From: Eric Dumazet <edumazet@xxxxxxxxxx>
-------------------
This is a commit scheduled for the next v2.6.34 longterm release.
http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git
If you see a problem with using this for longterm, please comment.
-------------------
commit ae62ca7b03217be5e74759dc6d7698c95df498b3 upstream.
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@xxxxxx>
Bisected-by: Willy Tarreau <w@xxxxxx>
Tested-by: Willy Tarreau <w@xxxxxx>
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
---
fs/splice.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/fs/splice.c b/fs/splice.c
index 3bec7c63be64..1c991d6a64b4 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -640,8 +640,10 @@ static int pipe_to_sendpage(struct pipe_inode_info *pipe,
ret = buf->ops->confirm(pipe, buf);
if (!ret) {
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;
+
if (file->f_op && file->f_op->sendpage)
ret = file->f_op->sendpage(file, buf->page, buf->offset,
sd->len, &pos, more);
--
1.8.5.2
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