have to reacquire lock before continuing

delete read-only checking; it must be done by the filesystem layers

merge vfs_lock and vfs_busy; interlock mount points properly

convert VOP_UNLOCK and vrele into vput's; add proc parameter to union_dircache

convert VOP_LOCK to vn_lock; add parameters to VOP_UNLOCK

don't call VFS_SYNC for read-only filesystems

disallow unmount of root fs

change mountlist to CIRCLEQ so we can do unmountall (from mycroft)

mount now takes a name rather than a number, vfssw => vfsconf

lstat returns inode number of symbolic link to match directory entry

reverse arguments to VOP_LINK (to get them right)

allow revoke on any file; vgoneall => VOP_REVOKE

new argument passing conventions. minor type size cleanup.

fix readdir for non-linear union stacks

check (and fix) mounted-on current directories

get rid of usecount mount restriction (needed for union mounts)

return EBUSY if reference count on mount point is greater than 1 to
avoid problems in lookup from programs referencing the hidden vnode

unwhiteout => undelete to be more general

fix olstat to give the correct symlink info

clean up error case

have to recompute the next pointer after possibly sleeping in sync
(from mycroft)

LEASE_CHECK => VOP_LEASE

changes for whiteouts and union filesystem

first pass at allowing user mounts/unmounts

add unwhiteout system call to delete a whiteout entry