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[68.61.232.219]) by smtp.gmail.com with ESMTPSA id u203sm2378288iod.54.2020.05.21.07.35.50 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Thu, 21 May 2020 07:35:50 -0700 (PDT) Received: from klimt.1015granger.net (klimt.1015granger.net [192.168.1.55]) by gateway.1015granger.net (8.14.7/8.14.7) with ESMTP id 04LEZnal000909; Thu, 21 May 2020 14:35:49 GMT Subject: [PATCH v3 24/32] SUNRPC: Refactor svc_recvfrom() From: Chuck Lever To: bfields@fieldses.org Cc: linux-nfs@vger.kernel.org, linux-rdma@vger.kernel.org Date: Thu, 21 May 2020 10:35:49 -0400 Message-ID: <20200521143549.3557.41493.stgit@klimt.1015granger.net> In-Reply-To: <20200521141100.3557.17098.stgit@klimt.1015granger.net> References: <20200521141100.3557.17098.stgit@klimt.1015granger.net> User-Agent: StGit/0.22-31-g4b47 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org This function is not currently "generic" so remove the documenting comment and rename it appropriately. Its internals are converted to use bio_vecs for reading from the transport socket. In existing typical sunrpc uses of bio_vecs, the bio_vec array is allocated dynamically. Here, instead, an array of bio_vecs is added to svc_rqst. The lifetime of this array can be greater than one call to xpo_recvfrom(): - Multiple calls to xpo_recvfrom() might be needed to read an RPC message completely. - At some later point, rq_arg.bvecs will point to this array and it will carry the received message into svc_process(). I also expect that a future optimization will remove either the rq_vec or rq_pages array in favor of rq_bvec, thus conserving the size of struct svc_rqst. Signed-off-by: Chuck Lever --- include/linux/sunrpc/svc.h | 1 net/sunrpc/svcsock.c | 109 +++++++++++++++++++++++++++----------------- 2 files changed, 69 insertions(+), 41 deletions(-) diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h index fd390894a584..05da19a0516d 100644 --- a/include/linux/sunrpc/svc.h +++ b/include/linux/sunrpc/svc.h @@ -254,6 +254,7 @@ struct svc_rqst { struct page * *rq_page_end; /* one past the last page */ struct kvec rq_vec[RPCSVC_MAXPAGES]; /* generally useful.. */ + struct bio_vec rq_bvec[RPCSVC_MAXPAGES]; __be32 rq_xid; /* transmission id */ u32 rq_prog; /* program number */ diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c index 5b2981a0711c..3e25511b800e 100644 --- a/net/sunrpc/svcsock.c +++ b/net/sunrpc/svcsock.c @@ -223,26 +223,62 @@ static int svc_one_sock_name(struct svc_sock *svsk, char *buf, int remaining) return len; } +#if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE +static void svc_flush_bvec(const struct bio_vec *bvec, size_t size, size_t seek) +{ + struct bvec_iter bi = { + .bi_size = size, + }; + struct bio_vec bv; + + bvec_iter_advance(bvec, &bi, seek & PAGE_MASK); + for_each_bvec(bv, bvec, bi, bi) + flush_dcache_page(bv.bv_page); +} +#else +static inline void svc_flush_bvec(const struct bio_vec *bvec, size_t size, + size_t seek) +{ +} +#endif + /* - * Generic recvfrom routine. + * Read from @rqstp's transport socket. The incoming message fills whole + * pages in @rqstp's rq_pages array until the last page of the message + * has been received into a partial page. */ -static ssize_t svc_recvfrom(struct svc_rqst *rqstp, struct kvec *iov, - unsigned int nr, size_t buflen, unsigned int base) +static ssize_t svc_tcp_read_msg(struct svc_rqst *rqstp, size_t buflen, + size_t seek) { struct svc_sock *svsk = container_of(rqstp->rq_xprt, struct svc_sock, sk_xprt); + struct bio_vec *bvec = rqstp->rq_bvec; struct msghdr msg = { NULL }; + unsigned int i; ssize_t len; + size_t t; rqstp->rq_xprt_hlen = 0; clear_bit(XPT_DATA, &svsk->sk_xprt.xpt_flags); - iov_iter_kvec(&msg.msg_iter, READ, iov, nr, buflen); - if (base != 0) { - iov_iter_advance(&msg.msg_iter, base); - buflen -= base; + + for (i = 0, t = 0; t < buflen; i++, t += PAGE_SIZE) { + bvec[i].bv_page = rqstp->rq_pages[i]; + bvec[i].bv_len = PAGE_SIZE; + bvec[i].bv_offset = 0; + } + rqstp->rq_respages = &rqstp->rq_pages[i]; + rqstp->rq_next_page = rqstp->rq_respages + 1; + + iov_iter_bvec(&msg.msg_iter, READ, bvec, i, buflen); + if (seek) { + iov_iter_advance(&msg.msg_iter, seek); + buflen -= seek; } len = sock_recvmsg(svsk->sk_sock, &msg, MSG_DONTWAIT); + if (len > 0) + svc_flush_bvec(bvec, len, seek); + /* If we read a full record, then assume there may be more * data to read (stream based sockets only!) */ @@ -775,13 +811,14 @@ static struct svc_xprt *svc_tcp_accept(struct svc_xprt *xprt) return NULL; } -static unsigned int svc_tcp_restore_pages(struct svc_sock *svsk, struct svc_rqst *rqstp) +static size_t svc_tcp_restore_pages(struct svc_sock *svsk, + struct svc_rqst *rqstp) { - unsigned int i, len, npages; + size_t len = svsk->sk_datalen; + unsigned int i, npages; - if (svsk->sk_datalen == 0) + if (!len) return 0; - len = svsk->sk_datalen; npages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT; for (i = 0; i < npages; i++) { if (rqstp->rq_pages[i] != NULL) @@ -917,20 +954,6 @@ static int receive_cb_reply(struct svc_sock *svsk, struct svc_rqst *rqstp) return -EAGAIN; } -static int copy_pages_to_kvecs(struct kvec *vec, struct page **pages, int len) -{ - int i = 0; - int t = 0; - - while (t < len) { - vec[i].iov_base = page_address(pages[i]); - vec[i].iov_len = PAGE_SIZE; - i++; - t += PAGE_SIZE; - } - return i; -} - static void svc_tcp_fragment_received(struct svc_sock *svsk) { /* If we have more data, signal svc_xprt_enqueue() to try again */ @@ -938,20 +961,33 @@ static void svc_tcp_fragment_received(struct svc_sock *svsk) svsk->sk_marker = xdr_zero; } -/* - * Receive data from a TCP socket. +/** + * svc_tcp_recvfrom - Receive data from a TCP socket + * @rqstp: request structure into which to receive an RPC Call + * + * Called in a loop when XPT_DATA has been set. + * + * Read the 4-byte stream record marker, then use the record length + * in that marker to set up exactly the resources needed to receive + * the next RPC message into @rqstp. + * + * Returns: + * On success, the number of bytes in a received RPC Call, or + * %0 if a complete RPC Call message was not ready to return + * + * The zero return case handles partial receives and callback Replies. + * The state of a partial receive is preserved in the svc_sock for + * the next call to svc_tcp_recvfrom. */ static int svc_tcp_recvfrom(struct svc_rqst *rqstp) { struct svc_sock *svsk = container_of(rqstp->rq_xprt, struct svc_sock, sk_xprt); struct svc_serv *serv = svsk->sk_xprt.xpt_server; - int len; - struct kvec *vec; - unsigned int want, base; + size_t want, base; + ssize_t len; __be32 *p; __be32 calldir; - int pnum; clear_bit(XPT_DATA, &svsk->sk_xprt.xpt_flags); len = svc_tcp_read_marker(svsk, rqstp); @@ -960,16 +996,7 @@ static int svc_tcp_recvfrom(struct svc_rqst *rqstp) base = svc_tcp_restore_pages(svsk, rqstp); want = len - (svsk->sk_tcplen - sizeof(rpc_fraghdr)); - - vec = rqstp->rq_vec; - - pnum = copy_pages_to_kvecs(&vec[0], &rqstp->rq_pages[0], base + want); - - rqstp->rq_respages = &rqstp->rq_pages[pnum]; - rqstp->rq_next_page = rqstp->rq_respages + 1; - - /* Now receive data */ - len = svc_recvfrom(rqstp, vec, pnum, base + want, base); + len = svc_tcp_read_msg(rqstp, base + want, base); if (len >= 0) { trace_svcsock_tcp_recv(&svsk->sk_xprt, len); svsk->sk_tcplen += len;