linux-kernel - [PATCH v3 08/14] ext4: cleanup zeroout in ext4_split_extent

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20251129103247.686136-9-yi.zhang@huaweicloud.com>
Date: Sat, 29 Nov 2025 18:32:40 +0800
From: Zhang Yi <yi.zhang@...weicloud.com>
To: linux-ext4@...r.kernel.org
Cc: linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	tytso@....edu,
	adilger.kernel@...ger.ca,
	jack@...e.cz,
	ojaswin@...ux.ibm.com,
	yi.zhang@...wei.com,
	yi.zhang@...weicloud.com,
	yizhang089@...il.com,
	libaokun1@...wei.com,
	yangerkun@...wei.com
Subject: [PATCH v3 08/14] ext4: cleanup zeroout in ext4_split_extent_at()

From: Zhang Yi <yi.zhang@...wei.com>

zero_ex is a temporary variable used only for writing zeros and
inserting extent status entry, it will not be directly inserted into the
tree. Therefore, it can be assigned values from the target extent in
various scenarios, eliminating the need to explicitly assign values to
each variable individually.

Signed-off-by: Zhang Yi <yi.zhang@...wei.com>
Reviewed-by: Ojaswin Mujoo <ojaswin@...ux.ibm.com>
Reviewed-by: Jan Kara <jack@...e.cz>
Reviewed-by: Baokun Li <libaokun1@...wei.com>
---
 fs/ext4/extents.c | 87 ++++++++++++++++++++---------------------------
 1 file changed, 36 insertions(+), 51 deletions(-)

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 945995d68c4d..2cfce2c01208 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3287,63 +3287,48 @@ static struct ext4_ext_path *ext4_split_extent_at(handle_t *handle,
 	ex = path[depth].p_ext;
 
 	if (EXT4_EXT_MAY_ZEROOUT & split_flag) {
-		if (split_flag & (EXT4_EXT_DATA_VALID1|EXT4_EXT_DATA_VALID2)) {
-			if (split_flag & EXT4_EXT_DATA_VALID1) {
-				err = ext4_ext_zeroout(inode, ex2);
-				zero_ex.ee_block = ex2->ee_block;
-				zero_ex.ee_len = cpu_to_le16(
-						ext4_ext_get_actual_len(ex2));
-				ext4_ext_store_pblock(&zero_ex,
-						      ext4_ext_pblock(ex2));
-			} else {
-				err = ext4_ext_zeroout(inode, ex);
-				zero_ex.ee_block = ex->ee_block;
-				zero_ex.ee_len = cpu_to_le16(
-						ext4_ext_get_actual_len(ex));
-				ext4_ext_store_pblock(&zero_ex,
-						      ext4_ext_pblock(ex));
-			}
-		} else {
-			err = ext4_ext_zeroout(inode, &orig_ex);
-			zero_ex.ee_block = orig_ex.ee_block;
-			zero_ex.ee_len = cpu_to_le16(
-						ext4_ext_get_actual_len(&orig_ex));
-			ext4_ext_store_pblock(&zero_ex,
-					      ext4_ext_pblock(&orig_ex));
-		}
+		if (split_flag & EXT4_EXT_DATA_VALID1)
+			memcpy(&zero_ex, ex2, sizeof(zero_ex));
+		else if (split_flag & EXT4_EXT_DATA_VALID2)
+			memcpy(&zero_ex, ex, sizeof(zero_ex));
+		else
+			memcpy(&zero_ex, &orig_ex, sizeof(zero_ex));
+		ext4_ext_mark_initialized(&zero_ex);
 
-		if (!err) {
+		err = ext4_ext_zeroout(inode, &zero_ex);
+		if (err)
+			goto fix_extent_len;
+
+		/*
+		 * 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) {
 			/*
-			 * 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.
+			 * Drop extent cache to prevent stale unwritten
+			 * extents remaining after zeroing out.
 			 */
-			if (split_flag & EXT4_EXT_DATA_PARTIAL_VALID1) {
-				/*
-				 * Drop extent cache to prevent stale unwritten
-				 * extents remaining after zeroing out.
-				 */
-				ext4_es_remove_extent(inode,
+			ext4_es_remove_extent(inode,
 					le32_to_cpu(zero_ex.ee_block),
 					ext4_ext_get_actual_len(&zero_ex));
-				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);
-			err = ext4_ext_dirty(handle, inode, path + path->p_depth);
-			if (!err)
-				/* update extent status tree */
-				ext4_zeroout_es(inode, &zero_ex);
-			/* If we failed at this point, we don't know in which
-			 * state the extent tree exactly is so don't try to fix
-			 * length of the original extent as it may do even more
-			 * damage.
-			 */
-			goto out;
+			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);
+		err = ext4_ext_dirty(handle, inode, path + path->p_depth);
+		if (!err)
+			/* update extent status tree */
+			ext4_zeroout_es(inode, &zero_ex);
+		/*
+		 * If we failed at this point, we don't know in which
+		 * state the extent tree exactly is so don't try to fix
+		 * length of the original extent as it may do even more
+		 * damage.
+		 */
+		goto out;
 	}
 
 fix_extent_len:
-- 
2.46.1