From 862a81c79f0bea8ede0352b637b44716f02f71b9 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Fri, 13 Jun 2025 11:01:49 -0600 Subject: io_uring/kbuf: don't truncate end buffer for multiple buffer peeks If peeking a bunch of buffers, normally io_ring_buffers_peek() will truncate the end buffer. This isn't optimal as presumably more data will be arriving later, and hence it's better to stop with the last full buffer rather than truncate the end buffer. Cc: stable@vger.kernel.org Fixes: 35c8711c8fc4 ("io_uring/kbuf: add helpers for getting/peeking multiple buffers") Reported-by: Christian Mazakas Signed-off-by: Jens Axboe --- io_uring/kbuf.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/io_uring/kbuf.c +++ b/io_uring/kbuf.c @@ -270,8 +270,11 @@ static int io_ring_buffers_peek(struct i /* truncate end piece, if needed, for non partial buffers */ if (len > arg->max_len) { len = arg->max_len; - if (!(bl->flags & IOBL_INC)) + if (!(bl->flags & IOBL_INC)) { + if (iov != arg->iovs) + break; buf->len = len; + } } iov->iov_base = u64_to_user_ptr(buf->addr);