SUNRPC: Handle NULL entries in svc_rqst_release_pages

svc_rqst_release_pages() releases response pages between rq_respages
and rq_next_page. It currently passes the entire range to
release_pages(), which does not expect NULL entries.

A subsequent patch preserves the rq_next_page pointer in
svc_rdma_save_io_pages() so that it accurately records how many
response pages were consumed. After that change, the range

  [rq_respages, rq_next_page)

can contain NULL entries where pages have already been transferred
to a send context.

Iterate through the range entry by entry, skipping NULLs, to handle
this case correctly.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index 9abef638b1e093bd803ae1f64f13f525d520740b..0ce16e9abdf63399baece6fdd101f3e7eae88c4b 100644 (file)
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -990,18 +990,24 @@ EXPORT_SYMBOL_GPL(svc_rqst_replace_page);
  * svc_rqst_release_pages - Release Reply buffer pages
  * @rqstp: RPC transaction context
  *
- * Release response pages that might still be in flight after
- * svc_send, and any spliced filesystem-owned pages.
+ * Release response pages in the range [rq_respages, rq_next_page).
+ * NULL entries in this range are skipped, allowing transports to
+ * transfer pages to a send context before this function runs.
  */
 void svc_rqst_release_pages(struct svc_rqst *rqstp)
 {
-       int i, count = rqstp->rq_next_page - rqstp->rq_respages;
-
-       if (count) {
-               release_pages(rqstp->rq_respages, count);
-               for (i = 0; i < count; i++)
-                       rqstp->rq_respages[i] = NULL;
+       struct page **pp;
+
+       for (pp = rqstp->rq_respages; pp < rqstp->rq_next_page; pp++) {
+               if (*pp) {
+                       if (!folio_batch_add(&rqstp->rq_fbatch,
+                                            page_folio(*pp)))
+                               __folio_batch_release(&rqstp->rq_fbatch);
+                       *pp = NULL;
+               }
        }
+       if (rqstp->rq_fbatch.nr)
+               __folio_batch_release(&rqstp->rq_fbatch);
 }
 
 /**