From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sender4-op-o15.zoho.com (sender4-op-o15.zoho.com [136.143.188.15]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F0AE2387344; Wed, 8 Apr 2026 11:21:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=pass smtp.client-ip=136.143.188.15 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775647319; cv=pass; b=X6ZWLj2CZE0xhJ5vyTob9zidTruqr9WuSp3d0ygFQo4K+MleGtRA/SeF3qTZNsvT+dnqpE0oTkZld8Fwe2kEUhKyWe7a7ZhULmtiBWdVZCPAK69StsAqeJ6VbDa9rwdkNyEBJOVVoQQI0/PiaMT56U0+caSthElYr85YGG0MU8o= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775647319; c=relaxed/simple; bh=AKr5Ne+SOqQ2MaUdKMWOqeKOBdL1X/iPI5Ry+IZPdr8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=XuaJyIyvpkP+QkLPOfCn8wkcgtp6hBIFmLD0k1mRO6Llk2cSF2Kx7ZQw2nGXG/Gfg2y0SFCDxCP0/vpVVcxy8qevQej3YeQDl2/9QZHR4W8i6rE/Ofc+Knkk5oxtmmGI9Ni1xIkro8vOkJ8OrvowQKbvw5ouVaog+eoesv50MeU= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.beauty; spf=pass smtp.mailfrom=linux.beauty; dkim=pass (1024-bit key) header.d=linux.beauty header.i=me@linux.beauty header.b=qlYwjWHf; arc=pass smtp.client-ip=136.143.188.15 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.beauty Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.beauty Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.beauty header.i=me@linux.beauty header.b="qlYwjWHf" ARC-Seal: i=1; a=rsa-sha256; t=1775647260; cv=none; d=zohomail.com; s=zohoarc; b=mziqE4wg/C9GBLJS71Zn/o6TAWIp7Oj+fInmxOTf9Nt42aapgACmOQZ0EpdrUiHxiv0ByKgGn47a1pWJkk5i/Ray+XYGVP6/1VxAMOhsovltR20nMiZGQNtX6Iz5T24jghw1IFymHRIYbkphmsWDUfY5/w7m4HmbnSoJpg6r2nw= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1775647260; h=Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:MIME-Version:Message-ID:References:Subject:Subject:To:To:Message-Id:Reply-To; bh=YnM0+++sh+xA2p+4r3PPfquGYLX2NEmrLyqDB3uwNlg=; b=lacuzT+xOkwtOAMp9FGn/119Vqx5cNgvERdgMndWiazFWZecpMtzXK2XrrTesQsrk0PhFu8nxvvC1mAVB47ehNQunMw/agmHINeaFx7K9QtgvMzR8XVNfBdonX59ZOP4lTylCzRAGJ71EgoOE+Y72eOrn3BTMnVMk9ofUWxNYM4= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass header.i=linux.beauty; spf=pass smtp.mailfrom=me@linux.beauty; dmarc=pass header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1775647260; s=zmail; d=linux.beauty; i=me@linux.beauty; h=From:From:To:To:Cc:Cc:Subject:Subject:Date:Date:Message-ID:In-Reply-To:References:MIME-Version:Content-Transfer-Encoding:Message-Id:Reply-To; bh=YnM0+++sh+xA2p+4r3PPfquGYLX2NEmrLyqDB3uwNlg=; b=qlYwjWHfHlB1bX8HEH/Xh/8uTq69KF5S9dcSePfkvrZCpZqe9OBXD3euI0eY+Vrg TR47cmoTTcWX6JzebaKeKunJSu5dG67ps2UFZz14IKFeGwbtp+vTPfJzKkuUlfagjUE 6VouT+k1tHjs/ST9tc5WRlpV4xF6NuV1wEDg42Yw= Received: by mx.zohomail.com with SMTPS id 1775647257949387.91951926297907; Wed, 8 Apr 2026 04:20:57 -0700 (PDT) From: Li Chen To: Zhang Yi , Theodore Ts'o , Andreas Dilger , Baokun Li , Jan Kara , Ojaswin Mujoo , "Ritesh Harjani (IBM)" , Zhang Yi , linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , linux-trace-kernel@vger.kernel.org, Li Chen Subject: [RFC v6 2/7] ext4: lockdep: handle i_data_sem subclassing for special inodes Date: Wed, 8 Apr 2026 19:20:13 +0800 Message-ID: <20260408112020.716706-3-me@linux.beauty> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260408112020.716706-1-me@linux.beauty> References: <20260408112020.716706-1-me@linux.beauty> Precedence: bulk X-Mailing-List: linux-ext4@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-ZohoMailClient: External Fast commit can hold s_fc_lock while writing journal blocks. Mapping the journal inode can take its i_data_sem. Normal inode update paths can take a data inode i_data_sem and then s_fc_lock, which makes lockdep report a circular dependency. lockdep treats all i_data_sem instances as one lock class and cannot distinguish the journal inode i_data_sem from a regular inode i_data_sem. The journal inode is not tracked by fast commit and no FC waiters ever depend on it, so this is not a real ABBA deadlock. Assign the journal inode a dedicated i_data_sem lockdep subclass to avoid the false positive. Inode cache objects can be recycled, so also reset i_data_sem to I_DATA_SEM_NORMAL when allocating an ext4 inode. Otherwise a new inode may inherit an old subclass (journal/quota/ea) and trigger lockdep warnings. Signed-off-by: Li Chen --- Changes in v6: - Rebase onto linux-next master as of 2026-04-08. - Refresh the patch context around upstream ext4_alloc_inode() changes, without changing the subclassing logic. fs/ext4/ext4.h | 4 +++- fs/ext4/super.c | 8 ++++++++ 2 files changed, 11 insertions(+), 1 deletion(-) diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 98857292c707..66de888ae411 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -1016,12 +1016,14 @@ do { \ * than the first * I_DATA_SEM_QUOTA - Used for quota inodes only * I_DATA_SEM_EA - Used for ea_inodes only + * I_DATA_SEM_JOURNAL - Used for journal inode only */ enum { I_DATA_SEM_NORMAL = 0, I_DATA_SEM_OTHER, I_DATA_SEM_QUOTA, - I_DATA_SEM_EA + I_DATA_SEM_EA, + I_DATA_SEM_JOURNAL }; struct ext4_fc_inode_snap; diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 578508eb4f1a..286f05834900 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -1425,6 +1425,9 @@ static struct inode *ext4_alloc_inode(struct super_block *sb) ext4_fc_init_inode(&ei->vfs_inode); spin_lock_init(&ei->i_fc_lock); mmb_init(&ei->i_metadata_bhs, &ei->vfs_inode.i_data); +#ifdef CONFIG_LOCKDEP + lockdep_set_subclass(&ei->i_data_sem, I_DATA_SEM_NORMAL); +#endif return &ei->vfs_inode; } @@ -5904,6 +5907,11 @@ static struct inode *ext4_get_journal_inode(struct super_block *sb, return ERR_PTR(-EFSCORRUPTED); } +#ifdef CONFIG_LOCKDEP + lockdep_set_subclass(&EXT4_I(journal_inode)->i_data_sem, + I_DATA_SEM_JOURNAL); +#endif + ext4_debug("Journal inode found at %p: %lld bytes\n", journal_inode, journal_inode->i_size); return journal_inode; -- 2.53.0