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 93E9C13B7AE; Sun, 1 Mar 2026 01:21:35 +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=1772328095; cv=none; b=O1x5jQEuJ/9scHKB60vfBRUsbOSySHUuUbuqC4I//ACNPRw7mQvJjiOaAAPPr1PG/YEd10xjq7JWCwQVZ9waGEHYXc3UeeYTLfmPmVJAiiQfr9LodKPS8ATioxXt2zE6vJjzzAto8T50sbfib2NY5th235m639GX42BiYnFJ7to= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772328095; c=relaxed/simple; bh=ITFcchFOCLKHJogMeJB5bvEk10Os72dFV/7D3K1d54E=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=hOlzASgefSFcnNL1u43Eri+fHDcUsdCd0PdvfDAkKaw1IeUPnjDjbLjI9NQNGNzvF/QrpKa0E7Bp1fO9Qkk6e0+UW2nYfocgG+qLuxrsqacqa0AKjRlaAjeckxOIivBRq4PtMtdGtCKCSI7cD1pYfCeF5gjOQRO180iGFpAR4YM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=LYoCKHLg; 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="LYoCKHLg" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B64A1C19421; Sun, 1 Mar 2026 01:21:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772328095; bh=ITFcchFOCLKHJogMeJB5bvEk10Os72dFV/7D3K1d54E=; h=From:To:Cc:Subject:Date:From; b=LYoCKHLg0TXqisdpBQMYM/zlWEvcXtwyQ61GwoncGHCb0ZD9nPRUbrWo082fHx4Ku UzGN9c2G9yPvn6MPpGkqqAliSv7/V9vE3DRah4E4JUWZboYfY8gWzDBKhNnC4uuBKR 2X+inYROhyOhIlPupx74C9XhpakYwq4qBGpuS+2Q1pGTtPyaELOnc5MGAXqLMbggLo qEJppOGkpQE9q3NHAfl7ATplVeOD5cDovVQVcH6WjYZeXG7nGjPOlkknqO6a/7vn8e gHR9r0eZcbvpZT25WEkkltqKnAqZWDAOxzFBwmbRTZ0O8uy2zAfVFEC8akupYZnmQN lHrrjrw6ETOUQ== 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 6.12-stable tree Date: Sat, 28 Feb 2026 20:21:33 -0500 Message-ID: <20260301012133.1677563-1-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 6.12-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