SYNOPSIS

In geom/geom.h Ft struct g_consumer * Fn g_new_consumer struct g_geom *gp Ft void Fn g_destroy_consumer struct g_consumer *cp

DESCRIPTION

A GEOM consumer is the backdoor through which a geom connects to another GEOM provider and through which I/O requests are sent.

The Fn g_new_consumer function creates a new consumer on geom Fa gp . Before using the new consumer, it has to be attached to a provider with g_attach9 and opened with g_access9.

The Fn g_destroy_consumer function destroys the given consumer and cancels all related pending events. This function is the last stage of killing an unwanted consumer.

RESTRICTIONS/CONDITIONS

Fn g_new_consumer :

The geom

Fa gp has to have an orphan method defined.

The topology lock has to be held.

Fn g_destroy_consumer :

The consumer must not be attached to a provider.

The access count has to be 0.

The topology lock has to be held.

RETURN VALUES

The Fn g_new_consumer function returns a pointer to the newly created consumer.

EXAMPLES

Create consumer, attach it to given provider, gain read access and clean up.

void
some_function(struct g_geom *mygeom, struct g_provider *pp)
{
        struct g_consumer *cp;
        g_topology_assert();
        /* Create new consumer on 'mygeom' geom. */
        cp = g_new_consumer(mygeom);
        /* Attach newly created consumer to given provider. */
        if (g_attach(cp, pp) != 0) {
                g_destroy_consumer(cp);
                return;
        }
        /* Open provider for reading through our consumer. */
        if (g_access(cp, 1, 0, 0) != 0) {
                g_detach(cp);
                g_destroy_consumer(cp);
                return;
        }
        g_topology_unlock();
        /*
         * Read data from provider.
         */
        g_topology_lock();
        /* Disconnect from provider (release access count). */
        g_access(cp, -1, 0, 0);
        /* Detach from provider. */
        g_detach(cp);
        /* Destroy consumer. */
        g_destroy_consumer(cp);
}

AUTHORS

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