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