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 Received: from lists.sourceforge.net (lists.sourceforge.net [216.105.38.7]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4DBC9C79F9F for ; Thu, 10 Sep 2026 14:11:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.sourceforge.net; s=beta; h=Content-Transfer-Encoding:Content-Type:Cc: Reply-To:From:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:Subject:MIME-Version:Message-ID:Date:To:Sender: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References:List-Owner; bh=m/d6ySbxCfsUCE4jJRsrm9YICuD4ZoyxLoQIWlYAPDs=; b=KHNFnVoVNCEY+dldsN2ilOysP0 2BQUsbVmoWFnEKDUUyzoO7ZDeuh8yF8npm3OirlImw3+/aruJ/2nyLon4SvPkOCKwfP2/BzmLrqaX f93IJ4swFfNmOEx0Ch6WANqT78CQiqwOCEzI/wrEnE7uWMUj3u554xNxOok36cfNs0AA=; Received: from [127.0.0.1] (helo=sfs-ml-2.v29.lw.sourceforge.com) by sfs-ml-2.v29.lw.sourceforge.com with esmtp (Exim 4.95) (envelope-from ) id 1x4fV7-0004wl-C5; Thu, 10 Sep 2026 14:11:42 +0000 Received: from [172.30.29.66] (helo=mx.sourceforge.net) by sfs-ml-2.v29.lw.sourceforge.com with esmtps (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1x4fV5-0004wZ-8h for linux-f2fs-devel@lists.sourceforge.net; Thu, 10 Sep 2026 14:11:40 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sourceforge.net; s=x; h=Content-Transfer-Encoding:MIME-Version:Message-ID: Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:In-Reply-To:References:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=lLAqtjys13v8tLrbWLlIUVt/Fd351A9zIJ5wib7pFzk=; b=dsvoofxj1ac9jRdr0F546h7Yhn vk5WTfkQY03Y/SH3DW6eSV27aMs4J1Jdzc1k6MJwwoLbwVySjH10My9D+GlD440f9MkNCWHR0NWHa 8NnF7HKmTPdsVq3+U7NteW+N9sS7/WmsUMj+a3IymKq1EBbGyGjpDrO3zZmX1T+Mg3oE=; DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sf.net; s=x ; h=Content-Transfer-Encoding:MIME-Version:Message-ID:Date:Subject:Cc:To:From :Sender:Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To: References:List-Id:List-Help:List-Unsubscribe:List-Subscribe:List-Post: List-Owner:List-Archive; bh=lLAqtjys13v8tLrbWLlIUVt/Fd351A9zIJ5wib7pFzk=; b=U DI1Fnp4qd8yscPr8NuCPx2UrbvBb+HWu8QM2J2E2q3SBOHMQVUvI98tyVpXX6novH7Yp098hsn0Cu yMioDwmc507UUddAaBI8twf34TqAyxbtetZn5PxdFismsJSGxBFpzqeYkbLkydG+JAundMlUFCjVm dm/7I6adj/4ttKmg=; Received: from sea.source.kernel.org ([172.234.252.31]) by sfi-mx-2.v28.lw.sourceforge.com with esmtps (TLS1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.95) id 1x4fV4-0002hO-DH for linux-f2fs-devel@lists.sourceforge.net; Thu, 10 Sep 2026 14:11:39 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id F0104408C0; Thu, 10 Sep 2026 14:11:32 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 932041F000FF; Thu, 10 Sep 2026 14:11:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789049492; bh=lLAqtjys13v8tLrbWLlIUVt/Fd351A9zIJ5wib7pFzk=; h=From:To:Cc:Subject:Date; b=FQsyExdwj3+gfD/vJkurNxCcccf6ZwHpcfxTLN7KvYLmoL/SaFvLZAwDdIOMe2AQ7 9EN0Ahc9ZsjmvSf4ZTcqWRkA8laqj7mPz1fDMDKfi90+STB2T4dRrYwrU3BVwWarDC 5G/Bbmwmr7REdRhhQIEgASmhqv4LxW8p1Op3S+ypqhUBJmkN5NKjyFNhQUbwrv1RUn J687HNkvyuOpuYyRbWYaHx8SGdvQZk50GShHer1np1FMrdKLlr+lNaRJTCxOqm6PHt RdDFDYv/tZ4OA2lXUDwFPHxJym3Za1cBm0TUtFE2pYJJ4Aa5YCeeuIOwjVBEFStns8 /xivgPQA4U6Sg== To: jaegeuk@kernel.org Date: Thu, 10 Sep 2026 22:11:26 +0800 Message-ID: <20260910141126.1309794-1-chao@kernel.org> X-Mailer: git-send-email 2.55.0.1003.g10538fe699-goog MIME-Version: 1.0 X-Headers-End: 1x4fV4-0002hO-DH Subject: [f2fs-dev] [PATCH v2] f2fs: compress: fix to handle race between truncate and writeback X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Chao Yu via Linux-f2fs-devel Reply-To: Chao Yu Cc: Zhiguo Niu , stable@kernel.org, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net From: Chao Yu fsstress reports a kernel BUG in f2fs_truncate_partial_cluster(): kernel BUG at fs/f2fs/compress.c:1238! RIP: 0010:f2fs_truncate_partial_cluster+0x292/0x2a0 Call Trace: f2fs_truncate+0xf6/0x210 f2fs_setattr+0x6b7/0x770 notify_change+0x33b/0x520 do_truncate+0xc2/0xf0 vfs_truncate+0x153/0x1d0 ksys_truncate+0x78/0xd0 __x64_sys_truncate+0x16/0x20 do_syscall_64+0xbe/0x540 The root cause is that Thread A (truncate) and Thread B (background writeback or fsync) can race as follows: Thread A Thread B - f2fs_setattr - f2fs_truncate - f2fs_truncate_blocks - f2fs_truncate_partial_cluster - f2fs_is_compressed_cluster return 1 - f2fs_write_cache_pages - f2fs_write_multi_pages - f2fs_write_raw_pages - f2fs_write_single_data_page dn.data_blkaddr != COMPRESS_ADDR (cluster converted to normal) - f2fs_prepare_compress_overwrite - f2fs_is_compressed_cluster return 0 - return 0 - f2fs_bug_on(sbi, err == 0): BUG! Writeback path does not acquire i_gc_rwsem or filemap_invalidate_lock. When a compressed cluster fails compression during writeback, it is overwritten with raw data blocks. If Thread A checked f2fs_is_compressed_cluster() before the conversion, but calls f2fs_prepare_compress_overwrite() after the conversion, f2fs_prepare_compress_overwrite() returns 0 because the cluster is no longer a compressed cluster. To fix this, remove the f2fs_bug_on() and retry checking the cluster status when f2fs_prepare_compress_overwrite() returns 0, so that it can fall back to f2fs_do_truncate_blocks() to handle it as a normal cluster. Cc: stable@kernel.org Fixes: 3265d3db1f16 ("f2fs: support partial truncation on compressed inode") Reviewed-by: Zhiguo Niu Signed-off-by: Chao Yu --- fs/f2fs/compress.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c index ce88092d9ce2..b71107604012 100644 --- a/fs/f2fs/compress.c +++ b/fs/f2fs/compress.c @@ -1222,6 +1222,7 @@ int f2fs_truncate_partial_cluster(struct inode *inode, u64 from, bool lock) int i; int err; +repeat: err = f2fs_is_compressed_cluster(inode, start_idx); if (err < 0) return err; @@ -1233,12 +1234,11 @@ int f2fs_truncate_partial_cluster(struct inode *inode, u64 from, bool lock) /* truncate compressed cluster */ err = f2fs_prepare_compress_overwrite(inode, &pagep, start_idx, &fsdata); - - /* should not be a normal cluster */ - f2fs_bug_on(F2FS_I_SB(inode), err == 0); - - if (err <= 0) + if (err < 0) return err; + else if (err == 0) + /* the cluster became non-compressed one due to race case */ + goto repeat; rpages = fsdata; -- 2.49.0 _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel