- Reference count the mfsnode to fix an aincent bug. Only destroy when
reference count drops to zero. In mfs_start(), busy the mount and get
a reference to the mfsnode to prevent it disappearing while the server
is running. If the file system is gone already, vfs_busy() will fail.
- Always destroy the bufq.
- Use a global mfs_lock for simplicity.
- Replace use of malloc/free. Fixes broken MALLOC_TYPE change.
- rather than embedding bufq_state in driver softc,
have a pointer to the former.
- move bufq related functions from kern/subr_disk.c to kern/subr_bufq.c.
- rename method to strategy for consistency.
- move some definitions which don't need to be exposed to the rest of kernel
from sys/bufq.h to sys/bufq_impl.h.
(is it better to move it to kern/ or somewhere?)
- fix some obvious breakage in dev/qbus/ts.c. (not tested)
queueing up buffers and awakening the MFS server process to do the I/O,
we do the I/O to the server process's address space directly using
facilities provided by UVM.
This makes it possible for buffers attempting to flush out while the
MFS is being unmounted to actually do the I/O, where before it would
fail if the server process wasn't in the MFS idle loop (i.e. had been
signaled and was attempting to exit).
Should fix kern/10122 (I can no longer reproduce the problem described
in the PR when running with these changes), and any number of other
MFS-related complaints made by people over time.
ad