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 9C6C3288C08 for ; Wed, 25 Feb 2026 03:13:51 +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=1771989231; cv=none; b=VNnUp3QRDjRir8lreVKR3MMNG3ouQux8HEpMadjlgbedz8i0y7eIe32p1ENkTEueorVkGRIrwRxR/5NHWTWKdddKLXKMDON1+Dm+0hgEOnNZ+ibrGALwnbBheDHBrVcz69mc7vWxRxhj3/M9l9kz+i95QRwIefPcuYQ6LgeQijQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771989231; c=relaxed/simple; bh=tyx33tr1fV4Xm6v+vTW+tcvoGeJuz4TXkEBPmVzuDyo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=YulvLhqmskPEMFRoq5KCvWVD0dTwXd1SP8MKtALvaTR2E+ndQ32E2cuqP8XSieopPLB4Z+Rtn3krffrgZij9/Fe1l4d6bWSL67EuovygE8Ko8qD2wdMqyy+WPinCm69DYbJGfjjbgUPpaeqm8jwaJSuU0bgh1vmk/0JC2qJ0juM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=l5Y8RDYd; 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="l5Y8RDYd" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C5BB1C2BC86; Wed, 25 Feb 2026 03:13:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1771989231; bh=tyx33tr1fV4Xm6v+vTW+tcvoGeJuz4TXkEBPmVzuDyo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=l5Y8RDYdiRyDib80IT6Cs1yAzJiLV6tecBBkrCONlBzpmBiAPoEH9mZ05RWSOpiR+ Y1w+HnKZX4VSIZvim83JKS6GGm+kC+laMWNGMEhx0S+3KhUwCXLnxfRX953MNnV5O4 2PoK0w29WPa+IG6djAjtce4OL+tr3KPPQJbAzuQyLlwL/ueyIsJRO21sYf9BA0BbS0 3dxjwe4oMOfurRZNLH2oY9vvSsoSRpfMwzbmUZw9+xqe4HjvUMXw8pvUV4qkNseFwE jGgy+U/oKWuxxGPDxxXNHhjIzQc1Kecnx0ijNwHsVyZ0mGnujr8+AzwxnVeZjrQKJU Fwjit0f80yQUQ== 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 7/7] ext4: don't zero the entire extent if EXT4_EXT_DATA_PARTIAL_VALID1 Date: Tue, 24 Feb 2026 22:13:43 -0500 Message-ID: <20260225031343.3858545-7-sashal@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260225031343.3858545-1-sashal@kernel.org> References: <2026022439-revered-giddily-d324@gregkh> <20260225031343.3858545-1-sashal@kernel.org> 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 1bf6974822d1dba86cf11b5f05498581cf3488a2 ] When allocating initialized blocks from a large unwritten extent, or when splitting an unwritten extent during end I/O and converting it to initialized, there is currently a potential issue of stale data if the extent needs to be split in the middle. 0 A B N [UUUUUUUUUUUU] U: unwritten extent [--DDDDDDDD--] D: valid data |<- ->| ----> this range needs to be initialized ext4_split_extent() first try to split this extent at B with EXT4_EXT_DATA_ENTIRE_VALID1 and EXT4_EXT_MAY_ZEROOUT flag set, but ext4_split_extent_at() failed to split this extent due to temporary lack of space. It zeroout B to N and mark the entire extent from 0 to N as written. 0 A B N [WWWWWWWWWWWW] W: written extent [SSDDDDDDDDZZ] Z: zeroed, S: stale data ext4_split_extent() then try to split this extent at A with EXT4_EXT_DATA_VALID2 flag set. This time, it split successfully and left a stale written extent from 0 to A. 0 A B N [WW|WWWWWWWWWW] [SS|DDDDDDDDZZ] Fix this by pass EXT4_EXT_DATA_PARTIAL_VALID1 to ext4_split_extent_at() when splitting at B, don't convert the entire extent to written and left it as unwritten after zeroing out B to N. The remaining work is just like the standard two-part split. ext4_split_extent() will pass the EXT4_EXT_DATA_VALID2 flag when it calls ext4_split_extent_at() for the second time, allowing it to properly handle the split. If the split is successful, it will keep extent from 0 to A as unwritten. Signed-off-by: Zhang Yi Reviewed-by: Ojaswin Mujoo Reviewed-by: Baokun Li Cc: stable@kernel.org Message-ID: <20251129103247.686136-3-yi.zhang@huaweicloud.com> Signed-off-by: Theodore Ts'o Signed-off-by: Sasha Levin --- fs/ext4/extents.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index dac8b758b6837..1bdd30926024c 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -3295,6 +3295,15 @@ static struct ext4_ext_path *ext4_split_extent_at(handle_t *handle, } if (!err) { + /* + * The first half contains partially valid data, the + * splitting of this extent has not been completed, fix + * extent length and ext4_split_extent() split will the + * first half again. + */ + if (split_flag & EXT4_EXT_DATA_PARTIAL_VALID1) + goto fix_extent_len; + /* update the extent length and mark as initialized */ ex->ee_len = cpu_to_le16(ee_len); ext4_ext_try_to_merge(handle, inode, path, ex); @@ -3367,7 +3376,9 @@ static int ext4_split_extent(handle_t *handle, split_flag1 |= EXT4_EXT_MARK_UNWRIT1 | EXT4_EXT_MARK_UNWRIT2; if (split_flag & EXT4_EXT_DATA_VALID2) - split_flag1 |= EXT4_EXT_DATA_ENTIRE_VALID1; + split_flag1 |= map->m_lblk > ee_block ? + EXT4_EXT_DATA_PARTIAL_VALID1 : + EXT4_EXT_DATA_ENTIRE_VALID1; path = ext4_split_extent_at(handle, inode, path, map->m_lblk + map->m_len, split_flag1, flags1); if (IS_ERR(path)) { -- 2.51.0