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=-19.0 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 CBAB1C07E9A for ; Sun, 4 Jul 2021 23:07:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B5E136193E for ; Sun, 4 Jul 2021 23:07:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231186AbhGDXKS (ORCPT ); Sun, 4 Jul 2021 19:10:18 -0400 Received: from mail.kernel.org ([198.145.29.99]:48032 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230103AbhGDXIk (ORCPT ); Sun, 4 Jul 2021 19:08:40 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id F1EC3613F1; Sun, 4 Jul 2021 23:06:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1625439964; bh=S6WU4q0VaFrz8X2GaTSL4Y4hPxSAdB7d1yQ7EEGeF+Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=T/HvCR7elDomjJSa4sr5LW2NkUmabRs3yz4iQMhZpdaJwjWvMd6bK/kiVEOvVN8X0 3QdVpian5pFZ0+kzvW3hbkRDlGbmmklBamOmUVwp4U1Go6rxq4spxqi+QDOAWKnG5z cE2/0b+Hz3LYjTMTPIM0PIEas4cJ4GFhS1iamOo7jqoMSvhiFXjfm+vEQkh0RK+uUU 60VTg6XjuaEvxnjjqfHIOGisIDhjf7U9puy6EsrAeriIS0v7fKNgN5Hi0LWxXRK2tB YZub8fN34gZgPdvl78jbMhDGQDZ6TREqycmfGeElqLBRI6vp2Ntpw4VuKmJbczsUaQ sc3oD6I79RwUg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Qu Wenruo , Ritesh Harjani , Anand Jain , David Sterba , Sasha Levin , linux-btrfs@vger.kernel.org Subject: [PATCH AUTOSEL 5.13 77/85] btrfs: don't clear page extent mapped if we're not invalidating the full page Date: Sun, 4 Jul 2021 19:04:12 -0400 Message-Id: <20210704230420.1488358-77-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210704230420.1488358-1-sashal@kernel.org> References: <20210704230420.1488358-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Qu Wenruo [ Upstream commit bcd77455d590eaa0422a5e84ae852007cfce574a ] [BUG] With current btrfs subpage rw support, the following script can lead to fs hang: $ mkfs.btrfs -f -s 4k $dev $ mount $dev -o nospace_cache $mnt $ fsstress -w -n 100 -p 1 -s 1608140256 -v -d $mnt The fs will hang at btrfs_start_ordered_extent(). [CAUSE] In above test case, btrfs_invalidate() will be called with the following parameters: offset = 0 length = 53248 page dirty = 1 subpage dirty bitmap = 0x2000 Since @offset is 0, btrfs_invalidate() will try to invalidate the full page, and finally call clear_page_extent_mapped() which will detach subpage structure from the page. And since the page no longer has subpage structure, the subpage dirty bitmap will be cleared, preventing the dirty range from being written back, thus no way to wake up the ordered extent. [FIX] Just follow other filesystems, only to invalidate the page if the range covers the full page. There are cases like truncate_setsize() which can call btrfs_invalidatepage() with offset == 0 and length != 0 for the last page of an inode. Although the old code will still try to invalidate the full page, we are still safe to just wait for ordered extent to finish. So it shouldn't cause extra problems. Tested-by: Ritesh Harjani # [ppc64] Tested-by: Anand Jain # [aarch64] Signed-off-by: Qu Wenruo Signed-off-by: David Sterba Signed-off-by: Sasha Levin --- fs/btrfs/inode.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index f9942560866b..5d147f204fca 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -8390,7 +8390,19 @@ static void btrfs_invalidatepage(struct page *page, unsigned int offset, */ wait_on_page_writeback(page); - if (offset) { + /* + * For subpage case, we have call sites like + * btrfs_punch_hole_lock_range() which passes range not aligned to + * sectorsize. + * If the range doesn't cover the full page, we don't need to and + * shouldn't clear page extent mapped, as page->private can still + * record subpage dirty bits for other part of the range. + * + * For cases that can invalidate the full even the range doesn't + * cover the full page, like invalidating the last page, we're + * still safe to wait for ordered extent to finish. + */ + if (!(offset == 0 && length == PAGE_SIZE)) { btrfs_releasepage(page, GFP_NOFS); return; } -- 2.30.2