[PATCH] fs/ntfs3: fix syncing wrong inode on DIRSYNC cross-directory rename

[Zhan Xusheng]

In ntfs3_rename(), when IS_DIRSYNC(new_dir) is true, the code syncs
the renamed file inode instead of the target directory new_dir:
    if (IS_DIRSYNC(new_dir))
        ntfs_sync_inode(inode);      /* should be new_dir */

DIRSYNC requires that directory metadata changes are written to disk
synchronously.  Since new_dir was modified (a new directory entry was
added), it is new_dir that must be synced to satisfy the guarantee,
not the renamed file itself.

This bug has existed since the initial ntfs3 implementation and was
carried through the refactoring in commit 78ab59fee07f
("fs/ntfs3: Rework file operations").

Fix by syncing new_dir instead of inode.

Fixes: 4342306f0f0d ("fs/ntfs3: Add file operations and implementation")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Zhan Xusheng <zhanxusheng@xxxxxxxxxx>
---
v2:
 - Cc ntfs3@xxxxxxxxxxxxxxx (was missing in v1, see
   https://lore.kernel.org/all/20260422152010.205694-1-zhanxusheng@xxxxxxxxxx/).
 - Add Cc: stable@xxxxxxxxxxxxxxx; this is a data-persistence bug under
   DIRSYNC and affects all ntfs3 since 4342306f0f0d.
v1: https://lore.kernel.org/all/20260422152010.205694-1-zhanxusheng@xxxxxxxxxx/
---
 fs/ntfs3/namei.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/ntfs3/namei.c b/fs/ntfs3/namei.c
index b2af8f695e60..64cde1a856f4 100644
--- a/fs/ntfs3/namei.c
+++ b/fs/ntfs3/namei.c
@@ -340,7 +340,7 @@ static int ntfs_rename(struct mnt_idmap *idmap, struct inode *dir,
 			ntfs_sync_inode(dir);
 
 		if (IS_DIRSYNC(new_dir))
-			ntfs_sync_inode(inode);
+			ntfs_sync_inode(new_dir);
 	}
 
 	if (dir_ni != new_dir_ni)
-- 
2.43.0