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 326E8299AB1 for ; Wed, 25 Feb 2026 02:57:35 +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=1771988255; cv=none; b=rWOy69Z7aIZX8rl0/L6DzHzanJX8uw5QL0oKD6bB49NbXs5/qg7ncZ/8eyHezTfN2YoQzjPMEq/w8hOK5WjCtxK71xqbtjI4wEDGsku9O1E+reGl6RuQuL1E169wygwRFmQGFWb9Tua2MmqOEAk/UABtKkTK3tLTRkWm99xoTso= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771988255; c=relaxed/simple; bh=1qx+AqVD33249s12ffeocRfItCv+rPaBYVnOWemxYZs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=r6e2BfdJmBo+2Bvlt8oS2ueghmLEKG3tKDx/wtzyU6G4RriXBXcPMSPSZIgspjTvW9cbbxF5Xes0ghMQYo/BRmHBFW1RQY6xS+7c2gfdpD1rSU7VF9dePPImZoZyiKURJR7wgJjz6sFlzBxhQaQbqjeA+M8o2ttchYlEm6Nhslo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=e5xrOAoN; 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="e5xrOAoN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 51583C116D0; Wed, 25 Feb 2026 02:57:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1771988255; bh=1qx+AqVD33249s12ffeocRfItCv+rPaBYVnOWemxYZs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=e5xrOAoNcKdhLUwPaLiN6Jz+tGCSr5j/Y10LNdWUGaCjeRrSORcdjsDnwPvO70BPE 1Utq1OnzK6fyX6CW2cNR2ppomJE2wL5+hmOKJe4euuPe+RrpbbVQqmPivch+9TFJ85 bW986/u2qDWGeGV3wEVqxMmZtaC5b+5/Ij7gV6fmqCnenwwnAOsm+Zahe5V4LqW7Yo Vi0qokgRTfE3DtiRKo9oUCKvjANCBIrGjm1zXkjoAf0vcULm/6u9oicBDoHPIAhWaq uf9IE00Wk9scd5MGSiHxmp7f3lDEy7F664IEr5rXVuq+QU4EmNz7Gry09m25MlYGVi Y/FkaEGAJ0yFw== From: Sasha Levin To: stable@vger.kernel.org Cc: Zhang Yi , Ojaswin Mujoo , Baokun Li , stable@kernel.org, Theodore Ts'o , Sasha Levin Subject: [PATCH 6.1.y] ext4: don't set EXT4_GET_BLOCKS_CONVERT when splitting before submitting I/O Date: Tue, 24 Feb 2026 21:57:32 -0500 Message-ID: <20260225025732.3839126-1-sashal@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <2026022422-humorous-scam-a54d@gregkh> References: <2026022422-humorous-scam-a54d@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Zhang Yi [ Upstream commit feaf2a80e78f89ee8a3464126077ba8683b62791 ] When allocating blocks during within-EOF DIO and writeback with dioread_nolock enabled, EXT4_GET_BLOCKS_PRE_IO was set to split an existing large unwritten extent. However, EXT4_GET_BLOCKS_CONVERT was set when calling ext4_split_convert_extents(), which may potentially result in stale data issues. Assume we have an unwritten extent, and then DIO writes the second half. [UUUUUUUUUUUUUUUU] on-disk extent U: unwritten extent [UUUUUUUUUUUUUUUU] extent status tree |<- ->| ----> dio write this range First, ext4_iomap_alloc() call ext4_map_blocks() with EXT4_GET_BLOCKS_PRE_IO, EXT4_GET_BLOCKS_UNWRIT_EXT and EXT4_GET_BLOCKS_CREATE flags set. ext4_map_blocks() find this extent and call ext4_split_convert_extents() with EXT4_GET_BLOCKS_CONVERT and the above flags set. Then, ext4_split_convert_extents() calls ext4_split_extent() with EXT4_EXT_MAY_ZEROOUT, EXT4_EXT_MARK_UNWRIT2 and EXT4_EXT_DATA_VALID2 flags set, and it calls ext4_split_extent_at() to split the second half with EXT4_EXT_DATA_VALID2, EXT4_EXT_MARK_UNWRIT1, EXT4_EXT_MAY_ZEROOUT and EXT4_EXT_MARK_UNWRIT2 flags set. However, ext4_split_extent_at() failed to insert extent since a temporary lack -ENOSPC. It zeroes out the first half but convert the entire on-disk extent to written since the EXT4_EXT_DATA_VALID2 flag set, but left the second half as unwritten in the extent status tree. [0000000000SSSSSS] data S: stale data, 0: zeroed [WWWWWWWWWWWWWWWW] on-disk extent W: written extent [WWWWWWWWWWUUUUUU] extent status tree Finally, if the DIO failed to write data to the disk, the stale data in the second half will be exposed once the cached extent entry is gone. Fix this issue by not passing EXT4_GET_BLOCKS_CONVERT when splitting an unwritten extent before submitting I/O, and make ext4_split_convert_extents() to zero out the entire extent range to zero for this case, and also mark the extent in the extent status tree for consistency. Fixes: b8a8684502a0 ("ext4: Introduce FALLOC_FL_ZERO_RANGE flag for fallocate") Signed-off-by: Zhang Yi Reviewed-by: Ojaswin Mujoo Reviewed-by: Baokun Li Cc: stable@kernel.org Message-ID: <20251129103247.686136-4-yi.zhang@huaweicloud.com> Signed-off-by: Theodore Ts'o [ different function signatures ] Signed-off-by: Sasha Levin --- fs/ext4/extents.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 1aad4ae0e7ae4..dfc365b021094 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -3705,11 +3705,15 @@ static int ext4_split_convert_extents(handle_t *handle, /* Convert to unwritten */ if (flags & EXT4_GET_BLOCKS_CONVERT_UNWRITTEN) { split_flag |= EXT4_EXT_DATA_VALID1; - /* Convert to initialized */ - } else if (flags & EXT4_GET_BLOCKS_CONVERT) { + /* Split the existing unwritten extent */ + } else if (flags & (EXT4_GET_BLOCKS_UNWRIT_EXT | + EXT4_GET_BLOCKS_CONVERT)) { split_flag |= ee_block + ee_len <= eof_block ? EXT4_EXT_MAY_ZEROOUT : 0; - split_flag |= (EXT4_EXT_MARK_UNWRIT2 | EXT4_EXT_DATA_VALID2); + split_flag |= EXT4_EXT_MARK_UNWRIT2; + /* Convert to initialized */ + if (flags & EXT4_GET_BLOCKS_CONVERT) + split_flag |= EXT4_EXT_DATA_VALID2; } flags |= EXT4_GET_BLOCKS_PRE_IO; return ext4_split_extent(handle, inode, ppath, map, split_flag, flags); @@ -3874,7 +3878,7 @@ ext4_ext_handle_unwritten_extents(handle_t *handle, struct inode *inode, /* get_block() before submitting IO, split the extent */ if (flags & EXT4_GET_BLOCKS_PRE_IO) { ret = ext4_split_convert_extents(handle, inode, map, ppath, - flags | EXT4_GET_BLOCKS_CONVERT); + flags); if (ret < 0) { err = ret; goto out2; -- 2.51.0