SYNOPSIS

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 *gp

DESCRIPTION

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);
}

AUTHORS

An -nosplit This manual page was written by An Pawel Jakub Dawidek Aq [email protected] .