Rather than using lock_rename(), use the more obvious is_subdir() for
ensuring that neither upper nor workdir contain the other.
Also be explicit in the comment that the two directories cannot be the
same.
Signed-off-by: NeilBrown <neil@xxxxxxxxxx>
---
fs/overlayfs/super.c | 14 ++++----------
1 file changed, 4 insertions(+), 10 deletions(-)
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index cf99b276fdfb..db046b0d6a68 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -438,18 +438,12 @@ static int ovl_lower_dir(const char *name, struct path *path,
return 0;
}
-/* Workdir should not be subdir of upperdir and vice versa */
+/* Workdir should not be subdir of upperdir and vice versa, and
+ * they should not be the same.
+ */
static bool ovl_workdir_ok(struct dentry *workdir, struct dentry *upperdir)
{
- bool ok = false;
-
- if (workdir != upperdir) {
- struct dentry *trap = lock_rename(workdir, upperdir);
- if (!IS_ERR(trap))
- unlock_rename(workdir, upperdir);
- ok = (trap == NULL);
- }
- return ok;
+ return !is_subdir(workdir, upperdir) && !is_subdir(upperdir, workdir);
}
static int ovl_setup_trap(struct super_block *sb, struct dentry *dir,
--
2.49.0
