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 A94AFC433F5 for ; Tue, 16 Nov 2021 01:38:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7CB7861246 for ; Tue, 16 Nov 2021 01:38:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1357504AbhKPBle (ORCPT ); Mon, 15 Nov 2021 20:41:34 -0500 Received: from mail.kernel.org ([198.145.29.99]:46112 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242405AbhKOSkx (ORCPT ); Mon, 15 Nov 2021 13:40:53 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 70E8161AAA; Mon, 15 Nov 2021 18:04:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1636999483; bh=GmjGkJnunf7uEOm60B7d8f8ctLDz3XwBubtOELLd0fU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=X2PTgLOtOTuzeBl8R6ae3k6LP/v8C/j3mII6+3aapOqDC7HMa5jYx/hppzDann0yT Cy9o2s4LvhFE+xkbVuM4W9vAv1rTzsNpPBz7QncPoISdAxfMRyk+zXY31pzBIQ9gyQ O/bIOMRS2SPS+U9dQf09XtaKMlyyroUcFyS0Hn4Y= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alexander Aring , Andreas Gruenbacher , Sasha Levin Subject: [PATCH 5.14 312/849] gfs2: Fix glock_hash_walk bugs Date: Mon, 15 Nov 2021 17:56:35 +0100 Message-Id: <20211115165430.803024330@linuxfoundation.org> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20211115165419.961798833@linuxfoundation.org> References: <20211115165419.961798833@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 7427f3bb49d81525b7dd1d0f7c5f6bbc752e6f0e ] So far, glock_hash_walk took a reference on each glock it iterated over, and it was the examiner's responsibility to drop those references. Dropping the final reference to a glock can sleep and the examiners are called in a RCU critical section with spin locks held, so examiners that didn't need the extra reference had to drop it asynchronously via gfs2_glock_queue_put or similar. This wasn't done correctly in thaw_glock which did call gfs2_glock_put, and not at all in dump_glock_func. Change glock_hash_walk to not take glock references at all. That way, the examiners that don't need them won't have to bother with slow asynchronous puts, and the examiners that do need references can take them themselves. Reported-by: Alexander Aring Signed-off-by: Andreas Gruenbacher Signed-off-by: Sasha Levin --- fs/gfs2/glock.c | 22 ++++++++++++---------- 1 file changed, 12 insertions(+), 10 deletions(-) diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index fea68ed127b89..b17b6350c0317 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -1894,10 +1894,10 @@ static void glock_hash_walk(glock_examiner examiner, const struct gfs2_sbd *sdp) do { rhashtable_walk_start(&iter); - while ((gl = rhashtable_walk_next(&iter)) && !IS_ERR(gl)) - if (gl->gl_name.ln_sbd == sdp && - lockref_get_not_dead(&gl->gl_lockref)) + while ((gl = rhashtable_walk_next(&iter)) && !IS_ERR(gl)) { + if (gl->gl_name.ln_sbd == sdp) examiner(gl); + } rhashtable_walk_stop(&iter); } while (cond_resched(), gl == ERR_PTR(-EAGAIN)); @@ -1939,7 +1939,6 @@ static void flush_delete_work(struct gfs2_glock *gl) &gl->gl_delete, 0); } } - gfs2_glock_queue_work(gl, 0); } void gfs2_flush_delete_work(struct gfs2_sbd *sdp) @@ -1956,10 +1955,10 @@ void gfs2_flush_delete_work(struct gfs2_sbd *sdp) static void thaw_glock(struct gfs2_glock *gl) { - if (!test_and_clear_bit(GLF_FROZEN, &gl->gl_flags)) { - gfs2_glock_put(gl); + if (!test_and_clear_bit(GLF_FROZEN, &gl->gl_flags)) + return; + if (!lockref_get_not_dead(&gl->gl_lockref)) return; - } set_bit(GLF_REPLY_PENDING, &gl->gl_flags); gfs2_glock_queue_work(gl, 0); } @@ -1975,9 +1974,12 @@ static void clear_glock(struct gfs2_glock *gl) gfs2_glock_remove_from_lru(gl); spin_lock(&gl->gl_lockref.lock); - if (gl->gl_state != LM_ST_UNLOCKED) - handle_callback(gl, LM_ST_UNLOCKED, 0, false); - __gfs2_glock_queue_work(gl, 0); + if (!__lockref_is_dead(&gl->gl_lockref)) { + gl->gl_lockref.count++; + if (gl->gl_state != LM_ST_UNLOCKED) + handle_callback(gl, LM_ST_UNLOCKED, 0, false); + __gfs2_glock_queue_work(gl, 0); + } spin_unlock(&gl->gl_lockref.lock); } -- 2.33.0