sunrpc: Replace the rq_bvec 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_bvec[] array in struct svc_rqst
with a chunk of dynamically-allocated memory.

The rq_bvec[] array contains enough bio_vecs to handle each page in
a maximum size RPC message.

On a system with 8-byte pointers and 4KB pages, pahole reports that
the rq_bvec[] array is 4144 bytes. This patch replaces that array
with a single 8-byte pointer field.

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

diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
index 57be6953988866a05874e28afe52bdc013001b5e..538bea716c6b1ea85759143fb1971fe82c4214e2 100644 (file)
--- a/include/linux/sunrpc/svc.h
+++ b/include/linux/sunrpc/svc.h
@@ -213,7 +213,7 @@ struct svc_rqst {
 
        struct folio_batch      rq_fbatch;
        struct kvec             rq_vec[RPCSVC_MAXPAGES]; /* generally useful.. */
-       struct bio_vec          rq_bvec[RPCSVC_MAXPAGES];
+       struct bio_vec          *rq_bvec;
 
        __be32                  rq_xid;         /* transmission id */
        u32                     rq_prog;        /* program number */

diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index d320837e09f03280bcf1cd6b5128e62ff1200048..2c1c4aa93f43fe689f774b944fda72d6b9d6c716 100644 (file)
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -672,6 +672,7 @@ static void
 svc_rqst_free(struct svc_rqst *rqstp)
 {
        folio_batch_release(&rqstp->rq_fbatch);
+       kfree(rqstp->rq_bvec);
        svc_release_buffer(rqstp);
        if (rqstp->rq_scratch_page)
                put_page(rqstp->rq_scratch_page);
@@ -710,6 +711,12 @@ svc_prepare_thread(struct svc_serv *serv, struct svc_pool *pool, int node)
        if (!svc_init_buffer(rqstp, serv, node))
                goto out_enomem;
 
+       rqstp->rq_bvec = kcalloc_node(rqstp->rq_maxpages,
+                                     sizeof(struct bio_vec),
+                                     GFP_KERNEL, node);
+       if (!rqstp->rq_bvec)
+               goto out_enomem;
+
        rqstp->rq_err = -EAGAIN; /* No error yet */
 
        serv->sv_nrthreads += 1;

diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index 60f2883268faf15b8e01a5d12d67a5d01b278a5e..d9fdc6ae802056e7cc1e2735b5e42a7c016f8e53 100644 (file)
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -713,8 +713,7 @@ static int svc_udp_sendto(struct svc_rqst *rqstp)
        if (svc_xprt_is_dead(xprt))
                goto out_notconn;
 
-       count = xdr_buf_to_bvec(rqstp->rq_bvec,
-                               ARRAY_SIZE(rqstp->rq_bvec), xdr);
+       count = xdr_buf_to_bvec(rqstp->rq_bvec, rqstp->rq_maxpages, xdr);
 
        iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, rqstp->rq_bvec,
                      count, rqstp->rq_res.len);
@@ -1219,8 +1218,8 @@ static int svc_tcp_sendmsg(struct svc_sock *svsk, struct svc_rqst *rqstp,
        memcpy(buf, &marker, sizeof(marker));
        bvec_set_virt(rqstp->rq_bvec, buf, sizeof(marker));
 
-       count = xdr_buf_to_bvec(rqstp->rq_bvec + 1,
-                               ARRAY_SIZE(rqstp->rq_bvec) - 1, &rqstp->rq_res);
+       count = xdr_buf_to_bvec(rqstp->rq_bvec + 1, rqstp->rq_maxpages,
+                               &rqstp->rq_res);
 
        iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, rqstp->rq_bvec,
                      1 + count, sizeof(marker) + rqstp->rq_res.len);