In all cases where the function (or cg_is_empty_recursive()) ignoring
the calling process is actually wrong, as a process keeps a cgroup busy
regardless if its the current one or another. Hence, let's simplify
things and drop the "ignore_self" parameter.
Merge write_string_file(), write_string_file_no_create() and
write_string_file_atomic() into write_string_file() and provide a flags mask
that allows combinations of atomic writing, newline appending and automatic
file creation. Change all users accordingly.
We allow to specify a callback but then ignore the result. Looks like a trivial typo.
From 7b3fd6313c4b07b6f822a9f979d0c22350a401d9#diff-f010fa21ba7b659b519c122743e55604
Lennart Poettering