K 10
svn:author
V 7
glebius
K 8
svn:date
V 27
2020-02-25T19:29:05.987219Z
K 7
svn:log
V 707
Generalize resources freeing in sendfile with different scenarios.
Now we execute sendfile_iodone() in all possible cases, which
guarantees that vm_object_pip_wakeup() is called and sfio structure
is freed.

At the beginning of sendfile initialize sfio->m to NULL, that would
indicate that the mbuf chain either doesn't exist, or belongs to the
syscall (not to I/O completion).  Fill sfio->m only at a point when
we are positive that there are I/Os ongoing and before releasing
syscall's reference on sfio.

In sendfile_iodone() perform vm_object_pip_wakeup() once last
reference is released, then check for sfio->m.  NULL pointer
indicates that we need only to free the memory.

Reviewed by:	jtl, gallatin

END