mm/writeback: commit reason of WB_REASON_FORKER_THREAD mismatch name

After commit 839a8e8660b6 ("writeback: replace custom worker pool
implementation with unbound workqueue"), there is no bdi forker thread
any more.  However, WB_REASON_FORKER_THREAD is still used due to it is
TPs userland visible and we won't be exposing exactly the same
information with just a different name.

Signed-off-by: Wanpeng Li <[email protected]>
Reviewed-by: Tejun Heo <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
1 file changed