| From 6ab1806169c92aadc5a1cc1224647a8d83363f1e Mon Sep 17 00:00:00 2001 |
| From: Eric Dumazet <edumazet@google.com> |
| Date: Sun, 6 Jan 2013 18:21:49 +0000 |
| Subject: tcp: fix MSG_SENDPAGE_NOTLAST logic |
| |
| |
| From: Eric Dumazet <edumazet@google.com> |
| |
| [ Upstream commit ae62ca7b03217be5e74759dc6d7698c95df498b3 ] |
| |
| commit 35f9c09fe9c72e (tcp: tcp_sendpages() should call tcp_push() once) |
| added an internal flag : MSG_SENDPAGE_NOTLAST meant to be set on all |
| frags but the last one for a splice() call. |
| |
| The condition used to set the flag in pipe_to_sendpage() relied on |
| splice() user passing the exact number of bytes present in the pipe, |
| or a smaller one. |
| |
| But some programs pass an arbitrary high value, and the test fails. |
| |
| The effect of this bug is a lack of tcp_push() at the end of a |
| splice(pipe -> socket) call, and possibly very slow or erratic TCP |
| sessions. |
| |
| We should both test sd->total_len and fact that another fragment |
| is in the pipe (pipe->nrbufs > 1) |
| |
| Many thanks to Willy for providing very clear bug report, bisection |
| and test programs. |
| |
| Reported-by: Willy Tarreau <w@1wt.eu> |
| Bisected-by: Willy Tarreau <w@1wt.eu> |
| Tested-by: Willy Tarreau <w@1wt.eu> |
| Signed-off-by: Eric Dumazet <edumazet@google.com> |
| Signed-off-by: David S. Miller <davem@davemloft.net> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| fs/splice.c | 4 +++- |
| 1 file changed, 3 insertions(+), 1 deletion(-) |
| |
| --- a/fs/splice.c |
| +++ b/fs/splice.c |
| @@ -696,8 +696,10 @@ static int pipe_to_sendpage(struct pipe_ |
| return -EINVAL; |
| |
| more = (sd->flags & SPLICE_F_MORE) ? MSG_MORE : 0; |
| - if (sd->len < sd->total_len) |
| + |
| + if (sd->len < sd->total_len && pipe->nrbufs > 1) |
| more |= MSG_SENDPAGE_NOTLAST; |
| + |
| return file->f_op->sendpage(file, buf->page, buf->offset, |
| sd->len, &pos, more); |
| } |
