[ Upstream commit 46c87441 ]

symlink body shouldn't be freed without an RCU delay.  Switch securityfs
to ->destroy_inode() and use of call_rcu(); free both the inode and symlink
body in the callback.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>