[PATCH 1/2] sunrpc: add an extra reserve page to svc_serv_maxpages()

[Mike Snitzer <snitzer@xxxxxxxxxx>]

nfsd_iter_read() might need two extra pages when a READ payload is not
DIO-aligned -- but nfsd_iter_read() and nfsd_splice_actor() are
mutually exclusive (so reuse page reserved for nfsd_splice_actor).

Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
---
 include/linux/sunrpc/svc.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
index e64ab444e0a7f..190c2667500e2 100644
--- a/include/linux/sunrpc/svc.h
+++ b/include/linux/sunrpc/svc.h
@@ -163,10 +163,13 @@ extern u32 svc_max_payload(const struct svc_rqst *rqstp);
  * pages, one for the request, and one for the reply.
  * nfsd_splice_actor() might need an extra page when a READ payload
  * is not page-aligned.
+ * nfsd_iter_read() might need two extra pages when a READ payload
+ * is not DIO-aligned -- but nfsd_iter_read() and nfsd_splice_actor()
+ * are mutually exclusive (so reuse page reserved for nfsd_splice_actor).
  */
 static inline unsigned long svc_serv_maxpages(const struct svc_serv *serv)
 {
-	return DIV_ROUND_UP(serv->sv_max_mesg, PAGE_SIZE) + 2 + 1;
+	return DIV_ROUND_UP(serv->sv_max_mesg, PAGE_SIZE) + 2 + 1 + 1;
 }
 
 /*
-- 
2.44.0