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authorEric Dumazet <edumazet@google.com>2013-01-06 13:21:49 -0500
committerDavid S. Miller <davem@davemloft.net>2013-01-06 23:58:13 -0500
commitae62ca7b03217be5e74759dc6d7698c95df498b3 (patch)
tree417481b4ddfbd7f05589ae331b41f20939391b50
parent9dd4a13a89d7c27e51cb87b9e95e82d8999826da (diff)
tcp: fix MSG_SENDPAGE_NOTLAST logic
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>
-rw-r--r--fs/splice.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/fs/splice.c b/fs/splice.c
index 8890604e3fcd..6909d89d0da5 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -696,8 +696,10 @@ static int pipe_to_sendpage(struct pipe_inode_info *pipe,
696 return -EINVAL; 696 return -EINVAL;
697 697
698 more = (sd->flags & SPLICE_F_MORE) ? MSG_MORE : 0; 698 more = (sd->flags & SPLICE_F_MORE) ? MSG_MORE : 0;
699 if (sd->len < sd->total_len) 699
700 if (sd->len < sd->total_len && pipe->nrbufs > 1)
700 more |= MSG_SENDPAGE_NOTLAST; 701 more |= MSG_SENDPAGE_NOTLAST;
702
701 return file->f_op->sendpage(file, buf->page, buf->offset, 703 return file->f_op->sendpage(file, buf->page, buf->offset,
702 sd->len, &pos, more); 704 sd->len, &pos, more);
703} 705}