From mboxrd@z Thu Jan 1 00:00:00 1970 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3F8ADC28D17 for ; Mon, 15 Nov 2021 19:52:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3587B61B3F for ; Mon, 15 Nov 2021 19:52:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347952AbhKOTtJ (ORCPT ); Mon, 15 Nov 2021 14:49:09 -0500 Received: from mail.kernel.org ([198.145.29.99]:40734 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239198AbhKOR5m (ORCPT ); Mon, 15 Nov 2021 12:57:42 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id C50C260F38; Mon, 15 Nov 2021 17:34:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1636997697; bh=MMazxAV7PO/kMsDmIWerrt5q+fB4BzEy63MLdftmtB4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=vRB/gpYxKP+e6smcZZVdcbri/v1Zk2sQWlkZwBaoAeBL/3PSqmlP4kCzUfzXr8xXU GF1H/CbESrWfYiFbwFqhDH9FSh11XepYyDuxbCEbWoKP64PiBuQQkaf+zskA6L+BOj cQXAolCH+fCZbkkmzuTDz4806JuY6yrLMGatC0oY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Andreas Gruenbacher , Bob Peterson , Sasha Levin Subject: [PATCH 5.10 242/575] gfs2: Cancel remote delete work asynchronously Date: Mon, 15 Nov 2021 17:59:27 +0100 Message-Id: <20211115165352.109274537@linuxfoundation.org> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20211115165343.579890274@linuxfoundation.org> References: <20211115165343.579890274@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Andreas Gruenbacher [ Upstream commit 486408d690e130c3adacf816754b97558d715f46 ] In gfs2_inode_lookup and gfs2_create_inode, we're calling gfs2_cancel_delete_work which currently cancels any remote delete work (delete_work_func) synchronously. This means that if the work is currently running, it will wait for it to finish. We're doing this to pevent a previous instance of an inode from having any influence on the next instance. However, delete_work_func uses gfs2_inode_lookup internally, and we can end up in a deadlock when delete_work_func gets interrupted at the wrong time. For example, (1) An inode's iopen glock has delete work queued, but the inode itself has been evicted from the inode cache. (2) The delete work is preempted before reaching gfs2_inode_lookup. (3) Another process recreates the inode (gfs2_create_inode). It tries to cancel any outstanding delete work, which blocks waiting for the ongoing delete work to finish. (4) The delete work calls gfs2_inode_lookup, which blocks waiting for gfs2_create_inode to instantiate and unlock the new inode => deadlock. It turns out that when the delete work notices that its inode has been re-instantiated, it will do nothing. This means that it's safe to cancel the delete work asynchronously. This prevents the kind of deadlock described above. Signed-off-by: Andreas Gruenbacher Signed-off-by: Bob Peterson Signed-off-by: Sasha Levin --- fs/gfs2/glock.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index 03c3407c8e26f..533adcd480310 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -1911,7 +1911,7 @@ bool gfs2_queue_delete_work(struct gfs2_glock *gl, unsigned long delay) void gfs2_cancel_delete_work(struct gfs2_glock *gl) { - if (cancel_delayed_work_sync(&gl->gl_delete)) { + if (cancel_delayed_work(&gl->gl_delete)) { clear_bit(GLF_PENDING_DELETE, &gl->gl_flags); gfs2_glock_put(gl); } -- 2.33.0