From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 9595F231C9F for ; Tue, 5 Aug 2025 06:29:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754375361; cv=none; b=hF8GSfVYwuQR3GLmzus04nzI+mji8PLmCwekLCVX4JGXG7nCQx7WXJlKiN4Ov3gjnAtV63EYc6gK/i2EVYLSTw6s92WtSajuVgqFTTw/kzIp0xmrersFqScq+UqIvZJQ4bSB5XFVU7Sw685aR5ftRmLDtPA3A9xWv8DF1D8Hnig= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754375361; c=relaxed/simple; bh=EwTLvFeBezG7V6z2Hw0a8N8j6VdCJXp0nWCQ1ghQkZ8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=btNYfhdBjgii5XTUE4C1aI+ocIzuPqpxaNezCT6vMHgJFYxqS2FlispwwC8yv0lXYIjvXMcRF5D3eF6hhOSW9coKWcDiLBFybKpUa/myq1FkPdd4t0t32MD2k7UXcyjusz5kq8ymi5dk7cSLL4KnsBrlzdJpmbrzo+u+DG8cHYc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=MAFzDZgb; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="MAFzDZgb" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8E433C4CEF8; Tue, 5 Aug 2025 06:29:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1754375361; bh=EwTLvFeBezG7V6z2Hw0a8N8j6VdCJXp0nWCQ1ghQkZ8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MAFzDZgbc1lwC+ilNoAw2zjnISevehWzq55U41ETYesGG47LnUs0YR9PYKZmWWJrk UIhYARK/TWVw8SIjI7J47RWy00ApRG36iXXeERpelLt81XwMxYc2IoergSRGt9Zdko tURQfX+SuiAbU5gSHBQrl3ehCaV17UpEYW3VjtYisz5X4oYu2FoBAaGzaIg/PGn4ov Lj2QZupPQdowVLUNcGQKdgnKOJRCJWyOL4dEFDGQ7tNfga+pq5dQ0X7Okz0a93z27+ IMWxoXVndoDI4hVMJYDkteSEpxivhYa91Q0uMIl/2ssU5UEfekuLSaaSFax8odgdS4 l5CifOW962hZw== From: Chao Yu To: jaegeuk@kernel.org Cc: linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, Chao Yu , Jan Prusakowski Subject: [PATCH v3 2/3] f2fs: fix to zero data after EOF for compressed file correctly Date: Tue, 5 Aug 2025 14:29:11 +0800 Message-ID: <20250805062912.3070949-2-chao@kernel.org> X-Mailer: git-send-email 2.50.1.565.gc32cd1483b-goog In-Reply-To: <20250805062912.3070949-1-chao@kernel.org> References: <20250805062912.3070949-1-chao@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit generic/091 may fail, then it bisects to the bad commit ba8dac350faf ("f2fs: fix to zero post-eof page"). What will cause generic/091 to fail is something like below Testcase #1: 1. write 16k as compressed blocks 2. truncate to 12k 3. truncate to 20k 4. verify data in range of [12k, 16k], however data is not zero as expected Script of Testcase #1 mkfs.f2fs -f -O extra_attr,compression /dev/vdb mount -t f2fs -o compress_extension=* /dev/vdb /mnt/f2fs dd if=/dev/zero of=/mnt/f2fs/file bs=12k count=1 dd if=/dev/random of=/mnt/f2fs/file bs=4k count=1 seek=3 conv=notrunc sync truncate -s $((12*1024)) /mnt/f2fs/file truncate -s $((20*1024)) /mnt/f2fs/file dd if=/mnt/f2fs/file of=/mnt/f2fs/data bs=4k count=1 skip=3 od /mnt/f2fs/data umount /mnt/f2fs Analisys: in step 2), we will redirty all data pages from #0 to #3 in compressed cluster, and zero page #3, in step 3), f2fs_setattr() will call f2fs_zero_post_eof_page() to drop all page cache post eof, includeing dirtied page #3, in step 4) when we read data from page #3, it will decompressed cluster and extra random data to page #3, finally, we hit the non-zeroed data post eof. However, the commit ba8dac350faf ("f2fs: fix to zero post-eof page") just let the issue be reproduced easily, w/o the commit, it can reproduce this bug w/ below Testcase #2: 1. write 16k as compressed blocks 2. truncate to 8k 3. truncate to 12k 4. truncate to 20k 5. verify data in range of [12k, 16k], however data is not zero as expected Script of Testcase #2 mkfs.f2fs -f -O extra_attr,compression /dev/vdb mount -t f2fs -o compress_extension=* /dev/vdb /mnt/f2fs dd if=/dev/zero of=/mnt/f2fs/file bs=12k count=1 dd if=/dev/random of=/mnt/f2fs/file bs=4k count=1 seek=3 conv=notrunc sync truncate -s $((8*1024)) /mnt/f2fs/file truncate -s $((12*1024)) /mnt/f2fs/file truncate -s $((20*1024)) /mnt/f2fs/file echo 3 > /proc/sys/vm/drop_caches dd if=/mnt/f2fs/file of=/mnt/f2fs/data bs=4k count=1 skip=3 od /mnt/f2fs/data umount /mnt/f2fs Anlysis: in step 2), we will redirty all data pages from #0 to #3 in compressed cluster, and zero page #2 and #3, in step 3), we will truncate page #3 in page cache, in step 4), expand file size, in step 5), hit random data post eof w/ the same reason in Testcase #1. Root Cause: In f2fs_truncate_partial_cluster(), after we truncate partial data block on compressed cluster, all pages in cluster including the one post eof will be dirtied, after another tuncation, dirty page post eof will be dropped, however on-disk compressed cluster is still valid, it includes invalid data post eof, result in exposing previous data post eof while reading. Fix: In f2fs_truncate_partial_cluster(), let change as below to fix: - call filemap_write_and_wait_range() to flush dirty page - call truncate_pagecache() to drop pages or zero partial page post eof - call f2fs_do_truncate_blocks() to truncate non-compress cluster to last vali block Fixes: 3265d3db1f16 ("f2fs: support partial truncation on compressed inode") Reported-by: Jan Prusakowski Signed-off-by: Chao Yu --- v3: - reorder patch 2 and patch 3 fs/f2fs/compress.c | 23 ++++++++++++++++------- 1 file changed, 16 insertions(+), 7 deletions(-) diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c index 6cd8902849cf..72bc05b913af 100644 --- a/fs/f2fs/compress.c +++ b/fs/f2fs/compress.c @@ -1246,19 +1246,28 @@ int f2fs_truncate_partial_cluster(struct inode *inode, u64 from, bool lock) for (i = cluster_size - 1; i >= 0; i--) { struct folio *folio = page_folio(rpages[i]); loff_t start = (loff_t)folio->index << PAGE_SHIFT; + loff_t offset = from > start ? from - start : 0; - if (from <= start) { - folio_zero_segment(folio, 0, folio_size(folio)); - } else { - folio_zero_segment(folio, from - start, - folio_size(folio)); + folio_zero_segment(folio, offset, folio_size(folio)); + + if (from >= start) break; - } } f2fs_compress_write_end(inode, fsdata, start_idx, true); + + err = filemap_write_and_wait_range(inode->i_mapping, + round_down(from, cluster_size << PAGE_SHIFT), + LLONG_MAX); + if (err) + return err; + + truncate_pagecache(inode, from); + + err = f2fs_do_truncate_blocks(inode, + round_up(from, PAGE_SIZE), lock); } - return 0; + return err; } static int f2fs_write_compressed_pages(struct compress_ctx *cc, -- 2.49.0