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=-8.2 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 AD199C3A5A1 for ; Thu, 29 Aug 2019 01:27:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 74E29215EA for ; Thu, 29 Aug 2019 01:27:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="UOON+qrM" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726369AbfH2B1I (ORCPT ); Wed, 28 Aug 2019 21:27:08 -0400 Received: from mail-pg1-f193.google.com ([209.85.215.193]:45112 "EHLO mail-pg1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726128AbfH2B1I (ORCPT ); Wed, 28 Aug 2019 21:27:08 -0400 Received: by mail-pg1-f193.google.com with SMTP id o13so648027pgp.12 for ; Wed, 28 Aug 2019 18:27:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=lybQwmkSywGY6VJPerqA1d4tZAxxHJ7vK0Gvnr9Vtvc=; b=UOON+qrM0pHG7/vVxYs95AOICSCJJBMQPJ/kyngXdGrrwRqkIJ/xQXn6fluwvb9fkX m1UPbT3XDkv1XtuUTuf7cuF6SVpd5ltUg3bG46RasNuZVHg9FNP4Myg8VW3+p8rPQolS ISLrOkuhlodgYDKwyi2zJVI5Auh2e3pmQ5evLJKSA/Zc+g9ODMwYqXbv4FbToMRAUDzD 6/OHz+5esMRZ08aVkTravWkGJcDffoEIJe6Uaq5ilgb3zSI9N2VvlvJa94goKFpsyZBc SVXwmpAx2robpKOLl2UXT3DRvde6grvO73gX3dSRPiibrqHUjvKfNezFhyGKHQPShcH0 VZBA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=lybQwmkSywGY6VJPerqA1d4tZAxxHJ7vK0Gvnr9Vtvc=; b=jRbyYMKFUxoMpxkNmnD7UXDgRRxmzsepS+a9EEW/BNSWrQWBE6Tchte4VXKtOVClbJ MJUxth2q5US4TDcIS0dkwktiBZEqu2ULW1KPxsnmNBORaJz0ZPrhoBWIy9VzGsQsrqD7 D0wq/h4TKhB8iqry24U9LpSOK2y/vsyht/abUqIzAwTjWyRTozo4sW5AT+05AX1Meipv mHZlsu05mOqu0cC00BUGpBCBVS17xRHezWTnQUBxpmOTSzmB+9nVrtiR5G9patK4sJtb S9To3wn0f3fyktKeC++Fp3CO0jkXAyy4uXhJCJujdMXiG/wuas82vaPEgKxXULNnN8V4 98qQ== X-Gm-Message-State: APjAAAXLG9X7dR7KEMtX6djEwm9fn9eCxauWpDew4EetL6dsEspPLmOX sqhFyqLYX9qjoOEbK2HgsA== X-Google-Smtp-Source: APXvYqxKwYyhErFUJ+yBeO0bv3zh7DPhc/FNPqy+6qbaF5DA2yk0pxgsmOSdTIBDhiZMiFMr3Ae6gg== X-Received: by 2002:a63:c246:: with SMTP id l6mr6097961pgg.210.1567042027426; Wed, 28 Aug 2019 18:27:07 -0700 (PDT) Received: from [10.76.90.34] ([203.205.141.123]) by smtp.gmail.com with ESMTPSA id 65sm672853pff.148.2019.08.28.18.27.04 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 28 Aug 2019 18:27:06 -0700 (PDT) Subject: Re: [PATCH v3] xfs: Fix ABBA deadlock between AGI and AGF when performing rename() with RENAME_WHITEOUT flag To: linux-xfs@vger.kernel.org, "Darrick J. Wong" Cc: Dave Chinner , Brian Foster , newtongao@tencent.com, jasperwang@tencent.com References: <55d0f202-62a7-0b1c-a386-2395b19b47c5@gmail.com> From: kaixuxia Message-ID: <51bf333b-7694-68dc-4434-d15cbb24ccfb@gmail.com> Date: Thu, 29 Aug 2019 09:27:03 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <55d0f202-62a7-0b1c-a386-2395b19b47c5@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org ping... Because there isn't this patch in the latest xfs-for-next branch update... On 2019/8/27 10:54, kaixuxia wrote: > When performing rename operation with RENAME_WHITEOUT flag, we will > hold AGF lock to allocate or free extents in manipulating the dirents > firstly, and then doing the xfs_iunlink_remove() call last to hold > AGI lock to modify the tmpfile info, so we the lock order AGI->AGF. > > The big problem here is that we have an ordering constraint on AGF > and AGI locking - inode allocation locks the AGI, then can allocate > a new extent for new inodes, locking the AGF after the AGI. Hence > the ordering that is imposed by other parts of the code is AGI before > AGF. So we get an ABBA deadlock between the AGI and AGF here. > > Process A: > Call trace: > ? __schedule+0x2bd/0x620 > schedule+0x33/0x90 > schedule_timeout+0x17d/0x290 > __down_common+0xef/0x125 > ? xfs_buf_find+0x215/0x6c0 [xfs] > down+0x3b/0x50 > xfs_buf_lock+0x34/0xf0 [xfs] > xfs_buf_find+0x215/0x6c0 [xfs] > xfs_buf_get_map+0x37/0x230 [xfs] > xfs_buf_read_map+0x29/0x190 [xfs] > xfs_trans_read_buf_map+0x13d/0x520 [xfs] > xfs_read_agf+0xa6/0x180 [xfs] > ? schedule_timeout+0x17d/0x290 > xfs_alloc_read_agf+0x52/0x1f0 [xfs] > xfs_alloc_fix_freelist+0x432/0x590 [xfs] > ? down+0x3b/0x50 > ? xfs_buf_lock+0x34/0xf0 [xfs] > ? xfs_buf_find+0x215/0x6c0 [xfs] > xfs_alloc_vextent+0x301/0x6c0 [xfs] > xfs_ialloc_ag_alloc+0x182/0x700 [xfs] > ? _xfs_trans_bjoin+0x72/0xf0 [xfs] > xfs_dialloc+0x116/0x290 [xfs] > xfs_ialloc+0x6d/0x5e0 [xfs] > ? xfs_log_reserve+0x165/0x280 [xfs] > xfs_dir_ialloc+0x8c/0x240 [xfs] > xfs_create+0x35a/0x610 [xfs] > xfs_generic_create+0x1f1/0x2f0 [xfs] > ... > > Process B: > Call trace: > ? __schedule+0x2bd/0x620 > ? xfs_bmapi_allocate+0x245/0x380 [xfs] > schedule+0x33/0x90 > schedule_timeout+0x17d/0x290 > ? xfs_buf_find+0x1fd/0x6c0 [xfs] > __down_common+0xef/0x125 > ? xfs_buf_get_map+0x37/0x230 [xfs] > ? xfs_buf_find+0x215/0x6c0 [xfs] > down+0x3b/0x50 > xfs_buf_lock+0x34/0xf0 [xfs] > xfs_buf_find+0x215/0x6c0 [xfs] > xfs_buf_get_map+0x37/0x230 [xfs] > xfs_buf_read_map+0x29/0x190 [xfs] > xfs_trans_read_buf_map+0x13d/0x520 [xfs] > xfs_read_agi+0xa8/0x160 [xfs] > xfs_iunlink_remove+0x6f/0x2a0 [xfs] > ? current_time+0x46/0x80 > ? xfs_trans_ichgtime+0x39/0xb0 [xfs] > xfs_rename+0x57a/0xae0 [xfs] > xfs_vn_rename+0xe4/0x150 [xfs] > ... > > In this patch we move the xfs_iunlink_remove() call to > before acquiring the AGF lock to preserve correct AGI/AGF locking > order. > > Signed-off-by: kaixuxia > Reviewed-by: Brian Foster > --- > fs/xfs/xfs_inode.c | 83 +++++++++++++++++++++++++++--------------------------- > 1 file changed, 42 insertions(+), 41 deletions(-) > > diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c > index 6467d5e..8ffd44f 100644 > --- a/fs/xfs/xfs_inode.c > +++ b/fs/xfs/xfs_inode.c > @@ -3282,7 +3282,8 @@ struct xfs_iunlink { > spaceres); > > /* > - * Set up the target. > + * Check for expected errors before we dirty the transaction > + * so we can return an error without a transaction abort. > */ > if (target_ip == NULL) { > /* > @@ -3294,6 +3295,46 @@ struct xfs_iunlink { > if (error) > goto out_trans_cancel; > } > + } else { > + /* > + * If target exists and it's a directory, check that whether > + * it can be destroyed. > + */ > + if (S_ISDIR(VFS_I(target_ip)->i_mode) && > + (!xfs_dir_isempty(target_ip) || > + (VFS_I(target_ip)->i_nlink > 2))) { > + error = -EEXIST; > + goto out_trans_cancel; > + } > + } > + > + /* > + * Directory entry creation below may acquire the AGF. Remove > + * the whiteout from the unlinked list first to preserve correct > + * AGI/AGF locking order. This dirties the transaction so failures > + * after this point will abort and log recovery will clean up the > + * mess. > + * > + * For whiteouts, we need to bump the link count on the whiteout > + * inode. After this point, we have a real link, clear the tmpfile > + * state flag from the inode so it doesn't accidentally get misused > + * in future. > + */ > + if (wip) { > + ASSERT(VFS_I(wip)->i_nlink == 0); > + error = xfs_iunlink_remove(tp, wip); > + if (error) > + goto out_trans_cancel; > + > + xfs_bumplink(tp, wip); > + xfs_trans_log_inode(tp, wip, XFS_ILOG_CORE); > + VFS_I(wip)->i_state &= ~I_LINKABLE; > + } > + > + /* > + * Set up the target. > + */ > + if (target_ip == NULL) { > /* > * If target does not exist and the rename crosses > * directories, adjust the target directory link count > @@ -3312,22 +3353,6 @@ struct xfs_iunlink { > } > } else { /* target_ip != NULL */ > /* > - * If target exists and it's a directory, check that both > - * target and source are directories and that target can be > - * destroyed, or that neither is a directory. > - */ > - if (S_ISDIR(VFS_I(target_ip)->i_mode)) { > - /* > - * Make sure target dir is empty. > - */ > - if (!(xfs_dir_isempty(target_ip)) || > - (VFS_I(target_ip)->i_nlink > 2)) { > - error = -EEXIST; > - goto out_trans_cancel; > - } > - } > - > - /* > * Link the source inode under the target name. > * If the source inode is a directory and we are moving > * it across directories, its ".." entry will be > @@ -3417,30 +3442,6 @@ struct xfs_iunlink { > if (error) > goto out_trans_cancel; > > - /* > - * For whiteouts, we need to bump the link count on the whiteout inode. > - * This means that failures all the way up to this point leave the inode > - * on the unlinked list and so cleanup is a simple matter of dropping > - * the remaining reference to it. If we fail here after bumping the link > - * count, we're shutting down the filesystem so we'll never see the > - * intermediate state on disk. > - */ > - if (wip) { > - ASSERT(VFS_I(wip)->i_nlink == 0); > - xfs_bumplink(tp, wip); > - error = xfs_iunlink_remove(tp, wip); > - if (error) > - goto out_trans_cancel; > - xfs_trans_log_inode(tp, wip, XFS_ILOG_CORE); > - > - /* > - * Now we have a real link, clear the "I'm a tmpfile" state > - * flag from the inode so it doesn't accidentally get misused in > - * future. > - */ > - VFS_I(wip)->i_state &= ~I_LINKABLE; > - } > - > xfs_trans_ichgtime(tp, src_dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG); > xfs_trans_log_inode(tp, src_dp, XFS_ILOG_CORE); > if (new_parent) > -- kaixuxia