From 2dc334f1a63a8839b88483a3e73c0f27c9c1791c Mon Sep 17 00:00:00 2001 From: David Howells Date: Wed, 7 Jun 2023 19:19:09 +0100 Subject: [PATCH] splice, net: Use sendmsg(MSG_SPLICE_PAGES) rather than ->sendpage() Replace generic_splice_sendpage() + splice_from_pipe + pipe_to_sendpage() with a net-specific handler, splice_to_socket(), that calls sendmsg() with MSG_SPLICE_PAGES set instead of calling ->sendpage(). MSG_MORE is used to indicate if the sendmsg() is expected to be followed with more data. This allows multiple pipe-buffer pages to be passed in a single call in a BVEC iterator, allowing the processing to be pushed down to a loop in the protocol driver. This helps pave the way for passing multipage folios down too. Protocols that haven't been converted to handle MSG_SPLICE_PAGES yet should just ignore it and do a normal sendmsg() for now - although that may be a bit slower as it may copy everything. Signed-off-by: David Howells Reviewed-by: Jakub Kicinski cc: Jens Axboe cc: Matthew Wilcox Signed-off-by: Jakub Kicinski --- fs/splice.c | 158 +++++++++++++++++++++++++++++++++++++++---------- include/linux/fs.h | 2 - include/linux/splice.h | 2 + net/socket.c | 26 +------- 4 files changed, 131 insertions(+), 57 deletions(-) diff --git a/fs/splice.c b/fs/splice.c index 3e06611..e337630 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -33,6 +33,7 @@ #include #include #include +#include #include #include @@ -448,30 +449,6 @@ const struct pipe_buf_operations nosteal_pipe_buf_ops = { }; EXPORT_SYMBOL(nosteal_pipe_buf_ops); -/* - * 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_sendpage(struct pipe_inode_info *pipe, - struct pipe_buffer *buf, struct splice_desc *sd) -{ - struct file *file = sd->u.file; - loff_t pos = sd->pos; - int more; - - if (!likely(file->f_op->sendpage)) - return -EINVAL; - - more = (sd->flags & SPLICE_F_MORE) ? MSG_MORE : 0; - - if (sd->len < sd->total_len && - pipe_occupancy(pipe->head, pipe->tail) > 1) - more |= MSG_SENDPAGE_NOTLAST; - - return file->f_op->sendpage(file, buf->page, buf->offset, - sd->len, &pos, more); -} - static void wakeup_pipe_writers(struct pipe_inode_info *pipe) { smp_mb(); @@ -652,7 +629,7 @@ static void splice_from_pipe_end(struct pipe_inode_info *pipe, struct splice_des * Description: * This function does little more than loop over the pipe and call * @actor to do the actual moving of a single struct pipe_buffer to - * the desired destination. See pipe_to_file, pipe_to_sendpage, or + * the desired destination. See pipe_to_file, pipe_to_sendmsg, or * pipe_to_user. * */ @@ -833,8 +810,9 @@ done: EXPORT_SYMBOL(iter_file_splice_write); +#ifdef CONFIG_NET /** - * generic_splice_sendpage - splice data from a pipe to a socket + * splice_to_socket - splice data from a pipe to a socket * @pipe: pipe to splice from * @out: socket to write to * @ppos: position in @out @@ -846,13 +824,131 @@ EXPORT_SYMBOL(iter_file_splice_write); * is involved. * */ -ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out, - loff_t *ppos, size_t len, unsigned int flags) +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_sendpage); -} + struct socket *sock = sock_from_file(out); + struct bio_vec bvec[16]; + struct msghdr msg = {}; + ssize_t ret = 0; + 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; -EXPORT_SYMBOL(generic_splice_sendpage); + 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 = MSG_SPLICE_PAGES; + if (flags & SPLICE_F_MORE) + msg.msg_flags |= MSG_MORE; + if (remain && pipe_occupancy(pipe->head, tail) > 0) + msg.msg_flags |= MSG_MORE; + + 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 static int warn_unsupported(struct file *file, const char *op) { diff --git a/include/linux/fs.h b/include/linux/fs.h index 133f064..df92f4b 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2759,8 +2759,6 @@ extern ssize_t generic_file_splice_read(struct file *, loff_t *, struct pipe_inode_info *, size_t, unsigned int); extern ssize_t iter_file_splice_write(struct pipe_inode_info *, struct file *, loff_t *, size_t, unsigned int); -extern ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, - struct file *out, loff_t *, size_t len, unsigned int flags); extern long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, loff_t *opos, size_t len, unsigned int flags); diff --git a/include/linux/splice.h b/include/linux/splice.h index a55179f..991ae31 100644 --- a/include/linux/splice.h +++ b/include/linux/splice.h @@ -84,6 +84,8 @@ extern long do_splice(struct file *in, loff_t *off_in, extern long do_tee(struct file *in, struct file *out, size_t len, unsigned int flags); +extern ssize_t splice_to_socket(struct pipe_inode_info *pipe, struct file *out, + loff_t *ppos, size_t len, unsigned int flags); /* * for dynamic pipe sizing diff --git a/net/socket.c b/net/socket.c index 3df96e9..c4d9104 100644 --- a/net/socket.c +++ b/net/socket.c @@ -57,6 +57,7 @@ #include #include #include +#include #include #include #include @@ -126,8 +127,6 @@ static long compat_sock_ioctl(struct file *file, unsigned int cmd, unsigned long arg); #endif static int sock_fasync(int fd, struct file *filp, int on); -static ssize_t sock_sendpage(struct file *file, struct page *page, - int offset, size_t size, loff_t *ppos, int more); static ssize_t sock_splice_read(struct file *file, loff_t *ppos, struct pipe_inode_info *pipe, size_t len, unsigned int flags); @@ -162,8 +161,7 @@ static const struct file_operations socket_file_ops = { .mmap = sock_mmap, .release = sock_close, .fasync = sock_fasync, - .sendpage = sock_sendpage, - .splice_write = generic_splice_sendpage, + .splice_write = splice_to_socket, .splice_read = sock_splice_read, .show_fdinfo = sock_show_fdinfo, }; @@ -1066,26 +1064,6 @@ int kernel_recvmsg(struct socket *sock, struct msghdr *msg, } EXPORT_SYMBOL(kernel_recvmsg); -static ssize_t sock_sendpage(struct file *file, struct page *page, - int offset, size_t size, loff_t *ppos, int more) -{ - struct socket *sock; - int flags; - int ret; - - sock = file->private_data; - - flags = (file->f_flags & O_NONBLOCK) ? MSG_DONTWAIT : 0; - /* more is a combination of MSG_MORE and MSG_SENDPAGE_NOTLAST */ - flags |= more; - - ret = kernel_sendpage(sock, page, offset, size, flags); - - if (trace_sock_send_length_enabled()) - call_trace_sock_send_length(sock->sk, ret, 0); - return ret; -} - static ssize_t sock_splice_read(struct file *file, loff_t *ppos, struct pipe_inode_info *pipe, size_t len, unsigned int flags) -- 2.7.4