[PATCH 6.6.y] ext4: get rid of ppath in get_ext_path()

[PATCH 6.6.y] ext4: get rid of ppath in get_ext_path()

[Yoann Congal]

From: Baokun Li <libaokun1@huawei.com>

[ Upstream commit 6b854d552711aa33f59eda334e6d94a00d8825bb ]

The use of path and ppath is now very confusing, so to make the code more
readable, pass path between functions uniformly, and get rid of ppath.

After getting rid of ppath in get_ext_path(), its caller may pass an error
pointer to ext4_free_ext_path(), so it needs to teach ext4_free_ext_path()
and ext4_ext_drop_refs() to skip the error pointer. No functional changes.

Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Tested-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://patch.msgid.link/20240822023545.1994557-13-libaokun@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Signed-off-by: Yoann Congal <yoann.congal@smile.fr>
---
 fs/ext4/extents.c     |  5 +++--
 fs/ext4/move_extent.c | 34 +++++++++++++++++-----------------
 2 files changed, 20 insertions(+), 19 deletions(-)

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index a94798e23c1af..9c2d23958146b 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -114,7 +114,7 @@ static void ext4_ext_drop_refs(struct ext4_ext_path *path)
 {
 	int depth, i;
 
-	if (!path)
+	if (IS_ERR_OR_NULL(path))
 		return;
 	depth = path->p_depth;
 	for (i = 0; i <= depth; i++, path++) {
@@ -125,6 +125,8 @@ static void ext4_ext_drop_refs(struct ext4_ext_path *path)
 
 void ext4_free_ext_path(struct ext4_ext_path *path)
 {
+	if (IS_ERR_OR_NULL(path))
+		return;
 	ext4_ext_drop_refs(path);
 	kfree(path);
 }
@@ -4242,7 +4244,6 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
 	path = ext4_find_extent(inode, map->m_lblk, NULL, 0);
 	if (IS_ERR(path)) {
 		err = PTR_ERR(path);
-		path = NULL;
 		goto out;
 	}
 
diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
index d5636a2a718a8..96a84de321690 100644
--- a/fs/ext4/move_extent.c
+++ b/fs/ext4/move_extent.c
@@ -17,27 +17,23 @@
  * get_ext_path() - Find an extent path for designated logical block number.
  * @inode:	inode to be searched
  * @lblock:	logical block number to find an extent path
- * @ppath:	pointer to an extent path pointer (for output)
+ * @path:	pointer to an extent path
  *
- * ext4_find_extent wrapper. Return 0 on success, or a negative error value
- * on failure.
+ * ext4_find_extent wrapper. Return an extent path pointer on success,
+ * or an error pointer on failure.
  */
-static inline int
+static inline struct ext4_ext_path *
 get_ext_path(struct inode *inode, ext4_lblk_t lblock,
-		struct ext4_ext_path **ppath)
+	     struct ext4_ext_path *path)
 {
-	struct ext4_ext_path *path = *ppath;
-
-	*ppath = NULL;
 	path = ext4_find_extent(inode, lblock, path, EXT4_EX_NOCACHE);
 	if (IS_ERR(path))
-		return PTR_ERR(path);
+		return path;
 	if (path[ext_depth(inode)].p_ext == NULL) {
 		ext4_free_ext_path(path);
-		return -ENODATA;
+		return ERR_PTR(-ENODATA);
 	}
-	*ppath = path;
-	return 0;
+	return path;
 }
 
 /**
@@ -95,9 +91,11 @@ mext_check_coverage(struct inode *inode, ext4_lblk_t from, ext4_lblk_t count,
 	int ret = 0;
 	ext4_lblk_t last = from + count;
 	while (from < last) {
-		*err = get_ext_path(inode, from, &path);
-		if (*err)
-			goto out;
+		path = get_ext_path(inode, from, path);
+		if (IS_ERR(path)) {
+			*err = PTR_ERR(path);
+			return ret;
+		}
 		ext = path[ext_depth(inode)].p_ext;
 		if (unwritten != ext4_ext_is_unwritten(ext))
 			goto out;
@@ -634,9 +632,11 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp, __u64 orig_blk,
 		int offset_in_page;
 		int unwritten, cur_len;
 
-		ret = get_ext_path(orig_inode, o_start, &path);
-		if (ret)
+		path = get_ext_path(orig_inode, o_start, path);
+		if (IS_ERR(path)) {
+			ret = PTR_ERR(path);
 			goto out;
+		}
 		ex = path[path->p_depth].p_ext;
 		cur_blk = le32_to_cpu(ex->ee_block);
 		cur_len = ext4_ext_get_actual_len(ex);

Re: [PATCH 6.6.y] ext4: get rid of ppath in get_ext_path()

[Yoann Congal]

On Thu Jul 2, 2026 at 5:48 PM CEST, Yoann Congal wrote:
> From: Baokun Li <libaokun1@huawei.com>
>
> [ Upstream commit 6b854d552711aa33f59eda334e6d94a00d8825bb ]
>
> The use of path and ppath is now very confusing, so to make the code more
> readable, pass path between functions uniformly, and get rid of ppath.
>
> After getting rid of ppath in get_ext_path(), its caller may pass an error
> pointer to ext4_free_ext_path(), so it needs to teach ext4_free_ext_path()
> and ext4_ext_drop_refs() to skip the error pointer. No functional changes.
>
> Signed-off-by: Baokun Li <libaokun1@huawei.com>
> Reviewed-by: Jan Kara <jack@suse.cz>
> Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
> Tested-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
> Link: https://patch.msgid.link/20240822023545.1994557-13-libaokun@huaweicloud.com
> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
>
> Signed-off-by: Yoann Congal <yoann.congal@smile.fr>
> ---

Hello,

I missed it at first but a discussion about the same issue is happening
here:
https://lore.kernel.org/all/tencent_C982B0201FE8F041BD5B4FC1ED7D646A740A@qq.com/
But the above is a partial backport whereas mine is the full backport.

Regards,
-- 
Yoann Congal
Smile ECS

Re: [PATCH 6.6.y] ext4: get rid of ppath in get_ext_path()

[Sasha Levin]

On Thu, Jul 02, 2026 at 05:48:10PM +0200, Yoann Congal wrote:
> From: Baokun Li <libaokun1@huawei.com>
>
> [ Upstream commit 6b854d552711aa33f59eda334e6d94a00d8825bb ]
>
> The use of path and ppath is now very confusing, so to make the code more
> readable, pass path between functions uniformly, and get rid of ppath.
>
> After getting rid of ppath in get_ext_path(), its caller may pass an error
> pointer to ext4_free_ext_path(), so it needs to teach ext4_free_ext_path()
> and ext4_ext_drop_refs() to skip the error pointer. No functional changes.

Queued for 6.6.y, thanks!

-- 
Thanks,
Sasha