Fix minor spelling error in a comment.
Rewrite the vfs_bio_clrbuf(9) to not access the b_data for B_VMIO
buffers directly, use pmap_zero_page_area(9) for each zeroing page
region instead.

Sponsored by:	The FreeBSD Foundation
Tested by:	pho
MFC after:	2 weeks
Remove excessive and inconsistent initializers for the various kernel
maps and submaps.

MFC after:	2 weeks
Sort sections.
Correct type for DIOCGSTRIPESIZE.  Without this there
would be a stack overflow which will crash the program
later.

PR:		bin/176953
Submitted by:	r4721 tormail org
MFC after:	3 days
Add pmap function pmap_copy_pages(), which copies the content of the
pages around, taking array of vm_page_t both for source and
destination.  Starting offsets and total transfer size are specified.

The function implements optimal algorithm for copying using the
platform-specific optimizations.  For instance, on the architectures
were the direct map is available, no transient mappings are created,
for i386 the per-cpu ephemeral page frame is used.  The code was
typically borrowed from the pmap_copy_page() for the same
architecture.

Only i386/amd64, powerpc aim and arm/arm-v6 implementations were
tested at the time of commit. High-level code, not committed yet to
the tree, ensures that the use of the function is only allowed after
explicit enablement.

For sparc64, the existing code has known issues and a stab is added
instead, to allow the kernel linking.

Sponsored by:	The FreeBSD Foundation
Tested by:	pho (i386, amd64), scottl (amd64), ian (arm and arm-v6)
MFC after:	2 weeks
When pidptr was passed as NULL to pidfile_open(3), we were returning
EAGAIN/EWOULDBLOCK when another daemon was running and had the pidfile open.
We should return EEXIST in that case, fix it.

Reported by:	Dirk Engling <erdgeist@erdgeist.org>
Reviewed by:	jhb, Dirk Engling <erdgeist@erdgeist.org>
MFC after:	1 week