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 X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DBE48C3815B for ; Mon, 20 Apr 2020 12:40:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BAD0820736 for ; Mon, 20 Apr 2020 12:40:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587386445; bh=61WFqwITioEntxRH6QDaMEwXKdxo0S5pX28b3CWeGdc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=UOB4bY3RClS1aImMPAlrGzJEXy46ETS+WRvenyt/iIiUOJw6AntaoTdNAZaZxmytT 3EGUdKRlvB8po6C7lEDwjPCeJNifyJhL2zjyz7f6RePKnEZ6MSC/lS1K5HMkKpi79R cH1FT1omOptHvvx2vey9bwpDsF5jUJ+FS5gGtVEM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727835AbgDTMkp (ORCPT ); Mon, 20 Apr 2020 08:40:45 -0400 Received: from mail.kernel.org ([198.145.29.99]:33072 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727820AbgDTMkm (ORCPT ); Mon, 20 Apr 2020 08:40:42 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C6CD82070B; Mon, 20 Apr 2020 12:40:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587386442; bh=61WFqwITioEntxRH6QDaMEwXKdxo0S5pX28b3CWeGdc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bWYalH9mBkyV2PM7H99mhox+Qp9z8vtUjuDE+reObChzistMmbgKWfm+L542R9mMS PjpQg6iIPjOOINhAW6m36jwybvpE6sP++Z2sx9wTBJfAcVz03NqB2EEVeMCfLjaQiQ S0phWhZlJPJshv5uwAflI6eAVayXoaNIPpXG16RI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jan Kara , "zhangyi (F)" , Theodore Tso Subject: [PATCH 5.5 24/65] jbd2: improve comments about freeing data buffers whose page mapping is NULL Date: Mon, 20 Apr 2020 14:38:28 +0200 Message-Id: <20200420121511.700998688@linuxfoundation.org> X-Mailer: git-send-email 2.26.1 In-Reply-To: <20200420121505.909671922@linuxfoundation.org> References: <20200420121505.909671922@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: zhangyi (F) commit 780f66e59231fcf882f36c63f287252ee47cc75a upstream. Improve comments in jbd2_journal_commit_transaction() to describe why we don't need to clear the buffer_mapped bit for freeing file mapping buffers whose page mapping is NULL. Link: https://lore.kernel.org/r/20200217112706.20085-1-yi.zhang@huawei.com Fixes: c96dceeabf76 ("jbd2: do not clear the BH_Mapped flag when forgetting a metadata buffer") Suggested-by: Jan Kara Reviewed-by: Jan Kara Signed-off-by: zhangyi (F) Signed-off-by: Theodore Ts'o Signed-off-by: Greg Kroah-Hartman --- fs/jbd2/commit.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) --- a/fs/jbd2/commit.c +++ b/fs/jbd2/commit.c @@ -997,9 +997,10 @@ restart_loop: * journalled data) we need to unmap buffer and clear * more bits. We also need to be careful about the check * because the data page mapping can get cleared under - * out hands, which alse need not to clear more bits - * because the page and buffers will be freed and can - * never be reused once we are done with them. + * our hands. Note that if mapping == NULL, we don't + * need to make buffer unmapped because the page is + * already detached from the mapping and buffers cannot + * get reused. */ mapping = READ_ONCE(bh->b_page->mapping); if (mapping && !sb_is_blkdev_sb(mapping->host->i_sb)) {