g_geom(9)

NAME

g_new_geomf, g_destroy_geom - geom management

#include <geom/geom.h>
struct g_geom *
g_new_geomf(struct g_class *mp, const char *fmt, ...);
void
g_destroy_geom(struct g_geom *gp);

The geom (do not confuse ``geom'' with ``GEOM'') is an in
stance of a GEOM class. For example: in a typical i386 FreeBSD system, there
will be one geom of class MBR for each disk. The geom's name is not re
ally important, it is only used in the XML dump and for debugging pur
poses. There can be many geoms with the same name.
The g_new_geomf() function creates a new geom, which will be
an instance of the class mp. The geom's name is created in a
printf(3)-like way from the rest of the arguments.
The g_destroy_geom() function destroys the given geom imme
diately and cancels all related pending events.
The 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):: g_start_t * start
Pointer to a function used for I/O processing.
g_spoiled_t * spoiled: Pointer to a function used for consumers; spoiling.
g_dumpconf_t * dumpconf: Pointer to a function used for configuration; in XML format
dumping.
g_access_t * access: Pointer to a function used for access control.
g_orphan_t * orphan: Pointer to a function used to inform about or; phaned consumer.
g_ioctl_t * ioctl: Pointer to a function used for handling ioctl; requests.
void * softc: Field for private use.

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.
g_new_geomf():: Class mp must be valid (registered in GEOM).; The topology lock has to be held.
g_destroy_geom():: The geom cannot posses any providers.; The geom cannot posses any consumers.; The topology lock has to be held.

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);

}