Commit ed603bcf authored by Chuck Lever's avatar Chuck Lever
Browse files

sunrpc: Replace the rq_pages array with dynamically-allocated memory 



As a step towards making NFSD's maximum rsize and wsize variable at
run-time, replace the fixed-size rq_vec[] array in struct svc_rqst
with a chunk of dynamically-allocated memory.

On a system with 8-byte pointers and 4KB pages, pahole reports that
the rq_pages[] array is 2080 bytes. This patch replaces that with
a single 8-byte pointer field.

Reviewed-by: default avatarJeff Layton <jlayton@kernel.org>
Reviewed-by: default avatarNeilBrown <neil@brown.name>
Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
parent 1a587912

include/linux/sunrpc/svc.h

+2 −1
Original line number Diff line number Diff line
@@ -205,7 +205,8 @@ struct svc_rqst { 
	struct xdr_stream	rq_res_stream;

	struct page		*rq_scratch_page;

	struct xdr_buf		rq_res;

	struct page		*rq_pages[RPCSVC_MAXPAGES + 1];

	unsigned long		rq_maxpages;	/* num of entries in rq_pages */

	struct page *		*rq_pages;

	struct page *		*rq_respages;	/* points into rq_pages */

	struct page *		*rq_next_page; /* next reply page to use */

	struct page *		*rq_page_end;  /* one past the last page */

net/sunrpc/svc.c

+17 −14
Original line number Diff line number Diff line
@@ -636,20 +636,22 @@ svc_destroy(struct svc_serv **servp) 
EXPORT_SYMBOL_GPL(svc_destroy);



static bool

svc_init_buffer(struct svc_rqst *rqstp, unsigned int size, int node)

svc_init_buffer(struct svc_rqst *rqstp, const struct svc_serv *serv, int node)

{

	unsigned long pages, ret;

	unsigned long ret;



	pages = size / PAGE_SIZE + 1; /* extra page as we hold both request and reply.

				       * We assume one is at most one page

				       */

	WARN_ON_ONCE(pages > RPCSVC_MAXPAGES);

	if (pages > RPCSVC_MAXPAGES)

		pages = RPCSVC_MAXPAGES;

	rqstp->rq_maxpages = svc_serv_maxpages(serv);



	/* rq_pages' last entry is NULL for historical reasons. */

	rqstp->rq_pages = kcalloc_node(rqstp->rq_maxpages + 1,

				       sizeof(struct page *),

				       GFP_KERNEL, node);

	if (!rqstp->rq_pages)

		return false;



	ret = alloc_pages_bulk_node(GFP_KERNEL, node, pages,

	ret = alloc_pages_bulk_node(GFP_KERNEL, node, rqstp->rq_maxpages,

				    rqstp->rq_pages);

	return ret == pages;

	return ret == rqstp->rq_maxpages;

}



/*
@@ -658,11 +660,12 @@ svc_init_buffer(struct svc_rqst *rqstp, unsigned int size, int node) 
static void

svc_release_buffer(struct svc_rqst *rqstp)

{

	unsigned int i;

	unsigned long i;



	for (i = 0; i < ARRAY_SIZE(rqstp->rq_pages); i++)

	for (i = 0; i < rqstp->rq_maxpages; i++)

		if (rqstp->rq_pages[i])

			put_page(rqstp->rq_pages[i]);

	kfree(rqstp->rq_pages);

}



static void
@@ -704,7 +707,7 @@ svc_prepare_thread(struct svc_serv *serv, struct svc_pool *pool, int node) 
	if (!rqstp->rq_resp)

		goto out_enomem;



	if (!svc_init_buffer(rqstp, serv->sv_max_mesg, node))

	if (!svc_init_buffer(rqstp, serv, node))

		goto out_enomem;



	rqstp->rq_err = -EAGAIN; /* No error yet */
@@ -896,7 +899,7 @@ EXPORT_SYMBOL_GPL(svc_set_num_threads); 
bool svc_rqst_replace_page(struct svc_rqst *rqstp, struct page *page)

{

	struct page **begin = rqstp->rq_pages;

	struct page **end = &rqstp->rq_pages[RPCSVC_MAXPAGES];

	struct page **end = &rqstp->rq_pages[rqstp->rq_maxpages];



	if (unlikely(rqstp->rq_next_page < begin || rqstp->rq_next_page > end)) {

		trace_svc_replace_page_err(rqstp);

net/sunrpc/svc_xprt.c

+1 −9
Original line number Diff line number Diff line
@@ -652,18 +652,10 @@ static void svc_check_conn_limits(struct svc_serv *serv) 


static bool svc_alloc_arg(struct svc_rqst *rqstp)

{

	struct svc_serv *serv = rqstp->rq_server;

	struct xdr_buf *arg = &rqstp->rq_arg;

	unsigned long pages, filled, ret;



	pages = (serv->sv_max_mesg + 2 * PAGE_SIZE) >> PAGE_SHIFT;

	if (pages > RPCSVC_MAXPAGES) {

		pr_warn_once("svc: warning: pages=%lu > RPCSVC_MAXPAGES=%lu\n",

			     pages, RPCSVC_MAXPAGES);

		/* use as many pages as possible */

		pages = RPCSVC_MAXPAGES;

	}



	pages = rqstp->rq_maxpages;

	for (filled = 0; filled < pages; filled = ret) {

		ret = alloc_pages_bulk(GFP_KERNEL, pages, rqstp->rq_pages);

		if (ret > filled)

net/sunrpc/xprtrdma/svc_rdma_rw.c

+1 −1
Original line number Diff line number Diff line
@@ -765,7 +765,7 @@ static int svc_rdma_build_read_segment(struct svc_rqst *rqstp, 
		}

		len -= seg_len;



		if (len && ((head->rc_curpage + 1) > ARRAY_SIZE(rqstp->rq_pages)))

		if (len && ((head->rc_curpage + 1) > rqstp->rq_maxpages))

			goto out_overrun;

	}