nilfs2: use common implementation of file type

nilfs2: use common implementation of file type

Patch series "nilfs2: assorted cleanups".

This is a collection of cleanup patches, with only the last three focused
on the log writer thread, the rest are miscellaneous.

Patches 1/8, 4/8, and 7/8 adopt common implementations, 2/8 uses a generic
macro, 5/8 removes dead code, 6/8 removes an unnecessary reference, and
3/8 and 8/8 each simplify a paticular messy implementation.

This patch (of 8):

Deduplicate the nilfs2 file type conversion implementation.

Link: https://lkml.kernel.org/r/20240826174116.5008-1-konishi.ryusuke@gmail.com
Link: https://lkml.kernel.org/r/20240815013442.1220909-1-huangxiaojia2@huawei.com
Link: https://lkml.kernel.org/r/20240826174116.5008-2-konishi.ryusuke@gmail.com
Signed-off-by: Huang Xiaojia <huangxiaojia2@huawei.com>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>