 	tmp_folio = folio_alloc(GFP_NOFS | __GFP_HIGHMEM, 0);
 	if (!tmp_folio)
-		goto err_free;
+		goto err;
 
 	error = -EIO;
-	wpa->ia.ff = fuse_write_file_get(fi);
-	if (!wpa->ia.ff)
+	ff = fuse_write_file_get(fi);
+	if (!ff)
 		goto err_nofile;
 
-	fuse_writepage_add_to_bucket(fc, wpa);
-	fuse_write_args_fill(&wpa->ia, wpa->ia.ff, folio_pos(folio), 0);
+	wpa = fuse_writepage_args_setup(folio, ff);
+	error = -ENOMEM;
+	if (!wpa)
+		goto err_writepage_args;
 
-	folio_copy(tmp_folio, folio);
-	wpa->ia.write.in.write_flags |= FUSE_WRITE_CACHE;
-	wpa->next = NULL;
-	ap->args.in_pages = true;
+	ap = &wpa->ia.ap;
 	ap->num_pages = 1;
-	ap->pages[0] = &tmp_folio->page;
-	ap->descs[0].offset = 0;
-	ap->descs[0].length = PAGE_SIZE;
-	ap->args.end = fuse_writepage_end;
-	wpa->inode = inode;
 
-	inc_wb_stat(&inode_to_bdi(inode)->wb, WB_WRITEBACK);
-	node_stat_add_folio(tmp_folio, NR_WRITEBACK_TEMP);
+	folio_start_writeback(folio);
+	fuse_writepage_args_page_fill(wpa, folio, tmp_folio, 0);
 
 	spin_lock(&fi->lock);
 	tree_insert(&fi->writepages, wpa);
@@ -2101,13 +2129,12 @@ static int fuse_writepage_locked(struct folio *folio)
 
 	return 0;
 
+err_writepage_args:
+	fuse_file_put(ff, false);
 err_nofile:
 	folio_put(tmp_folio);
-err_free:
-	kfree(wpa);
 err:
 	mapping_set_error(folio->mapping, error);
-	folio_end_writeback(folio);
 	return error;
 }
 
@@ -2285,36 +2312,20 @@ static int fuse_writepages_fill(struct folio *folio,
 	 */
 	if (data->wpa == NULL) {
 		err = -ENOMEM;
-		wpa = fuse_writepage_args_alloc();
+		wpa = fuse_writepage_args_setup(folio, data->ff);
 		if (!wpa) {
 			folio_put(tmp_folio);
 			goto out_unlock;
 		}
-		fuse_writepage_add_to_bucket(fc, wpa);
-
+		fuse_file_get(wpa->ia.ff);
 		data->max_pages = 1;
-
 		ap = &wpa->ia.ap;
-		fuse_write_args_fill(&wpa->ia, data->ff, folio_pos(folio), 0);
-		wpa->ia.write.in.write_flags |= FUSE_WRITE_CACHE;
-		wpa->ia.ff = fuse_file_get(data->ff);
-		wpa->next = NULL;
-		ap->args.in_pages = true;
-		ap->args.end = fuse_writepage_end;
-		ap->num_pages = 0;
-		wpa->inode = inode;
 	}
 	folio_start_writeback(folio);
 
-	folio_copy(tmp_folio, folio);
-	ap->pages[ap->num_pages] = &tmp_folio->page;
-	ap->descs[ap->num_pages].offset = 0;
-	ap->descs[ap->num_pages].length = PAGE_SIZE;
+	fuse_writepage_args_page_fill(wpa, folio, tmp_folio, ap->num_pages);
 	data->orig_pages[ap->num_pages] = &folio->page;
 
-	inc_wb_stat(&inode_to_bdi(inode)->wb, WB_WRITEBACK);
-	inc_node_page_state(&tmp_folio->page, NR_WRITEBACK_TEMP);
-
 	err = 0;
 	if (data->wpa) {
 		/*