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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,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 B8753C33CB2 for ; Tue, 28 Jan 2020 14:35:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 84A5B20716 for ; Tue, 28 Jan 2020 14:35:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1580222141; bh=la3xfm77mTHrN9MjZAExRmGreRCnVATFwQRG5TLWQBw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=CmMT9sOZQxJPCIzQFdvcyyKDYg3TrmfYTCGNp5DFKIE36Z17eLocAPAMiG/z7/WVe ko/S9aRD8yAo/Dhg58+s/GQ4b3yBZcsfkIR1+o75cIbxerVocTTGubSsbdD7bDisBi ZYaoLPpF1xSJ10oP/mrHtderljAFmEhvdsplMkJM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731463AbgA1Ofk (ORCPT ); Tue, 28 Jan 2020 09:35:40 -0500 Received: from mail.kernel.org ([198.145.29.99]:48776 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731737AbgA1OWv (ORCPT ); Tue, 28 Jan 2020 09:22:51 -0500 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 3A6F724688; Tue, 28 Jan 2020 14:22:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1580221370; bh=la3xfm77mTHrN9MjZAExRmGreRCnVATFwQRG5TLWQBw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LUoxNo2qzf4f/k1qmSFjtZbmH+1sPIdNMLgYNshJ8Gz10MhVNqee2ylGB/JyODb2I cJcdOGCGWH77KpiFe6+rgAiVLMEAIoh0BuAthEph6TEXra4Ml+c+U1On9p+j1r6vCj Mg2Rv2V1AMGFBDXTrkrzudGAximjYmsv49xmaa6o= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Nikolay Borisov , Filipe Manana , David Sterba , Sasha Levin Subject: [PATCH 4.9 198/271] Btrfs: fix hang when loading existing inode cache off disk Date: Tue, 28 Jan 2020 15:05:47 +0100 Message-Id: <20200128135907.318671466@linuxfoundation.org> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200128135852.449088278@linuxfoundation.org> References: <20200128135852.449088278@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: Filipe Manana [ Upstream commit 7764d56baa844d7f6206394f21a0e8c1f303c476 ] If we are able to load an existing inode cache off disk, we set the state of the cache to BTRFS_CACHE_FINISHED, but we don't wake up any one waiting for the cache to be available. This means that anyone waiting for the cache to be available, waiting on the condition that either its state is BTRFS_CACHE_FINISHED or its available free space is greather than zero, can hang forever. This could be observed running fstests with MOUNT_OPTIONS="-o inode_cache", in particular test case generic/161 triggered it very frequently for me, producing a trace like the following: [63795.739712] BTRFS info (device sdc): enabling inode map caching [63795.739714] BTRFS info (device sdc): disk space caching is enabled [63795.739716] BTRFS info (device sdc): has skinny extents [64036.653886] INFO: task btrfs-transacti:3917 blocked for more than 120 seconds. [64036.654079] Not tainted 5.2.0-rc4-btrfs-next-50 #1 [64036.654143] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [64036.654232] btrfs-transacti D 0 3917 2 0x80004000 [64036.654239] Call Trace: [64036.654258] ? __schedule+0x3ae/0x7b0 [64036.654271] schedule+0x3a/0xb0 [64036.654325] btrfs_commit_transaction+0x978/0xae0 [btrfs] [64036.654339] ? remove_wait_queue+0x60/0x60 [64036.654395] transaction_kthread+0x146/0x180 [btrfs] [64036.654450] ? btrfs_cleanup_transaction+0x620/0x620 [btrfs] [64036.654456] kthread+0x103/0x140 [64036.654464] ? kthread_create_worker_on_cpu+0x70/0x70 [64036.654476] ret_from_fork+0x3a/0x50 [64036.654504] INFO: task xfs_io:3919 blocked for more than 120 seconds. [64036.654568] Not tainted 5.2.0-rc4-btrfs-next-50 #1 [64036.654617] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [64036.654685] xfs_io D 0 3919 3633 0x00000000 [64036.654691] Call Trace: [64036.654703] ? __schedule+0x3ae/0x7b0 [64036.654716] schedule+0x3a/0xb0 [64036.654756] btrfs_find_free_ino+0xa9/0x120 [btrfs] [64036.654764] ? remove_wait_queue+0x60/0x60 [64036.654809] btrfs_create+0x72/0x1f0 [btrfs] [64036.654822] lookup_open+0x6bc/0x790 [64036.654849] path_openat+0x3bc/0xc00 [64036.654854] ? __lock_acquire+0x331/0x1cb0 [64036.654869] do_filp_open+0x99/0x110 [64036.654884] ? __alloc_fd+0xee/0x200 [64036.654895] ? do_raw_spin_unlock+0x49/0xc0 [64036.654909] ? do_sys_open+0x132/0x220 [64036.654913] do_sys_open+0x132/0x220 [64036.654926] do_syscall_64+0x60/0x1d0 [64036.654933] entry_SYSCALL_64_after_hwframe+0x49/0xbe Fix this by adding a wake_up() call right after setting the cache state to BTRFS_CACHE_FINISHED, at start_caching(), when we are able to load the cache from disk. Fixes: 82d5902d9c681b ("Btrfs: Support reading/writing on disk free ino cache") Reviewed-by: Nikolay Borisov Signed-off-by: Filipe Manana Signed-off-by: David Sterba Signed-off-by: Sasha Levin --- fs/btrfs/inode-map.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/btrfs/inode-map.c b/fs/btrfs/inode-map.c index d27014b8bf727..075b59516c8c0 100644 --- a/fs/btrfs/inode-map.c +++ b/fs/btrfs/inode-map.c @@ -159,6 +159,7 @@ static void start_caching(struct btrfs_root *root) spin_lock(&root->ino_cache_lock); root->ino_cache_state = BTRFS_CACHE_FINISHED; spin_unlock(&root->ino_cache_lock); + wake_up(&root->ino_cache_wait); return; } -- 2.20.1