Update comments and code since aio daemons are kprocs, not kthreads.

[jhb]

Summary

AIO daemons have always been kernel processes to facilitate switching to
user VM spaces while servicing jobs. Update various comments and data
structures that refer to AIO daemons as threads to refer to processes
instead.

Ironically, aiothreadlist used to be aioproclist before it was misnamed
to aiothreadlist when threads were added to the kernel. I don't like
the 'foolist' name that the AIO code uses for objects that are list
members ('foolist' should be a list head, not a list member IMO), so I'm
using this opportunity to drop the 'list' suffix as well. I might do a
pass to rename aiocblist to something less rediculous as well, perhaps
before the rework since it is smaller and more contained right now.

Test Plan

• Run the aio tests.

[kib]

sys/kern/vfs_aio.c

133 ↗

(On Diff #12485)

Change indent to 4 spaces, as it is done in other places even in vfs_aio.c ?

498 ↗

(On Diff #12485)

Side question, why these zones are NOFREE ?

1800 ↗

(On Diff #12485)

Remove extra () while you are there ?

1820 ↗

(On Diff #12485)

And there too.

[jhb]

Mmm, I might do a separate whitespace / style sweep removing extra parens. I think this is the last "cleanup" patch in my changes so far, so this would be a good time as any to do it.

sys/kern/vfs_aio.c

133 ↗

(On Diff #12485)

Hmm, I'd have to change the line above which would then be mixing in a pure whitespace
change. I could do a followup change to fix the whitespace though.

498 ↗

(On Diff #12485)

It looks like Jeff set NOFREE when converting this over from the old zone allocator. The old zone allocator never reclaimed memory, so Jeff may have done that as a general rule when converting away from zinit().

I'm pretty sure that most of these zones do not need to be NOFREE. The only one I'm possibly unsure of is the kaio_zone.