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 E2C9C296BD1 for ; Wed, 25 Feb 2026 02:57:36 +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=1771988257; cv=none; b=ercbJKls7R0SZcaG+oBTtB15fhm+NJskWrvCmVjBPamff4akIHrD8Kyy1YZ0Nx1QEewgxod5ZT3kQbVTgGxgtxT/VA6ymFPc7sA1c3TyfHnIp3TUP1MGtYd2faI8reTMc7h80J8fwNXyPIyV/3cqIDU+FH0iyuKpg8nCBh9GxAs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771988257; c=relaxed/simple; bh=pkvmTAQZEAvcYU6s55Dcl5omaruk3nk/NrTVJY5YScI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=OycPYeeUTfbwLn/BBaZhvfOIG1rv1ctqNAHxDx8CBf0B5kuwDsihTLzn7pzibXxypdhyEqWCdnhq9x6aj4Bpv4Url9vCMqZcxVezmcyOLEr1QYpvgMxBFs4cTCz0CF1CL5+lm4OE2bxwyZVQB1c8xfrF+gImuv481pWU8T5wdTA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=cTCJwB/P; 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="cTCJwB/P" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 06F41C116D0; Wed, 25 Feb 2026 02:57:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1771988256; bh=pkvmTAQZEAvcYU6s55Dcl5omaruk3nk/NrTVJY5YScI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cTCJwB/PB4QQMP8B/xk0oMyZaeZ+fgGKuRn4BCbZwlZ1awqsQRPZM73YJ5rYBaDL8 8M4ehPZ4Ukek6ZkGkq53nOFlk6D1yzfd+gB/1fBawDKMFx5WePabDpX5yAlNyFKz2X AXychvOOocLzYQHsjRCGQ2mG0Zb/+D+UsQzj4bx+rZM9DJjFx6z9DPqpDqcGHhYwyk sgtmQa4OAUXUVjIRspHlgUi0mv+IZNSvUmNJOEf25aU1BbB5DVNtX1UfhbVRJtpgL9 iXN0NABeUn50OHk7JEOcfvZqLavvPucHXqQeTGsu14dJzLoknUtsV/HS1IJ4H9/Bj/ cFPDDf1OK/cuA== 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 6.6.y 6/6] ext4: don't zero the entire extent if EXT4_EXT_DATA_PARTIAL_VALID1 Date: Tue, 24 Feb 2026 21:57:29 -0500 Message-ID: <20260225025729.3839073-6-sashal@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260225025729.3839073-1-sashal@kernel.org> References: <2026022438-resample-unlit-c02b@gregkh> <20260225025729.3839073-1-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 1a29c2056eef5..2d322b06ccd88 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -3293,6 +3293,15 @@ 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); @@ -3365,7 +3374,9 @@ 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