net: introduce page_frag_cache_drain()

When draining a page_frag_cache, most user are doing
the similar steps, so introduce an API to avoid code
duplication.

Signed-off-by: Yunsheng Lin <[e-mail]>
Acked-by: Jason Wang <[e-mail]>
Reviewed-by: Alexander Duyck <[e-mail]>
Acked-by: Michael S. Tsirkin <[e-mail]>
Signed-off-by: Paolo Abeni <[e-mail]>

drivers/net/ethernet/google/gve/gve_main.c

···
 
 static void gve_drain_page_cache(struct gve_priv *priv)
 {
-	struct page_frag_cache *nc;
 	int i;
 
-	for (i = 0; i < priv->rx_cfg.num_queues; i++) {
-		nc = &priv->rx[i].page_cache;
-		if (nc->va) {
-			__page_frag_cache_drain(virt_to_page(nc->va),
-						nc->pagecnt_bias);
-			nc->va = NULL;
-		}
-	}
+	for (i = 0; i < priv->rx_cfg.num_queues; i++)
+		page_frag_cache_drain(&priv->rx[i].page_cache);
 }
 
 static void gve_qpls_get_curr_alloc_cfg(struct gve_priv *priv,

drivers/net/ethernet/mediatek/mtk_wed_wo.c

···
 static void
 mtk_wed_wo_queue_tx_clean(struct mtk_wed_wo *wo, struct mtk_wed_wo_queue *q)
 {
-	struct page *page;
 	int i;
 
 	for (i = 0; i < q->n_desc; i++) {
···
 		entry->buf = NULL;
 	}
 
-	if (!q->cache.va)
-		return;
-
-	page = virt_to_page(q->cache.va);
-	__page_frag_cache_drain(page, q->cache.pagecnt_bias);
-	memset(&q->cache, 0, sizeof(q->cache));
+	page_frag_cache_drain(&q->cache);
 }
 
 static void
 mtk_wed_wo_queue_rx_clean(struct mtk_wed_wo *wo, struct mtk_wed_wo_queue *q)
 {
-	struct page *page;
-
 	for (;;) {
 		void *buf = mtk_wed_wo_dequeue(wo, q, NULL, true);
 
···
 		skb_free_frag(buf);
 	}
 
-	if (!q->cache.va)
-		return;
-
-	page = virt_to_page(q->cache.va);
-	__page_frag_cache_drain(page, q->cache.pagecnt_bias);
-	memset(&q->cache, 0, sizeof(q->cache));
+	page_frag_cache_drain(&q->cache);
 }
 
 static void

drivers/nvme/host/tcp.c

···
 
 static void nvme_tcp_free_queue(struct nvme_ctrl *nctrl, int qid)
 {
-	struct page *page;
 	struct nvme_tcp_ctrl *ctrl = to_tcp_ctrl(nctrl);
 	struct nvme_tcp_queue *queue = &ctrl->queues[qid];
 	unsigned int noreclaim_flag;
···
 	if (queue->hdr_digest || queue->data_digest)
 		nvme_tcp_free_crypto(queue);
 
-	if (queue->pf_cache.va) {
-		page = virt_to_head_page(queue->pf_cache.va);
-		__page_frag_cache_drain(page, queue->pf_cache.pagecnt_bias);
-		queue->pf_cache.va = NULL;
-	}
+	page_frag_cache_drain(&queue->pf_cache);
 
 	noreclaim_flag = memalloc_noreclaim_save();
 	/* ->sock will be released by fput() */

drivers/nvme/target/tcp.c

···
 
 static void nvmet_tcp_release_queue_work(struct work_struct *w)
 {
-	struct page *page;
 	struct nvmet_tcp_queue *queue =
 		container_of(w, struct nvmet_tcp_queue, release_work);
 
···
 	if (queue->hdr_digest || queue->data_digest)
 		nvmet_tcp_free_crypto(queue);
 	ida_free(&nvmet_tcp_queue_ida, queue->idx);
-	page = virt_to_head_page(queue->pf_cache.va);
-	__page_frag_cache_drain(page, queue->pf_cache.pagecnt_bias);
+	page_frag_cache_drain(&queue->pf_cache);
 	kfree(queue);
 }
 

include/linux/gfp.h

···
 extern void free_pages(unsigned long addr, unsigned int order);
 
 struct page_frag_cache;
+void page_frag_cache_drain(struct page_frag_cache *nc);
 extern void __page_frag_cache_drain(struct page *page, unsigned int count);
 void *__page_frag_alloc_align(struct page_frag_cache *nc, unsigned int fragsz,
 			      gfp_t gfp_mask, unsigned int align_mask);

mm/page_alloc.c

···
 	return page;
 }
 
+void page_frag_cache_drain(struct page_frag_cache *nc)
+{
+	if (!nc->va)
+		return;
+
+	__page_frag_cache_drain(virt_to_head_page(nc->va), nc->pagecnt_bias);
+	nc->va = NULL;
+}
+EXPORT_SYMBOL(page_frag_cache_drain);
+
 void __page_frag_cache_drain(struct page *page, unsigned int count)
 {
 	VM_BUG_ON_PAGE(page_ref_count(page) == 0, page);