From eff042ddf4b9587fa7394d502b93e06ec6015177 Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Mon, 28 Apr 2025 15:36:50 -0400 Subject: [PATCH] sunrpc: Add a helper to derive maxpages from sv_max_mesg This page count is to be used to allocate various arrays of pages and bio_vecs, replacing the fixed RPCSVC_MAXPAGES value. The documenting comment is somewhat stale -- of course NFSv4 COMPOUND procedures may have multiple payloads. Reviewed-by: Jeff Layton Reviewed-by: NeilBrown Signed-off-by: Chuck Lever --- include/linux/sunrpc/svc.h | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h index 74658cca0f38f..749f8e53e8a61 100644 --- a/include/linux/sunrpc/svc.h +++ b/include/linux/sunrpc/svc.h @@ -159,6 +159,23 @@ extern u32 svc_max_payload(const struct svc_rqst *rqstp); #define RPCSVC_MAXPAGES ((RPCSVC_MAXPAYLOAD+PAGE_SIZE-1)/PAGE_SIZE \ + 2 + 1) +/** + * svc_serv_maxpages - maximum count of pages needed for one RPC message + * @serv: RPC service context + * + * Returns a count of pages or vectors that can hold the maximum + * size RPC message for @serv. + * + * Each request/reply pair can have at most one "payload", plus two + * 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. + */ +static inline unsigned long svc_serv_maxpages(const struct svc_serv *serv) +{ + return DIV_ROUND_UP(serv->sv_max_mesg, PAGE_SIZE) + 2 + 1; +} + /* * The context of a single thread, including the request currently being * processed. -- 2.50.1