Manual Pages  — G_CONSUMER

g_new_consumer, g_destroy_consumer – GEOM consumers management

SYNOPSIS DESCRIPTION RESTRICTIONS/CONDITIONS RETURN VALUES EXAMPLES SEE ALSO AUTHORS

#include <geom/geom.h>

struct g_consumer *
g_new_consumer(struct g_geom *gp);

void
g_destroy_consumer(struct g_consumer *cp);

g_new_consumer():

	The geom gp has to have an orphan method defined.
	The topology lock has to be held.

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.

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

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);
}

This manual page was written by Pawel Jakub Dawidek <Mt pjd@FreeBSD.org>.