Re: [PATCH v3 2/3] SUNRPC: Add svc_rqst_replace_page() API

[Chuck Lever III <chuck.lever@oracle.com>]

> On Jul 8, 2021, at 7:30 PM, Matthew Wilcox <willy@infradead.org> wrote:
> 
> On Thu, Jul 08, 2021 at 11:26:29AM -0400, Chuck Lever wrote:
>> @@ -256,6 +256,9 @@ struct svc_rqst {
>> 	struct page *		*rq_next_page; /* next reply page to use */
>> 	struct page *		*rq_page_end;  /* one past the last page */
>> 
>> +	struct page		*rq_relpages[16];
>> +	int			rq_numrelpages;
> 
> This is only one struct page away from being a pagevec ... ?
> 
>> @@ -838,6 +839,33 @@ svc_set_num_threads_sync(struct svc_serv *serv, struct svc_pool *pool, int nrser
>> }
>> EXPORT_SYMBOL_GPL(svc_set_num_threads_sync);
>> 
>> +static void svc_rqst_release_replaced_pages(struct svc_rqst *rqstp)
>> +{
>> +	release_pages(rqstp->rq_relpages, rqstp->rq_numrelpages);
>> +	rqstp->rq_numrelpages = 0;
> 
> This would be pagevec_release()

 986 void __pagevec_release(struct pagevec *pvec)
 987 {
 988         if (!pvec->percpu_pvec_drained) {
 989                 lru_add_drain();
 990                 pvec->percpu_pvec_drained = true;
 991         }
 992         release_pages(pvec->pages, pagevec_count(pvec));
 993         pagevec_reinit(pvec);
 994 }

Pretty much the same under the bonnet. Fair enough!


--
Chuck Lever