lkml.org 
[lkml]   [2023]   [Mar]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[RFC PATCH v2 28/48] splice: Reimplement splice_to_socket() to pass multiple bufs to sendmsg()
    Date
    Reimplement splice_to_socket() so that it can pass multiple pipe buffer
    pages to sendmsg() in a single go.

    Signed-off-by: David Howells <dhowells@redhat.com>
    ---
    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

    \
     
     \ /
      Last update: 2023-03-29 16:24    [W:4.287 / U:0.784 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site