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 D9F322E2DF2; Sun, 1 Mar 2026 01:50:32 +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=1772329832; cv=none; b=MrkktpakCoXmrgf8RH5cI+QZo4uIPuzV3V4BQi2pRIcPdhhyqK4kZnsY4ukApt3d4TX0aqyLGUgQA1wdJItZH/O4p4F/ZzgFcfB1ZR5igVsz3kKDsIb8vD27947JeobOqzTWUZO70+JJcr5NjOsnpAcy3xAsXiI7LcftHSNfaMw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772329832; c=relaxed/simple; bh=ow2/a8v3fd0nPpTzAoSOlL7ZVvXCvohti+S6z6ialIU=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=oN7J7HTIXFxYEbWOOD50tAqNwn/ATGWTo4mm/r+FtTEKwE4LC+19A3jpxHCL6amMJ0Sgs1g5sECYR0gWeDXhjR5fjL99cjWCZx4CxTEX1+1D119BwHHdWcj7ivkIorunu58Z9DX+wNbhoza2oJEa1tuLdu7wpee04ISiki8OA7Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=FO9k8o5T; 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="FO9k8o5T" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0AB46C19424; Sun, 1 Mar 2026 01:50:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772329832; bh=ow2/a8v3fd0nPpTzAoSOlL7ZVvXCvohti+S6z6ialIU=; h=From:To:Cc:Subject:Date:From; b=FO9k8o5T4K2g4xLL8OJeZ2M5wkN3xozxBVHzsBEWEOYjjRIk0ma7HgVJi+wajkRm9 J8noz0uBTW87EhniTZdQii4yJ18rYQzbnvWJ4RaXcqp0qKCJBHFKvSgsHHeQDeFPg7 c5El6MeCSp2OmguLbBjp04SZ5vj1pJfwNHi8SR8zcpoa9YyIsQra0WR8eItq9WD/o3 1q3P2cS6Hcln8Q/ZBTcqkghYJxCjE+YtEEddfoXaS4cgw1VnK1eUA1UD9ZxppJmyC4 GLhZOW2FTOQV4lnOTGBZgFIg5cVAv3gImrpWQBw0NdagqcFXd8gkqmueGJI0M3HGFN M1zJ66XBnYqSg== From: Sasha Levin To: stable@vger.kernel.org, yi.zhang@huawei.com Cc: Ojaswin Mujoo , Baokun Li , stable@kernel.org, Theodore Ts'o , linux-ext4@vger.kernel.org Subject: FAILED: Patch "ext4: don't zero the entire extent if EXT4_EXT_DATA_PARTIAL_VALID1" failed to apply to 5.15-stable tree Date: Sat, 28 Feb 2026 20:50:30 -0500 Message-ID: <20260301015030.1716539-1-sashal@kernel.org> X-Mailer: git-send-email 2.51.0 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Hint: ignore X-stable: review Content-Transfer-Encoding: 8bit The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . Thanks, Sasha ------------------ original commit in Linus's tree ------------------ >From 1bf6974822d1dba86cf11b5f05498581cf3488a2 Mon Sep 17 00:00:00 2001 From: Zhang Yi Date: Sat, 29 Nov 2025 18:32:34 +0800 Subject: [PATCH] ext4: don't zero the entire extent if EXT4_EXT_DATA_PARTIAL_VALID1 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 --- 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 8d5ca450aa5d2..1fee84ea20af1 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -3310,6 +3310,15 @@ 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); @@ -3379,7 +3388,9 @@ static struct ext4_ext_path *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