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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: David Howells , Al Viro , Christoph Hellwig , Jens Axboe , Jeff Layton , Christian Brauner , Chuck Lever III , Linus Torvalds , netdev@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [RFC PATCH v2 28/48] splice: Reimplement splice_to_socket() to pass multiple bufs to sendmsg() Date: Wed, 29 Mar 2023 15:13:34 +0100 Message-Id: <20230329141354.516864-29-dhowells@redhat.com> In-Reply-To: <20230329141354.516864-1-dhowells@redhat.com> References: <20230329141354.516864-1-dhowells@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.10 X-Spam-Status: No, score=-0.2 required=5.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H2,SPF_HELO_NONE,SPF_NONE autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1761713431860542817?= X-GMAIL-MSGID: =?utf-8?q?1761713431860542817?= Reimplement splice_to_socket() so that it can pass multiple pipe buffer pages to sendmsg() in a single go. Signed-off-by: David Howells --- fs/splice.c | 148 ++++++++++++++++++++++++++++++++++++++++++---------- 1 file changed, 120 insertions(+), 28 deletions(-) diff --git a/fs/splice.c b/fs/splice.c index 23ead122d631..d5bc28b59720 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -411,33 +411,6 @@ const struct pipe_buf_operations nosteal_pipe_buf_ops = { }; EXPORT_SYMBOL(nosteal_pipe_buf_ops); -#ifdef CONFIG_NET -/* - * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos' - * using sendpage(). Return the number of bytes sent. - */ -static int pipe_to_sendmsg(struct pipe_inode_info *pipe, - struct pipe_buffer *buf, struct splice_desc *sd) -{ - struct socket *sock = sock_from_file(sd->u.file); - struct bio_vec bvec; - struct msghdr msg = { - .msg_flags = MSG_SPLICE_PAGES, - }; - - if (sd->flags & SPLICE_F_MORE) - msg.msg_flags |= MSG_MORE; - - if (sd->len < sd->total_len && - pipe_occupancy(pipe->head, pipe->tail) > 1) - msg.msg_flags |= MSG_MORE; - - bvec_set_page(&bvec, buf->page, sd->len, buf->offset); - iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bvec, 1, sd->len); - return sock_sendmsg(sock, &msg); -} -#endif - static void wakeup_pipe_writers(struct pipe_inode_info *pipe) { smp_mb(); @@ -816,7 +789,126 @@ EXPORT_SYMBOL(iter_file_splice_write); ssize_t splice_to_socket(struct pipe_inode_info *pipe, struct file *out, loff_t *ppos, size_t len, unsigned int flags) { - return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendmsg); + struct socket *sock = sock_from_file(out); + struct bio_vec bvec[16]; + struct msghdr msg = {}; + ssize_t ret; + size_t spliced = 0; + bool need_wakeup = false; + + pipe_lock(pipe); + + while (len > 0) { + unsigned int head, tail, mask, bc = 0; + size_t remain = len; + + /* + * Check for signal early to make process killable when there + * are always buffers available + */ + ret = -ERESTARTSYS; + if (signal_pending(current)) + break; + + while (pipe_empty(pipe->head, pipe->tail)) { + ret = 0; + if (!pipe->writers) + goto out; + + if (spliced) + goto out; + + ret = -EAGAIN; + if (flags & SPLICE_F_NONBLOCK) + goto out; + + ret = -ERESTARTSYS; + if (signal_pending(current)) + goto out; + + if (need_wakeup) { + wakeup_pipe_writers(pipe); + need_wakeup = false; + } + + pipe_wait_readable(pipe); + } + + head = pipe->head; + tail = pipe->tail; + mask = pipe->ring_size - 1; + + while (!pipe_empty(head, tail)) { + struct pipe_buffer *buf = &pipe->bufs[tail & mask]; + size_t seg; + + if (!buf->len) { + tail++; + continue; + } + + seg = min_t(size_t, remain, buf->len); + seg = min_t(size_t, seg, PAGE_SIZE); + + ret = pipe_buf_confirm(pipe, buf); + if (unlikely(ret)) { + if (ret == -ENODATA) + ret = 0; + break; + } + + bvec_set_page(&bvec[bc++], buf->page, seg, buf->offset); + remain -= seg; + if (seg >= buf->len) + tail++; + if (bc >= ARRAY_SIZE(bvec)) + break; + } + + if (!bc) + break; + + msg.msg_flags = 0; + if (flags & SPLICE_F_MORE) + msg.msg_flags = MSG_MORE; + if (remain && pipe_occupancy(pipe->head, tail) > 0) + msg.msg_flags = MSG_MORE; + msg.msg_flags |= MSG_SPLICE_PAGES; + + iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, bvec, bc, len - remain); + ret = sock_sendmsg(sock, &msg); + if (ret <= 0) + break; + + spliced += ret; + len -= ret; + tail = pipe->tail; + while (ret > 0) { + struct pipe_buffer *buf = &pipe->bufs[tail & mask]; + size_t seg = min_t(size_t, ret, buf->len); + + buf->offset += seg; + buf->len -= seg; + ret -= seg; + + if (!buf->len) { + pipe_buf_release(pipe, buf); + tail++; + } + } + + if (tail != pipe->tail) { + pipe->tail = tail; + if (pipe->files) + need_wakeup = true; + } + } + +out: + pipe_unlock(pipe); + if (need_wakeup) + wakeup_pipe_writers(pipe); + return spliced ?: ret; } #endif