From patchwork Mon Dec 28 12:50:17 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 353196 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=-18.7 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,URIBL_RED, USER_AGENT_GIT autolearn=unavailable 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 00FF4C43333 for ; Mon, 28 Dec 2020 15:56:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CC3F720829 for ; Mon, 28 Dec 2020 15:56:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389122AbgL1NeR (ORCPT ); Mon, 28 Dec 2020 08:34:17 -0500 Received: from mail.kernel.org ([198.145.29.99]:34738 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389098AbgL1NeR (ORCPT ); Mon, 28 Dec 2020 08:34:17 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id C2A8620867; Mon, 28 Dec 2020 13:33:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1609162416; bh=bctFitTEeo52VyCh0ydGO5T7uJluqm3P91V+Q30OYy8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=RwWt57Dq7523dCuKD62uFFB+c+A+rOdXyzZfb8jyIBI9ZehZ9iFArBCnRCy9llB57 8Uh6C1ms9am1gD/UxirLOYWnX+0YF9WK2pJ4XilZS9AJlGxb9tsSBBtAqjPZk6NXTW yk5BW/f1TrlhncF8pow2O5nQJieyfKge6rwR+vE0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jan Kara , Andreas Dilger , Theodore Tso Subject: [PATCH 4.19 298/346] ext4: fix deadlock with fs freezing and EA inodes Date: Mon, 28 Dec 2020 13:50:17 +0100 Message-Id: <20201228124934.188145516@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201228124919.745526410@linuxfoundation.org> References: <20201228124919.745526410@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Jan Kara commit 46e294efc355c48d1dd4d58501aa56dac461792a upstream. Xattr code using inodes with large xattr data can end up dropping last inode reference (and thus deleting the inode) from places like ext4_xattr_set_entry(). That function is called with transaction started and so ext4_evict_inode() can deadlock against fs freezing like: CPU1 CPU2 removexattr() freeze_super() vfs_removexattr() ext4_xattr_set() handle = ext4_journal_start() ... ext4_xattr_set_entry() iput(old_ea_inode) ext4_evict_inode(old_ea_inode) sb->s_writers.frozen = SB_FREEZE_FS; sb_wait_write(sb, SB_FREEZE_FS); ext4_freeze() jbd2_journal_lock_updates() -> blocks waiting for all handles to stop sb_start_intwrite() -> blocks as sb is already in SB_FREEZE_FS state Generally it is advisable to delete inodes from a separate transaction as it can consume quite some credits however in this case it would be quite clumsy and furthermore the credits for inode deletion are quite limited and already accounted for. So just tweak ext4_evict_inode() to avoid freeze protection if we have transaction already started and thus it is not really needed anyway. Cc: stable@vger.kernel.org Fixes: dec214d00e0d ("ext4: xattr inode deduplication") Signed-off-by: Jan Kara Reviewed-by: Andreas Dilger Link: https://lore.kernel.org/r/20201127110649.24730-1-jack@suse.cz Signed-off-by: Theodore Ts'o Signed-off-by: Greg Kroah-Hartman --- fs/ext4/inode.c | 21 +++++++++++++++------ 1 file changed, 15 insertions(+), 6 deletions(-) --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -203,6 +203,7 @@ void ext4_evict_inode(struct inode *inod */ int extra_credits = 6; struct ext4_xattr_inode_array *ea_inode_array = NULL; + bool freeze_protected = false; trace_ext4_evict_inode(inode); @@ -250,9 +251,14 @@ void ext4_evict_inode(struct inode *inod /* * Protect us against freezing - iput() caller didn't have to have any - * protection against it - */ - sb_start_intwrite(inode->i_sb); + * protection against it. When we are in a running transaction though, + * we are already protected against freezing and we cannot grab further + * protection due to lock ordering constraints. + */ + if (!ext4_journal_current_handle()) { + sb_start_intwrite(inode->i_sb); + freeze_protected = true; + } if (!IS_NOQUOTA(inode)) extra_credits += EXT4_MAXQUOTAS_DEL_BLOCKS(inode->i_sb); @@ -271,7 +277,8 @@ void ext4_evict_inode(struct inode *inod * cleaned up. */ ext4_orphan_del(NULL, inode); - sb_end_intwrite(inode->i_sb); + if (freeze_protected) + sb_end_intwrite(inode->i_sb); goto no_delete; } @@ -312,7 +319,8 @@ void ext4_evict_inode(struct inode *inod stop_handle: ext4_journal_stop(handle); ext4_orphan_del(NULL, inode); - sb_end_intwrite(inode->i_sb); + if (freeze_protected) + sb_end_intwrite(inode->i_sb); ext4_xattr_inode_array_free(ea_inode_array); goto no_delete; } @@ -341,7 +349,8 @@ stop_handle: else ext4_free_inode(handle, inode); ext4_journal_stop(handle); - sb_end_intwrite(inode->i_sb); + if (freeze_protected) + sb_end_intwrite(inode->i_sb); ext4_xattr_inode_array_free(ea_inode_array); return; no_delete: