[PATCH 4/6] kernfs: update kernfs_rename_ns() to consider KERNFS_STATIC_NAME

[Tejun Heo <tj@kernel.org>]

kernfs_rename_ns() currently assumes that the target sysfs_dirent has
a copied name.  This has been okay because sysfs supports rename only
for directories which always have copied names; however, there's
nothing in kernfs interface which calls for such restriction and
currently invoking kernfs_rename_ns() on a regular file leads to oops
because it ends up trying to kfree() a static name.

This patch updates kernfs_rename_ns() so that it skips kfree() of the
old name if it's static.  This allows it to be used for all node
types.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/kernfs/dir.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index e168177..d33af95 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -886,7 +886,11 @@ int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent,
 		if (!new_name)
 			goto out;
 
-		kfree(kn->name);
+		if (kn->flags & KERNFS_STATIC_NAME)
+			kn->flags &= ~KERNFS_STATIC_NAME;
+		else
+			kfree(kn->name);
+
 		kn->name = new_name;
 	}
 
-- 
1.8.4.2