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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 A03ECC4320E for ; Sun, 29 Aug 2021 05:25:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 89B7B60F39 for ; Sun, 29 Aug 2021 05:25:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234800AbhH2F0Z (ORCPT ); Sun, 29 Aug 2021 01:26:25 -0400 Received: from smtp-out1.suse.de ([195.135.220.28]:59418 "EHLO smtp-out1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234784AbhH2F0X (ORCPT ); Sun, 29 Aug 2021 01:26:23 -0400 Received: from imap1.suse-dmz.suse.de (imap1.suse-dmz.suse.de [192.168.254.73]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 0C0B021D6A for ; Sun, 29 Aug 2021 05:25:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1630214731; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=xnPty9NpjNaK8w9BEXEdx93WEuA4DkXxoQo+onTUaC0=; b=uhQxK3jshxzseqWFPFXYXowycVTVY6BPIAqOyhQPP+wIaONnYeTniszdjbmos3DDIfPVwE B28YkPdC+cL9UQGNP6v1pAz2hZrr3LFCvrqpNzNlZE5kRBEZpbK8Fo9PGomol8c/+MAEG9 uN5WjuVXH/rmHgf2vaCZZ8l5c7THF7c= Received: from imap1.suse-dmz.suse.de (imap1.suse-dmz.suse.de [192.168.254.73]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap1.suse-dmz.suse.de (Postfix) with ESMTPS id 4910713964 for ; Sun, 29 Aug 2021 05:25:30 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap1.suse-dmz.suse.de with ESMTPSA id AMVfA0oaK2HnPAAAGKfGzw (envelope-from ) for ; Sun, 29 Aug 2021 05:25:30 +0000 From: Qu Wenruo To: linux-btrfs@vger.kernel.org Subject: [PATCH v2 24/26] btrfs: allow page to be unlocked by btrfs_page_end_writer_lock() even if it's locked by plain page_lock() Date: Sun, 29 Aug 2021 13:24:56 +0800 Message-Id: <20210829052458.15454-25-wqu@suse.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210829052458.15454-1-wqu@suse.com> References: <20210829052458.15454-1-wqu@suse.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org There are several call sites of extent_clear_unlock_delalloc() which gets @locked_page = NULL. So that extent_clear_unlock_delalloc() will try to call process_one_page() to unlock every page even the first page is not locked by btrfs_page_start_writer_lock(). This will trigger an ASSERT() in btrfs_subpage_end_and_test_writer() as previously we require every page passed to btrfs_subpage_end_and_test_writer() to be locked by btrfs_page_start_writer_lock(). But compression path doesn't go that way. Thankfully it's not hard to distinguish page locked by lock_page() and btrfs_page_start_writer_lock(). So do the check in btrfs_subpage_end_and_test_writer() so now it can handle both cases well. Signed-off-by: Qu Wenruo --- fs/btrfs/subpage.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/fs/btrfs/subpage.c b/fs/btrfs/subpage.c index 50b3d96289ca..39d63a21dcb9 100644 --- a/fs/btrfs/subpage.c +++ b/fs/btrfs/subpage.c @@ -292,6 +292,17 @@ bool btrfs_subpage_end_and_test_writer(const struct btrfs_fs_info *fs_info, btrfs_subpage_assert(fs_info, page, start, len); + /* + * We have call sites passing @lock_page into + * extent_clear_unlock_delalloc() for compression path. + * + * Those @locked_page is locked by plain lock_page(), thus its + * subpage::writers is 0. + * Handle them specially. + */ + if (atomic_read(&subpage->writers) == 0) + return true; + ASSERT(atomic_read(&subpage->writers) >= nbits); return atomic_sub_and_test(nbits, &subpage->writers); } -- 2.32.0