From patchwork Tue Feb 28 04:54:59 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joseph Qi X-Patchwork-Id: 13154416 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0F57BC64ED6 for ; Tue, 28 Feb 2023 04:55:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229512AbjB1EzG (ORCPT ); Mon, 27 Feb 2023 23:55:06 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60864 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229520AbjB1EzF (ORCPT ); Mon, 27 Feb 2023 23:55:05 -0500 Received: from out30-111.freemail.mail.aliyun.com (out30-111.freemail.mail.aliyun.com [115.124.30.111]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 36F799EC4 for ; Mon, 27 Feb 2023 20:55:03 -0800 (PST) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R141e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046056;MF=joseph.qi@linux.alibaba.com;NM=1;PH=DS;RN=5;SR=0;TI=SMTPD_---0Vchb1Cz_1677560099; Received: from localhost(mailfrom:joseph.qi@linux.alibaba.com fp:SMTPD_---0Vchb1Cz_1677560099) by smtp.aliyun-inc.com; Tue, 28 Feb 2023 12:55:00 +0800 From: Joseph Qi To: Jens Axboe Cc: io-uring@vger.kernel.org, ocfs2-devel@oss.oracle.com, Heming Zhao , Xiaoguang Wang Subject: [PATCH] io_uring: fix fget leak when fs don't support nowait buffered read Date: Tue, 28 Feb 2023 12:54:59 +0800 Message-Id: <20230228045459.13524-1-joseph.qi@linux.alibaba.com> X-Mailer: git-send-email 2.24.4 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org Heming reported a BUG when using io_uring doing link-cp on ocfs2. [1] Do the following steps can reproduce this BUG: mount -t ocfs2 /dev/vdc /mnt/ocfs2 cp testfile /mnt/ocfs2/ ./link-cp /mnt/ocfs2/testfile /mnt/ocfs2/testfile.1 umount /mnt/ocfs2 Then umount will fail, and it outputs: umount: /mnt/ocfs2: target is busy. While tracing umount, it blames mnt_get_count() not return as expected. Do a deep investigation for fget()/fput() on related code flow, I've finally found that fget() leaks since ocfs2 doesn't support nowait buffered read. io_issue_sqe |-io_assign_file // do fget() first |-io_read |-io_iter_do_read |-ocfs2_file_read_iter // return -EOPNOTSUPP |-kiocb_done |-io_rw_done |-__io_complete_rw_common // set REQ_F_REISSUE |-io_resubmit_prep |-io_req_prep_async // override req->file, leak happens This was introduced by commit a196c78b5443 in v5.18. Fix it by don't re-assign req->file if it has already been assigned. [1] https://lore.kernel.org/ocfs2-devel/ab580a75-91c8-d68a-3455-40361be1bfa8@linux.alibaba.com/T/#t Fixes: a196c78b5443 ("io_uring: assign non-fixed early for async work") Cc: Reported-by: Heming Zhao Signed-off-by: Joseph Qi Cc: Xiaoguang Wang --- io_uring/io_uring.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index 1df68da89f99..7ad3b8af2a4b 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -1777,7 +1777,7 @@ int io_req_prep_async(struct io_kiocb *req) const struct io_issue_def *def = &io_issue_defs[req->opcode]; /* assign early for deferred execution for non-fixed file */ - if (def->needs_file && !(req->flags & REQ_F_FIXED_FILE)) + if (def->needs_file && !(req->flags & REQ_F_FIXED_FILE) && !req->file) req->file = io_file_get_normal(req, req->cqe.fd); if (!cdef->prep_async) return 0;