From: Hao Xu Date: Sat, 11 Jun 2022 12:29:52 +0000 (+0800) Subject: io_uring: kbuf: fix bug of not consuming ring buffer in partial io case X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=42db0c00e275877eb92480beaa16b33507dc3bda;p=linux.git io_uring: kbuf: fix bug of not consuming ring buffer in partial io case When we use ring-mapped provided buffer, we should consume it before arm poll if partial io has been done. Otherwise the buffer may be used by other requests and thus we lost the data. Fixes: c7fb19428d67 ("io_uring: add support for ring mapped supplied buffers") Signed-off-by: Hao Xu [pavel: 5.19 rebase] Signed-off-by: Pavel Begunkov --- diff --git a/fs/io_uring.c b/fs/io_uring.c index e6d8cafdd28e6..84b45ed91b2d3 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -1729,9 +1729,16 @@ static void io_kbuf_recycle(struct io_kiocb *req, unsigned issue_flags) if (!(req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING))) return; - /* don't recycle if we already did IO to this buffer */ - if (req->flags & REQ_F_PARTIAL_IO) + /* + * For legacy provided buffer mode, don't recycle if we already did + * IO to this buffer. For ring-mapped provided buffer mode, we should + * increment ring->head to explicitly monopolize the buffer to avoid + * multiple use. + */ + if ((req->flags & REQ_F_BUFFER_SELECTED) && + (req->flags & REQ_F_PARTIAL_IO)) return; + /* * We don't need to recycle for REQ_F_BUFFER_RING, we can just clear * the flag and hence ensure that bl->head doesn't get incremented. @@ -1739,8 +1746,13 @@ static void io_kbuf_recycle(struct io_kiocb *req, unsigned issue_flags) */ if (req->flags & REQ_F_BUFFER_RING) { if (req->buf_list) { - req->buf_index = req->buf_list->bgid; - req->flags &= ~REQ_F_BUFFER_RING; + if (req->flags & REQ_F_PARTIAL_IO) { + req->buf_list->head++; + req->buf_list = NULL; + } else { + req->buf_index = req->buf_list->bgid; + req->flags &= ~REQ_F_BUFFER_RING; + } } return; }