MFp4: Fix two bugs causing possible deadlocks or panics, and one nit:

- Emulate lock draining (LK_DRAIN) in null_lock() to avoid deadlocks
  when the vnode is being recycled.
- Don't allow null_nodeget() to return a nullfs vnode from the wrong
  mount when multiple nullfs's are mounted. It's unclear why these checks
  were removed in null_subr.c 1.35, but they are definitely necessary.
  Without the checks, trying to unmount a nullfs mount will erroneously
  return EBUSY, and forcibly unmounting with -f will cause a panic.
- Bump LOG2_SIZEVNODE up to 8, since vnodes are >256 bytes now. The old
  value (7) didn't cause any problems, but made the hash algorithm
  suboptimal.

These changes fix nullfs enough that a parallel buildworld succeeds.

Submitted by:	tegge (partially; LK_DRAIN)
Tested by:	kris

0 files changed, 0 insertions, 0 deletions