[ Upstream commit1f0fc3374f] Give an afs_server object a ref on the afs_cell object it points to so that the cell doesn't get deleted before the server record. Whilst this is circular (cell -> vol -> server_list -> server -> cell), the ref only pins the memory, not the lifetime as that's controlled by the activity counter. When the volume's activity counter reaches 0, it detaches from the cell and discards its server list; when a cell's activity counter reaches 0, it discards its root volume. At that point, the circularity is cut. Fixes:d2ddc776a4("afs: Overhaul volume and server record caching and fileserver rotation") Signed-off-by: David Howells <dhowells@redhat.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: Simon Horman <horms@kernel.org> cc: linux-afs@lists.infradead.org Link: https://patch.msgid.link/20250218192250.296870-6-dhowells@redhat.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>