Not all filesystems now provide the rename i_op - ext4 for one - but rather
provide the rename2 i_op. CacheFiles checks that the filesystem has rename
and so will reject ext4 now with EPERM:
CacheFiles: Failed to register: -1
Fix this by checking for rename2 as an alternative. The call to vfs_rename()
actually handles selection of the appropriate function, so we needn't worry
about that.
Turning on debugging shows:
[cachef] ==> cachefiles_get_directory(,,cache)
[cachef] subdir -> ffff88000b22b778 positive
[cachef] <== cachefiles_get_directory() = -1 [check]
where -1 is EPERM.
Signed-off-by: David Howells <dhowells@redhat.com>