vnode_pager_purge_range
invalidates the cached content within the given byte range from the
specified vnode
vp.
The range to be purged is
[
start,
,,
end
).
If the
end
parameter is the value zero, the affected range starts from
start
continues to the end of the object.
Pages within the specified range will be removed from the object's queue.
If
start
or
end
is not aligned to a page boundary, the invalidated part of the page is zeroed.
This function only cleans the resident pages in the affected region, it is up to
the callers to ensure reading the backing store gets back zeroes.
In case the vnode
vp
does not have a VM object allocated, the effect of calling this function is a
no-op.
