Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFC r268238:

Add an option, -p, which makes gstat(8) to only display physical providers
(those with rank of 1).

MFC r266320:
Add -o option to gstat to display "other" operatins (e.g. BIO_FLUSH).

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

o Turn the batch mode on if stdout is not tty.

Submitted by: vsevolod
MFC after: 1 week

- Allow gstat to print values to different kind of outputs.
- Introduce batch mode, where gstat will collect the numbers, print them, and
exit.
- Document batch mode in the gstat man page.

Submitted by: anders

When the ms/req fields exceed 1 second, drop the fractions to fit more digits.

This is unfortunately necessary with some flash based devices which can
get hundreds of seconds behind with softupdates enabled.

Deterministically set the default refresh interval to one second.

Approved by: phk
MFC after: 1 week

- Add support for filtering the the list of providers by a regular
expression, which makes it possible to only see interesting
providers. "f" is used inside gstat to set a filter, "F" is used to
remove current filter.
- Do not print some uninteresting values in the gstat title line.
- Do not print past the end of the screen.
- Read multiple keystrokes per "wait" when gstat is running.
- Remove a redundant != check, right after check of NULL against the
same variable ("gid").
- Use sysexits.h.
- Do not link against libkvm and libsbuf, they are not actually used.
- Fix a few style(9) issues where I had to touch nearby code anyway.

Approved by: cperciva (mentor)
MFC after: 2 weeks

Add forgotten -a to the usage() message.

Add an '-a' switch to only display providers that are at least
0.1% busy.

OK'ed by: phk

Added forgotten -d to the usage().

Remove spurious semicolons. Outside of functions they are actually errors but
GCC doesn't warn about them without -pedantic.

Approved by: das (mentor)
PR: 56649
Reviewed by: md5

Correct a typo in column header.

Submitted by: phk
Obtained from: BSDCan

Make libgeom usable by C++ programs:
- Add DECL wrappers to libgeom.h.
- Rename structure members in libgeom.h to use a lg_ prefix for member
names. This is required because a few structures had members named
'class' which made g++ very unhappy.
- Catch gstat(8) and gconcat(8) up to these API changes.

Reviewed by: phk

Add -d flag to monitor BIO_DELETE operations too

Make -c only set flag_c and not a toggle. With flag_c disabled by
default, this makes the behavior of gstat more predictable when -c is
specified multiple times on the command line.

Add & use a usage() function.

Add error and range checking to strtoul() to avoid ending up with a
delay time of ULONG_MAX when -I is passed a non-numeric arg.

Call endwin() to restore terminal state just before exiting.

Approved by: phk

Add a rudimentary gstat(8) to the system.

This is a small curses based program which shows the diskactivity
inside GEOM.