Initial bcachefs pull request for 6.7-rc1

Here's the bcachefs filesystem pull request.

One new patch since last week: the exportfs constants ended up
conflicting with other filesystems that are also getting added to the
global enum, so switched to new constants picked by Amir.

I'll also be sending another pull request later on in the cycle bringing
things up to date my master branch that people are currently running;
that will be restricted to fs/bcachefs/, naturally.

Testing - fstests as well as the bcachefs specific tests in ktest:
  https://evilpiepirate.org/~testdashboard/ci?branch=bcachefs-for-upstream

It's also been soaking in linux-next, which resulted in a whole bunch of
smatch complaints and fixes and a patch or two from Kees.

The only new non fs/bcachefs/ patch is the objtool patch that adds
bcachefs functions to the list of noreturns. The patch that exports
osq_lock() has been dropped for now, per Ingo.

Prereq patch list:

faf1dce85275 objtool: Add bcachefs noreturns
73badee4280c lib/generic-radix-tree.c: Add peek_prev()
9492261ff246 lib/generic-radix-tree.c: Don't overflow in peek()
0fb5d567f573 MAINTAINERS: Add entry for generic-radix-tree
b414e8ecd498 closures: Add a missing include
48b7935722b8 closures: closure_nr_remaining()
ced58fc7ab9f closures: closure_wait_event()
bd0d22e41ecb MAINTAINERS: Add entry for closures
8c8d2d9670e8 bcache: move closures to lib/
957e48087dfa locking: export contention tracepoints for bcachefs six locks
21db931445d8 lib: Export errname
83feeb195592 lib/string_helpers: string_get_size() now returns characters wrote
7d672f40941a stacktrace: Export stack_trace_save_tsk
771eb4fe8b42 fs: factor out d_mark_tmpfile()
2b69987be575 sched: Add task_struct->faults_disabled_mapping