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=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 6901CC352A3 for ; Mon, 10 Feb 2020 13:00:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4010320714 for ; Mon, 10 Feb 2020 13:00:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581339648; bh=+hVjet8x8xhCop3w3Qv6XSKiht3LeBG54hjzdtOxshE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=md12CDHtHP4b6IoOE7iwTcaFka3m0ppXK52ki5pnMgBmo75C23Jh+aqZXe6sNQ3MF joBKgnaR+9Vk1I/y93jGTS+oVmllWxoFR43BbMOYgVprepB1PdI6nJ1uRwa0K7DYMM joVmlEXt/Dq+bn8pOkyISxEvAQfmwcv9wF33nqAo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730419AbgBJNAr (ORCPT ); Mon, 10 Feb 2020 08:00:47 -0500 Received: from mail.kernel.org ([198.145.29.99]:42010 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729397AbgBJMk6 (ORCPT ); Mon, 10 Feb 2020 07:40:58 -0500 Received: from localhost (unknown [209.37.97.194]) (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 7B79121739; Mon, 10 Feb 2020 12:40:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581338457; bh=+hVjet8x8xhCop3w3Qv6XSKiht3LeBG54hjzdtOxshE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=a/WUVy82z1NLI2LFDuNedKiYCxd0U6dwBbeXtIrK69uTKGLqCwHKecMb/nfh/gk80 aGSgGxMu6lEYKRSOsh5v3pHch5EzgOub2W4wZHtw20ml0Mq5tQ7nixG7KWFR6HO0mT /rbNG/9NM5fs4u7SYUfcK+lQEf5pCeOD/jA30Dos= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Nikolay Borisov , David Sterba Subject: [PATCH 5.5 203/367] btrfs: Correctly handle empty trees in find_first_clear_extent_bit Date: Mon, 10 Feb 2020 04:31:56 -0800 Message-Id: <20200210122443.241981326@linuxfoundation.org> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200210122423.695146547@linuxfoundation.org> References: <20200210122423.695146547@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: Nikolay Borisov commit 5750c37523a2c8cbb450b9ef31e21c2ba876b05e upstream. Raviu reported that running his regular fs_trim segfaulted with the following backtrace: [ 237.525947] assertion failed: prev, in ../fs/btrfs/extent_io.c:1595 [ 237.525984] ------------[ cut here ]------------ [ 237.525985] kernel BUG at ../fs/btrfs/ctree.h:3117! [ 237.525992] invalid opcode: 0000 [#1] SMP PTI [ 237.525998] CPU: 4 PID: 4423 Comm: fstrim Tainted: G U OE 5.4.14-8-vanilla #1 [ 237.526001] Hardware name: ASUSTeK COMPUTER INC. [ 237.526044] RIP: 0010:assfail.constprop.58+0x18/0x1a [btrfs] [ 237.526079] Call Trace: [ 237.526120] find_first_clear_extent_bit+0x13d/0x150 [btrfs] [ 237.526148] btrfs_trim_fs+0x211/0x3f0 [btrfs] [ 237.526184] btrfs_ioctl_fitrim+0x103/0x170 [btrfs] [ 237.526219] btrfs_ioctl+0x129a/0x2ed0 [btrfs] [ 237.526227] ? filemap_map_pages+0x190/0x3d0 [ 237.526232] ? do_filp_open+0xaf/0x110 [ 237.526238] ? _copy_to_user+0x22/0x30 [ 237.526242] ? cp_new_stat+0x150/0x180 [ 237.526247] ? do_vfs_ioctl+0xa4/0x640 [ 237.526278] ? btrfs_ioctl_get_supported_features+0x30/0x30 [btrfs] [ 237.526283] do_vfs_ioctl+0xa4/0x640 [ 237.526288] ? __do_sys_newfstat+0x3c/0x60 [ 237.526292] ksys_ioctl+0x70/0x80 [ 237.526297] __x64_sys_ioctl+0x16/0x20 [ 237.526303] do_syscall_64+0x5a/0x1c0 [ 237.526310] entry_SYSCALL_64_after_hwframe+0x49/0xbe That was due to btrfs_fs_device::aloc_tree being empty. Initially I thought this wasn't possible and as a percaution have put the assert in find_first_clear_extent_bit. Turns out this is indeed possible and could happen when a file system with SINGLE data/metadata profile has a 2nd device added. Until balance is run or a new chunk is allocated on this device it will be completely empty. In this case find_first_clear_extent_bit should return the full range [0, -1ULL] and let the caller handle this i.e for trim the end will be capped at the size of actual device. Link: https://lore.kernel.org/linux-btrfs/izW2WNyvy1dEDweBICizKnd2KDwDiDyY2EYQr4YCwk7pkuIpthx-JRn65MPBde00ND6V0_Lh8mW0kZwzDiLDv25pUYWxkskWNJnVP0kgdMA=@protonmail.com/ Fixes: 45bfcfc168f8 ("btrfs: Implement find_first_clear_extent_bit") CC: stable@vger.kernel.org # 5.2+ Signed-off-by: Nikolay Borisov Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman --- fs/btrfs/extent_io.c | 32 ++++++++++++++++++-------------- fs/btrfs/tests/extent-io-tests.c | 9 +++++++++ 2 files changed, 27 insertions(+), 14 deletions(-) --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -1593,21 +1593,25 @@ void find_first_clear_extent_bit(struct /* Find first extent with bits cleared */ while (1) { node = __etree_search(tree, start, &next, &prev, NULL, NULL); - if (!node) { + if (!node && !next && !prev) { + /* + * Tree is completely empty, send full range and let + * caller deal with it + */ + *start_ret = 0; + *end_ret = -1; + goto out; + } else if (!node && !next) { + /* + * We are past the last allocated chunk, set start at + * the end of the last extent. + */ + state = rb_entry(prev, struct extent_state, rb_node); + *start_ret = state->end + 1; + *end_ret = -1; + goto out; + } else if (!node) { node = next; - if (!node) { - /* - * We are past the last allocated chunk, - * set start at the end of the last extent. The - * device alloc tree should never be empty so - * prev is always set. - */ - ASSERT(prev); - state = rb_entry(prev, struct extent_state, rb_node); - *start_ret = state->end + 1; - *end_ret = -1; - goto out; - } } /* * At this point 'node' either contains 'start' or start is --- a/fs/btrfs/tests/extent-io-tests.c +++ b/fs/btrfs/tests/extent-io-tests.c @@ -441,8 +441,17 @@ static int test_find_first_clear_extent_ int ret = -EINVAL; test_msg("running find_first_clear_extent_bit test"); + extent_io_tree_init(NULL, &tree, IO_TREE_SELFTEST, NULL); + /* Test correct handling of empty tree */ + find_first_clear_extent_bit(&tree, 0, &start, &end, CHUNK_TRIMMED); + if (start != 0 || end != -1) { + test_err( + "error getting a range from completely empty tree: start %llu end %llu", + start, end); + goto out; + } /* * Set 1M-4M alloc/discard and 32M-64M thus leaving a hole between * 4M-32M