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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 A884EC33CAF for ; Thu, 16 Jan 2020 18:04:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8373824685 for ; Thu, 16 Jan 2020 18:04:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579197871; bh=/hDmGflEhq6AeFLHnnAF4uDxCRj0GD0kkhCevuf4HuE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=1kfWcj+dzrO8NiAJZ8hPs4UxlNikLgydOps20t/HrNqFV1/2hqy1ncPQgYyrloCm6 QBhx3/Cyxp5lJnJwhXq/AK1jF81ivSjDKrdsx0n717ioIandOVxLYWc0R1miPZns5b DY84WnHEUFv1jS2IhvZ2o4XHc2yUfV3HTHWDb/Lg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387459AbgAPSEa (ORCPT ); Thu, 16 Jan 2020 13:04:30 -0500 Received: from mail.kernel.org ([198.145.29.99]:57742 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732417AbgAPRkc (ORCPT ); Thu, 16 Jan 2020 12:40:32 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 1553024706; Thu, 16 Jan 2020 17:40:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579196432; bh=/hDmGflEhq6AeFLHnnAF4uDxCRj0GD0kkhCevuf4HuE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HaxJGcbIKrgc1GSu82/B0dIORT5Rqgn/joSAWqUlOeJRqgQ5HnxjMKDxsDxrcLaHE eBWnqYdBRbNxQyWN0HoZ54gJvNBq9EaPbm55eKHGdZFaXK64Ry6xmyx8I7cv+ceTGM L7VxF8AtOWhpWqI33Lsl1ZBWRy9Bqn9LYOXQTwc8= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Filipe Manana , Nikolay Borisov , David Sterba , Sasha Levin , linux-btrfs@vger.kernel.org Subject: [PATCH AUTOSEL 4.9 198/251] Btrfs: fix hang when loading existing inode cache off disk Date: Thu, 16 Jan 2020 12:35:47 -0500 Message-Id: <20200116173641.22137-158-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200116173641.22137-1-sashal@kernel.org> References: <20200116173641.22137-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@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 d27014b8bf72..075b59516c8c 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