aiocb's allocated by zalloc(). In other words, zfree() was never
called. Now, we call zfree(). Why eliminate this micro-
optimization? At some later point, when we multithread the AIO
system, we would need a mutex to synchronize access to aio_freejobs,
making its use nearly indistinguishable in cost from zalloc() and
zfree().
Remove unnecessary fhold() and fdrop() calls from aio_qphysio(),
undo'ing a part of revision 1.86. The reference count on the file
structure is already incremented by _aio_aqueue() before it calls
aio_qphysio(). (Update the comments to document this fact.)
Remove unnecessary casts from _aio_aqueue(), aio_read(), aio_write()
and aio_waitcomplete().
Remove an unnecessary "return;" from aio_process().
Add "static" in various places.
a27aa6e3d5