Added first part of GEOM kernel API manuals pages.

Documented function and macros are:
	- DECLARE_GEOM_CLASS(),
	- g_attach(),
	- g_detach(),
	- g_new_bio(),
	- g_clone_bio(),
	- g_destroy_bio(),
	- g_new_consumer(),
	- g_destroy_consumer(),
	- g_read_data(),
	- g_write_data(),
	- g_post_event(),
	- g_waitfor_event(),
	- g_cancel_event(),
	- g_new_geomf(),
	- g_destroy_geom(),
	- g_new_providerf(),
	- g_destroy_provider(),
	- g_error_provider(),
	- g_provider_by_name(),
	- g_wither_geom().
and more to come.

I want to thanks following people for help with those documents:
	Slawek Zak <zaks@prioris.mini.pw.edu.pl>
	Simon L. Nielsen <simon@FreeBSD.org>
	Pieter de Boer <g.p.de.boer@st.hanze.nl>
and of course
	Poul-Henning Kamp <phk@FreeBSD.org>

Reviewed by:	phk, scottl
Approved by:	phk, scottl (mentor)

1 files changed, 144 insertions, 0 deletions

diff --git a/share/man/man9/g_provider.9 b/share/man/man9/g_provider.9
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+.\"
+.\" Copyright (c) 2004 Pawel Jakub Dawidek <pjd@FreeBSD.org>
+.\" All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR
+.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT,
+.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+.\"
+.\" $FreeBSD$
+.\"
+.Dd January 16, 2004
+.Dt g_provider 9
+.Os
+.Sh NAME
+.Nm g_new_providerf ,
+.Nm g_destroy_provider ,
+.Nm g_error_provider
+.Nd "GEOM providers management"
+.Sh SYNOPSIS
+.In geom/geom.h
+.Ft "struct g_provider *"
+.Fn g_new_providerf "struct g_geom *gp" "const char *fmt" ...
+.Ft void
+.Fn g_destroy_provider "struct g_provider *pp"
+.Ft void
+.Fn g_error_provider "struct g_provider *pp" "int error"
+.Sh DESCRIPTION
+The GEOM provider is the front gate at which a geom offers service.
+A provider is
+.Dq a disk\-like thing which appears in Pa /dev
+\- a logical disk in other words.
+All providers have three main properties: name, sectorsize and size.
+.Pp
+The
+.Fn g_new_providerf
+function creates a new provider and attaches it to geom
+.Fa gp .
+The provider name is created in a printf\-like way from the rest of
+the arguments.
+After creation, the provider is unusable, because
+.Fn g_new_providerf
+sets its error to
+.Er ENXIO .
+The function
+.Fn g_error_provider
+should be used to reset this error, but before it is called, two
+fields should be set in the provider structure:
+.Va mediasize
+and
+.Va sectorsize
+as well as other initialization things should be done first.
+.Pp
+The
+.Fn g_destroy_provider
+function destroys the given provider, cancels all related pending events and
+removes corresponding devfs entry.
+.Pp
+The
+.Fn g_error_provider
+function is used to set a provider error value.
+If it set to a nonzero value, all I/O requests will be denied,
+increasing its access count will not be possible (error
+.Fa error
+will be returned).
+.Sh RESTRICTIONS/CONDITIONS
+.Fn g_new_provider :
+.Bl -item -offset indent
+.It
+The provider name should be unique, but this is not enforced by GEOM.
+If the name is not unique, one will end up with two (or more) files
+with the same name, which is programmer error.
+.It
+The geom related to the created provider must have
+.Fa start
+field defined.
+.It
+The topology lock has to be held.
+.El
+.Pp
+.Fn g_destroy_provider :
+.Bl -item -offset indent
+.It
+No consumers have to be attached.
+.It
+The access count has to be 0.
+.It
+The topology lock has to be held.
+.El
+.Sh RETURN VALUES
+.Fn g_new_providerf
+returns a pointer to the newly created provider or
+.Dv NULL
+if an error occured.
+.Sh EXAMPLES
+Create an example provider, set its parameters and make it usable.
+.Bd -literal -offset indent
+struct g_provider *
+create_example_provider(struct g_geom *gp)
+{
+	struct g_provider *pp;
+
+	g_topology_lock();
+	pp = g_new_providerf(gp, "example_provider");
+	g_topology_unlock();
+	if (pp != NULL) {
+		pp->mediasize = 65536;
+		pp->sectorsize = 512;
+		g_error_provider(pp, 0);
+	}
+
+	return (pp);
+}
+.Ed
+.Sh SEE ALSO
+.Xr DECLARE_GEOM_CLASS 9 ,
+.Xr geom 4 ,
+.Xr g_attach 9 ,
+.Xr g_bio 9 ,
+.Xr g_consumer 9 ,
+.Xr g_data 9 ,
+.Xr g_event 9 ,
+.Xr g_geom 9 ,
+.Xr g_provider_by_name 9 ,
+.Xr g_wither_geom 9
+.Sh AUTHORS
+.An -nosplit
+This manual page was written by
+.An Pawel Jakub Dawidek Aq pjd@FreeBSD.org .