g_wither_geom(9) [debian man page]

G_WITHER_GEOM(9)					   BSD Kernel Developer's Manual					  G_WITHER_GEOM(9)

NAME

     g_wither_geom -- destroy geom and related providers and consumers when you get a chance

SYNOPSIS

     #include <geom/geom.h>

     void
     g_wither_geom(struct g_geom *gp, int error);

DESCRIPTION

     The g_wither_geom() function tells GEOM that geom gp is to be destroyed.  GEOM sets an error on each provider of the given geom (in the
     orphaning process) and waits for a chance to destroy the geom.  If the access count of any possessed consumer goes to 0, the consumer will be
     detached and destroyed automatically.  If the last consumer attached to any possessed provider will be detached, the provider will be
     destroyed.  If there are no more providers nor consumers, the geom will be destroyed.

     This is an automatic ``garbage collect'' to avoid duplicated code in all classes.	Before it is called, field softc should be disposed off
     and set to NULL.  Note that the g_wither_geom() function gives no guarantee that the geom will be immediately destroyed, mostly because the
     access counts of the geom's consumers and providers may not be 0.	That is why calling this function for every geom from a given class is not
     enough to be sure that the class can be unloaded.

RESTRICTIONS
/CONDITIONS
     The argument error must be nonzero.

     The topology lock has to be held.

SEE ALSO

     geom(4), DECLARE_GEOM_CLASS(9), g_access(9), g_attach(9), g_bio(9), g_consumer(9), g_data(9), g_event(9), g_geom(9), g_provider(9),
     g_provider_by_name(9)

AUTHORS

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

BSD
								 January 16, 2004							       BSD

G_CONSUMER(9)						   BSD Kernel Developer's Manual					     G_CONSUMER(9)

NAME

     g_new_consumer, g_destroy_consumer -- GEOM consumers management

SYNOPSIS

     #include <geom/geom.h>

     struct g_consumer *
     g_new_consumer(struct g_geom *gp);

     void
     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 g_new_consumer() function creates a new consumer on geom gp.  Before using the new consumer, it has to be attached to a provider with
     g_attach(9) and opened with g_access(9).

     The 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
     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.

RETURN VALUES

     The 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);
	   }

SEE ALSO

     geom(4), DECLARE_GEOM_CLASS(9), g_access(9), g_attach(9), g_bio(9), g_data(9), g_event(9), g_geom(9), g_provider(9), g_provider_by_name(9),
     g_wither_geom(9)

AUTHORS

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

BSD
								 January 16, 2004							       BSD