mksnap_ffs.8: update /home examples

The default location for home directories is moving from /usr/home
to /home. Update the examples accordingly.

Reviewed by: emaste
Differential Revision: https://reviews.freebsd.org/D40205

FFS/UFS snapshots: improve documentation for removal (deletion) and unlinking.

Clarification of the size of the snapshot file.

Suggested by: Matteo Riondato
PR: 266358
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D38817

FFS/UFS snapshots: improve documentation for removal (deletion) and unlinking.

Minor clarification.

FFS/UFS snapshots: improve documentation.

This update provides a more detailed description of FFS/UFS snapshots
and adds links to useful man pages.

Requested by: Graham Perrin
Submitted by: darius-dons.net.au
Reviewed by: Ravi Pokala
PR: 266358
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D38817

mksnap_ffs appeared in FreeBSD 5.1.

PR: 212510
Approved by: bcr (mentor)
MFC after: 4 days
Differential Revision: https://reviews.freebsd.org/D8105

Note that a UFS filesystem can have up to 20 active snapshots.

PR: docs/151104
Submitted by: Aldis Berjoza <aldis@bsdroot.lv>
MFC after: 3 days

A new jail(8) with a configuration file, to replace the work currently done
by /etc/rc.d/jail.

mdoc: move CAVEATS, BUGS and SECURITY CONSIDERATIONS sections to the
bottom of the manpages and order them consistently.

GNU groff doesn't care about the ordering, and doesn't even mention
CAVEATS and SECURITY CONSIDERATIONS as common sections and where to put
them.

Found by: mdocml lint run
Reviewed by: ru

Create the altix project branch. The altix project will add support
for the SGI Altix 350 to FreeBSD/ia64. The hardware used for porting
is a two-module system, consisting of a base compute module and a
CPU expansion module. SGI's NUMAFlex architecture can be an excellent
platform to test CPU affinity and NUMA-aware features in FreeBSD.

MFC: r197275

Fix an xref.

Approved by: re (kib)

Fix an xref.

PR: 138833
Submitted by: Alex Keda <admin@lissyara.su>
MFC after: 3 days

- Move from mount(2) to nmount(2). This should allow to convert MNT_SNAPSHOT
flag from a mount flag to FS-specific flag.
- Simplify usage. Instead of 'mksnap_ffs /mnt/foo /mnt/foo/snap' allow to
give only one argument: 'mksnap_ffs /mnt/foo/snap'. Old usage is also
accepted for now.
- Add an example of how to mount a snapshot.

- Import the HEAD csup code which is the basis for the cvsmode work.

Note that snapshots may cause a panic on the full UFS filesystem.

Submitted by: pho
MFC after: 3 days

Replace a reference to non existant mount_ffs(8) by a reference to mount(8).

mdoc(7) fixes.

Approved by: re (blanket)

Add the mksnap_ffs command to the sbin directory. This setuid root
program allows users in the operator group to take filesystem
snapshots. Its first use will be in support of `dump -L'.

Approved by: Technical Review Board <trb@FreeBSD.org>
Sponsored by: DARPA & NAI Labs.