g_geom (9)
Leading comments
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 d...
NAME
g_new_geomf g_destroy_geom - geom managementSYNOPSIS
In geom/geom.h Ft struct g_geom * Fn g_new_geomf struct g_class *mp const char *fmt ... Ft void Fn g_destroy_geom struct g_geom *gpDESCRIPTION
The geom (do not confuse ``geom'' with ``GEOM'' is an instance of a GEOM class. For example: in a typical i386 Fx system, there will be one geom of class MBR for each disk. The geom's name is not really important, it is only used in the XML dump and for debugging purposes. There can be many geoms with the same name.The Fn g_new_geomf function creates a new geom, which will be an instance of the class Fa mp . The geom's name is created in a printf(3) -like way from the rest of the arguments.
The Fn g_destroy_geom function destroys the given geom immediately and cancels all related pending events.
The Vt g_geom structure contains fields that should be set by the caller after geom creation, but before creating any providers or consumers related to this geom (not all are required):
- Vt g_start_t * start
- Pointer to a function used for I/O processing.
- Vt g_spoiled_t * spoiled
- Pointer to a function used for consumers spoiling.
- Vt g_dumpconf_t * dumpconf
- Pointer to a function used for configuration in XML format dumping.
- Vt g_access_t * access
- Pointer to a function used for access control.
- Vt g_orphan_t * orphan
- Pointer to a function used to inform about orphaned consumer.
- Vt g_ioctl_t * ioctl
- Pointer to a function used for handling ioctl requests.
- Vt void * softc
- Field for private use.
RESTRICTIONS/CONDITIONS
If you intend to use providers in this geom you must set field start of your geom.If you are planning to use consumers in your geom you must set fields orphan and access for it.
Fn g_new_geomf :
- Class
- Fa mp must be valid (registered in GEOM).
- The topology lock has to be held.
Fn g_destroy_geom :
- The geom cannot possess any providers.
- The geom cannot possess any consumers.
- The topology lock has to be held.
RETURN VALUES
The Fn g_new_geomf function returns a pointer to the newly created geom.EXAMPLES
Create an example geom.
static struct geom *
g_example_start(struct bio *bp)
{
[...]
}
static void
g_example_orphan(struct g_consumer *cp)
{
g_topology_assert();
[...]
}
static void
g_example_spoiled(struct g_consumer *cp)
{
g_topology_assert();
[...]
}
static void
g_example_access(struct g_provider *pp, int dr, int dw, int de)
{
[...]
}
static struct g_geom *
create_example_geom(struct g_class *myclass)
{
struct g_geom *gp;
g_topology_lock();
gp = g_new_geomf(myclass, "example_geom");
g_topology_unlock();
gp->start = g_example_start;
gp->orphan = g_example_orphan;
gp->spoiled = g_example_spoiled;
gp->access = g_example_access;
gp->softc = NULL;
return (gp);
}
static int
destroy_example_geom(struct g_geom *gp)
{
g_topology_lock();
if (!LIST_EMPTY(&gp->provider) ||
!LIST_EMPTY(&gp->consumer)) {
g_topology_unlock();
return (EBUSY);
}
g_destroy_geom(gp);
g_topology_unlock();
return (0);
}